1

EMERGENCY EXEMPTION REQUEST 

(Specific Exemption) 

FOR THE USE OF THE ANTIBIOTICS 

FireWallTM 50WP Fungicide/Bactericide (streptomycin sulfate) 

FireLineTM 17WP (oxytetracycline hydrochloride) 

Mycoshield® (oxytetracycline calcium) 

TO SUPPRESS 

Huanglongbing (HLB) (Candidatus Liberibacter asiaticus) 

and IMPROVE TREE HEALTH 

ON 

Citrus 

IN FLORIDA 

December 2, 2015 
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TABLE OF CONTENTS 

CONTACT PERSON(S) AND QUALIFIED EXPERTS (166.20(a)(1)) .................... 3 

DESCRIPTION OF PESTICIDE REQUESTED (166.20(a)(2)) .............................. 3 

DESCRIPTION OF PROPOSED USE (166.20(a)(3)) ........................................... 4 

ALTERNATIVE METHODS OF CONTROL (166.20(a)(4)) .................................. 12 

EFFICACY OF USE PROPOSED UNDER SECTION 18 (166.20(a)(5))............... 17 

DISCUSSION OF RESIDUES IN FOOD (166.20(a)(6)) .................................... 23 

DISCUSSION OF RISK INFORMATION (166.20(a)(7)) ................................... 25 

FQPA INFORMATION (OCTOBER 24, 1996 EPA LETTER) ................................. 31 

COORDINATION WITH OTHER AFFECTED FEDERAL, STATE, AND LOCAL 

AGENCIES (166.20(a)(8) ................................................................................. 31 

NOTIFICATION OF REGISTRANT (166.20(a)(9))............................................ 31 

DESCRIPTION OF ENFORCEMENT PROGRAM (166.20(a)(10)) ...................... 32 

REPEAT USES (166.20(a)(11)) ........................................................................ 32 

PROGRESS TOWARD REGISTRATION (166.20(b)(2)(ii)) ............................... 32 

NAME OF PEST (166.20(b)(1)) ........................................................................ 33 

DISCUSSION OF THE EMERGENCY CONDITION (166.20(b)(2)).................... 33 

DISCUSSION OF ECONOMIC LOSS (166.20(b)(4)) ......................................... 38 

ESTIMATED REVENUES FOR THE SITE TO BE TREATED 

(166.20(B)(4) ii & iii) ........................................................................................ 52 

 
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CONTACT PERSON(S) AND QUALIFIED EXPERTS(S) (166.20(a)(1)) 

(i) The Contact Person for matters relating to the administration of this 

exemption: 

 

Daniel A. Botts/Michael J. Aerts Charlie Clark, Environmental Admin. 

Florida Fruit & Vegetable Association FL Dept. of Ag and Consumer Services 

800 Trafalgar Ct.; Suite 200 Pesticide Registration Section 

 Post Office Box 948153 3125 Conner Blvd. (Bldg. 6) 

Maitland, FL 32794-8153 Tallahassee, FL 32399-1650 

 Phone: (321) 214-5200 Phone: (850) 617-7940 

Fax: (321) 214-0210 Fax: (850) 617-7949 

daniel.botts@ffva.com charlie.clark@freshfromflorida.com

mike.aerts@ffva.com 

(ii) The contact people for matters relating to the technical aspects of this 

exemption: 

For Florida, it has been agreed that questions relating to technical aspects in the 

field for this emergency exemption petition will work through the Florida 

Department of Agriculture and Consumer Services and the Emergency Response 

Team within EPA’s OPP. 

For other technical aspects related to this petition, the contact is: 

Agrosource: Nufarm: 

Mark Trimmer Bill Bewlay 

Director; R&D Director, Business Development 

AgroSource, Inc. Nufarm Americas, Inc. 

9889 Wilkinson Road 4020 Aerial Center Parkway, Suite 101 

Mazomanie, WI 53560 Morrisville, NC 27560 

Mobile: 608-628-2654 (919) 379-2506 

Mark@TrimmerConsulting.com bill.bewlay@us.nufarm.com 

 

DESCRIPTION OF PESTICIDE REQUESTED (166.20(a)(2)) 

a. Common Chemical Names (Active Ingredients):

Streptomycin Sulfate, Oxytetracycline Hydrochloride and Oxytetracycline 

Calcium 
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Trade Names and EPA Registration Numbers:

 FireWallTM 50WP Fungicide/Bactericide 

 EPA Registration Number: 80990-4 

 FireLineTM 17WP Fungicide/Bactericide 

 EPA Registration Number: 80990-1 

 Mycoshield®

 EPA Registration Number: 55146-97 

 Formulation:

All products are Wettable Powders 

Percent Active Ingredient:

FireWallTM 50WP: 65.8% Streptomycin Sulfate (equivalent to 50% 

streptomycin) 

FireLineTM 17WP: 18.3% Oxytetracycline Hydrochloride (equivalent 

to 17% oxytetracycline) 

Mycoshield®: 31.5% Oxytetracycline Calcium Complex 

(equivalent to 17% oxytetracycline) 

 Manufacturers:

FireWallTM and FireLineTM: AgroSource, Inc. 

Mycoshield®: Nufarm Americas, Inc. 

b. Additional labeling: see Appendix D (FireLine TM and FireWallTM) and 

Appendix E (Mycoshield®) for the proposed Section 18 labels. 

DESCRIPTION OF PROPOSED USE (166.20(a)(3)) 

(i) Site to be Treated:

Rationale for Multiple Active Ingredient Products: 

The Citrus Research and Development Foundation, Inc., (CRDF), a Florida based 

independent grower research support organization was created and funded by grower 

assessments to guide the search for solutions to the recently introduced disease/vector 

complex Huanglongbing disease/Asian citrus psyllid. This research effort has proceeded 

across many fronts, one of which is the discovery and development of therapeutic 

treatments for infected trees. This program has directly participated in the funding of 
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projects with registrants of agricultural antibiotics to determine the role if any these 

compounds may provide in addressing this industry need. These projects were initiated 

over the past twenty-four months and have provided indications of value in maintaining 

the health and productive vigor in citrus trees that are infected with the pathogen. 

Initial experimentation and experience gained in commercial citrus groves with this 

disease/complex suggests that multiple bactericide applications will be necessary in order 

to improve tree health and suppress the effects of Huanglongbing (HLB) disease seasonlong/year-round on infected citrus trees. The information developed independently by 

the two registrants in cooperation with the Citrus Research and Development Foundation 

over the past two years indicates a measure of suppression and overall increase in tree 

health in HLB-infected citrus trees. Each registrant developed their research package 

independently of the other’s involvement and the resulting data indicates the three 

products have efficacy when used in a season long program targeted to the flush periods 

in citrus. The use patterns of the oxytetracycline products, while somewhat 

complementary, were not based on the same treatment regimes. This petition has 

attempted to consolidate use patterns across those treatment regimens and develop a 

package that would allow the flexibility of the treatments proposed in each individual 

package. It is important to note that the research program to refine and finalize final use 

patterns are on-going and will result in label expansion actions by each registrant. It 

must be recognized that while all of these products have activity on other citrus plant 

pathogens, the reason for this petition is the need for a therapeutic treatment to prolong 

the life and viability of trees infected with HLB. 

Additionally, the further rationale supporting the use of multiple active ingredients for this 

particular Section 18 request include the following: 

 The Candidatus Liberibacter asiaticus (CLas) bacterium is a difficult organism to 

work with, starting with the fact that this organism has never been successfully 

cultured in the laboratory. Its potential to develop resistance to antibacterial 

compounds applied for its control in the field is therefore unknown. 

 Since CLas may develop resistance if treated with just a single bactericide product, 

an effective resistance management strategy must be part of any antibacterial HLB 

management program from the start. 

 The heart of any effective resistance management strategy against CLas will be 

the use of at least two bacterial control agents, each having a unique mode of 

action against the pathogen. 

 Based on their respective and unique modes of action, streptomycin sulfate is 

classified as a Group 25 fungicide; oxytetracycline is classified as a Group 41 

fungicide according to the Fungicide Resistance Action Committee (FRAC). 
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 The use of streptomycin and oxytetracycline in alternation will thus minimize any 

selection pressure on CLas for development of resistance to either streptomycin or 

oxytetracycline. 

 Since both streptomycin and oxytetracycline are individually efficacious against 

CLas in HLB-infected citrus, attacking the situation with these multiple products in 

rotation constitutes an effective resistance management program for HLB 

management and tree health improvement, thereby ensuring the long-term 

efficacy of these products against the CLas pathogen. 

 This resistance management program should also help in preventing development 

of resistance in non-target bacteria as well. 

All citrus (statewide) is the site to be treated. The proposed crop spectrum to be treated 

is slightly different for the two formulations of oxytetracycline. The FireLineTM label and 

FireWall TM label covers all of the Citrus Crop Group 10, whereas the Mycoshield® label is 

proposing use on Orange, Crop Subgroup 10-10A and Grapefruit, Crop Subgroup 10-10C. 

According to the latest figures available from the 2015 Citrus Reference Book (Florida 

Agricultural Statistics Service Citrus Summary, 2013 – 2014; February 2015), in 2014 

there was a total of 515,147 acres of Florida commercial citrus acreage (452,364 acres 

oranges, 45,922 acres grapefruit, and 16,861 acres specialty citrus). In a subsequent 

report (September 17, 2015), The National Agricultural Statistics Service reported 

126,613 acres of abandoned or untended citrus acreage. This acreage would be 

deducted from the above number resulting in potentially treated acreage of 388,534 

acres. See Appendix A for Florida counties and acreages in citrus. 

(ii) Method of Application:

Ground application only. 

(iii) Rates of Application (in terms of a.i. and product):

FireWallTM 50WP 

0.45 pounds active ingredient (a.i.) per acre per application 

0.69 pounds of formulated FireWallTM 50WP per acre per application 

FireLineTM 17WP 

0.27 pounds of active ingredient (a.i.) per acre per application 

1.5 pounds of formulated FireLineTM 17WP per acre per application 

 Mycoshield®

0.255 pounds of active ingredient (a.i.) (oxytetracycline base) per 

acre per application 

 1.5 pounds of formulated Mycoshield® per acre per application 

Rates of application for Mycoshield® are based on reaching a 200 ppm 

oxytetracycline (1.5 pounds of formulated product in 150 gallons of water) 
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concentration in a finished spray volume necessary to fully cover the foliage 

of the tree to be treated. Spray volume and use rates per acre can be 

scaled downward in smaller trees depending on the amounts of spray 

volume to provide full coverage. 

 Maximum Number of Applications: 

 FireWallTM 50WP

A maximum of 3 applications per year is proposed, totaling no more than 

2.07 pounds of formulated FireWallTM 50WP per acre per year (1.35 pounds 

active ingredient). 

Allow a minimum of 21 days between applications. 

FirelineTM 17WP 

A maximum of 3 applications of this formulation per year is proposed, 

totaling no more than 4.5 pounds of formulated FireLineTM 17WP per acre 

per year (0.81 pounds active ingredient). 

Allow a minimum of 21 days between applications. 

Mycoshield®

A maximum of 8 applications per year is proposed, totaling no more than 

12 pounds of formulated Mycoshield® per acre per year (2.04 pounds 

oxytetracycline base). Mycoshield® would be labeled to suppress infections 

of HLB in foliage with applications beginning two weeks after the initiation 

of a new leaf flush. Closer spray intervals are conducive to better 

performance but limit the ability to use the product on multiple flushes. 

Wider spray intervals and fewer applications on a given flush may not be as 

effective but allows for more applications on successive flushes, especially 

in young small frame citrus trees. 

(iv) Total Acreage (or other units) to be Treated: 

During 2013-14, approximately 515,147 acres of citrus were grown in 

Florida. Of this acreage 388,534 acres remain under commercial 

management. 

(v) Total Amount of Pesticide to be Used (in terms of a.i. and product):

FireWallTM 50WP 

In an absolute worst-case scenario, 804,265 pounds of formulated 

FireWallTM 50WP Fungicide/Bactericide, or 695,448 pounds of streptomycin 

sulfate, would be needed. (388,534 acres X 0.69 pounds of formulated 

FireWallTM 50WP X 3 applications = 1,066,354 pounds FireWallTM 50WP 

Fungicide/Bactericide; 388,534 acres X 0.45 lbs. a.i. X 3 applications = 

524,520 lbs. a.i. streptomycin sulfate). 
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FireLineTM 17WP 

At the maximum, 1,748,403 pounds of FireLineTM 17WP or 314,712 pounds 

of oxytetracycline hydrochloride, would be needed. (388,534 acres X 1.5 

pounds of formulated FireLineTM 17WP X 3 applications = 1,748,403 pounds 

FireLineTM 17WP; 388,534 acres X 0.27 pounds a.i. X 3 applications = 

314,712 pounds of oxytetracycline hydrochloride). 

Mycoshield®

The total amount of Mycoshield® that could be used under the specific 

exemption assuming all trees are treated the maximum number of 

recommended applications would be a total of 4,662,408 pounds of 

formulated Mycoshield® or 762,309 pounds of oxytetracycline calcium. 

(388,534 acres X 1.5 pounds of Mycoshield® X 8 applications = 4,662,408 

pounds of Mycoshield®; 388,534 acres X 0.255 pounds oxytetracycline base 

X 8 applications = 762,309 pounds of oxytetracycline base). While the use 

of Mycoshield® is limited to citrus crop subgroups 10 A and 10 C, the 

members of crop subgroup 10B (limes and lemons) represent less than 

2,000 acres of production in Florida (less than 2,550 lbs of active 

ingredient. 

Note Oxytetracycline Formulations: 

Across the two formulations of oxytetracycline, the total amount of the 

active ingredient oxytetracycline that would be allowed under the proposed 

use patterns included in this petition is equivalent to the maximum amount 

of active ingredient that could be applied per individual acre of treated 

citrus under the proposed Mycoshield® Section 18 label plus the amount 

adjusted for the three applications on Citrus Subgroup B, which is allowed 

on the proposed FireLineTM 17 Section 18 label (0.81lbs X 2,000 Acres of 

lemons and limes = 1,620 lbs). This is (762,309 lbs. – (2,550 lbs. (5 

applications at .255 lbs.)) = 759,759 lbs. of oxytetracycline. The use 

across the two formulated products (on Citrus Subgoups 10 A and 10 C) 

would be additive over the season and capped at the maximum level of 

active ingredient per acre of 2.04 lbs. of oxytetracycline for Citrus 

Subgroups A & C and 0.81lbs. on Citrus Subgroup B. We would encourage 

the Agency in their decision document to clearly state that the maximum 

amount of oxytetracycline per acre per season is capped so that if growers 

choose to use both products they do not exceed the maximum per acre use 

allowed. 

