July 22, 2005
Source: United States Department of Agriculture (USDA), 22 Jul 2005

National soybean rust update 22 Jul 2005

The first occurrence of Asian soybean rust (ASR) in Mississippi in 2005 was reported from soybean samples collected on 13 July from a sentinel plot in George County. 3 counties in Georgia have also reported ASR. The latest is Decatur County (on kudzu); Tift County, reported ASR on soybean, while the Seminole County report was on volunteer soybeans which have since been destroyed. 8 counties in Florida have now reported soybean rust on kudzu with 2 reports from soybean. The newest report is from soybean grown in a sentinel plot in Escambia County near some production fields. In Alabama, ASR has now been reported on soybeans from a sentinel plot and a commercial soybean field. This was the first report from a commercial soybean field in 2005. Intensive scouting is continuing wherever soybean is grown. It is expected that more counties in the south will report ASR over the next week from spore deposition from prior storms.

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According to XB Yang (Iowa State University) and Saitao Pan (St Louis University), computer models show an increase in the transport of ASR spores from known sources in the south up to northern regions, but the
higher concentration of spores being predicted is still limited to Florida, Georgia, Alabama, southern South Carolina, and Mississippi. Our analysis of environmental conditions using the past month's precipitation data
indicates that moisture conditions have been favorable for rust development in the Gulf Coastal states, but not favorable in the northern production regions because of prevailing dry conditions.

The newest soybean rust detections are within the regions our models predicted for both high concentration of spores and favorable conditions for disease development. For the next weeks, modeling results show increasingly favorable conditions for rust to establish in the northern regions of gulf coastal states, up to Kentucky and Tennessee. Conditions are not favorable in northern states, except in southern Illinois and Missouri.

Due to the limited rust activities in the south, there is a low chance that serious epidemics will develop at this stage. For most of the North Central region, considering the present scenario, it is unlikely that ASR will appear in fields before mid-August. If ASR is found around mid-August, the disease is unlikely to cause any significant damage. - Mod.DH]

[see also in the archive:
Soybean rust, Asian strain - USA (multistate)(03) 20050714.2005
Soybean rust, Asian strain - USA (multistate)(02): Florida 20050708.1938
Soybean rust, Asian strain - USA (multistate) 20050702.1868
Soybean rust, Asian strain - USA (LA) 20050624.1769
Soybean rust, Asian strain - USA (FL) (02) 20050620.1731
Soybean rust, Asian strain - Americas: alert 20050528.1476
Soybean rust, Asian strain - USA (GA) 20050505.1245
Soybean rust, Asian strain - USA (GA) 20050429.1196
Soybean rust, Asian strain - USA (FL): 1st report 2005 20050309.0693]