Peas and beans: Pests, problems and diseases

Here are solutions to some common problems, pests and diseases found in peas and beans.


Greenfly and blackfly group on plant stems, especially at new growth tips, and suck the sap. Broad beans are specially vulnerable to blackfly in early to mid summer. Remove the insects by hand or hose them off leaves and shoots. Use an insecticidal soap to spray badly infected plants. Attract ladybirds, lacewings and hoverflies, who eat quantities of these pests.

Chocolate spot

Brown, chocolate-colour blotches on leaves and stems of broad beans are symptoms of chocolate spot fungus. Pull up and burn badly affected plants. This is a sign of overcrowding and lack of feeding. Prevent it in the future by following instructions for growing healthy plants and feed plants adequately.

Flowers don’t set

This usually occurs when the plant roots are dry. The flowers wilt and bees and other pollinating insects cannot reach the pollen. Water plants well in dry weather. Dig in plenty of organic matter before you plant beans so that moisture will he retained around the roots.

Halo blight

A problem of French and runner beans, the leaves have dark spots surrounded with a lighter colour halo. Spray diseased plants with a copper fungicide. In future check seeds and reject those that are blistered as this is a seed-borne disease. Buy only from a reputable seed supplier and replace your own if they caused the problem.

Pea and bean weevil

This beetle eats pea and bean leaves, leaving serrated edges. If young plants are attacked dust with derris; older plants will be little harmed.

Pea moth

Maggots inside the pods are the tiny caterpillars of the pea moth which lays its eggs on the flowers. In a severe attack use derris hut as this is also harmful to beneficial insects it is not an ideal answer. Look out for pheromone traps which commercial growers use.

Pea thrips

These live on pea foliage and leave a silvery trace behind.


Young plants are prone to attack by slugs. Protect with cut-off plastic bottles pushed into the ground around the plant.