Integrated Crop Management

Fungicides for soybean: Considerations for 2008

Risk of soybean rust for 2008

Even though soybean rust was found in Iowa in 2007, the pathogen cannot survive in Iowa. The pathogen can only survive on living plant tissue of susceptible plants. Likely overwintering sites are in Florida and Texas on kudzu and in Central America on legumes, such as jicama and soybean. This means the risk of rust getting to Iowa in 2008 is the same as it was at the beginning of past years. For rust to get to Iowa, it will need to successfully overwinter somewhere in the South and retrace the path it traveled in 2007.

What happens if soybean rust gets to Iowa earlier in the season?

There are no resistant cultivars available for soybean rust and there may not be for several years. The main management strategy is well-timed foliar fungicide applications. In 2007, several fungicides that received Section 18 labels for soybean rust in 2004 were granted Section 3 labels for use on soybean. Also, a few additional Section 18 fungicides were approved by the EPA in 2007. Section 18 labels for Folicur® and Headline® SBR expired in November, so they will need to be renewed if these fungicides will be available in Iowa in 2008. Below are two lists of fungicides available (or potentially available) for soybean rust.

Table 1. Available fungicides for management of soybean rust in Iowa.

Active Ingredient Product (Trade Name) Section 18 Status in Iowa Section 3 Registration Status
azoxystrobin Quadris Registered
azoxystrobin + propiconazole Quilt Registered
chlorothalonil Bravo, Echo, Equus Registered
myclobutanil Laredo EC Registered
propiconazole Tilt, Bumper Registered
propiconazole + trifloxystrobin Stratego Registered
pyraclostrobin Headline Registered
tetraconazole Domark Registered
azoxystrobin + cyproconazole Quadris Xtra Expires 3/31/09 Decision expected in early 2008
cyproconazole Alto Expires 3/31/09 Decision expected in early 2008
flusilazole Punch Expires 6/15/10 Decision expected in 2009
flutriafol Topguard Expires 2/12/10 Decision expected in early 2009
metconazole Caramba Expires 4/19/09 Decision expected in late 2008

Table 2. Fungicides that may be available for management of soybean rust pending a decision by the EPA.

Active Ingredient Product (Trade Name) Section 18 Status in Iowa Section 3 Registration Status
tebuconazole Folicur, Orius, Uppercut Expired* Decision expected in late 2008
tebuconazole + pyraclostrobin Headline SBR Expired* Registrant has not made a decision on the fate of this product.
famoxadone + flusilazole Charisma Pending Decision expected in 2008
prothioconazole Not available Pending Decision expected in early 2008
tebuconazole + trifloxystrobin Absolute None Decision expected in early 2008

*Section 18 label may be extended.

Daren Mueller is an extension plant pathologist with the Iowa State University Corn and Soybean Initiative and the Pest Management and the Environment Program.

This article originally appeared on page 288 of the IC-498(26) -- December 10, 2007 issue.


Source URL:
http://www.ipm.iastate.edu/ipm/icm//ipm/icm/2007/12-10/fungicides.html