猝倒病幼苗出土后真叶未展开前,茎基部受病菌侵染呈细线状缢缩倒伏地面,苗床湿度大时在病菌或其附近苗床常密生白色絮状菌丝。立枯病出土幼苗茎基部受病菌侵染后变褐色、缢缩,茎叶萎垂枯死;稍大后幼苗白天萎蔫,夜间恢复,枯死后 Damping disease seedlings unearthed after the true leaves did not start before the base of the stems were infected by bacteria was thin line shy down on the ground, when the seedbed humidity in the germs or its nearby seedbed often dense white flocculent mycelium. Stem blight unearthed seedling stem base infected by pathogenic bacteria after brown, shrinking, withered leaves wilt; slightly larger seedlings wilting during the day, night recovery, after the dead