UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASH I NGTON , D

. C

. 20460 

### AUG I' 8 2015

MEMORANDUM OFFICE OF CHEMICAL SAF ETY AND POLLUTIO N PREVENTIO N

SUBJECT: Qualitative Assessment of the Benefits of Hydrogen Cyanamide (014002) FROM:

THRU: Sunil Ratnayake , Biologi s t

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# A**~ ~**  Biological Analysis Branch (_

## ~,;**~** \ Stephen Smearman, Economist 

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# ~**~ ~~**  Economic Analysis Branch**~** Biological and Economic Analysis Division 7503P)
Arnet Jones, Chief 

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## .uf' Biological Analysis

### Bran~//~ l"fY Timothy Kiely , Chief (,}-- 

# V\.\.t · Economic Analysis Branch V 

# J**~** Biological and Economic Analysis Division (7503P) TO: Dana Friedman , Chemical Review Manager Pesticide Re-evaluation Division (7508P)

Peer Review Panel date: March 4, 2015

SUMMARY As part of the registration review process for hydrogen cyanamide , this document provides an assessment on the benefits and available alternatives for hydrogen cyanamide in U.S. fruit production. Hydrogen cyanamide is the only plant growth regulator (PGR) registered in the U.S. that is used to induce uniform bud break in fruits and berries in areas of the country where winter temperatures are not cold enough to induce it naturally. Uneven bud break can significantly reduce fruit production and lead to a lack of uniformity in fruit development , which hampers production practices , including pest management and harvest.

Page 1The economic benefits of u s ing h ydrogen cyanamide are s ignifi cant 

### in fruit producing areas where the critical number of chilling hours needed for bud break doe s not occur or i s not consistent. In the se areas , the critical chilling hours needed for bud break can be supplemented by the application of hydr ogen cyanamide. There is n o need for hydrogen cyanamide in th e areas where the number of required chilling hours are fulfill e d

. A lthough not regi s tered as pesticides, fertilizer based compounds s uc h as calcium ammonium nitrate are u sed in certain areas of Cali fornia for enhancing bud break. Accord in g to th e avai lable information, h ydrogen cyanamide is used annually on fruits and berries such as app le s, blueberries , cherries, grape s, kiwi fruit , peaches and plums. Use may be sporadic and depends on local conditions. Hydrogen cyanamide i s probably not a t yp ical input into production, with th e exception ofkiwifruit where about 30 percent of the crop i s treated. INTRODUCTION Bud dormancy in deciduous woody p ere nnial s is a compl ex proce ss that enabl es plants to survive l ong period s of adverse weather conditions. In temperate perennial sp ecies , a pe rio d of low temp e ratures , referred to as winter-chilling , is needed to release bud dormancy. This chilling requirement varies with the plant species , individual variety , and the area 

### in which they are grown. In the areas where the chilling temperatures are marginal , h ydro gen cyanarnide is applied to supplement the n eeded chi lli ng hours to e n sure uniform bud break. Other plant growth regulators , such as auxins , gibbere llin s, and cytokinins, are used for purposes s uch as to thin blo ssoms or to improve fruit s iz e , quality as well as to enhance fruit ripening. T hey are not us e d to promote uniform bud bre ak.
Use of Hydrogen Cyanamide In fruit crops such as apples, blueberries , grapes, c he rri es , peaches and kiwifruit a minimum number of c hillin g hours are needed for uniform bud break an d a hi gh er y ield

. For exam ple , a study conducted in the southern and central parts of the San Joaquin valley in C alifornia found that 600 hour s of temperatures at or below 7 ° C (45 °F) are ample for normal bud break in tabl e grapes (Dokoozlian , Undate d). A l so, less than 50 percent bud break has been observed in conditions with less than 200 chilling hours at a temperature of 3°C (37°F). (Dokoozlian et al., 1995). A separate study h as reported that the ' Ru sto n Red ' a variety of peach g rown in sou thern Alabama, require s 850 hour s of temperature s at or be low 45°F for a p e ak production. Unde r conditions where the numb er of chilling hours range from 700 to 750 hours at or below 45 °F, production cou ld d e cline 25 percent or more , and fruit q uality is diminished for thi s variety (Powell , 1999). The same stu dy reported that applications of h ydro gen cyanamide can effective ly replace 250 to 290 chilling hours in peach production (Powe ll ( 1999)

