Plant Health Problems
Diseases caused by Fungi:
Seed decay and root rot, various common soil fungi.
When the weather gets warm, pea plants with root rot appear yellow, spindly, and stunted. The stem near the ground is withered. The inside of the stem is not discolored. The disease is caused by a number of fungi which live in the soil and rot the roots and lower part of the stem during periods of very cool, wet weather.
To avoid this disease, plant peas as early as possible in hilled-up rows on well-drained soil. Control can be achieved by using a two-year rotation with nonsusceptible plants, such as corn, to prevent the buildup of pathogenic organisms.
Fusarium wilt, Fusarium sp.
The symptoms of wilt plants are very much like those of peas with root rot. The main differences are that the base of the stem of a wilt plant is not withered, and the inside of the stem shows discoloration.
Fungicides are ineffective in controlling this disease. Avoid planting peas in the same areas. There are varieties that are resistant to some strains of the fungus.
Blight, Ascochyta pisi.
This fungus disease is most prominent on the pods where it shows as dark or tan, sunken, circular pits. Small, black dots are scattered across the surface of spots. These spots may also be found on the leaves and stems. They are more purple on the stems. If young plants are attacked, they may be killed. The blight fungus is favored by cool, wet weather. The fungus survives in seed, old pea vines, and in the soil.
To avoid the disease, use clean seed, plant on well-drained soil, remove and discard old pea vines, and practice crop rotation.
Diseases caused by Viruses:
Mosaic, virus. Pea plants with mosaic are usually stunted, have light-colored mottled leaves, and set few and poor pods. Mosaic is caused by a virus which is carried by aphids. The virus also attacks clover.
To keep down mosaic, avoid planting peas near clover, remove pea plants which show leaf mottle, and control aphids.
Green cloverworm, Hypena scabra.
This caterpillar also feeds upon pea foliage. In some years, bean plants may be injured by inch long green wiggling caterpillars that riddle the leaves. Control is not often necessary.
Pea aphid, Acyrthosiphon pisi.
This is a green, long-legged aphid with prominent red eyes. It may infest the leaves and stems of peas in June. Pea aphids suck the sap and may stunt the crop, but have not been a serious pest. See Aphid fact sheet.
Pea weevil, Bruchus pisorum.
The adult of this insect is a brownish beetle, spotted with gray, dark brown and white, and measuring about 1/5" long. These beetles appear in the field about the time the peas are in blossom, and after light feeding on the foliage, the females lay their eggs on the surface of the newly formed pods. In about 12 days, the eggs hatch and the young larvae or grubs drill into the pods and work their way into the peas where they feed until fully grown. When they pupate, the insects often remain in the seeds until the following spring. There is only one generation each year, and this weevil does not breed in the dried seeds, as does the bean weevil.