The most common cause of post-emergence damping off throughout the world Rhizoctonia invades the cotton plant at soil level. In wet conditions, the lesion can extend upwards several centimeters from the soil line. Excessive soil moisture predisposes cotton seedling to infection by reducing their rate of growth.
Infection occurs over a wide range of soil moisture levels.
Root Rot Pythium infects the seed and radical, causing seed rot and pre-emergence damping off. At later stages of plant development, Pythium may cause stunting and chlorosis. Pythium is most damaging to cotton seedlings at low temperatures and high soil moisture content. Degree of infestation is also impacted by soil texture and organic matter. Black Root Thielaviopsis is most prevalent in Texas, Mississippi, New Mexico, and the San Joaquin Valley area of California.