Michigan State University Extension
Ornamental Plants plus Version 2.0 - 00000742
01/01/98
Yellow rot causes yellowish water-soaked stripes extending downward from the leaf tips. The stripes turn brown and the leaves die. Infected flower stalks appear water- soaked and become brown and shriveled. The bulbs will decay. A stem cross section shows masses of yellowish slime, oozing from the conducting tissue. Destroy infected plants.
Black slime causes yellowish leaves which wither and are easily detached from the bulbs. The bulbs disintegrate. Avoid infested soil.
Root rot causes dwarfed plants that flower poorly. The roots are decayed and the basal plate destroyed. Discard infested bulbs. No chemical control is listed for this disease caused by a Fusarium sp. fungus.
Gray mold causes discolored leaves which become shrunken, rotted and covered with gray mold. The blossoms are rotted in cold wet weather. Don't work in the plants when the soil is wet. Destroy diseased blossoms. The disease is caused by Botrytis cinerea.
Mosaic causes blue green mottling, streaking or blotching of leaves. The few flowers produced wilt. Destroy infected plants and control insects which spread the disease.