. The t iming of h yd ro gen cyanamide applications is c riti cal to avoid y ie ld reduction s of grapes. Late a pplication s of hydrogen cyanam ide ( less than fo ur weeks before bud break) may injure the buds and reduce the bud break ( Fidelibus et a l. , 201 2).
Data on the u se of plant growth regu lators in fruit and berry production are limite d

. While th e in fom 1atio n in Table I illu strates the use of hydroge n cyanamid e i n different states and u se s ites, it may s ubstan tia ll y understate the extent of u se. The information was comp il ed from three
Page 2different data sources and includes by u se s ite , the states with reported usage , the average total amount applied annually , the average app li cation rate , and th e average percent of the crop treated at the national level. Use of hydrogen cyanamide was confirmed in at least five states includin g California , Georgia, Nort h Carol ina, Texas and Washington and on at least eight crops. The University of Florida Agricultural Extension Service also recommends the use of hydrogen cyanamide on blueberries for bud break (U niv. of Florida IFES , 2007). How ever , no usage data are available in Florida. According to availab le data , the top three use sites of hydro gen cyanam ide, by amount of chemical used are: grapes, cherries, and kiwifruit grown in Ca lifornia. Other s ites with use include app les, b lueberries , figs, peaches and plums (Table I).

Table 1. Average Annual Hydrogen Cyanamide Usage by S tate and Site (2004-2012) Use Site States with Average Total Aver age Per Average Percent Crop Reported Usage* Amount Application Treated Natio na ll y Applied (lb) Rate (lb/Ac r e) Apples Cali fornia, 7,000 13.0 < 1% Washington Blueberries Californi a, Georgia, 2,000 8.2 <2.5% North Carol in a Cherries California 100,000 15.0 5% Grapes Ca lifornia 100,000 5.8 5% Figs** California 2,000 6.2 5% Kiwifruit Ca liforni a 20,000 16 .8 30% Peaches Texas (D) Plums Ca lifornia (D)



### .. Source: S L UA (E PA 2014). The data time penod was 2004-2012. Data sources include California Department of Pesticide Regulation (CDP R); USDA NASS and EPA proprietary Private Market Research. (D) =data from survey information that reponed usage but the information is not published to avoid di sclosure of practices on individual estab li shments. • These are the sta tes that hav e been su rveyed and reported use. Use could occur on label ed sites in other states that are not captured in survey data. Due to li mited data, there is some unc ertai nty of use for s ites in states with low r eported usage such as blueberries , peaches and plums. • •figs

- EPA found reported use even though there appears to be no registered label use for figs or emergency exemption requests for the use ofhydrogen cyanamide on figs in California. For apples , blueberries , cherries, grapes, kiwifruit, peaches and plums , hydrogen cyanamide is used in the dormant stage of the crop production cycle in states where consistently co ld temperature requirements may not be met to induce bud break. App les, blueberries , cherries , grapes and kiwifruit had consistent usage of hydrogen cyanamide from year to year over the 2004 to 2012 time period. Hydrogen cyanamide appears to be especially important for kiwifruit , per h aps because varieties adapted to warmer winters are not available as in other fruits and berries (Engin, 2010). Nearly 30 percent of the kiwifruit crop grown in Cali fornia is treated annually (Tab le 

### 1 ).
For fruit crops s uch as peac hes, plums and b lueberries grown in states other than Californi a and Washington , use may be more sporadic

. Although, it should be noted that BEAD 's data sources do not regularly survey for the use of growth regulators in other states and crops. Given the Page 3nature of use , however, it is likely that the need for the use of hydrogen cyanamide does not arise every year. However , in years and locations with atypically warm winters, u se would still be important in crop production areas. 

