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Brown Spot

Source: Gary Bergstrom
Source: U. of Tennessee
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Septoria glycines
Brown spot is very common and widespread throughout NY, and can often be found in most soybean production fields each year.   The disease is favored by warm, humid conditions.  Symptoms include irregularly shaped brown lesions of varying sizes that quickly become necrotic spots with yellow margins, which may expand and coalesce.  Lesions usually develop on the lower leaves and move upward through the canopy.  In a severe epidemic, premature defoliation may occur and may result in up to 15% yield loss.  However, severe epidemics are rare in NY and fungicide applications for management may not be cost effective.      


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