Controlling Whiteflies in Your Garden – Marin Independent Journal

Whiteflies: The Tiny Pests Causing Big Problems in Gardens

If you’ve ever encountered a cloud of white particles when brushing a plant or noticed your veggies turning a silvery gray, you may have come face to face with whiteflies. These tiny pests, more closely related to aphids and scale insects than actual flies, can wreak havoc on a variety of plants, including garden vegetables, ornamentals, and even cacti.

With over 1,300 species of whiteflies known to feed on around 500 different host plants, these pests are a common nuisance for gardeners. Ranging in size from 1/12th to 1/20th of an inch, whiteflies may be small, but their damage can be significant. They feed on plant juices, causing yellowing leaves, stem blanching, and chlorotic spots. They also leave behind a sticky substance called honeydew, which can lead to the growth of black sooty mold and attract ants.

Managing whiteflies can be challenging, as they reproduce quickly and hide on the undersides of leaves. Prevention is key, but there are several strategies you can use to control infestations. These include spraying the undersides of leaves with water to wash off the pests, vacuuming them up in the early morning, using yellow sticky traps, and encouraging natural predators like parasitic wasps, birds, and ladybugs.

Chemical treatments are less effective against whiteflies, but insecticidal soaps, horticultural oils, and the chemical imidacloprid can be used with caution. It’s important to protect beneficial insects like bees when using pesticides. Pruning infested plant parts, controlling ants, and using reflective mulch can also help manage whitefly populations.

While whiteflies play a role in some ecosystems, they can be a nuisance in gardens. Taking proactive steps to prevent and control infestations can help protect your plants and keep your garden healthy. For more gardening tips and information, visit the University of California Marin Master Gardeners website.