How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

The external surfaces and internal tissues of infected roots are water-soaked and dark in color and are rotted. Leaves, especially older ones, first turn purple-red and later yellow and then wilt. The plant may be stunted, and with time, the entire plant wilts. The stem near the soil line may turn black and become soft.

COMMENTS ON THE DISEASE

Phytophthora root rot occurs on cauliflower, Brussels sprouts, and other crucifers in the coastal areas. It usually occurs only if cole crops are planted in poorly draining, fine-textured soils that are kept overly wet. Hence, root rot is most often found at low spots in the field or at the tail-end of irrigation runs. The fungus is a soil inhabitant that survives in the soil for long periods.

MANAGEMENT

Control is difficult, but soil management that improves drainage, such as planting high, well-drained beds, and carefully irrigating to avoid prolonged saturation of the soil, will reduce chances of infection. Because drought stress also makes plants susceptible to Phytophthora, ensure an even supply of moisture without major fluctuations to help suppress disease development. If a field has a history of Phytophthora disease problems, a treatment can be applied at planting.

PUBLICATION

UC IPM Pest Management Guidelines: Cole Crops
UC ANR Publication 3442
Diseases
S. T. Koike, UC Cooperative Extension, Monterey County
K. V. Subbarao, Plant Pathology,UC Davis, Salinas

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