Alabama has reported that this week a commercial field in Baldwin County has been found with soybean rust. The incidence of the disease appears to be low, but it is believed to be the first commercial field reported infected this year.
The state first reported the disease in sentinel plots June 28. Ed Sikora, extension plant pathologist, Auburn University, notes that disease incidence in those polots is at 75 to 100% as of July 12.
Timing is now the issue with soybeans at R1 to R6 most susceptible to the disease. Growers in those areas are being advised to "consider applying a premix or tank mix of a strobilurin and triazole-type fungicide," according to the state report. The report notes that application at R3 would provide three weeks of protection and reduce damage from Cercospora blight and frogeye leaf spot.
Adds Sikora in his report: "Hurricane Dennis likely spread spores of soybean rust throughout Alabama and neighboring states. Symptoms of rust should appear five to 10 days after infection."