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  3. Identify and Control Whiteflies


Whiteflies are tenacious, destructive pests that cause extensive damage to many types of plants, from tomatoes and sweet potatoes to roses and houseplants. Closely related to aphids and mealybugs, they get their name from the waxy, white powder that covers them. Whiteflies reproduce rapidly, especially during warm weather, and become extremely difficult to control once populations build. With warm conditions — outdoors or indoors — whiteflies reproduce year-round. Both adult whiteflies and immature nymphs damage plants.

Identification: Adult whiteflies have yellow-white, wedge-shaped bodies and white wings. About 1/10 inch long, they resemble small, white moths. The waxy powder on their wings and bodies is very similar to that of mealybugs. Depending on the species, wingless whitefly nymphs vary in color from translucent yellow-white to black.

Signs/Damage: Whiteflies congregate in large numbers on the undersides of leaves. They damage plants by piercing the tissue and sucking out vital plant sap. Like aphids and mealybugs, whiteflies excrete a sticky, sweet substance known as “honeydew," which often attracts nuisance ants and develops black sooty mold. Damaged leaves turn yellow or silvery and become dry or drop from plants. Vegetables and fruits become deformed or fail to develop. Heavily infested plants eventually die.

Control: Effective whitefly control starts at the earliest possible sign of the pest. If you've had whitefly problems in the past, don't wait. Apply preventive, proactive treatments before the pests reappear. GardenTech® brand offers several highly effective options to kill whiteflies by contact and keep protecting for up to three months. These products treat edibles* and ornamentals. Reapply as needed, but not more than once every seven days:

  • Sevin® Insect Killer Ready to Use simplifies targeted spot treatments of individual plants or small garden areas. Adjust the nozzle for a direct stream or a broad spray. Treat to cover all plant surfaces thoroughly, giving special attention to the undersides of leaves.
  • Sevin® Insect Killer Concentrate provides an easy, economical alternative for large-scale preventive and active whitefly treatment. Use with a pump-style sprayer that allows you to adjust your spray and easily reach the undersides of plant leaves. Treat to cover all plant surfaces thoroughly, including the undersides of leaves close to the ground.

Tip: Whitefly infestations take over houseplants and spread quickly. Remove and destroy heavily infested leaves. To treat houseplants, take them outside and spray all plant parts thoroughly, especially the undersides of leaves. Allow the spray to dry completely before bringing houseplants back inside.

* Always read product labels and follow the instructions carefully, including guidelines for pre-harvest intervals on edible crops.



"Ash whitefly - Siphoninus phillyreae" by Oregon State University is licensed under CC BY-SA 2.0

"Ash whitefly - Siphoninus phillyreae" by Oregon State University is licensed under CC BY-SA 2.0

"Trialeurodes vaporariorum" by Erin Finkle is licensed under CC BY 2.0 

"Whiteflies and their pupae on a leaf" by Scot Nelson licensed under CC BY 2.0 

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