The disease has become more widespread during the past several years, and now it can be found in most soybean growing areas in the Midwest. In Indiana, the incidence and severity of brown stem rot are usually higher in the northern portion of the state, especially in productive, well drained soils. It is considered to be one of the more serious soybean diseases in the Midwest. Losses depend upon the weather, cultivar, time of disease appearance, and strain of the causal fungus.
Damage is greatest when cool, wet weather during early pod fill is followed by dry weather.
Brown stem rot is usually first noticed when plants in patches or portions of a field prematurely die in mid-August or later. Premature plant death is not a diagnostic symptom and is frequently confused with early maturity or dry weather. Withered, brown leaves that remain attached to plants for several days after death usually indicate that plants were prematurely killed by some factor. Affected plants must be carefully examined to determine the cause. The most reliable symptom for the field diagnosis of brown stem rot is revealed by splitting the lower stem of affected plants.