### Available Alternatives to Hydrogen Cyanamide Hydrogen cyanamide is used to induce bud break in U.S. fruit production. Other plant g rowth regulators s uch as auxins, gibberellins , cytokinins , and ethylene are used in the production of fruits and other crops to enhance the characteristics such as fruit quality , size , thinning, and fruit ripenin g (Dokoozlian , undated). Calcium ammonium nitrate (CAN-17) and other nitrogen based fertilizer compounds are being used in certain areas of California with marginal chilling temperatures for bud break in grapes and cherries (C line , 2003; Caprile , 2009). The effe ctiveness of the se material s varies depending on the application rate , application timing , weather conditions , adjuvant(s) included , and the planted variety (Weis , et al., 1998). These fertilizer based compounds are less likely to injure the crop than hydrogen cyanarnide and the y are able to compensate for fewer chilling hour s than hydro gen cyanamide (Capri le , 2009). However, they are not registered as plant growth regulators and crop profiles and extension recommendations in California and other s tate s do not specifically identify fertilizer based compounds as alternative treatments fo r bud-breaking. Usage data are unavailable for these products, so it is not known how widely they are use d. 

### Benefits of Us ing Hydrogen Cyanamide
Uneven bud break due to insufficient chilling hours can significantly reduce production and lead to lack of uniform1ty in fruit development , which hampers production practices , including pest management and harvest, and can lead to loss of y ield

. For example , as mentioned above, for Alabama peach growers that produce the Ruston Red variety , a yield lo ss of up to 25 percent could be realized if growers do not rec e ive the minimum number of chilling days for this variety ofpeach (Powe ll , 19 99). This is an indication of the benefits of using hydrogen cyanarnide for the Ruston Red and simi lar temperature sensitive peach varieties grown in sout hern climates. The potential yield loss in Alabama for the Ru ston Red peach variety indicates potential negative impacts to Ruston Red peach grower gross revenues. While yield lo ss data for all temperature sens iti ve fruits is scarce , growers of other temperature sensitive fruits that need a minimum number of chilling hours to induce bud break would probably realize simi lar b enefits to avoid crop loss due to variabl e temperature fluctuations in years when the minimum number of hours of chilling may not be reached. For example, with up to 30 percent of the kiwifruit crop treated annually with hydrogen cyanamide, it can be considered a critical use for kiwifruit growers in California. A yield lo ss of 25 percent on 30 percent of the crop area grown would be significant for kiwifruit growers and for kiwifruit production in the U.S. For fruit crops with a much larger number of acres in production nationally than kiwifruit, suc h as cherries and grapes , yie ld and quality lo sses on these crops can result in significant gross revenue impacts for cherry and grape growers. Based on the reported usage data in Tabl e 1 above , both cherries and grapes have on average, 5 percent of their crop treated with hydrogen cyanamide annually.

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### Conclusion The benefits of using hydrogen cyanamide are significant in fruit producing areas where the critical number of chilling hours needed for bud breaking during the dormant season is not realized. In these areas, the use of hydrogen cyanam ide can be used to supp lement the critical number of chilling hours needed to induce uniform bud break

. For growers of temperature sensitive varieties of tree and berry fruits, the niche u se of hydro ge n cyanamide to induce bud break can provide s ignificant benefits through improved quality and increased yield in areas w h ere the numb e r of chilling hours may not be sufficient for uniform bud break.
No other plant growth regu lators are registered for bud break. Some nitrogen-based fertilizer compo unds m ay also provide s imilar benefits and can be used as a non-pesticide alternative for hydrogen cyanarnide, at lea st in California. However, these products are not as effective as h ydroge n cyanamide and are not registered as p l ant growth regul ators.



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