Phytophthora Root and Crown Rot
Phytophthora spp. (P. cinnamomi, P. capsici, P. megasperma, P. citrophthora)
Overview
A group of devastating oomycete diseases that attack roots and crowns of a wide range of plants, causing rot, wilting, and death. Thrives in waterlogged soils and is one of the most important plant pathogens worldwide.
Symptoms
Dark, water-soaked lesions on roots and crown. Roots turn brown to black and become mushy. Wilting despite adequate soil moisture. Yellowing and stunting. Bark at the soil line may appear dark and waterlogged. Sudden collapse.
Environmental Conditions
Humid
Prevention
Ensure excellent soil drainage. Avoid overwatering. Plant on raised beds or mounds. Use resistant rootstocks. Avoid compacting soil around root zones. Use clean nursery stock.
Management
Improve drainage immediately. Apply phosphorous acid (phosphonate) products as a drench or foliar spray. Remove severely infected plants. Amend soil with organic matter. Avoid replanting susceptible species in the same location.