Pacific Pests, Pathogens and Weeds

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Summary

• Worldwide distribution. On onions, a preferred host, but infestations also occur on onion relatives, beans, brassicas, carrot, cotton, cucurbits, legumes, papaya, pineapple, potato, tobacco, tomato and many ornamentals. At least 25 plant families are infested.
• Thrips pierce cells and suck up the contents, leaving white specks. They spread viruses.
• Spread is by flight from weeds, on air currents, and in the trade in bulbs. 
• Natural enemies. many predators.
• Cultural control: nurseries far from field crops; inspect transplants carefully; avoid planting new crops next to old, and not downwind; remove weeds and “volunteers”; mulch; use yellow sticky cards to check for thrips; collect plant trash and burn after harvest; 2-3-year rotations.
• Chemical control: soap, white or horticultural oils, neem or spinosad; note, thrips have developed resistance to many pesticides, which will kill natural enemies.