V1.0; last modified 12/21/10 Page 1 of 2 

APHIS-Approved Fungicides for Elsinoë australis, 

Causal Agent of Sweet Orange Scab (SOS)

For Use in Plant Nurseries

Citrus spp. and Fortunella spp. nursery stock from SOS quarantined areas can move with a 

limited permit interstate to non-commercial citrus-producing States provided that all conditions 

of the SOS Federal Order are met, including scheduled nursery inspections and pre-shipment 

inspections to verify absence of SOS, and the plants are treated with an APHIS-approved 

fungicide.

Fungicides registered for managing Elsinoë australis, the causal organism of SOS, have different 

modes of action. Although all fungicides work best when applied prior to disease onset, some 

offer protection only when applied pre-infection (protectant), while others offer some level of 

control when applied post-infection.

• Copper-based active ingredient products such as Kocide, TopCop, and others not listed,

are examples of fungicides that prevent spore germination and strictly provide a

protectant effect. They are not effective at preventing infection if plant tissues are

infected with the fungus prior to application as they adhere to plant tissues by means of

surfactants and adjuvants.

• Strobilurin active ingredient products such as Gem and Headline prevent fungal spore

germination and consequently host penetration, but provide little effect after tissues are

colonized. These products have trans-laminar, albeit systemic, movement within plant

tissues.

• As a general rule, products with triazole active ingredients prevent further development

of established infections and may also provide some anti-sporulant activity. Enable,

BannerMaxx, Bumper EC, Orbit, ProCon-Z and Tilt are expected to provide this effect to

varying degrees.

• Mixing strobilurin and triazole products, or using a premix product, provides the greatest

control potential due to the dual mode of actions consisting of enhanced residual activity

from strobilurins, and greater in-plant movement from triazoles.
V1.0; last modified 12/21/10 Page 2 of 2 

Table 1. Fungicides for managing Sweet Orange Scab on Citrus Nursery Stock

Active Ingredient Product Name Company FRAC3

Group

Re-entry 

Interval

(hours)

Copper hydroxide Kocide 3000 1,2 Dupont M1 24

Copper sulfate + sulfur TopCop w/sulfur2 Stoller M1+M2 24

Fenbuconazole Enable2 Dow 3 12

Propiconazole BannerMaxx Syngenta 3 12

Propiconazole Bumper EC Makhteshim 3 12

Propiconazole Orbit Syngenta 3 12

Propiconazole ProCon-Z Loveland 3 12

Propiconazole Tilt Syngenta 3 12

Trifloxystrobin Gem2 Bayer 11 12

Pyraclostrobin Headline2 BASF 11 12

1

Phytotoxicity may occur on young tender flush in greenhouses and shade houses.

2

Specifically lists control of Elsinoë fawcettii, causal organism of Citrus scab on the label. 

3

FRAC, Fungicide Resistance Action Committee

Note: Table is used for illustrative purposes only and list of products is not exhaustive. Product 

inclusion does not infer endorsement by USDA APHIS. Always read and follow label 

instructions. The products listed are registered for use in the following citrus producing states: 

AL, AZ, CA, FL, GA, LA, MS, TX

References:

USDA APHIS PPQ. 2010. Survey and Treatment of Nurseries from

Known Sweet Orange Scab (Elsinoë australis) Infested Areas. Personal communication, C. 

Hollingworth to L. Evans-Goldner, on file with USDA APHIS PPQ EDP.

USDA APHIS PPQ, December 2010. Federal Domestic Quarantine Order. Elsinoë australis 

Bitanc. & Jenkins, Causal Agent of Sweet Orange Scab (SOS). 

http://www.aphis.usda.gov/plant_health/plant_pest_info/citrus/sweet_orange.shtml