Soybean Rust Increasing in Texas and Louisiana! Should we be Concerned?

The recent rains in parts of Texas and Louisiana this month has provided a favourable environment for new soybean rust infections and spread. Since July 12, soybean rust has been found in 14 new counties in Texas (12 counties), Louisiana (1) and Mississippi (1).

Although many of these new infections are on kudzu, over the past few days soybean rust has been reported in commercial fields in Texas (three new counties - Jackson, Fort Bend, Austin) and in southwestern (Acadia Parish) and central (Rapides Parish and Avoyelles Parish) Louisiana.

Surveys over the past few days by Louisiana State University personnel have confirmed the spread of soybean rust to other commercial soybean fields in these parishes. Their survey included nine (9) fields in Rapides Parish, seven (7) of which were positive for ASR with incidence levels ranging from 1 to 30% and severity levels ranging from 5 to 40%. In Avoyelles Parish seven (7) fields were surveyed with three (3) being positive with incidence and severity levels being 5%. Based on surveys in Texas, these new northern areas are showing low incidence and severity of soybean rust.

The increase in Texas and Louisiana does not at this time change the risk to Ontario and Canadian soybean producers - which is low. Over the next week or so I would not be surprised to find more counties in Louisiana and Texas reporting soybean rust infections. The question will be "how severe and could these areas be a significant inoculum (spore) source for Canada and the US corn belt"?

Eventhough the US soybean rust situation is ahead of last year (Figures 1 and 2), time will only tell. The next two weeks or so will be critical. 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.

Figure 1. Soybean Rust distribution in the southern US as of July 20, 2007

Figure 2. Soybean rust distribution last year at this time (July 20, 2006) had not developed much in Louisiana and Texas

Related Links

• Ontario Soybean Growers

• US PIPE/SBR