Management of Soybean Rust

There are no commercial soybean varieties with resistance to soybean rust at this time. Management of soybean rust will be with fungicides. All fungicides are not effective against soybean rust. With the arrival of soybean rust in the emergency registration of additional fungicides went into effect for three years (Table 1). In general the recommendation will be to make an application if infection is likely and a second application 10-21 days later if conditions are favorable for disease development. Late season sprays (after R5 to R6) have not been effective in South America unless they follow an earlier spray. The primary classes of fungicides that will be used for rust are the strobulurin, and triazole fungicides. Chlorothalonil (a nitrile fungicide) is also effective in protecting against rust but has less residual activity and may require more frequent applications than strobulurin and triazole fungicides. The triazole type fungicides have curative and preventative activity, whereas strobulurin fungicides and chorothalonil are preventative. If a soybean field has already been exposed to the rust fungus or active sporulation is observed, a triazole type fungicide is preferred since it may eradicate some infections. Because soybean rust may develop resistance to the triazole and strobilurin class of fungicides, it may be best to rotate the use of strobulurin and triazole fungicides or use mixtures. An example of rotation of chemical class would be to make the first spray with a triazole fungicide and the second spray with a strobilurin. If a third spray is required chlorothalonil might be the best option since it differs in mode of action from other materials. Mixtures of a triazole and strobulurin type fungicide will provide for longer residual control of the rust fungus as will higher rates of these materials.

Table 1. Fungicides for management of soybean rust.

Brand Name	Common Name	Fungicide Classa	Label Status	Action	Rate oz/acreb	FRAC MOA
Various	chorothalonil	nitrile	Full label	preventative	24.0-38.4	M4
Quadris	azoxystrobin	strobilurin	Full label	preventative	6.2-15.4	11
Headline	pyraclostrobin	strobilurin	Full label	preventative	6.0-12.0	11
Tilt, PropiMax, Bumper	propiconazole	triazole	Section 18	curative and preventative	4.0-8.0	3
Folicur	tebuconazole	triazole	Section 18	curative and preventative	3.0-4.0	3
Laredo	myclobutanil	triazole	Section 18	curative and preventative	4.0-8.0	3
Domark	tetraconazole	triazole	Section 18	curative and preventative	4.0-6.0	3
Stratego	propiconazole + trifloxystrobin	triazole + strobilurin	Section 18	curative and preventative	10.0	3+11
Quilt	propiconazole +azoxystrobin	triazole + strobilurin	Section 18	curative and preventative	14.0-20.0	3+11
Headline SBR	pyraclostrobin +tebuconazole	triazole + strobilurin	Section 18	curative and preventative	7.8	3+11

Labels and MSDS Sheets

U.S. Environmental Protection Agency
http://www.epa.gov/oppfead1/cb/csb_page/updates/soybean_rust.htm

CDMS
http://www.cdms.net/manuf/default.asp

BASF Ag Products
http://www.agproducts.basf.com/about/aboutgroup.asp

Bayer CropScience
http://www.bayercropscienceus.com/

Syngenta
http://www.syngentacropprotection.com/

Farm Saver
http://www.farmsaver.com/

Makhteshim
http://www.makhteshim.co.il/makhteshim/

Dow AgroSciences
http://www.dowagro.com/homepage/index.htm

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