Watch out for aphids, pea weevils, thrips. Crop rotation is one of the best ways to avoid persistant problems. Don't grow peas in the same spot more than once every five years.
Plant resistant cultivars to avoid Fusarium wilt, which turns the plants yellow, then brown, and causes them to shrivel and die. Root rot fungi causes water-soaked areas or brown lesions to appear on the lower stems and roots. To avoid root rot, provide good fertility and good drainage for strong, rapid growth. Warm weather brings on powdery mildew, which covers the plant with a downy, white fungal coating. Sulfur dust if applied early can be effective or avoid powedry mildew by planting resistant culitvars.
Pods are ready to pick about three weeks after a plant blossoms, but check frequently to avoid harvesting late. You should harvest peas daily to catch them at their prime and to encourage vines to keep producing. Also, their taste and texture are much better if you prepare and eat them immediately after harvesting; the sugar in peas turns to starch within a few hours after picking.