Destroy badly infested leaves. Use only sterilzed soil. Improve air circulation. Spray plants with Copper Spray and repeat at 7 to 10 day intervals. Water the soil but not the leaves.
Stems have water-soaked spots, turn black and rot, causing the plants to collapse.
Crowns may be affected too. Remove and destroy infested plant parts immediately. Space plants far apart thus improving air circulation and control insects, such as Aphids that will spread the disease. Use only sterilized soil. Leaves turn yellow.