Botrytis cinerea Reduce the humidity in the greenhouse. Space plants to insure good air circulation. Apply azoxystrobin, chlorothalonil, copper, fludioxonil, iprodione, or vinclozolin to protect healthy plants. Infected plants become very yellow. Vascular tissue in the corm turns dark brown to black.
Mature plants wilt and die.
Fusarium oxysporum f. sp. Discard infected plants. Leaf Spots Yellow or brown or gray circular spots develop on leaves and may have a zonate pattern within them. Small dark brown dots can be seen within the spots. Septoria , Gloeosporium , or Phyllosticta Water plants in a manner that does not wet the leaves.