While the amounts of product that could be needed is projected above; it is 

highly probable that not all of the eligible acreage will be treated, and a 

portion of the treated acreage will be treated at lower use rates than the 

maximum rate because of smaller canopy size in the younger age classes of 
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trees. This will result in less material being used than the numbers 

projected above. 

 (vi) Use Season (period of time for which use of chemical is 

requested):

Access would be needed by February 1, 2016, to coincide and overlap with 

the typical spring foliage flush emergence. Availability subsequent to the 

date of approval is requested and crucial over the ensuing 12 months, 

especially when considering the continued infection rates and subsequent 

tree losses resulting from HLB disease. 

FireWallTM 50WP 

FireWallTM 50WP will be applied to all varieties and cultivars included in the 

Citrus Crop Group 10. Make an initial application at initiation of spring flush 

to suppress HLB titer and disease symptoms. Make a second application 

mid-summer (not less than 21 days after first application). Make a third 

application in late summer to reduce the incidence of HLB-induced fruit 

drop and to further suppress HLB titer and disease symptoms (not less than 

21 days after second application). Spray to near runoff. Applications of 

FireWallTM 50WP should be rotated with another bactericidal product having 

a different mode of action, to reduce risks of selecting for streptomycinresistant organisms. 

FireLineTM 17WP 

FireLineTM 17WP will be applied to all varieties and cultivars included in the 

Citrus Crop Group 10. Make an initial application at initiation of spring flush 

to suppress HLB titer and disease symptoms. Make a second application 

mid-summer (not less than 21 days after first application). Make a third 

application in late summer to reduce the incidence of HLB-induced fruit 

drop and to further suppress HLB titer and disease symptoms (not less than 

21 days after second application). Spray to near runoff. 

Mycoshield®

The recommendation is to make 3 to 4 applications to growth flushes in the 

spring and fall. Applications to the spring flush could be initiated in 

February through April depending on the citrus variety and the severity of 

the winter. It may take until the end of May to complete the entire 

application program on the spring flush. Fall flushes would consist of 

periods of new growth initiating after September 1st. 

Foliar applications of these antibiotics are not expected to cure systemic 

infections of HLB in the branches, trunks or roots of a diseased tree. 

Application flexibility is needed so growers can target periods of disease 
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suppression and relief of associated symptoms that best fit their overall 

production program. 

(vii) Additional Restrictions, User Precautions and Requirements, 

Qualifications of Applicators, etc.:

All active ingredients will be applied in accordance with the proposed 

Section 18 label and all applicable provisions of the Section 3 registered 

labels. Examples of various restrictions, requirements and qualifications 

include but are not limited to: 

FireWallTM 50WP 

 A total of three (3) applications of FireWallTM 50WP may be made at no 

less than 21 day intervals. 

 Do not apply at less than 40 days prior to harvest. 

 Do not apply through irrigation systems or by aircraft. 

 Do not apply more than 2.07 pounds of formulated FireWallTM 50WP 

(1.35 pounds active ingredient) per acre. 

 Personal protective equipment for applicators and handlers includes: 

o Long sleeved shirt 

o Long pants 

o Chemical resistant gloves made of a waterproof material 

o Shoes plus socks 

o Protective eyewear 

o MSHA/NIOSH approved dust/mist respirator with any N, R, P or 

HE filter. 

 Worker re-entry into treated areas during the restricted entry interval of 

12 hours is not allowed. For early entry to treated areas that is 

permitted under the Worker Protection Standard and that involves 

contact with anything that has been treated, such as plants, soil or 

water, wear: 

o Coveralls over long-sleeved shirt and long pants 

o Chemical-resistant gloves made of a waterproof material 

o Shoes plus socks 

o Protective eyewear. 

 Do not apply directly to water, to areas where surface water is present 

or to intertidal areas below the mean high water mark. 

 Do not contaminate water by cleaning of equipment or disposal of 

equipment washwater. 

 The FireWallTM 50WP label contains a CAUTION statement of hazard and 

this product is considered to be a “General Use” pesticide. As a nonrestricted pesticide, farmers without private applicator certification, 
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farmers with private applicator certification, and licensed commercial 

applicators are allowed to apply FireWallTM 50WP. 

FireLineTM 17WP 

 A total of three (3) applications of FireLineTM 17WP may be made at no 

less than 21 day intervals. 

 Do not apply at less than 40 days prior to harvest. 

 Do not apply through irrigation systems or by aircraft. 

 Do not apply more than 4.5 pounds of formulated FireLineTM 17WP (0.81 

pounds active ingredient) per acre. 

 Personal protective equipment for applicators and handlers includes: 

o Long sleeved shirt and long pants 

o Chemical resistant gloves made of a waterproof material 

o Shoes plus socks 

o Protective eyewear 

o Dust/mist filtering respirator (MSHA/NIOSH approval number 

prefix TC -21C) or a NIOSH approved respirator with any N , R, P 

or HE filter. 

 Worker re-entry into treated areas during the restricted entry interval of 

12 hours is not allowed. For early entry to treated areas that is 

permitted under the Worker Protection Standard and that involves 

contact with anything that has been treated, such as plants, soil or 

water, wear: 

o Coveralls over long-sleeved shirt and long pants 

o Chemical-resistant gloves made of a waterproof material 

o Shoes plus socks 

o Protective eyewear. 

 Do not apply directly to water, to areas where surface water is present 

or to intertidal areas below the mean high water mark. 

 Do not contaminate water by cleaning of equipment or disposal of 

equipment washwater. 

 The FireLineTM 17WP label contains a CAUTION statement of hazard and 

this product is considered to be a “General Use” pesticide. As a nonrestricted pesticide, farmers without private applicator certification, 

farmers with private applicator certification, and licensed commercial 

applicators are allowed to apply FireLineTM 17WP. 

Mycoshield® 

 A total of eight (8) applications of Mycoshield® may be made at no 

less than 21 day intervals. 

 Do not apply at less than 21 days prior to harvest. 

 Do not apply through irrigation systems or by aircraft. 
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 Do not apply more than 12.0 pounds of formulated Mycoshield®

(2.04 pounds oxytetracycline base) per acre. 

 Personal protective equipment for applicators and handlers includes: 

 Long sleeved shirt. 

 Long pants. 

 Chemical resistant gloves made of a waterproof material. 

 Shoes plus socks. 

 Protective eyewear. 

 Dust/Mist filtering respirator (MSHA/NIOSH approval number prefix 

TC-21C) or a NIOSH approved respirator with any N, R, P or HE 

filter. 

 Worker re-entry into treated areas during the restricted entry interval 

of 12 hours is not allowed. For early entry to treated areas that is 

permitted under the Worker Protection Standard and that involves 

contact with anything that has been treated, such as plants, soil or 

water, wear: 

o Coveralls over long-sleeved shirt and long pants 

o Chemical-resistant gloves made of a waterproof material 

o Shoes plus socks 

o Protective eyewear. 

 Do not apply directly to water, to areas where surface water is 

present or to intertidal areas below the mean high water mark. 

 Do not contaminate water by cleaning of equipment or disposal of 

equipment washwater. 

 The Mycoshield® label contains a WARNING statement of hazard and 

this product is considered to be a “General Use” pesticide. As a nonrestricted pesticide, farmers without private applicator certification, 

farmers with private applicator certification and licensed commercial 

applicators are allowed to apply Mycoshield®. 

Other specific use directions to be followed are found on the proposed 

Section 18 labels and the Section 3 labels found in Appendices D and E. 

ALTERNATIVE METHODS OF CONTROL (166.20(a)(4) ): 

(i) Detailed Explanation of Why Currently Registered Pesticides Are 

Not Available in Adequate Supply and/or Are Not Effective to Control the 

Emergency:

The Huanglongbing (HLB) disease/vector complex and its impact on the industry have 

been rapidly increasing since the disease was first identified in Florida in August of 2005. 

The fact that HLB was on the U.S. Department of Homeland Security’s Select Agent List 

made field work next to impossible until that status was modified. As experience with the 

disease has progressed, it has become apparent that managing the disease at levels that 
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will allow continued commercial production in Florida depends on a multifaceted 

management strategy. This strategy includes the ability to replace non-productive trees 

with a realistic expectation that the newly planted replacement trees will have a 

reasonably productive life. Even with the complexities created by the lack of ability to 

culture the bacteria outside of the citrus vascular system and the digestive system of the 

insect, the industry has made significant strides in identifying the critical components of 

this management process. 

From the beginning, there have been a range of approaches attempted to manage the 

devastation that HLB has caused to Florida citrus, and the pursuit of many parallel 

strategies continues. Challenges of managing HLB disease in Florida citrus are many and 

the application of tools that are available and emerging from research have yet to provide 

for a sustained leveling of disease impact or to restore tree health and productivity to 

trees infected with the pathogen. The graphic below highlights the breadth of effort 

underway in research to discover, test and deliver solutions to HLB, identifying the 

primary targets for intervention. Vector control, combined with therapy to reduce CLas 

titers (bacterial concentrations) in infected trees and ultimately, deployment of resistant 

or tolerant plant materials offers the balanced approach to disease management. 

Because of the absence of effective tools for bacterial therapy (the basis for this petition) 

and no proven plant resistance, the disease continues to impact all Florida growers and is 

discouraging the much-needed replanting to complement the current struggling tree 

inventory. 

From the outset, it has been clear that vector control was tantamount to slow the spread 

of the disease, and many strategies were advanced to achieve this goal. Insecticidal 

suppression, biological control, attractants and repellants and other approaches have 
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been pursued, and as a result, Asian citrus psyllid (ACP) populations are well below initial 

levels. Similarly, as CLas infection spread and the numbers of infected trees grew, 

expansion of ACP control was necessary to protect new plants in existing groves and new 

plantings from becoming infected. Soil-applied neonicotinoid insecticides play a major 

role in protecting young trees during critical periods as they grow through the first 5 

years, and these insecticides become more important as the disease reservoirs of 

inoculum and vector populations continue to expand. ACP suppression remains a critical 

component of HLB management with research and grower experience continuing to 

demonstrate the value of this segment of HLB management. 

Florida citrus growers realized early that sustaining plant health through horticultural 

practices was an important response to onset and advancement of HLB disease. While 

trees possess considerable resilience in response to stresses, a chronically declining tree 

loses much of its resilience, and therefore must be managed more carefully. “Just-intime inputs” or “spoon-feeding” trees showing advanced HLB symptoms with irrigation 

and fertilization can dampen limitations of compromised root systems, and cultural 

practices have been modified to more intensively manage tree health. In addition, plant 

growth regulators are being evaluated and used in an effort to assist in phloem 

regeneration and to limit pre-harvest fruit drop associated with HLB decline. Other 

cultural practices are being investigated to sustain health and productivity of infected 

trees and perhaps prolong productive life of these trees. Some of these same practices 

of intensive management are likewise being applied to newly planted trees to meet the 

goal of accelerating tree growth and maturity, thereby allowing for economic return to 

growers before HLB-induced tree decline commences. However, consistent success in 

this effort remains elusive. 

Neither vector suppression nor cultural practices directly impact the bacterial pathogen, 

CLas, which is the target of the intervention proposed in this petition. 

The goal of reducing CLas titer in infected trees has proven quite challenging, and 

relatively little progress has been made in this arena. The location of the pathogen 

within the plant’s vascular system, difficulty of early detection of infection in citrus plants, 

and the inability of researchers to work with cultures of the bacteria CLas have limited 

development of CLas therapies to two strategies. 

The first of these strategies is application of thermal therapy, where external heat is 

applied actively or passively to infected trees to differentially cause bacterial mortality in 

phloem tissues, while not harming the host plant tissues. The differential time versus 

temperature requirements to achieve this goal are being pursued through research and 

field experimentation on commercial farms. 

The alternative to thermal therapy is the application of chemical therapy, wherein 

bactericidal chemicals are applied to trees to reduce CLas bacterial titer. This approach 

has been a priority focus for industry research efforts and extensive investment in 

evaluating efficacy, dose response, phytotoxicity and other parameters important to 
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development of a therapy tool. Chemical therapy encompasses a range of chemistries 

that correspond to various regulatory pathways, from conventional agricultural antibiotics 

to biopesticides to new active ingredients. Chemistries that fall within currently 

registered pesticides, 25(b) exempt list, or biopesticides offer the shorter term 

opportunities and these are being pursued aggressively while longer term new active 

ingredients are developed. Our strategy has focused most aggressively on agricultural 

antibiotics as these products offer an opportunity for label expansion from other U.S. crop 

uses as bactericides, and for which there is a broad pool of supporting data. 

Processes in place to evaluate chemical therapy candidates include: 

 A comprehensive laboratory bioassay system progressing from a high throughput 

surrogate bacterial assay to whole plant greenhouse assays; 

 A range of field research spanning single plant initial trials to large scale 

commercial trials conducted in concert with registrants; 

 Efficacy as a function of a.i., dose, timing, application method and disease 

intensity has been evaluated, as well as phytotoxicity, movement within the plant, 

and residues in plant parts. 

Finally, several long-term lines of technology are being developed to identify and move 

the genetic components necessary to convey resistance into horticulturally important 

citrus cultivars. Field trials have been initiated to further investigate the potential for this 

to serve as a long-term means of restoring the viability of the industry. But, results are 

still expected to be years off. 

All of this work in the state of Florida is being coordinated through the Citrus Research 

and Development Foundation (CRDF). This program of research to develop and deliver 

HLB solutions is also coordinated with existing national and international programs 

through USDA ARS, other research institutions, and, industry associations in Texas and 

California. 

(ii) Alternative Control Practices:

Alternative CLas therapy/suppression practices are outlined above and are restricted at 

present to thermal therapy and chemical therapy. While there are other approaches 

mentioned above for vector or plant health management, none of these address reducing 

CLas titer in infected trees, and these tools are not likely to affect decline of infected 

trees. 

