Phaseolus vulgaris · Annual
Slugs and snails: Use physical barriers like copper tape or beer traps, and hand-pick at night.
Black bean aphid: Encourage natural predators like ladybirds or use a strong jet of water to dislodge them.
Runner and French bean rust: Improve air circulation by thinning plants and remove heavily infected leaves to reduce spread.
Bean seed fly: Sow seeds later in the season when soil is warmer or use fine mesh covers to exclude flies.
Powdery mildew: Water at the base to keep foliage dry and choose resistant varieties where possible.