Castor Bean Diseases
Castor bean plants (Ricinus communis) are herbaceous perennials belonging to the spurge family (Euphorbiaceae). Native to the Middle East and Africa, they typically grow well in USDA hardiness zones 9 to 11. Castor bean plants are susceptible to a few common plant diseases. Does this Spark an idea?
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Types
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Castor bean plants occasionally suffer from bacterial leaf spot diseases and Alternaria leaf spot disease (Alternaria brassicae). These plant diseases cause small yellow lesions to form on the leaves.
Effects
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Alternaria and bacterial leaf spot diseases often cause premature leaf drop and stunted plant growth. Severe cases cause the castor bean plants to collapse and die.
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Factors
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Castor bean plant diseases are more prevalent during warm, wet weather. Alternaria leaf spot occurs more often in plants with nitrogen deficiencies.
Control
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Regular applications of fungicide help control castor bean diseases in humid climates. Gardeners should use only disease-free seeds.
Other Problems
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Castor bean plants sometimes suffer from cutworm, corn earworm, thrip or spider mite infestations. European corn borers, leaf miners and grasshoppers are also occasional problems.
Warnings
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The castor bean seed capsules contain poisonous seeds. The foliage triggers allergic skin reactions in some people.
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