Thermal therapy: 

Some success has been observed with application of passive solar energy or active steam 

heat to young trees. These field demonstrations and trials have been evolving since the 
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spring of 2014, when proof of concept was completed with solarization inside single-tree 

tents. Early attempts with both passive and active thermal treatment resulted in severe 

tree injury or actual tree death, leading to subsequent investigations to define 

time/temperature relationships and methods of delivery to achieve the differential 

thermal effects on bacteria while preventing tree injury. At present, all systems 

operating in the field to advance this approach are designed to treat individual trees up 

to a maximum height of about 3 meters. Results appear most predictable when trees are 

in early stage in infection and disease onset. While delivery systems and 

time/temperature characteristics are being resolved, predictability of response and 

expected duration of effects are in early stages of evaluation. Practical limitations of the 

number of trees that can be treated with thermal therapy and the expected outcomes in 

balancing bacterial titer reduction with increasing injury to leaves, limbs and fruit on 

treated trees are being evaluated in small-scale field trials in Florida. Research and 

commercialization funding is encouraging innovation to solve issues of practical 

application of this CLas suppression strategy, but progress is slow at present. It is 

anticipated that this approach will emerge on a commercial scale as a tool for managing 

early infection that will perhaps be limited to young (small) trees. 

Chemical Therapy of CLas: 

Chemical therapy of CLas is under intensive investigation in Florida citrus, with relatively 

few candidate materials advanced to commercial use or demonstrated effectiveness. The 

only antibiotics available for use in the agricultural sector include streptomycin, 

oxytetracycline and kasugamycin. Among the groups of chemistries under consideration, 

the bactericides labelled for use in other crops are the front-runners in terms of available 

data and performance testing in Florida citrus. These are the subjects for this Emergency 

Exemption petition. 

Alternatives available for field use against CLas are few. CLas bioassay and field trials are 

being conducted on the biopesticides that are labelled for pest or disease control in citrus 

to determine how effective these materials might be under current field use patterns. 

Field research is ongoing, but results that could indicate a clear effect are not yet 

available. Optimism around these products exists but none of these materials are 

currently considered as demonstrable CLas therapy. 

Other alternative chemistries that are being evaluated in Florida citrus for HLB 

suppression or tree health management include products based on plant essential oils. 

Some of these oils appear on the EPA 25(b) exempt list. Several products containing 

plant essential oils are available in Florida [e.g., Thymeguard (AgroResearch), and Ecotrol 

Plus (Keyplex®)]. These products are being field evaluated by growers to determine their 

impact on HLB through foliar application. 

Field trials are underway to quantify the impact of these potential tools, but it is too early 

to have meaningful results. Similarly, field evaluations by Florida growers in conventional 

and organic citrus blocks have failed to demonstrate a measurable effect of these plant 
17

essential oils. While these tools may complement the bactericides being considered in 

this petition, there is limited evidence for their effectiveness in reversing HLB. 

EFFECTIVENESS OF USE PROPOSED UNDER SECTION 18 (166.20(a)(5)) 

(166.20(a)(5)) 

FireWallTM 50WP and FireLineTM 17WP 

To assess the potential management of HLB disease, foliar applications of two 

bactericides, streptomycin sulfate and oxytetracycline hydrochloride were applied to 

commercially-grown grapefruit and oranges at 17 Florida field test locations in 2014 (year 

1) and 2015 (year 2). Trials were located in the Indian River, the Central Ridge and the 

Peace River regions of Florida’s citrus industry. Prior to treatment applications, all trees 

at each location were confirmed to test “positive” for HLB, based on PCR (polymerase 

chain reaction) analysis. Treatment effects for streptomycin and oxytetracycline 

applications were determined by quarterly DNA titer assays of the bacterium Candidatus 

Liberibacter asiaticus present in leaf samples collected from each treatment plot. In 

addition, multiple assessments of tree health were made, including improvement in tree 

canopy density (e.g. health), increased tree height and reductions in leaf drop, fruit drop, 

visual HLB symptoms, branch dieback and increases in fruit load in treated versus 

untreated trees. Foliar applications with streptomycin or oxytetracycline to grapefruit and 

orange trees in year-1 resulted in a statistically significant reduction (p < 0.05) in CLas 

titer, and this remained evident 4 to 5 months after the last application of streptomycin 

or oxytetracycline. In addition, significant improvements (p < 0.05) in leaf drop, fruit 

drop, visual HLB symptoms, and visual tree health, were noted in treated year-1 trees. 

Significant treatment effects (p < 0.05) were also recorded for these same parameters 

plus tree height in year-2. Results from these trials showed that foliar applications of 

streptomycin and oxytetracycline bactericides to commercially grown citrus significantly 

reduces titer for CLas in HLB-infected trees, and results in significant improvements to 

overall tree health. These field evaluations serve to illustrate that the reduction in CLas 

titer from the PCR results has correlation to healthier citrus trees in a production grove 

environment. 

Mycoshield®

Mycoshield® oxytetracycline calcium complex was first registered in 1979 for control of 

fire blight (Erwinia amylovora) of pear and bacterial spot (Xanthomonas arboricola pv.

pruni) of peach. Apple (fire blight) and nectarine (bacterial spot) were added to the label 

in later years. Oxytetracycline hydrochloride was first approved for agricultural use in 

2004. EPA has determined that oxytetracycline calcium complex and oxytetracycline 

hydrochloride rapidly convert to oxytetracycline when added to water and “both OTC 

calcium complex and OTC-HCL will be mainly introduced into the environment as OTC.” 

Thus, it was determined that environmental fate data for OTC calcium complex and OTC-
18

HCL are interchangeable. Disease control with the two forms is expected to be 

equivalent because the spray deposits would be oxytetracycline. 

Oxytetracycline is produced naturally by Streptomyces rimosus. Commercial production 

of Mycoshield® is achieved by fermentation of the natural organism. This is followed by 

an extraction and concentration process to obtain a manufacturing concentrate that is 

used to make the final end product. OTC is a reversible bacteriostat that inhibits protein 

synthesis at the ribosome. Susceptible bacteria may resume development if the exposure 

period is inadequate for action by a secondary mortality factor such as senescence, 

attempted cell division, environmental stress or a host plant response. 

Potted seedlings of various citrus cultivars were sprayed to run off with daily foliar 

applications of oxytetracycline at 100 ppm in a 1975 report (A. L. Martinez, 1975). A 

majority of the plants demonstrated partial recovery with obvious improvements in color 

and shoot production. However, none of the plants were completely cured. Injections of 

tetracycline to Sakkan orange and Fuju mandarin at 500 to 1000 ppm were effective at 

reducing disease symptoms and preserving higher yields in a 1991 article (K. Chung and 

W. Zhisheng, 1991). The trees were not cured and growth of the disease was evident 

one year later. Injection of tetracycline resulted in phytotoxic effects such as rotten 

tissue around the injection points and leaf drop. Oxytetracycline was not considered to 

be of value in the early stages of the Florida epidemic because of the inability to cure 

infected trees. 

The following characteristics are required for bactericides to make definitive claims for 

direct suppressive activity on HLB and have practical utility for use in the field: 

1. Proven activity on Liberibacter spp. in culture. It must inhibit Candidatus

Liberbacter crescens, the closest cultured relative of Candidatus Liberibacter 

asiaticus, at low concentrations. Oxytetracycline strongly inhibits Candidatus

Liberbacter crescens culture growth by more than 90 percent at a concentration of 

0.54 μM, a level suitable for field use. Thus, it is believed that oxytetracycline can 

inhibit Candidatus Liberbacter asiaticus. 

2. Phloem mobility. The chemical structure of oxytetracycline suggests that it can 

penetrate the phloem where the causal agent, Candidatus Liberibacter asiaticus, 

resides in the tree. 

3. Excellent crop safety. Mycoshield® applied twice weekly to citrus at 1000 ppm 

for 12 weeks (24 total applications) did not cause noticeable injury in a 2013 field 

trial by the University of Florida’s Dr. Eric Triplett (personal communication). 

Zebra chip disease is caused by Candidatus Liberibacter solanacearum, a very close 

relative of Candidatus Liberbacter asiaticus. As in HLB disease, the Liberibacter pathogen 

resides in the phloem after having been vectored by a phloem-feeding insect (potato 

psyllid). Testing bactericides against zebra chip disease on tomato or potato generates 
19

results much faster than can be obtained on citrus. Symptoms on tomato appear in 10 

days but can take many months on citrus. Disease suppression through the use of an 

effective bactericide can be observed in less than three weeks in tomato but can take 

many months on citrus. 

Zebra chip is not endemic to Florida, but laboratory and field research can be conducted 

in south Texas where the disease and potato psyllid are widely established. Dr. Erik 

Mirkov (Texas A&M AgriLife Research) has shown in laboratory studies that 

oxytetracycline effectively manages the symptoms of Zebra chip disease on tomato and 

dramatically reduces the number of bacteria residing in the plant (data in preparation for 

publication). Dr. Manuel Campos (Texas A&M AgriLife Research) conducted a field trial 

on potato in 2015. Five weekly applications of Mycoshield® at 200 ppm resulted in 13 

percent infected tubers as compared to 90 percent in the untreated. This study 

demonstrated that oxytetracycline can reduce disease caused by a phloem-limited 

pathogen very closely related to Candidatus Liberbacter asiaticus. 

Nufarm conducted experimental field trials in 2014 and 2015 (Better Crops, LLC, 2014 / 

2015) evaluating the suppressive activity of Mycoshield® foliar sprays against HLB in 

Florida groves with HLB symptoms. This was a commercial grapefruit grove with 7 – 10 

year old trees. 

In 2014, the treatment list was based on anecdotal information suggesting that a 

combination of a bactericide with a strong penetrant (Pentra-Bark®) plus fertilizers would 

provide the best results. Unfortunately, the treatments with Pentra-Bark®/fertilizer 

combinations (with or without a bactericide) resulted in phytotoxic effects in the form of 

severe leaf and fruit drop. Although 2014 growth information was confounded by the 

crop injury, qPCR data demonstrated that oxytetracycline foliar applications suppressed 

the incidence of HLB infection in new growth. Samples of mature foliage collected prior 

to the initiation of the program revealed an infection incidence of 75 – 100 percent 

throughout the study area. Samples of mature foliage collected after the treatment 

program (4 applications at 3 week intervals) had the same incidence of infection. 

However, samples of new foliage that was flushing during the treatment period showed 

that all Mycoshield® foliar treatments (treatments 6 – 12) only had an infection incidence 

of 25 – 50 percent. The untreated, fertilizer + Pentra-Bark® alone, Agri-Mycin® 17 

streptomycin (with and without Pentra-Bark®) and Mycoshield® trunk spray had an 

infection incidence of 50 – 75 percent. 

 
20

Table 1: Mycoshield® HLB Foliar Suppression - Grapefruit - St. Lucie W 2014 

Percent of Plots Positive for HLB / Old vs. New Foliage 

Treatment % Old Infect 7-27 % Old Infect 10-29 % New Infect 10-29 

Untreated 75 75 75 

Fertilizer (F) + Pentra-Bark® (P) 75 75 50 

Agri-Mycin® Low Vol (AL) 100 100 50 

AL + P 100 100 75 

Mycoshield® + P Trunk 75 75 50 

Mycoshield® Low Vol (ML) 100 100 25 

ML + P 75 75 50 

Mycoshield® High Vol (MH) + P 75 75 25 

ML + F + P 100 100 25 

MH + F + P 100 100 25 

MH + RTREX Plus 100 100 25 

MH + KeyPlex® 1400 DP 100 100 25 

Antibiotic Foliar and Trunk Applications: 7-27, 8-15, 9-12, 10-11 

Fertilizer Foliar Application: 7-27, 9-12 

Fertilizer: 1 gal chelated iron + 5 lb. zinc sulfate + 5 lb. manganese sulfate / A 

Agri-Mycin® 17 and Mycoshield® Low Vol: 1.5 lb. product in 100 GPA 

Mycoshield® High Vol: 1.5 lb. product in 150 GPA 

Mycoshield® Trunk: 1.5 lb. in 12.5 GPA @ approximately 8 oz./tree 

Pentra-Bark®: Applied at 0.5% v/v foliar; 2.5% v/v trunk 

Infection Incidence: % of plots testing positive for HLB based on PCR of old or young foliage 

Table 2: Mycoshield® HLB Foliar Suppression - Grapefruit - St. Lucie W 2014 

Percent of Tree Canopy a Contiguous Leaf Wall 

Treatment % leaf Wall Area 3-31-2015 

Untreated 49 b 

Fertilizer (F) + Pentra-Bark® (P) 48 b 

Agri-Mycin® Low Vol (AL) 53 ab 

AL + P 67 a 

Mycoshield® + P Trunk 59 ab 

Mycoshield® Low Vol (ML) 69 a 

ML + P 67 a 

Mycoshield® High Vol (MH) + P 71 a 

ML + F + P 63 ab 

MH + F + P 64 ab 

MH + RTREX Plus 58 ab 

MH + KeyPlex® 1400 DP 58 ab 

Percent Leaf Wall: Visual assessment of canopy fullness averaged for 4 angles of perspective on 

each tree. 

The 2014 study area recovered from the phytotoxicity and increased spring growth of the 

new canopy in 2015 was evident in all oxytetracycline foliar treatments relative to the 

untreated (9 – 22% denser canopy than the untreated). Several of the treatments were 

significantly superior to the untreated (5% probability level). 

 
21

Table 3: Mycoshield® HLB Foliar Suppression /Grapefruit - St. Lucie W 2015 

Treatment Vigor Rating 7-21-2015 

Untreated 5.2 c 

Mycoshield® + Pentra-Bark® Trunk 5.5 bc 

Phostrol® 4.5pt/100 gal 5.5 bc 

Mycoshield® LV 5.6 bc 

Mycoshield® HV 6.8 abc 

Mycoshield® + Phostrol® LV 6.3 abc 

Mycoshield® + Tactic® 0.125% LV 6.7 abc 

Mycoshield® + Tactic® 0.125% HV 6.2 abc 

Mycoshield® + Tactic® 0.125% LV 4 appl* 6.8 abc 

Mycoshield® + Dyne-Amic® 0.25% LV 5.7 bc 

Mycoshield® + Dyne-Amic® 0.25% HV 6.2 abc 

Mycoshield® + LI 700 0.25% LV 7.1 ab 

Mycoshield® + LI 700 0.25% LV 7.7 a 

Three applications to spring 2015 flush @ 2 week intervals 

* A 4th application made 6 days after the 3rd 

Mycoshield® Low Vol: 1.0 lb. product in 100 GPA 

Phostrol® Low Vol: 4.5 pints in 100 GPA 

Mycoshield® High Vol: 1.5 lb. product in 150 GPA 

Mycoshield® Trunk: 1.5 lb. in 12.5 GPA @ approximately 8 ounces per tree 

Pentra-Bark®: Applied at 0.5% v/v foliar; 2.5% v/v trunk 

Tree Vigor Rating: 0 = dead; 10 = completely healthy growth 

The 2015 grapefruit study was established on different trees. Application timing focused 

on periods of new growth flush in the spring, summer and fall. Periods of new growth 

are the optimal times for infection by CLas and it was expected that phloem penetration 

of oxytetracycline would occur at a greater concentration in newer foliage. 

