Scab causes neck and stem rot. Pale yellow, watersoaked, circular lesions appear on the corms. They later turn brown then black and become sunken with a raised brittle margin. Spots may exude a gummy substance. Early symptoms on the leaves are reddish specks. As the disease progresses, the neck rots and the plant falls over. Discard diseased corms and don't plant in infected soil. No chemical control is listed.
Corm rot causes yellow leaves and stem collapse. Infected corms rot in storage. Avoid wounding corms and store them in a dry cellar at temperatures between 35 and 45 degrees. Cure corms for 10 to 15 minutes at 85 degrees. This disease caused by Fusarium orthoceras is controlled with benomyl and is also called wilt.
Storage rot caused by Penicillium gladioli forms blue mold corms. Use benomyl to control the problem.