A ripe and juicy tomato is the perfect addition to a refreshing salad, a steaming bowl of soup or your favorite dinner dish. But tomatoes are also the prime targets of various insect pests, including the tomato leafminer. This tiny bug leaves white trails on the tomato plant's foliage and, if left untreated, can weaken and kill your tomato plants. Defend your tomato crop from the tomato leafminer with proper tomato care and an arsenal of organic and synthetic spray treatments.
Practice appropriate tomato care, as healthy tomato plants are less likely to be susceptible to diseases and pests. Rotate your crops, since repeatedly growing tomatoes in the same area can attract leafminers. Remove old tomato plants immediately. Avoid killing wasps in your garden, as several wasp species are natural predators of the tomato leafminer.
Spray down your tomato plants with a standard insecticidal soap, available from all garden stores and nurseries. Alternatively, make your own by mixing a quart of water with 2 tbsps. of liquid dish soap. Insecticidal soaps are sufficient for light infestations, and are typically gentler than using chemical-based insecticides.
Mist a commercially prepared insecticide intended for garden use onto your affected tomato plants if you have a heavy leafminer infestation. For best results, use an insecticide made with abamectin or cyromazine, to which leafminers are susceptible. Spray evenly on all exposed tomato vegetation according to the label's guidelines, as toxicity varies widely by brand.
Apply a spinosad-based spray, many of which are organic. Such sprays are ideal for those who want something more powerful than an insecticidal soap but don't want to apply chemical insecticides. Spinosad is a type of bacterium that's toxic to tomato leafminers but won't harm beneficial insects like lady beetles. Follow the spinosad spray's label, as bacterium concentrations vary by product.