Many of the treatments involved the identification of additives that would improve 

performance without causing crop injury and the comparison of two spray volumes (100 

and 150 gal/acre). Most treatments involved three applications at two week intervals 

initiated at a flush of new growth. Approximately six weeks after flush initiation, the 

foliage hardens, becomes less attractive to psyllid feeding and is less amenable to the 

penetration of oxytetracycline. One tank mix treatment of Mycoshield® + Tactic included 

a fourth spray applied six days after the third application. A trunk spray of Mycoshield®

+ Pentra-Bark® was added as a comparison with the foliar sprays which were applied to 

the point of runoff. Mid-season tree vigor ratings (0 – 10 scale) showed that all 

oxytetracycline foliar treatments were numerically higher than the untreated, trunk spray 

and Phostrol® alone. The mixture of Mycoshield® + LI 700 at 100 and 150 gal/acre was 

significantly superior to the untreated (5% probability level). Oxytetracycline degrades 

quicker at a neutral pH than under acidic conditions. LI 700 is an acidifying penetrating 

surfactant which may be stabilizing the applied residues and extending the period for leaf 

absorption. 

Leaves were collected from selected treatments in the 2015 grapefruit trial and 

forwarded to Dr. Xiaoan Sun (Florida Department of Agriculture and Consumer Services, 
22

Division of Plant Industry) for residue analysis. Dr. Sun uses a method that has a lower 

limit of quantification (1 ppm). Values lower than this may represent false detects. The 

analysis proved that oxytetracycline penetrated the foliage and was still detectable in the 

single treatment that was collected four days after application. As predicted the residues 

were higher in young leaves than old leaves. However, oxytetracycline was not found at 

the limit of quantification in leaves at 10 days after application. The grapefruit leaf 

residue analysis supports that the application needs to be less than 10 days to prevent 

HLB bacteria from recovering and resuming growth. 

Table 4: Mycoshield® - Grapefruit Leaf Residues 2015 

Treatment Additive # 

Appl 

Last 

Appl Sampled Foliage Residues (ppm) 

Mature New 

Untreated none 0 NA 22 May ND – all Reps ND, 0.5 

Mycoshield® Foliar 1.0 lb./100 GPA none 3 12 May 22 May ND – all Reps ND, 0.5 

Mycoshield® Foliar 1.5 lb./100 GPA none 3 12 May 22 May ND – all Reps ND, 0.7 

Phostrol® Foliar 4.5 pt./100 GPA none 3 12 May 22 May ND – all Reps ND – all Reps

Mycoshield® + Phostrol® /100 GPA none 3 12 May 22 May ND – all Reps ND – all Reps

Mycoshield® Foliar 1.0 lb./100 GPA Tactic 3 12 May 22 May ND – all Reps ND – all Reps

Mycoshield® Foliar 1.0 lb./100 GPA Tactic 4 18 May 22 May 1.4 ,0.9, 0.6, 0.8 2.9, 0.8, 1.6, 0.8 

Mycoshield® Foliar 1.0 lb./100 GPA LI 700 3 12 May 22 May ND – all Reps ND – all Reps

Mycoshield® Foliar 1.0 lb./100 GPA Dyne-Amic® 3 12 May 22 May ND – all Reps ND – all Reps

Comparison of oxytetracycline residues in mature and new flush foliage collected from the same trees. 

Residues determined by Bacillus subtilis bioassay. 

Leaf samples collected by John Curtis, Better Crops, LLC. 

Leaf analysis conducted by Dr. Xiaoan Sun, FDACS, Div. of Plant Industry. 

Table 5: Mycoshield® - Orange Leaf Residues 2015 

Treatment Additive # 

Appl 

Last 

Appl Sampled Foliage Residues (ppm) 

Mature New 

Untreated none 0 NA 19 Aug ND ND 

Untreated none 0 NA 22 Aug ND ND 

Mycoshield® Foliar 1.5 lb./150 GPA none 1 18 Aug 19 Aug 3.2 7.3 

Mycoshield® Foliar 1.5 lb./150 GPA none 1 18 Aug 22Aug ND ND

Comparison of oxytetracycline residues in mature and new flush foliage collected from the same trees. 

Residues determined by Bacillus subtilis bioassay. 

Leaf samples collected by Henry Younce, KAC Agricultural Research, Inc. 

Leaf analysis conducted by Dr. Xiaoan Sun, Florida Department of Agriculture and Consumer Services, Div. of Plant 

Industry 

Similar results were obtained from a residue analysis of treated orange (Hamlin) foliage 

from another location. One day after application, the oxytetracycline residue 

concentration in new flush foliage was 7.3 ppm, which exceeded the concentration in 

mature leaves by more than 2X. At the orange site, residues were not detected in foliage 

at four days after application 

Based on this information then, the following use instructions are proposed for the 

specific exemption: 
23

 A use concentration of 200 ppm that provides disease suppression in field trials 

and is consistent with the current maximum use concentration on the Mycoshield®

label. 

 Full coverage foliar application to the point of run-off. Oxytetracycline residues are 

rapidly degraded and inactivated in the soil. High volume applications that result 

in the run-off of excess material would be of no performance value. 

 Testing the crop safety of tank mixtures to avoid potential phytotoxicity issues. 

 Targeting applications to periods of new leaf flushes. This is supported by disease 

suppression results, leaf residue analysis and the infection properties of HLB. 

 Apply at 21 day intervals. Although there were distinct benefits with 2- and 3-

week intervals in 2014 and 2015 field trials, there was room for improvement. As 

a bacteriostat, the activity of oxytetracycline is improved by extended intervals of 

exposure. Residues were not detected in foliage at 10 days after application in the 

grapefruit trial and at four days after application in the orange trial. Applications 

at 3 – 7 day can be made for labeled use for control of fire blight on apples and 

pears. 

 Use in combination with an Asian citrus psyllid management programs 

recommended by local experts. Imperfect vector control and suppression of HLB 

would be complementary strategies. 

 Studies (Xia, 2012) have shown that high summer temperatures reduce the HLB 

levels in infected trees and in the psyllid. Thus, this emergency exemption request 

recommends targeting spring and fall flushes with oxytetracycline applications 

when the greatest benefit is expected. The exception would be a grower that 

intends to use oxytetracycline in combination with vector control to delay the 

infection of newly planted trees. In this situation, all flushes would need to be 

targeted with both technologies. Additional research is needed to investigate the 

use of oxytetracycline in a preventative program and large treatment areas are 

needed to optimize the activity of the vector control component. The expanded 

treatment acreage allowed under this emergency exemption request will enable 

the investigation of large area HLB prevention programs. 

DISCUSSION OF RESIDUES IN FOOD (166.20(a)(6)) (166.20(a)(6)) 

FireWallTM 50WP and FireLineTM 17WP 

AgroSource, Inc. and the IR-4 Project have performed Magnitude of Residue studies for 

streptomycin sulfate and oxytetracycline in/on citrus commodities. Field residue studies 

have been conducted and this information has been submitted to the Agency or is being 
24

submitted to the Agency. Dietary and drinking water exposure and risk assessment with 

the current crop uses plus citrus have been performed using DEEM-FCID version 4.02 

and citrus residue data from recent citrus field studies treated with three foliar 

applications at the proposed Section 18 label rates of both streptomycin and 

oxytetracycline each application. Based on available information, a temporary 

streptomycin tolerance of 0.5 ppm and a temporary oxytetracycline tolerance of 0.1 ppm 

on citrus are proposed. 

For the streptomycin dried pulp fraction, the proposed tolerance will be 3.5 ppm and for 

the oil and juice fractions the proposed tolerance is 0.005 ppm (50% of the LOQ). 

For oxytetracycline, no residues (LOQ=0.01 ppm) were found in whole fruit, orange peel, 

juice or dried pulp in crop residue trials. Residues of oxytetracycline in orange oil ranged 

from ND (<0.002 ppm) to <LOQ (0.01 ppm). Therefore, the NAFTA MRL of 0.01 ppm on 

the citrus fruit group 10-10 is proposed as the tolerance. 

The summary of the residue data and the corresponding risk assessments to support the 

use of FireWall TM and FireLine TM for on citrus is included in the Appendix D – 3 and D – 

4) 

Mycoshield® 

A GLP residue study on citrus fruit sponsored by Nufarm Americas Inc. was initiated in 

March 2015 to support a tolerance petition and registration application for the use of 

Mycoshield® on the Citrus Fruit Crop Group 10-10 commodities. The study is expected to 

be completed by the end of June 2016. Residue data are currently available for several 

of the field trials and include data for raw agricultural commodities and processed 

fractions. Based on available data, Nufarm is proposing the establishment of time-limited 

tolerances for residues of oxytetracycline in or on orange, Crop Subgroup 10-10A, at 0.4 

ppm and grapefruit, Crop Subgroup 10-10C, at 0.4 ppm. A summary of analytical results 

is provided in the Appendix E - 3. 

The proposed time-limited tolerances for orange and grapefruit commodities are 

consistent with the tolerances of 0.35 ppm already established for apples, pears and 

peaches. The processing study was conducted at the exaggerated rate of 5 times the 

proposed application rate of 1.5 pounds Mycoshield®/acre (7.5 lb. Mycoshield®/acre). No 

detectable residues were found in orange juice. Residues in whole oranges and 

grapefruit were approximately 0.2 and 0.02 ppm, respectively. 

To mitigate the small dietary risk posed by the specific exemption use on Florida orange 

and grapefruit crop subgroups 10-10A and 10-10C, a maximum of 8 applications per year 

and a maximum annual rate of 12 pounds of Mycoshield® per acre are proposed 

(compared to the 12 applications and the total rate of 21 pounds of Mycoshield® per acre 

used for the conduct of the residue study on citrus). In addition, a retreatment interval 

of 21 days is proposed instead of the 2-day retreatment interval used in the residue 
25

trials. With these risk mitigation measures in place, it is very unlikely that any residues 

detected in treated citrus commodities will exceed the proposed time-limited tolerances 

for oxytetracycline in/on orange and grapefruit crop subgroups 10-10A and 10-10C. The 

incremental risk associated with the Section 18 use is therefore expected to be below the 

Agency’s level of concern. 

The summary of the residue data and the corresponding risk assessments to support the 

use of Mycoshield on citrus subgroup 10(A) and 10(C) is included in the Appendix E – 3 

and E – 4) 

Proposed Time Limited Tolerance 

It is anticipated that a single time limited tolerance would be set for the use of 

Oxytetracycline under the Section 18. As a result of the status of the supporting data 

across both registrants we would propose the following: 

 Fruit, citrus, subgroup 10-10A at 0.4 ppm (the highest of the tolerance level 

needed for both FireLine 17WP and Mycoshield) 

 Fruit, citrus, subgroup 10-10B at 0.1 ppm (needed to cover anticipated 

residues resulting from the use of FireLine 17WP only) 

 Fruit, citrus, subgroup 10-10C at 0.4 ppm (the highest of the tolerance level 

needed for both FireLine 17WP and Mycoshield) 

DISCUSSION OF RISK INFORMATION (166.20(a)(7)) 

Description of application sites, including proximity to residential areas, 

aquatic systems, endangered or threatened species habitats, soil types, 

etc.: 

FireWallTM 50WP and FireLineTM 17WP 

FireWallTM 50WP and FireLineTM 17WP will only be applied to commercial citrus 

groves. These groves are typical of those found in Florida. Commercial groves 

are intensive and no unreasonable risks to human health, endangered or 

threatened species, beneficial organisms, or the environment are expected from 

the proposed use of this product. 

Also included in the Appendix is an executive summary of work done in association 

with FDA requirements #152, Resistance Risk Assessment for Foliar Applications of 

FireWallTM and FireLineTM to citrus crops. With integration of the effective 

resistance management options, this situation does not significantly change the 

existing Qualitative Risk Assessment for the emergence of streptomycin or 

oxytetracycline resistance among clinical pathogenic bacteria. Since this proposed 

new use of streptomycin and oxytetracycline on citrus crops to improve tree health 
26

and manage HLB is unlikely to represent a source for potential emergence of 

streptomycin or oxytetracycline resistance among clinical pathogens, approval of 

the proposed new use of streptomycin and oxytetracycline on citrus crops is 

believed to be in the public interest. 

Mycoshield®

Mycoshield® will be applied to commercial orange and grapefruit plantings, 

including all citrus fruit belonging to the citrus crop subgroups 10-10A and 10-10C 

(Calamondin; citron; citrus hybrids; grapefruit; Japanese summer grapefruit; 

Mediterranean mandarin; orange (sour); orange (sweet); pummelo; satsuma 

mandarin; tachibana orange; tangelo; tangerine (mandarin); tangor; trifoliate 

orange; uniq fruit; cultivars, varieties, and/or hybrids of these). Use under the 

Section 18 will occur in all areas of the state with commercial citrus groves. 

Possible risks posed by use: 

FireWallTM 50WP and FireLineTM 17WP 

FireWallTM 50WP Fungicide/Bactericide and FireLineTM 17WP Fungicide/Bactericide 

are approved products registered by the U.S. Environmental Protection Agency 

that have been used in the field for more than 40 years. Possible risks were 

evaluated during Section 3 registration and reregistration processes for both 

compounds. FireWallTM is currently registered for use on crops such as beans, 

celery, peppers, potatoes, tomatoes, apples and pears, and FireLineTM is currently 

registered for use on crops such as apples, pears, peaches and nectarines. No 

unreasonable adverse effects to man or the environment are anticipated with this 

proposed use of three applications of streptomycin and three applications of 

oxytetracycline to Florida citrus. Additional information for FireWallTM and 

FireLineTM on these subjects can be obtained from Taw Richardson with 

AgroSource. His phone number is (908) 215-3500. 

Facts associated with the potential for increasing the risk of human resistance to 

streptomycin and oxytetracycline have also been addressed in the TRED for 

oxytetracycline and the R.E.D. Facts publications for streptomycin, streptomycin 

sulfate and oxytetracycline. The streptomycin R.E.D. EPA report says that 

“regarding the problem of drug resistance, EPA has no data indicating that 

streptomycin residues remaining in the food supply have a significant or even a 

measurable potential for increasing human resistance to that drug.” The 

Regulatory Conclusion of that same publication says that “all currently registered 

pesticide products containing streptomycin or streptomycin sulfate as the active 

ingredient are not likely to cause unreasonable adverse effects in people or the 

environment.” The TRED for streptomycin says that “antibiotic resistance from 

pesticidal use of streptomycin is unlikely to result directly from dietary residues of 

streptomycin because dietary residues are very low. The drug dose is 3,000 times 

greater than the estimated pesticidal dietary exposure. The small dose from 
27

(streptomycin) pesticidal exposure would not be expected to select for resistant 

bacteria because very few bacteria would be killed by this small dose.” 

