红腐病常在棉花出苗15天后发生，严重威胁棉花全苗。壮苗。症状：幼茎被害时，导管变成暗褐色，近土面的幼茎基部先产生黄褐色的条状病斑，后变成黑褐色腐烂，土面以下的幼茎或幼根被侵染时则变成肥大的根、茎，随后亦变成黑褐色腐烂。子叶和真叶被害时，症状自边缘往内发展． Red rot often occurs 15 days after emergence of cotton, a serious threat to cotton seedlings. Strong seedlings. Symptoms: When the young stems are damaged, the catheter becomes dark brown, near the surface of the young stem base produces yellow-brown stripe lesions, which turn into dark brown decay, soil surface below the young stems or young roots are infected It turns into a hypertrophy root and stem, then turns into dark brown decay. When cotyledons and true leaves are killed, symptoms develop from the periphery.