Bacterial blight

Pseudomonas syringae

Bacterial blight is probably the most common and widespread foliar disease of minor concern to NY growers.  It is likely to be found in most soybean fields in any year with early- to mid-season periods of cool, wet weather.  Spread of the disease is usually halted as the season progresses and temperatures rise above 80F.  Symptoms include small, angular lesions that are initially translucent, but the centers of the lesions soon become necrotic and are surrounded by yellow-green halos.  Lesions are similar to those of bacterial pustule and brown spot.  Under favorable conditions, lesions may expand and coalesce, giving leaves a ragged appearance. 

The bacterium survives on crop residues and in seeds, and is splash dispersed. 

Though it is very common throughout NY, it causes minimal yield loss and requires no management recommendations. 

Foliar fungicides are not effective against this bacterial disease.