The streptomycin FDA #152 study summary paper notes that “streptomycin has 

been safely and effectively used in plant agriculture since 1955, yet a direct 

connection to the emergence of streptomycin resistance among clinical pathogens 

as a consequence of this use pattern remains undocumented. EPA has previously 

determined that the dietary exposure to streptomycin is below its level of concern. 

The use of streptomycin to manage HLB in commercially grown citrus crops does 

not increase the chronic aggregate exposure to a level of concern, since the 

combined aggregate residential and chronic dietary exposure to all agricultural 

applications of streptomycin, including the proposed us of streptomycin on citrus 

crops is 2,491 times less than the No Observed Adverse Effects Level (NOAEL) for 

the total U.S. population and 719 times less than the NOAEL for the most affected 

population subgroup, non-nursing infants. Dietary intake of streptomycin does not 

constitute a source of selection pressure for streptomycin resistance among enteric 

gut flora, since the dietary exposure from streptomycin applications to plant 

agriculture is so low and oral absorption for streptomycin is extremely low (<1%). 

Recent studies have revealed streptomycin-resistant isolates of many plant 

pathogenic bacteria exist as stable populations in the environment, even where 

streptomycin has never been applied, giving indication that factors other than 

streptomycin applications in the field influence the emergence of streptomycin 

resistance among plant pathogenic bacteria.” 

Similarly, the R.E.D. publication for oxytetracycline says that the “use of the active 

ingredients hydroxytetracycline monohydrochloride and oxytetracycline calcium in 

accordance with approved labeling will not result in unreasonable adverse effects 

to human health or the environment.” Facts pertaining to risks have also been 

addressed in association with the potential for increasing the risk of human 

resistance to oxytetracycline in EPA’s TRED for oxytetracycline, as well as the FDA 

#152 assessment. The EPA oxytetracycline TRED concluded that “because 

anticipated dietary residues are extremely low, it is unlikely that antibiotic 

resistance from pesticidal use of oxytetracycline would result from food exposure,” 

and “the drug dose is 50,000 times greater than the estimated pesticidal dietary 

exposure (25 mg/kg/day dose divided by maximum aggregate dietary exposure of 

0.000473 mg/kg/day). The small dose from pesticidal exposure would not be 

expected to select for resistant bacteria because very few bacteria would be killed 

by this small dose.” In the latest oxytetracycline dietary risk assessment, the drug 

dose is nearly 82,000 times greater than the estimated pesticidal dietary exposure 

[25 mg/kg/day dose divided by maximum aggregate dietary exposure of 0.000305 

mg/kg/day for non-nursing infants (the highest population sub-group)]. 

Therefore, anticipated dietary residues of oxytetracycline are extremely low, and it 

is also unlikely that antibiotic resistance from the pesticidal use of oxytetracycline 

would result from food exposure. 
28

The AgroSource oxytetracycline FDA #152 study summary paper notes that 

“oxytetracycline has been safely and effectively used in plant agriculture for more 

than 40 years yet a connection to the emergence of oxytetracycline resistance 

among clinical pathogens remains undocumented. EPA has previously determined 

that dietary exposure to oxytetracycline is below its level of concern. The use of 

oxytetracycline to combat HLB in citrus crops does not significantly increase the 

chronic aggregate exposure to oxytetracycline. Dietary intake of oxytetracycline is 

not expected to constitute a source of selection pressure for oxytetracycline 

resistance among enteric gut flora since the combined aggregate residential and 

chronic dietary exposure to all agricultural applications of oxytetracycline, including 

the proposed us of oxytetracycline on citrus crops, by non-nursing infants is 164 

times less than the NOAEL, and approximately 82,000 times less than the 

commonly prescribed therapeutic dose for this most affected population 

subgroup.” 

As a condition of the approval of a Section 18 exemption for the use of FireWallTM

50WP for the management of citrus canker (Xanthomonas citri pv. citri) on 

commercially-grown grapefruit in Florida, field studies were conducted during the 

2014 season designed to detect potential development of streptomycin resistance 

in the culturable microbial communities from both phyllosphere and rhizosphere 

zones of FireWallTM 50WP treated (tested) and untreated (control) trees. Two 

commercial grapefruit grower cooperators provided a total of five unique test sites, 

all located within the Indian River Citrus growing region of southeastern Florida. 

No test site had previously received any treatments with streptomycin or 

streptomycin-based products. FireWallTM 50WP was applied to the test sites 

following the Section 18 label directions. Samples for culturable bacteria (as found 

in soils from beneath each tree and leaves taken from each tree) were collected at 

four dates beginning in August 2014 (T0) and ending in December 2014 (T3). 

Samples from all FireWallTM 50WP treated and corresponding untreated plots were 

analyzed for evidence of streptomycin-resistant bacteria. When the data were 

analyzed across all five test sites, results indicated no consistent and significant 

change (p=0.05) in phyllosphere or rhizosphere microbial populations. More 

importantly, results revealed no evidence for development of streptomycin 

resistance among bacterial populations resident in FireWallTM 50WP treated 

grapefruit trees or soils in response to the use of FireWallTM 50WP on Florida 

grapefruit for management of citrus canker. 

Mycoshield® 

Mycoshield® is currently registered for use on apples, pears, peaches and 

nectarines. Occupational exposure and risk are not expected to exceed the 

Agency’s level of concern since airblast application at the same maximum rate of 

1.5 pounds of formulated product per acre per application is already registered for 

peaches, nectarines and apples. EPA stated in the 2008 Health Effects Division 

(HED) Scoping Document for Registration Review of oxytetracycline that an 
29

occupational assessment was not needed because of the low level of exposure 

anticipated from application of oxytetracycline products and the personal 

protective equipment required by the Section 3 label that includes protective 

clothing, chemical-resistant gloves, protective eyewear and a respirator. The 

occupational exposure and risk associated with the proposed Section 18 use on 

Florida citrus is therefore expected to be well below the Agency’s level of concern. 

The proposed time-limited tolerances of 0.4 ppm for residues of oxytetracycline in 

or on orange, Crop Subgroup 10-10A, and grapefruit, Crop Subgroup 10-10C, are 

based on data available to date from the ongoing magnitude of residue study 

(included in the Appendix E). Twelve foliar airblast applications of Mycoshield®

were made at the maximum use rate of 1.5 pounds of formulated product per acre 

per application with a 2-day retreatment interval plus two trunk applications of 

Mycoshield® at 1.5 pounds of formulated product per acre per application. This 

resulted in a total application rate of 21 pounds of formulated product/acre (3.57 

lb. oxytetracycline/acre) whereas the proposed Section 18 label limits application 

to 12 pounds of formulated product/acre (2.04 lb. oxytetracycline/acre) total per 

year. 

In the 2008 EPA Health Effects Division’s Scoping Document for Registration 

Review of oxytetracycline, EPA concluded that expected dietary (food and water) 

risk for the U.S. population and all subpopulations was conservative and below the 

level of concern. Acute dietary exposure was not estimated because no acute 

toxicity was identified in any of the relevant studies in the oxytetracycline 

database. As a result, EPA determined that acute dietary risks are not of concern. 

In order to investigate potential exposure and risk associated with the proposed 

Section 18 use on Florida citrus, Nufarm sponsored a chronic aggregate dietary 

assessment for currently registered uses of oxytetracycline and the proposed use 

on citrus in Florida. The available data from Nufarm’s residue study on citrus were 

used to assess dietary exposure. The resulting chronic risk estimates are not of 

concern for any population assessed. Based on this assessment, there are no 

dietary exposure issues that would preclude the specific exemption use on citrus 

trees in Florida. Since there is no residential use of oxytetracycline, an assessment 

that aggregates more than food plus water is not needed. 

A drinking water exposure assessment was also conducted for currently registered 

uses of Mycoshield® and the proposed Section 18 use on Florida citrus trees. The 

resulting drinking water concentrations were used in the dietary risk assessment. 

Concentrations were calculated to be very low or practically non-existent (report 

included in the aggregate dietary risk assessment). The impact of the Section 18 

use on the ecological risk is not expected to exceed the Agency’s level of concern. 

Oxytetracycline residues degrade rapidly in citrus foliage. As discussed in the 

section “Effectiveness of Proposed Use under Section 18”, leaf residue analysis has 

shown that oxytetracycline residues were no longer detectable in foliage 10 days 
30

after application to a grapefruit location and 4 days after application to an orange 

site. 

Nufarm has responded to Data Call-In notices issued for the TRED and 

Registration Review of Oxytetracycline. Several studies including environmental 

fate and ecotoxicology studies were conducted to support the continued 

registration of Mycoshield®. Most of these studies have already been submitted to 

the EPA or will be submitted in the near future. 

Regarding the potential for resistance development, it is unlikely that antibiotic 

resistance from pesticidal use of oxytetracycline would result from food exposure. 

Anticipated dietary residues for existing agricultural uses of oxytetracycline and the 

proposed Section 18 for Florida citrus are extremely low (conservatively estimated 

at 0.000076 mg/kg/day for the general U.S. population). The maximum aggregate 

dietary exposure calculated is very small when compared to pharmaceutical or 

veterinary doses. The small dose from pesticidal exposure would not be expected 

to select for resistant bacteria because very few bacteria would be killed by this 

small dose. An assessment of the potential for antibiotic resistance to develop as 

a result of the use of Mycoshield® on citrus was conducted following FDA Guidance 

#152 and is included in Appendix E-4. Additional information for Mycoshield® on 

these subjects can be obtained from Bill Bewlay with Nufarm. 

 
31

Proposals to mitigate risks: 

Existing use restrictions already listed on both the streptomycin and 

oxytetracycline labels will further reduce risk. These label restrictions include: do 

not apply directly to water, or to areas where surface water is present, or to 

intertidal areas below the mean high watermark; do not contaminate water when 

disposing of equipment wash water; do not apply by aircraft; do not apply these 

products through any type of irrigation system; and, only three applications of 

streptomycin and three applications of oxytetracycline are allowed per season. 

Current labeling directives are sufficient to mitigate any potential risks. Full 

reports of tests and investigations made with respect to the safety of streptomycin 

and oxytetracycline, including all information pertaining to the methods and 

controls used in conducting these tests and investigations have been submitted 

and reviewed by the Agency. 

The enforcement analytical methods for both products are available to monitor 

residues of streptomycin and oxytetracycline in citrus. 

FQPA INFORMATION (OCTOBER 24, 1996 EPA LETTER) 

EPA requested that additional information be submitted with Emergency Exemption 

requests to address new risk considerations associated with requirements of the Food 

Quality Protection Act. This information has been provided to the Agency. Since these 

products are approved for other Section 3 registrations an initial FQPA review has already 

occurred. 

COORDINATION WITH OTHER AFFECTED FEDERAL, STATE, AND LOCAL 

AGENCIES (166.20(a)(8)) 

As EPA’s state lead agency, the Florida Department of Agriculture and Consumer Services 

should provide this information. 

NOTIFICATION OF REGISTRANT (166.20(a)(9)) 

AgroSource, Inc. and Nufarm Americas Inc. have been notified of this request. The 

companies are supportive of this emergency exemption petition (see the Appendix for 

registrant support letters). 

 
32

DESCRIPTION OF ENFORCEMENT PROGRAM (166.20(a)(10)) 

As EPA’s state lead agency, the Florida Department of Agriculture and Consumer Services 

should provide this information. 

REPEAT USES (166.20(a)(11)) 

This is the first request for the use of each of the requested products, streptomycin and 

oxytetracycline on citrus by Florida for management of HLB and improvement of overall 

citrus tree health. The use of antibiotics under this Emergency Exemption Request will 

suppress HLB in new growth but will not cure the infection in the branches, trunk and 

roots. The reservoir of bacteria in the lower portions of the tree is a source for constant 

reinfection. Even new plantings are subjected to continuous pressure from ‘hot’ psyllids. 

A Section 18 Emergency Use Exemption would be needed until the Section 3 registrations 

are obtained. 

PROGRESS TOWARD REGISTRATION (166.25(b)(2)(ii)) 

FireWallTM 50WP and FireLineTM 17WP 

AgroSource, in conjunction with the IR-4 Project, continues to make progress toward new 

registrations for the use of streptomycin and oxytetracycline on the citrus crop group and 

a variety of other crops. The company is preparing or has prepared and submitted the 

necessary documentation for a Section 3 registration for citrus. The application to amend 

the Section 3 label for streptomycin has been submitted to EPA (Decision Number: 

486863) and a Pesticide Registration Improvement Extension Act (PRIA) due date of 

05/04/2015 had been assigned. EPA subsequently decided to require that this request 

go through a “public participation process”. As part of preparation for this process, EPA 

issued a deficiency letter to AgroSource (to provide more benefits information) and both 

parties “mutually agreed” on a new PRIA date of June 2016. Subsequently, the new 

submission goal for oxytetracycline on citrus is now October 1st, 2015 and for 

streptomycin the new citrus submission goal is November 1st, 2015. 

Mycoshield®

A GLP residue study on citrus fruit sponsored by Nufarm Americas Inc. was initiated in 

March 2015 to support the registration of Mycoshield® on the Citrus Fruit Crop Group 10-

10. The study is expected to be completed by the end of June 2016. It will then be 

submitted to the EPA in support of a tolerance petition and Section 3 registration 

application. Nufarm anticipates submitting the application by August 1st, 2016. 

Assuming a timeline of 15 months for the EPA review, the registration could possibly be 

granted by the end of November 2017. 
33

Nufarm is the basic registrant for Oxytetracycline Calcium and is responding to Data CallIn notices issued for the TRED and the Registration Review of Oxytetracycline. Several 

studies were required including environmental fate and ecotoxicology studies that also 

support the Registration Review of Oxytetracycline Hydrochloride (Appendix E-5). 

