Diagnosing Stem Damage on Scarlet Runner Beans

Scarlet runner bean stems are being severed 12–36 inches above ground. This suggests a chewing insect (likely caterpillar or beetle larvae).

Organic Controls

Bt (Bacillus thuringiensis): biological control for caterpillars/worms.
Rotenone dust: broad‑spectrum organic insecticide. Apply at dusk; wash off early morning to protect bees.

Inspect plants at night with a flashlight to catch the culprit in action.

— Mack Jean, Master Gardener, Tennessee

Organic Gardens: Rose Bugs on Grape Vines: Japanese Beetles and Milky Spore; Aphid Control on African Violets: Non-Chemical Methods First; Nepenthes Pests: Thrips, Scale, and Red Spot Fungus on ventricosa/sibuyanensis; Why Your Akebia Quinata (Chocolate Vine) Isn't Flowering; Top Survival Crops for Disaster Preparedness: Fast, Seed-Saving, and Resilient; Cutworms or Voles? Diagnosing Stem Damage in Pole Beans; Woodlice Eating Bean Sprouts: Pot Culture and Intercropping; Flea Beetle Damage on Green Beans: Identification and Control; Sugar-Based Organic Lawn Program: Complete Guide; Growing Beans: Pole and Bush Varieties for a Bountiful Harvest

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