Insect of the Month - Tarnished Plant Bugs

  Hort Snacks - May 2018
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 Causal Agent: Lygus lineolaris (& other species)

Crops Affected: Wide host range – many fruit, vegetable, field and forage crops and weed species

Life Cycle:

  • One of the most serious & widespread of strawberry pests
  • Sucking insects that pierce flower buds, blossoms, and developing fruits and plant parts
  • Adult has distinctive triangle or “V” mark on back; strong fliers
  • Overwinter as adults in leaf litter or under debris and migrate into fields in spring or fall to feed on weeds and crops
  • Lay eggs in spring in plant tissues
  • Young (nymph) resemble aphids without cornicles (tail pipes) and move more quickly; hatch & feed on developing blossoms & fruit
    • Nymphs feed through May and June, maturing in late June to early July
    • Most of damage results from nymphal feeding
  • Adults feed on developing fruit
    • Leave with fruiting complete in June or July (strawberries)
    • May have 2-3 generations per year (depending on season length)
  • Due to the fact that day neutral strawberries are flowering when TPB numbers are high, damage potential is higher
Tarnished Plant Bug - adult
Tarnished Plant Bug damage
Tarnished Plant Bug damage - catfacing
Photos by Robert Spencer

  • Presence of insect life stages
  • Range of damage to vegetables: reduced fruit set in bean, pepper & eggplant; blemishes on tomato fruit; necrotic spots on florets & curd of broccoli, cauliflower and heads of lettuce; dead leaves on potatoes; foliar injury on cucumbers; gummosis on zucchini
  • Raspberries (most damage occurs after petal fall)
    • Feeding on flower blossoms & developing fruit = crumbly berry
    • Reduced plant vigour
  • Saskatoon berries
    • Yellow, aborting flower buds; droplets of brownish liquid may exude from newly pierced buds
    • Fruit deformation
  • Strawberries
    • Feeding by nymphs – Nubbins or deformed fruit / Apical seediness
    • Adult feeding – CATFACING
      NOTE: Catfacing can be caused by other factors, producing identical symptoms
  • Feeding also reduces plant vigour due to removal of plant nutrients
  • Be aware of neighbouring crops that might be a host or that might release a large number of adults when cut (e.g. alfalfa or canola)
  • Crop should be monitored for the number of nymphs in flower blossoms. Sweep nets can determine adult numbers
    • Scout the field perimeter in new fields or entire established fields
    • Start monitoring in overwintered fields when they are uncovered onward
  • Blossoms may be sampled from across the field, counting the number of nymphs and adults present
    • Survey the field from pre-bloom until green fruit stage (strawberries)
      • Tap plants or shake fruit clusters over a non-metallic pie plate
      • Count the number of nymphs per 100 clusters
  • Strawberry Economic threshold = 1 nymph or adult per 8 blossoms
  • Careful monitoring of TPB populations
  • Remove weeds (especially leguminous species)
  • Ensure alternate host crops are not planted too close (e.g. alfalfa)
  • Make careful and timely chemical control applications
    • Controls are available with application timing restrictions
    • Chemical control is challenging due to continuous flowering and fruiting of day neutral strawberries
    • Only products with short Pre-Harvest Intervals (PHI) may be used
    • Do not apply products when bees are actively working
Tarnished Plant Bug – A Major Pest of Strawberry – OMAFRA article

Tarnished Plant Bug – Video
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on April 26, 2018.