NAME OF PEST (166.20(b)(1)) 

 

Scientific Name:

Candidatus Liberibacter asiaticus (CLas) 

Common Name:

Disease: 

Huanglongbing (HLB) or Citrus Greening or Yellow Dragon Disease 

Vector: 

Asian Citrus Psyllid (ACP) (Diaphorina citri Kuwayama) 

DISCUSSION OF THE EMERGENCY CONDITION (166.20(b)(2)) 

Citrus huanglongbing has been known in China for more than 100 years. In 1929, a 

disease with similar symptoms appeared in South Africa and was named ‘yellow branch’ 

in Western Transvaal and ‘greening’ in Eastern Transvaal. The agent associated with 

the disease was transmitted by graft-inoculation from citrus to citrus for the first time 

by Lin in China in 1956. This work remained unknown outside China; McLean and 

Oberholzer demonstrated independently that South African greening was grafttransmissible. Because ‘huanglongbing’ was the name used in the paper describing 

graft-transmission of the agent for the first time, it has priority over other names and 

has been unanimously adopted as the official name of the disease by the International 

Organization of Citrus Virologists (IOCV) at the 12th Congress of IOCV, Fuzhou, China, 

1995. 

In the 1960s, the agent was shown to be transmitted by two insects: the African citrus 

psyllid Trioza erytreae in Africa and the Asian citrus psyllid Diaphorina citri in Asia. 

Symptoms of HLB were reported in Sao Paulo state in Brazil in 2004. Then, in 2005, 

HLB, was found to be present in Florida. This disease is caused by the pathogen 

Candidatus Liberibacter asiaticus and is spread by the Asian citrus psyllid (Diaphorina 

citri Kuwayama), which is an invasive pest to Florida, first discovered in 1998. HLB is 

considered to be the most serious disease of citrus worldwide and has greatly limited 

commercial production of citrus in countries where it is present. Since its discovery in 

Florida, this disease has rapidly spread throughout citrus production area to all 
34

commercial production areas in the state. The graphic below illustrates the rapidity 

with which HLB invaded Florida commercial citrus counties: 

(Source: CRDF Presentation to EPA, February 5, 2014) 

HLB is a prime example of how an unintentional, but illegal, plant introduction into a 

country can cause multi-billion dollar crop losses, unemployment and industry-wide 

financial strain. The HLB bacterium lives in the vascular system component (phloem) 

that conducts synthesized food materials from the tree to the roots. Like the human 

blood vessels, a blockage of these vascular system conducting tissues by any foreign 

substance produces deleterious effect. The presence of CLas in the phloem prevents the 

tree from effectively transporting water, nutrients and minerals between the leaves, fruit 

and the roots in the ground, thereby driving the tree into decline. Since this disease’s 

appearance, citrus production has been compromised with the loss of millions of trees, 

and HLB has subsequently been detected in every county with commercial citrus and in 

residential dooryard citrus as well. Trees infected with HLB will continuously decline and 

eventually die, even when incorporating all management options available to the industry 

at this time. The HLB-causing bacterium found in Florida is the Asian species that occurs 

in warm low altitude areas. HLB survives and multiplies within the psyllid vector 

throughout the psyllid’s lifetime. The psyllid was first found in Florida in June 1998. 

The severity of HLB and declining tree health far exceeds that of any previously known 

citrus disease, and all citrus species and their hybrids are confirmed to be affected by 

HLB. Infected trees first produce leaf symptoms; typically leaf yellowing on one or more 

branches, then leaves develop a blotchy (irregular spotted) appearance with grades of 

color. Infected trees typically also show symptoms that resemble micronutrient 

deficiency, especially, zinc and manganese. Fruit set becomes thin, fruit appear lopsided, 

the lopsided fruit may contain aborted seeds, and juice quality is unacceptable. 

Impacts from HLB are numerous. On infected trees fruit are few in number, small, 

lopsided with a curved central core, and they fail to color properly, remaining green at 

the stylar end (hence the name “greening”). Excessive fruit drop occurs prematurely on 
35

afflicted trees, and this has been reported in the past three harvest seasons in Florida to 

exceed 10 percent per season across all varieties. Even if fruit remain on the tree until 

harvest, the fruit are undersized and contain bitter juice, rendering it of reduced 

economic value. From a fruit size standpoint, HLB-infected trees have a significantly 

greater portion of fruit in smaller size categories compared to healthy trees (more than 

95% of symptomatic fruit are less than 2.25 inches in diameter). Total juice volume 

produced is less from HLB-positive trees because of the smaller fruit size as well. 

Extensive research has been done to characterize the off-flavors associated with HLBinfected trees, highlighting both the general brix/acid ratio impacts as well as the 

components that contribute to flavor. This work is presented in detail by Baldwin, et al. 

2010, Ikpechukwu et. al, 2011, Plotto et. al., 2013 and Massenti et. al. 2015. 

HLB disease and the lack of any tree health improvement antibiotic has already pushed 

untold numbers of farmers out of the industry. Between 2004 and 2014, the amount of 

Florida land planted with citrus shrunk by nearly one-third, from 748,555 acres down to 

515,147 acres (USDA, FASS). During that same timeframe, overall citrus production in 

the state dropped from 292 million boxes of fruit down to 124 million boxes (a 58% 

reduction). Average orange yields sunk from 428 boxes per acre in 2004 down to 250 

boxes an acre in 2014 (a 42% reduction), despite the higher-density new plantings of 

orange trees, almost solely resulting from HLB infection. 

Also contributing to the situation (and the continued higher grove maintenance costs) are 

Asian citrus psyllid management requirements. Since the psyllid’s discovery, annual 

production costs have more than doubled. The majority of these increased costs are 

derived from psyllid management requirements and the necessary modified cultural 

practices. Psyllid management is an absolute necessity with respect to controlling HLB 

spread; the threshold for psyllid treatment has become “less than zero” in the industry. 

A high proportion of psyllids are now infected with the bacteria and capable of 

transmitting the disease. Florida citrus growers are currently spending more than $240 

million a year on insecticides directed solely to manage psyllids, which is about 30 

percent more than they were spending in 2004, even though they're farming about 30 

percent less land and yielding half as much fruit. 

Citrus production and research experts believe that looking forward, the pursuit of 

interventions to reduce Asian citrus psyllid populations, reducing HLB bacterial 

populations within infected trees, and promotion of optimal tree health in the presence of 

HLB are the keys to the citrus industry’s sustainability. The industry to this point has 

pursued a three-pronged approach to combating HLB, focusing on interventions on the 

three components of the disease pathosystem. The first component involves managing 

the psyllid. The second is understanding the bacterium itself, with the goal of hopefully 

neutralizing impact on psyllids or trees. Access to antibiotic materials such as 

streptomycin and oxytetracycline is vital to induce the improvement of tree health and 

subsequently keep trees viable until these other HLB management approaches can be 

developed. The third component is to breed new citrus trees that will hopefully tolerate 

or resist infection. 
36

HLB is truly a limiting factor for citrus production. In the attempt to improve tree health 

to the degree possible, cultural practices such as foliar micronutrient sprays are employed 

once HLB infects a tree, but these effects are short-lived and certainly will not sustain the 

industry. HLB is already directly responsible for the loss of thousands of acres of Florida 

citrus trees. An emergency exemption involving multiple antibacterial strategies that 

enables improved fruit production must be gained in order to counter the impact of this 

bacterium/vector complex that is threatening the short- and long-term viability of the 

state’s $7 billion citrus industry. Without such antibiotic access and without anything else 

changing, within five to eight years of becoming infected, diseased trees will no longer be 

economically productive. 

Limitations on replanting to replace declining tree inventories have made it critical to 

extend the productive life of the more than sixty million mature citrus trees in commercial 

groves. Continued production from this inventory of mature (infected) trees while new 

trees come on line is the process by which the Florida citrus industry can avoid failure 

and loss of critical nursery, production, harvesting, processing, packing and marketing 

infrastructure. 

The graphic above emphasizes the point that despite ACP management programs, new 

plantings are still becoming infected and these would be primary targets for bactericide 

treatment. 

Biology of CLas and Disease Onset/Progression 

The complicated biology of HLB and the interactions between vector, pathogen and host 

citrus plant make development of solutions challenging. Following inoculation of CLas 

into uninfected citrus trees, a period of latency follows during which time there is no 
37

evidence of infection. Early symptom development is manifested through mottled 

foliage, followed progressively by smaller and narrower leaves, reduced mature fruit size 

and thinning of canopies. Chronic symptoms include limb dieback, fruit yield and quality 

reduction, and pre-harvest shedding of mature fruit. The time period of this disease 

progression varies with tree age and inoculum pressure, but generally in mature trees 

chronic decline appears within three to four years of initial infection. 

New information on Root Impacts 

Research reported over the past three years (Graham et. al., 2012, Johnson et. al., 2014, 

and Graham and Morgan 2015) has revealed that CLas infection of citrus involves early 

movement of bacteria to root systems, where direct impacts on root health result. Root 

systems of infected trees have relatively fewer feeder root densities, diminishing water 

and nutrient uptake efficiencies and exposing diseased trees to additional stress. Further 

evidence from field research has demonstrated that HLB-infected trees are susceptible to 

lower populations of Phytophthora propagules than healthy trees, indicating that HLB 

infection allows soil diseases to overcome or break rootstock tolerance. 

Significant economic loss has been experienced through lower fruit quality and smaller 

fruit size as described below, and proposed bacterial therapies have the potential to 

improve this aspect of the disease as root systems are restored. Strategies that address 

reduction in CLas titers in infected plants are few, but focus on reduction of bacterial 

levels early in disease development. 

While research continues to further elucidate the impacts of early migration of CLas into 

root systems, it has become necessary for growers to apply additional treatments for 

Phytophthora, root weevils and other soil stressors. It is expected that this root health 

compromise will also impact the ability of citrus trees to respond to weather disruptions 

like freeze events or sustained heavy rainfall. 

Non-Routine Emergency Situation: 

The rapid decline of HLB-infected mature citrus trees as evidenced by reduction in fruit 

size and quality and with the dramatic increase of fruit drop as fruit reaches harvest 

maturity. 

Dr. Ariel Singerman of the University of Florida, IFAS, Citrus Research and Education 

Center has updated grower estimates of the spread of HLB in Florida and its impacts on 

production. This study is included in the Appendix and is posted at 

http://www.crec.ifas.ufl.edu/extension/economics/. Here are highlights regarding HLB 

incidence in Florida: 

 57 percent of growers surveyed report that 100 percent of their groves were 

infected, while 24 percent and 13 percent reported 80-99 percent and 60-80 

percent infection, respectively. 
38

 On a tree-by-tree basis, 15 percent reported 100 percent of their trees were 

infected, while 49 percent and 21 percent reported 80-99 percent and 60-80 

percent tree infection rates, respectively. 

 80 percent of respondents reports yield losses in the range of 20-60 percent, with 

13 percent of respondents reporting more than 60 percent yield loss. 

These estimates reinforce official crop production figures from USDA/FASS reported 

elsewhere in this petition and highlight the level of impact on individual growers as the 

disease decline continues. 

DISCUSSION OF ECONOMIC LOSS (166.20(b)(4))

The damage resulting from HLB infection is considerable. Diseased trees decline, yields 

are reduced, and fruit quality is affected. As the disease severity increases, yield is 

reduced through a combination of smaller crop set, preharvest fruit drop from affected 

branches and smaller fruit size. The yield reduction can reach 30 to 100 percent, 

depending on proportion of affected canopy. This level of disease progression makes the 

grove economically nonviable 7 to 10 years after planting. As disease severity increases, 

the percentage of affected fruit increases, reaching more than 40 percent. The affected 

fruit are smaller, lighter, very acidic, with reduced Brix, ratio, percentage of juice and 

soluble solids per box, and juice quality is negatively impacted. Millions of citrus trees in 

Florida have been affected by HLB and subsequently destroyed. The last projected value 

that has been established as a direct cost of HLB to Florida’s citrus industry is around 

$300 million annually. 

The loss of production is felt by more people than just the famers that grow citrus. As 

production declines, packing houses do not run, box makers do not sell their products, 

shipping companies do not operate, etc. 

Dr. Ariel Singerman, Assistant Professor of Agricultural Economics at the University of 

Florida, IFAS, Citrus Research and Education Center, has recently evaluated the impact of 

HLB on citrus production costs across the three general production regions of the state. 

His work is posted on http://www.crec.ifas.ufl.edu/extension/economics/. 

Below is a summary of Dr. Singerman’ s findings from citrus production operations in the 

three regions: 

Central Florida (Ridge) Cost of Production for Processed Oranges: 

The Table below shows total costs growers incurred for 2014-15, which includes cultural 

costs, tree replacement plus other costs such as management, regulatory and 

opportunity costs. The total cost of production for processed oranges for 2014-15 is 

reported to be $2,282.19 per acre. Contributions to cultural operations include foliar 
39

sprays at $705.30 per acre; Citrus Health Management Area (CHMA) sprays $56.65 per 

acre; fertilizer expense at $469.80, and weed control at $246.31. With thinner tree 

canopies and open spots where HLB has caused tree death, even weed management 

costs have escalated. This can be compared to production costs averaging $700-800 per 

acre prior to HLB. 

Table 6: Total Costs of Production per Acre for Processed Oranges in Central 

Florida (Ridge), 2014/15. 

 

Southwest Florida Cost of Production for Processed Oranges: 

Similarly, costs for production of oranges in southwest Florida continue to climb, in the 

Table below excerpted from this section of the Singerman report. In this case, foliar 

sprays average $666 per acre plus $20.55 for CHMA sprays. Fertilizer costs were 

$486.90 per acre, and weed control averaged $248.19. The total cultural operations 

costs of $1,998.10 per acre are more than double those experienced prior to HLB impact. 

Table 7: Total Costs of Production per Acre for Processed Oranges in 

Southwest Florida, 2014/15 

Indian River Cost of Production for Fresh Grapefruit: 

In the case of the Florida’s premier production area for fresh grapefruit, the Indian River, 

the production costs mirror the increases observed in the other regions for processed 
40

oranges, but are magnified due to the need for fresh fruit quality and its impacts on 

production costs. The Table below from the Indian River portion of the report indicates a 

total of $2,478.61 cultural costs for 2014-15 and an overall per acre average production 

cost of $3,073.38 per acre. Relevant operational costs are $1,300.40 per acre for foliar 

sprays and $14.75 for coordinated sprays (CHMA); fertilizer costs average $452.55 per 

acre and weed control averaged $190.60 per acre. This compares to fresh fruit 

production costs prior to HLB that averaged $1,000-1,200 per acre per year. 

Table 8: Total Costs of Production per Acre for Fresh Market Grapefruit Grown 

in Indian River, 2014/15. 

