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Pea Pests

Generally, insects are not considered much of a problem in field pea crops in Alberta. Grasshopper and pea aphid are the only insects that could potentially cause economic damage, and both are more of a problem in hot, dry years. Blister beetle can occasionally be found in pea crops, but have not caused economic damage.

Grasshoppers

Damage

  • pea is not considered a preferred food of grasshopper, so they will normally attack other crops before moving into a pea field – with direct seeding of pea into a perennial forage stand, however, grasshopper can become a problem
  • grasshopper can attack at any growth stage, but cause the most damage in the seedling stage – grasshopper nymphs will attack seedlings on the edge of a field as they emerge from ditches and fence rows in the spring
  • economic threshold in pea is 10 grasshoppers per square metre

Control

  • early seeding can help pea plants outgrow the susceptible stage before grasshoppers emerge
  • no insecticides are registered for the control of grasshopper in pea

Pea Aphids

Damage

  • aphids overwinter as eggs in alfalfa and clovers, but more commonly blow in on warm southerly winds from the United States in June and early July
  • aphids suck the sap from pea plants and weaken them and can also spread viruses from infected plants to healthy ones
  • aphids reproduce more slowly under cooler conditions, where pea is generally grown in Alberta, so rarely cause problems
  • economic threshold for spraying in pea is 10 aphids per plant in tenth node to early flowering stages

Control

  • there are products registered to control pea aphids (refer to The Blue Book for appropriate insecticide options)
  • heavy winds and rain can minimize the damaging effects