Pacific Pests, Pathogens and Weeds

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Summary

• Worldwide distribution. On beans, capsicum, cocoa, cucurbits, Caribbean pine. Minor fungal disease.
• Watery rot at ground level, spreading up the stem and into roots, causing wilts. On older plants, spots have ash-grey centres with dark margins. Black spots on seedling may girdle stems.
• Forms 'sclerotia' - balls of the fungus with black protective skin - giving stems sooty or charcoal look.
• Spread with movement of soil or plant debris containing sclerotia, and by seed. Sclerotia live up to 3 years.
• Cultural control: site nursery far from production areas; use pasteurised soil or soilless mixes; nursery hygiene; check seedlings for spots; in field, sterilise soil under tarps (30 days); 3-year rotation (maize, sorghum); avoid planting next to diseased beans; ensure rapid plant growth ( good tillage, nutrition, weed); collect and destroy trash after harvest.
• Chemical control: treat seed with thiram.