Integrating the increased production costs for Florida citrus with statewide declines in 

per-acre yields illustrates the emergency status and the business failure that is being 

witnessed in Florida. Small- and medium-sized operations are economically abandoning 

blocks of citrus which have fallen below break-even levels for several consecutive years, 

reducing any further losses associated with continued investment in the face of 

continuing decline in production. An option considered by some is reduction in inputs to 

offset smaller crop size and quality. Experience over recent years indicates that this pullback in intensity of management of tree health accelerates the disease decline and only 

hastens economic abandonment. At the same time, these unmanaged groves become a 

source for inoculum for the pathogen and reservoir for the vector ACP. 

Large citrus operations in Florida are facing similar decisions on the declining return or 

loss due to HLB, and are risk assessing individual blocks each year to determine where 

investments are warranted. They, too, are removing groves that have fallen below 

economic return thresholds from active management. 

This scenario also is not favorably affecting growers’ interest in replanting, as the 

uncertainties of being able to sustain production on new trees is influenced heavily by 

their experience with standing groves. Data on declines in nursery tree production in the 

past year attests to this uncertainty, despite availability of industry and other incentive 

programs to replant. The health of Florida’s citrus industry is usually mirrored in nursery 

production. As industry production falls or fruit prices weaken, citrus nursery tree orders 

suffer. A total of 54 citrus nurseries propagated 4,438,128 trees in 2014-15, which is a 

decrease (5.8%) from last year. Nursery activity was strong for several new nurseries 
41

that began producing trees this year; 6 new nurseries accounted for over 5 percent of 

the total nursery propagations. Existing nurseries mostly saw a decline in budding and 

tree orders. A total of 33 nurseries had reduced production from the previous year and 

only 15 saw an increase. Overall, tree production based on reports decreased by 

274,311 trees. Taking into account that six new nurseries contributed to the production 

figures, it signified a downward trend for most nurseries. (FDACS Budwood Certification 

Program, Annual Report 2014-15). 

The Economic Impact of HLB on the Florida Citrus Industry: 

As described in a recent publication, this disease and the resulting loss of production cost 

the industry over $7 billion in lost revenue by 2012 (Hodges A.W., Spreen T. H., 2012). 

This loss of production translates to more than 8,000 lost jobs over the same five-year 

period. As trees succumb to the effects of the disease, the industry is faced with the 

challenge of replanting groves to replace the lost production. Although these figures 

have not been formally updated, the losses have risen considerably since this analysis 

was published. 

Economic Effects of HLB in Florida: 

Florida’s iconic citrus industry is an essential part of the economy of Florida, especially in 

the 28 central and southern counties of Florida where citrus is grown and processed. 

The most recent study before HLB became endemic put the overall economic impact at 

$8.91 billion and provision of 75,827 jobs. 

However, in 2012 economists calculated that over $4.5 billion in economic impact had 

been lost because of the effects of HLB on the Florida orange juice industry for the period 

2006 to 2010. The report details the category of losses, i.e., direct economic impacts, 

indirect economic impacts and induced impacts. On average, Florida’s economy suffered 

with the loss of $908.2 million dollars each year, and 8,257 permanent jobs. 

These losses are mainly because of the reduced production of Florida oranges versus a 

scenario without the effects of HLB in the citrus growing environment. Losing orange 

production is exacerbated by further losses of the value-added segment of the industry, 

that is fruit processing, juice manufacturing, and juice packaging and distribution. Since 

most of the orange juice sold in the United States is produced solely in Florida, this 

becomes a loss of economic benefits for Florida residents. 

As the disease progresses, more losses are expected each year. An estimate of the most 

current losses are explained by looking at Florida citrus production statistics over the 

period prior to first detection of HLB in Florida (1996-1997 through 2005-2006) and the 

decline in production experienced in the recent three years as a result of both 

accumulation of disease across the state as well as the cumulative decline due to multiyear chronic HLB infection (Table 9). 
42

Table 9: Florida Citrus Production Statistics during the Period 1996-1997 through 

2013-2014. 

 Crop Production by Fruit Type 1996-1997 through 2014-2015 

Crop Year Oranges Grapefruit 

Other 

Citrus Total 

(1,000 Boxes) 

1996-1997 226,200 55,800 13,315 295,315 

1997-1998 244,000 49,550 10,900 304,450 

1998-1999 186,000 47,050 10,115 243,165 

1999-2000 233,000 53,400 12,030 298,430 

2000-2001 223,300 46,000 9,505 278,805 

2001-2002 230,000 46,700 10,565 287,265 

2002-2003 203,000 38,700 9,305 251,005 

2003-2004 242,000 40,900 8,900 291,800 

2004-2005 149,800 12,800 6,650 169,250 

2005-2006 147,700 19,300 7,600 174,600 

2006-2007 129,000 27,200 5,850 162,050 

2007-2008 170,200 26,600 7,000 203,800 

2008-2009 162,500 21,700 5,000 189,200 

2009-2010 133,700 20,300 5,350 159,350 

2010-2011 140,500 19,750 5,800 166,050 

2011-2012 146,600 18,850 5,440 170,890 

2012-2013 133,600 18,350 4,280 156,230 

2013-2014 

2014-2015 

 

115,000 

96,700 

16,500 

12,950 

4,400 

2,980 

135,900 

112,630 

Source: USDA, National Agricultural Statistics Service, FASS, Florida Citrus 

Statistics. 2011-2012, published February 12, 2013. Data for crop years 2012-

2013 and estimates for 2013-2014 provided by USDA, NASS, FASS, Citrus 

Forecast, January 10, 2014. 2014-15 July 10, 201 Final Forecast for Season. 
43

Note: The above graph depicts the data in the table for total production, all 

varieties, and is included as an alternative data presentation, or to be used 

elsewhere in the petition. 

Losses have now reached levels that annual citrus production is less than half of what it 

was as recently as 2003-2004. The decrease in fruit in successive harvests over the past 

three seasons is shown here: 

2010-2011 to 2011-2012 9% 

2012-2013 to 2013-2014 11% 

2013-2014 to 2014-2015 17% 

Net loss (3 years) = 34%

With the rapid spread of HLB disease, and the increasing infection rates within standing 

groves, the situation that we are experiencing now in Florida is a combination of: 

 Widespread infection of citrus trees throughout the growing region of Florida. 

 Heavy inoculum in infected trees available for acquisition by the vector, ACP. 

Recent samples indicate up to 100 percent of field-collected ACP are positive for 

CLas, the pathogen. 

 Limited removal of infected trees means that local spread can be rapid if psyllids 

are not managed effectively. With high rates of infection within a block, tree 

removal is not practical. 

0

50,000

100,000

150,000

200,000

250,000

300,000

350,000

Production              (x1000 boxes)
44

 The accumulation of years of progressive infection by CLas means that a higher 

percentage of trees are beginning to show chronic infection, including more 

widespread symptoms within trees, thinner canopies and impaired root systems. 

 These factors all contribute to the reduced fruit production (yield), even though 

the official acreage of citrus plantings has not declined significantly in the last few 

years. And, 

 Fruit quality is declining, in size, flavor and maturity. 

Thus, the productive population of mature trees is declining in health and productivity, 

and will likely continue to do so without effective therapeutics, which currently are not 

available. In addition, new citrus trees that are either inter-planted in existing groves of 

mature trees or planted solid in new blocks are at high risk to infection via the ACP vector 

bringing inoculum from CLas reservoirs. It is these new trees that will provide the ability 

for economic production of citrus to continue, and the confidence to replant is, at 

present, limited by early and fatal infection of young trees by CLas through psyllid 

transmission. Trees in the first 4-5 years of growth are particularly vulnerable since they 

grow new flush off-cycle when other trees are not producing new leaves. This makes 

them more attractive to ACP colonization and vulnerable to disease transmission. 

The importance of management of HLB in Florida citrus is reduced to two major 

considerations. The first is to delay further health decline in existing mature trees that 

will further erode production. Second, and more vital, is the ability to manage ACP 

populations in young plants, thereby providing confidence to growers to replant. Both of 

these considerations could be positively impacted by availability of effective bactericides. 

Consideration of Expected Economic Benefits of Improved HLB Management, 

Particularly Through Availability of Bactericides 

This overview adds insights by attempting to quantify potential economic benefits to 

Florida if research efforts change the trajectory of any one of several factors that affect 

the economic impact of citrus production (specifically oranges) in the state. The initial 

overview focuses on the various aspects of production, such as acreage, yields, fruit loss 

to drop and quality reduction and other measures of decline due to HLB that would be 

expected to show improvement with implementation of an effective bactericidal program, 

as well as the trends in replanting, which likewise would be expected to improve as 

bactericidal therapy is made available. 
45

To understand the economics of expected response to exposure of HLB-infected trees to 

a time course of one or more bactericidal treatments, it is important to outline the 

disease progression associated with this disease and to determine which aspects of the 

disease impact would be improved through treatment. As stated earlier in this petition, 

infection of citrus by CLas is initially invisible, followed in a multi-year time course by a 

series of symptoms and injury which begin as foliar mottling and chlorosis and 

progressing to reduction in canopy density, and leaf size, and overall appearance of 

decline in one or more branches of the infected tree. General decline reflects root injury 

and limited movement of plant products through the impaired vascular system. With 

time, the appearance of small fruit, further thinning of canopies, and leaf and premature 

fruit drop signal more advanced imbalance in the tree. Leaf symptoms also include 

general chlorosis (yellowing) and their noticeable appearance as thinned canopies, with 

bare patches within the canopy of chronically infected trees. These advanced symptoms, 

and the continued decline to death of chronically infected trees, may not appear for 

several years following infection, or even following first visual symptoms. The general 

decline is symptomatic of the breakdown of several plant systems, including roots (lower 

feeder root density), reduced vascular movement (phloem plugging) of nutrients from 

sources to areas of need (leaves to roots, roots to developing fruit, etc.), and impaired 

photosynthesis due to canopy loss. 

Thus, in evaluating the expected response to treatment of CLas in infected trees, the 

forgoing description also defines the measures necessary to determine stabilization or 

recovery from disease symptoms. Expected changes in the following parameters can be 

predicted from previous research on epidemiology of HLB in citrus and are the metrics 

associated with field evaluation of therapies as pursued by the registrants of the 

candidate bactericides. 

 Reduction in CLas titer in infected trees following bactericidal regimen: The first 

measurable impact of bactericidal treatment would be expected to be reduction in 

bacterial titer in infected tissues. This is best measured at present using qPCR, 

and the numerical scale changes in samples over time reflect increase or decrease 

in bacteria in tissues sampled. Following a time-course of bactericidal treatments, 

it would be expected to see a gradual increase in PCR CT values, indicating a 

decline in titer in infected plant parts sampled. This may occur as step-wise 

reduction following individual applications, as evidenced in the data summaries 

provided. This in itself is not a metric of improved plant health or economic 

benefit, but portends resumption of growth and response as bacterial levels 

decline. 
46

 Improved tree growth response: Biological response to the lessening of pathogen 

pressure in infected trees is manifest in a series of indicators that trees are 

returning to more normal growth and development. As in the description of the 

onset of disease symptoms above, the progressive lessening of disease injury 

would be expected to show itself through leaf, branch, root and fruit symptoms. 

This has been observed in field experiments where therapies (both chemical and 

thermal) have been applied, and specific field results are presented in this petition 

for the products being field tested. 

 Foliage response: Larger, greener, more robust flush appear in flushing periods 

following treatment, and the degree to which flushing phenology and the strength 

of new foliage resume a “normal pattern” is indicative of reduced disease. 

 Canopy density improvement: Increased photosynthetic capacity is a by-product 

of new, healthy flush and drives plant health. Tree growth, including laying down 

of new phloem also can follow. 

 Root health improvement: Photosynthate movement and lessening of root decline 

due directly to CLas follows resumption of tree flushing, and it is yet unclear to 

what extent this will occur following a treatment regime of bactericides. 

 Increased capacity to utilize irrigation and nutritional applications, including 

improved foliar uptake. Restoration of root health has immediate impacts on the 

tree’s ability to utilize nutrients and healthy roots buffer periods of dry and wet 

weather. 

 Ability to combat other stresses (root disease, cold, drought). Resumption of 

balanced flush with restored roots has the added advantage of providing the 

defense against other stresses that exist in groves. Overcoming these stresses 

also contributes to resumption of tree health and productivity. 

 Fruit set and productivity: Since successful fruiting is dependent on support from 

the canopy, the above improvements in tree health can be expected to contribute 

to improved fruiting, and in conjunction with lower CLas titer, less size and fruit 

quality issues. Metrics associated with fruit yield, size and quality thus are direct 

indicators of effect of treatment success. 

It should be clear that expected response in diseased citrus trees from application of a 

regimen of bactericidal applications will first be improvement in bacterial titers, followed 

by reduced visual symptoms, then impacts on the production and quality of fruit. While 
47

this is likely to occur across a full production season, it is also likely that accrued benefit 

of the suppression of CLas in infected plants will occur over multiple seasons. 

While none of the above discussion pinpoints economic benefit of grower use of the 

proposed bactericides in this petition, it provides the context for that economic 

assessment. Based on the preceding discussion, improvement in tree health should lead 

to following economic drivers: 

 Fruit yield and quality improvement – 

 Larger fruit set and retention through the production season; 

Increased capacity to hold fruit on the tree season-long; less pre-harvest 

fruit drop; 

Improved fruit size; 

Improved internal fruit quality; 

Normal growth progression for young trees (up to 5 years old) to full productivity 

(multi-year impact); and, 

Increases in new plantings with availability of tools to deter disease progression. 

Impacts at the Processing Facility: 

The economic loss resulting from HLB-induced reduction of quality can be measured by 

downgrading, which initially can be done while fruit are still on the tree. Quality 

standards are established for juice fruit and fresh fruit harvest per fruit variety, and 

delays in maturity, caused by HLB infection, postpone harvest, and allow an extended 

period for pre-harvest fruit drop to occur. Increasingly, harvesting of fruit, even for 

processing, is not “clean-picked”, where the entire crop is removed at once, then graded 

and routed to fresh and processing streams. In the presence of HLB, fewer groves are 

harvested in this manner, and the fruit left behind due to irregular shape, small size, and 

other quality parameters is lost production. 

Fresh-fruit harvest has traditionally used “spot-picking” to begin the season, where fruit 

of the desired size and maturity are harvested, allowing remaining, smaller fruit to “size 

up” and mature for later harvest. Under HLB conditions, some groves from which fresh 

fruit are harvested are spot-picked 3 times, dramatically increasing harvest and handling 

costs. In the past two seasons, fruit left after initial spot picking did not continue to size, 

another result of HLB disease. Ultimately, the remaining fruit on these trees are cleanpicked for routing to processing plants. 

