- Whiteflies are tiny but easily recognized pests of tomato. They look like very small white moths. You'll likely see them fly up from the undersides of leaves in swarms whenever you touch the plant. Whiteflies feed on the sap inside the leaf, causing a white stippling. Hundreds of these tiny white spots can give the leaf a transparent appearance. Eventually, infested leaves will turn yellow or bronze and drop off the plant.
- Controlling whiteflies with insecticides is not easy, as they are highly mobile and occur on the undersides of leaves. A strong jet of water from the hose sprayed on the undersides of leaves on a regular basis can help wash immature whiteflies and eggs off the plant. Vacuuming adults off the plant with a hand-held vacuum can also help. These methods work best if completed in the morning before adults are warm enough to take flight.
- Adult leafminers are small black and yellow flies. You may never see their maggots as they feed in between the upper and lower leaf surfaces. As they chew their way through the leaf interior, they leave behind transparent, whitish spots or winding trails. Severe infestations can cause leaves to prematurely drop off the plant.
- Avoid the use of insecticides wherever possible as they can kill the natural predators responsible for the majority of leafminer control. Prune and destroy heavily infested branches. Remove and destroy crop litter at the end of the growing season to reduce overwintering sites. If insecticides are deemed necessary, the University of California recommends products containing the chemical spinosad.