Soybean Rust Increasing in Texas, Louisiana, Arkansas and Now Oklahoma!

As I mentioned in my last update two weeks ago the weather conditions in the southern US especially in Louisiana and Texas have been very favourable for soybean rust development and that most likely we would see more infected areas. That has been the case and a good example is what occurred on August 9th in Louisiana where Asian soybean rust was reported on soybeans (commercial fields and/or sentinel plots) in 6 new counties (Jefferson Davis, Allen, Evangeline, Concordia, East Baton Rouge and Bossier Parishes). On August 8th, soybean rust was reported on soybeans in Tulsa County, Oklahoma, marking the farthest north the disease has been found in 2007.

In 2007, rust has now been reported in 24 counties in Texas (23 soybeans), five counties in Alabama (one soybean), four counties in Arkansas (soybean), 11 counties in Florida (two soybean), five counties in Georgia (all kudzu), 13 parishes in Louisiana (12 soybean), one county in Mississippi (kudzu), and five counties in Oklahoma(soybean). There also has been one account of soybean rust earlier this year in Mexico in the state of Veracruz on yam bean (Pachyrhizus erosus). Weather conditions have been favorable for rust development in many parts of the south and to the states just north of the gulf states. Soybean rust monitoring continues throughout the soybean growing areas in Ontario and the US.

The increase in Texas, Louisiana and Oklahoma does not at this time change the risk to Ontario and Canadian soybean producers. We will continue to see more counties and possible new states reporting soybean rust infections over the next week or so. The question remains "how severe and could these areas be a significant inoculum (spore) source for Canada and the US corn belt"? The US soybean rust situation is ahead of last year (Figures 1 and 2) but again time is on our time.

Figure 1. Soybean rust in Louisiana, Texas, Oklahoma and Arkansas continues

Figure 2 - Soybean rust distribution last year at this time (Aug 10, 2006) had not
developed in Arkansas and Oklahoma or much in Texas

One area that needs to be taken into consideration is the time it takes for the disease to develop in a new area. For instance if spores were to be deposited into Ontario over the next week or so and the environmental conditions were favourable it would still take 10-14 days for the disease to become visible. Even then it would take another two or more weeks to develop further. By this time the majority of Ontario's soybean crop would be nearing maturity.

Updates will continue to be provided through the Crop Pest Ontario, the Ontario Soybean Growers website and the US PIPE/SBR website. Alerts will also be posted through the CropLine if things change rapidly.

Funding for many of the Ontario soybean rust projects was provided in part through the Canada-Ontario Research and Development (CORD) Program administered by the Agricultural Adaptation Council as well as the AAFC Pest Management Centre, the Ontario Soybean Growers and the Ontario Soybean Rust Coalition.

Related Links

• Ontario Soybean Growers

• US PIPE/SBR