Status of soybean rust

In last week's sentinel plot teleconference, no new detections of soybean rust were reported in the South. Extensive survey and monitoring efforts have been carried out on soybean and kudzu plants and results suggest that the disease is still limited to Florida and southern Georgia. Computer models continue to show decreased northward movement of spores produced now in Florida compared with late April and early May.

Disease outlook

The observed development of soybean rust is slower than most people expected. However, it is too early to say the risk of having epidemics of this disease in the U.S. soybean production regions is diminished. The northern region is still within the window of having some outbreaks in the summer if new development of the disease is found during June in southern states. However, the risk is decreasing as the season is approaching July if no new development is found in Gulf Coast states (excluding Florida) and the Delta states. The key months for development of soybean rust in northern states are July and August.

If widespread outbreaks of the disease occur in the South before late July, Iowa is likely to see the disease in August, with level of severity depending on the weather that month.

The latest climate outlook by the National Oceanic and Atmospheric Administration (NOAA) shows an above-average temperature trend in the South for the months of June, July, and August, which is good news because high temperatures slow rust development. NOAA's outlook also shows a below-average precipitation trend for June, which should not be a concern since the disease may not reach these regions yet.