Black root rot of Japanese holly

Mar 5, 2011 7:24 AM

Crop: Ilex crenata (Japanese Holly)

Fungal causal agent: Thielaviopsis basicola

Symptoms: Yellowing of margins of the leaves, and can cause complete death of the plant, and typical blackened root rot.

Management: Black root rot is favored by wet conditions, weakened plants and cool temperatures ranging from 55-61 F. The fungus can survive for many years in soil in the presence or absence of susceptible plants. Resistant varieties available in other Ilex species. Clean plants and good sanitation is necessary. Plants with severe root infection (indicated by foliar symptoms; dieback) should be removed completely. Rest, can be treated with soil-drenching with fungicides in the class Thiophanate methyl.