Lower leaves turn yellow. White cobwebby strands may cover stems and spread over the soil. Large patches suddenly wilt and die during the first few warm, humid days of spring. Plants pull up easily, with most of the roots and crown rotted away. Tiny, hard, yellow-brown and white pellets are found in the soil.
This disease is caused by a fungus (Sclerotium species) that occurs mostly in wet, poorly drained soil. The fungus attacks many kinds of plants, and causes the only serious disease of ajuga. The fungus enters the plant through the roots and crown and spreads into the stem, rotting it and causing the plant to wilt and die. In mild infections, new growth sometimes sprouts from buds that have not been killed. The tiny fungal pellets found in the soil survive winters and other unfavorable conditions to infect other plants. The fungus most frequently enters the garden originally in infested soil or plants, and lives for years in the soil.
Remove and destroy all infected plants. Do not replant in the area until the infected soil has either been removed, or drenched with a fungicide containing PCNB. To prevent crown rot, plant ajuga in well-drained soil. (For instructions on improving soil drainage, see Soil Types, Soil Structure, Groundwater.)
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