The second stage for quality downgrading comes at fruit load receipt at either packing 

houses (fresh) or processing plants (juice). Typically, fresh packing operations sort, 

grade and pack cartons of fruit to specifications. The percent of fruit arriving at the 

packinghouse that ends up in cartons is referred to as pack-out. Even with spot-picking 

to select higher quality fruit, pack-out percentages have dropped 20 to 40% in the past 3 
48

years. The fruit not packed into cartons is redirected to processing streams, resulting in 

lower returns. For the 2014 fruit season, oranges averaged $16.31/box when utilized for 

fresh and $12.09/box average for processing (USDA, NASS Florida Agriculture Quick 

Statistics). The differential is even greater for grapefruit, where 2014 fresh grapefruit 

were valued at an average of $14.44 per box for fresh and $6.38 per box for processing 

utilization. 

Fruit arriving at processing plants is sampled by load and the quality is assessed. The 

FDACS State Test House measures percent brix (sugar), percent acid and the ratio of 

brix/acid. This ratio is the initial basis for juice quality, and provides the quality data for 

payment to the grower. Additional data recovered from the load sampling includes 

pounds solids per weight of fruit, percent juice and overall weight of the load. The 

formula for payment is quality based and calculated for the pounds solids delivered from 

the entire load. 

 

HLB-affected loads of fruit net a lower brix and lower ratio, and due to smaller size, have 

less percent juice, yielding less juice from processing. Based on the State Test House 

results, fruit loads are assigned a grade, and lower grades are discounted. In the case of 

shared pool processing situations, the grade determines your “pool share” at season’s 

end, and this can be as much as 15-20 % discount for grade B compared to grade A fruit 

loads. The more serious impact is when lower grade loads of fruit are routed for juice 

concentrate production rather than inclusion in the not-from-concentrate juice processing 

stream. A significant differential occurs between these two forms of orange juice 

utilization, and this varies by processor and by season. 

All of these parameters have declined progressively over the past 3 years, and are 

expected to continue in chronically infected trees. Treatment to suppress HLB in these 

infected trees would be expected to reverse this process and restore value for each of 

these variables. 

Impacts at the Fresh Fruit Packing House: 

In addition to the impact on the processing industry, the fresh fruit industry has 

paralleled the losses due to HLB. 

The loss in fresh utilization is due to: 

 Tree loss 

 Increased fruit drop 

 Lower pack outs, due to smaller size and quality issues associated with HLB. 

 
49

Table 10: Reduction in shipments of Fresh Fruit Varieties in Florida as a result 

of the impact of HLB 

 

Change 2014-2015 from 2007-2008

Variety Fresh Boxes 

(In 000)

% 

Reductions

Oranges (476) -10.8%

Grapefruit (4,645) -46.8%

Tangelos (74) -46.1%

Early Tangerines (730) -63.3%

Honey Tangerines (909) -63.3%

All Fresh (6,834) -38.6%

Data sourced from: Duke Chadwell, Citrus Administrative Committee

For one Florida shipper, the 3-year average pack out (fresh utilization) for the 2005, 2006, 

and 2007 seasons was 70.4%. The average pack out for the 2013, 2014, and 2015 

seasons was 53.7%. This 16.7% pack out reduction is due to HLB impacts on the size 

and quality of fresh fruit produced from our groves. 

Improving pack outs to pre-HLB levels would increase our company’s fresh output by 

126,487 boxes, or 33.0%, without considering any potential yield increases. 

Industry Wide Impacts: 

The following is a summary of previously published and presented material supplemented 

with data from the 2012-13 fruit season. This report was prepared by Bob Norberg, 

Economist, Florida Citrus Mutual, Economic and Market Research Associates, January 

2014. It summarizes several previously published reports regarding the economics of the 

Florida Citrus Industry and the impacts of HLB on Florida Citrus economics. Data from 

the most recent seasons is used to generate supplemental impacts based on the logic 

from the previous reports. 

The three factors examined in this economic evaluation were: tree mortality rates, replanting rates, and fruit yields. Reducing the mortality, and/or increasing the replanting 

rate, and/or improving fruit yields all have positive economic impacts. The following 

chart shows the combined effects on crop size with gradual improvements to these 

factors over the next 10 years. Reducing the mortality rate from 4 to 3 percent in 10 

years, increasing the planting rate from 2 percent to 3 percent over 10 years, and raising 

yields 1 percent per year would generate a total of 140 million additional boxes of fruit 

over the forecast horizon. Those additional boxes generate direct, indirect and induced 

economic impacts that would not be generated without them. 
50

The following chart from the presentation concludes that those boxes are worth $7.4 

billion dollars during those ten years. Farm gate revenues would be enhanced by $1.1 

billion dollars. 

Further increases in pre-season fruit drop and reductions in fruit size were forecasted in 

the January 2014 estimate highlighted in the table above and are expected to continue 

that trend in future production estimates. The reduced yields have contributed to the 

smallest orange crop since the freeze impacted crop of 1989/90. It is uncertain, but 
51

likely, that these yield effects will be seen in future seasons without dramatic advances in 

production management practices, disease mitigation strategies, and solutions from the 

comprehensive research efforts. 

Update on Economic Impacts, January, 2014: 

Using the methodology previously established by Hodges and Spreen in their 2012 

analysis, an updated estimate of the annual economic impacts of HLB (and other 

calamities) can be calculated. Although unit FOB values have risen recently, these 

increases do not compensate for the loss of volumes since the value-added portion of 

total economic output is a significant factor and is directly correlated to volumes of 

orange juice case goods produced and distributed. 

The following table shows the losses to be $3.3 billion over the period from 2011/12 to 

2013/14 (January forecast) and 10,089 annual jobs. Combined with the losses estimated 

previously, losses to date from the 2006/07 season are $7.8 billion. 

The annual rate of losses in both economic output and jobs is accelerating from the 

previous estimate. The average annual loss was $908.2 million per year between 2006/07 

and 2010/11, while the annual loss rate for the period 2011/12 to 2013/14 is $1.1 billion. 

Currently total economic losses versus a non-HLB forecast is estimated to be $1.8 billion 

for the 2013/14 season based on the January crop forecast. 

Table 11: Impact of HLB to the Florida Citrus Industry the three Previous 

Seasons 

CROP SEASONS 2011/12 – 

2013/14 Non-HLB HLB Difference 

FOB REVENUES (MM) $7,356 $6,103 ($1,253) 

DIRECT ECONOMIC OUTPUT 

(MM) $7,088 $5873 ($855) 

TOTAL ECONOMIC OUTPUT $19,245 $16,096 ($3,329) 

ANNUAL EMPLOYMENT 58,865 48,776 (10,089) 

This information has not been updated to include the 17 percent production loss 

experienced during the 2014-15 citrus season. 
52

ESTIMATED REVENUES FOR THE SITES TO BE TREATED (166.20(b)(4)(ii) & 

(iii)) (166.20(b)(4)(ii) & (iii)) 

Florida accounts for: 

66 percent of the total U.S. value for oranges; 

65 percent of the total U.S. value for grapefruit. 

Florida currently ranks 1st in the U.S. in the value of both the production of oranges and 

grapefruit. 

Table 12: Florida Production Information, Oranges 

Florida Orange Production Information*

Season 

Total Bearing 

Acres 

Total 

Production 

(1000 boxes**)

Yield per Acre 

(total boxes) 

Price per 

Box 

Total 

On-Tree 

Value 

(Millions) 

2013-14 418,700 104,600 250 $7.58 $ 792.7 

2012-13 429,200 133,600 311 $7.43 $ 992.5 

2011-12 433,400 146,700 338 $9.92 $1,455.7 

2010-11 440,000 140,500 319 $8.41 $1,181.9 

2009-10 451,000 133,700 296 $6.96 $ 929.9 

5-Year 

Average 434,460 131,820 303 $8.06 $1,070.5 

* Source: Latest Available Florida Agricultural Statistics Service Citrus Summary, February 2015. 

** Box = 90 pounds 
53

Table 13: Florida Production Information, Grapefruit 

Florida Grapefruit Production Information*

Season 

Total Bearing 

Acres 

Total 

Production 

(X 1000 boxes)

Yield per Acre 

(total boxes) 

Price per 

Box 

Total 

On-Tree 

Value 

(Millions) 

2013-14 43,100 15,650 363 $6.44 $100.8 

2012-13 44,900 18,350 409 $6.47 $118.7 

2011-12 45,500 18,850 414 $7.17 $135.3 

2010-11 46,500 19,750 425 $6.72 $132.7 

2009-10 48,100 20,300 422 $7.50 $152.2 

5-Year 

Average 45,620 18,580 407 $6.86 $127.9 

* Source: Latest Available Florida Agricultural Statistics Service Citrus Summary, February 2015. 

** Box =85 pounds 

Economics associated with HLB and potential impacts of Section 18 bactericidal 

treatments: 

Processed Oranges Metrics (>90% of Florida citrus Crop) 

Table 14: Emergency Loss When compared to Baseline Florida Orange 

Production Prior to HLB. 

Factor 

Baseline (preHLB) 

2005-06 

2014-15 Harvest 

Season 

Change 

(%) 

Bearing Orange Acreage 529,241 acres 441,628 acres -16.6

Annual Production (million 

boxes) 147,700,000 96,800,000 -34.5

Yields per acre (90 lb. box) 301 boxes/acre 250 boxes/acre -17

Fruit Size (average 

number/box) 221 (2007-08) 244 10.4

Pre-harvest fruit drop 

(Valencia) 15 % (2007-08) 25% 10

Source: USDA, Florida Agricultural Statistics Service 
54

Expected Benefit Due to Bactericide Treatments: 

Expected impacts are calculated based on historic statistics and expected impacts of the 

proposed treatment on citrus productivity and fruit quality. The factors that are most 

likely to show improvement following season-long treatments as described in the petition 

are improvement in fruit size, retention of more fruit on tree, and return crop production 

increases. 

Reduction in Fruit Drop: One of the most devastating impacts of HLB is loss of yield 

through fruit drop just prior to harvest. The impacts of 20 percent and 50 percent 

reduction in fruit drop are calculated here. 

A 20 percent reduction in the current 25 percent fruit drop rate would restore five 

percent to harvested yield for the same crop load. This five percent retention adds 12.5 

boxes per acre and at $12.09, on-tree value of $151.13 per acre. That translates into 

5,520,350 boxes of fruit saved from falling to the ground with a 25 percent 

reduction in the amount of fruit drop, and this is valued at $66,743,240 for 

orange acreage per year. 

Using the same calculations for fifty percent reduction in fruit drop would restore 12.5 

percent to yield. This translates into 31.25 boxes per acre additional impact on yield and, 

at $12.09, is valued at $378 per acre per season. Calculated benefit across all 

orange acreage provides addition of 13,800,875 boxes of fruit, or an economic 

benefit of $166,935,384 to Florida orange growers per season. 

Similar calculations can also be made for other citrus varieties and for the added value of 

fresh market, especially for grapefruit. 

Improvement in Fruit Size: HLB has reduced fruit size, and tree health recovery is 

expected to improve fruit size. The impact is calculated for 20 percent reduction and 50 

percent reduction in fruit size. 

Comparison of fruit size shows 23 additional fruit were needed to fill a 90 pound box 

because of HLB in 2014-15. 

 

A 20 percent treatment improvement in fruit size would lead to 4.6 fewer fruit per box 

(239.4 fruit/box), across 250 boxes per acre, for a total of 1,150 pieces, and at 239.4 

fruit/box, this would add 4.8 boxes per acre. The per-acre economic benefit of a 20 

percent change in fruit size reduction would lead to 4.8 boxes x $12.09 (ontree price, 2014-15) or $58.03 per acre. Across all orange acreage (441,628 

acres), this benefit would be 2,119,814 additional boxes of oranges, and 

$25,628,556 per season for just this minor improvement to fruit size. 
55

A 50 percent treatment improvement in fruit size reduction would similarly lead to 11.5 

fewer fruit needed to fill a 90 pound box (232.5 fruit), across 250 boxes per acre, for a 

total of 2,875 pieces, and at 232.5 fruit/box, that improves yield by 12.4 boxes per acre. 

The per-acre economic benefit of a 50 percent change in fruit size reduction 

would therefore lead to 12.4 additional boxes x $12.09, or $149.50 per acre. 

Across all orange acreage, this would add 5,343,699 boxes of yield worth 

$64,605,321 per season at 2014-15 prices. 

Similar calculations could be developed for non-orange varieties, and additional value 

could be calculated for considering fresh fruit value-added for the portion of the crop that 

is marketed fresh. 

Both of the above improvements to orange yields are possible within the existing crop 

load of fruit, and reflect within season improvements that could occur with effective 

bactericidal treatment. Additional value could be obtained with expected improvements 

in fruit quality (brix/acid ration, pounds solids and flavor-impacting components. These 

benefits are not included in the size and fruit drop considerations above. 

Improved annual production (successive years): In crop years following application of 

the emergency treatments, it is expected that restored tree health would lead to higher 

fruit set and increased yields above and beyond the benefits discussed above. 

Calculations of the value of this for varying rates of improved yield are: 

Five percent yield response would increment yield of 250 boxes to 262.5 per acre, 

or an increase of $151.13 per acre. The all-orange impact would be 

5,520,350 boxes and $66,736.800 per season, the same benefit 

(additive) to the reduction in fruit drop. 

10 percent yield response would increment yield of 250 boxes by 25 boxes per 

acre, or $302.25. Across all orange acres, this 10% improvement in 

current tree productivity would add 11,040,700 boxes of fruit and an 

economic benefit of $133,482,063 per season. 

25 percent yield response nets 62.5 boxes per acre additional fruit, or $755.63 per 

acre benefit. Across all orange acreage, this estimated benefit is 27,601,750 

boxes, or when added to 2014-15 season yields, 124,401,750 boxes per season. 

The estimated economic value of the additional production improvement 

of 25 percent is $333,705,158 per season. 

The actual benefit can be approximated by adding the improvement in fruit drop 

reduction, increased fruit size, and finally the gain in production that treatment to 

reduce CLas titer in infected trees might bring. Again, these calculations represent 

oranges and the acreage currently dedicated to this major element of the industry. 

Similar composite benefits could be calculated. 
56

Using the minimal improvements calculated above (20% reduction in fruit drop, 

20% improvement in fruit size reduction and 5% production increase in new crop) 

the economic benefit calculated for the orange acreage in Florida is $66,743,240 + 

$25,628,556 + $66,736,800 or $159,108,596 per season. 

Finally, the treatment benefits would encourage new plantings, and the new 

benefit would then by be multiplied as new plantings come into production.