Are Tomatoes Sensitive to 2,4-D Within a Certain Range?

2,4-D Overview

• 2,4-Dichlorophenoxyacetic acid, known as 2,4-D, is the most commonly used pesticide in the world. Released in 1946, this chemical is still used extensively in parks, agriculture, lakes, roadsides and lawns to control unwanted broad-leaved weeds. It is an auxin-type herbicide that affects protein synthesis as well as normal cell division. More than 1,000 products available in the United States contain 2,4-D. It can take the form of liquid, granules or dust.

Symptoms of 2,4-D Damage

• Gardeners may initially mistake 2,4-D damage for a tomato virus. One of the key differences is the fact that 2,4-D usually causes the leaves to thicken. Some leaves may exhibit a leathery appearance. In addition, the leaves become distorted. They may cup or roll up. Veins in the leaves thicken as well and become more parallel to the leaves. The growth of the entire plant becomes distorted and twisted. Damaged fruits are sometimes cat-faced and will ripen unevenly, or not ripen at all. If they do ripen, they're often harder to pull from the plant. Even minute amounts of drift will damage new growth, which will cause the tips and edges of the leaves to curl. Severe drift causes the plant to become brittle and the leaves may develop a whitish cast to the surface.

Recovery

• Tomato plants showing minor damage from 2,4-D pesticide drift may recover if growing conditions are good. Gardeners should make sure that the affected plants have plenty of water and nutrients. Although 2,4-D generally breaks down quickly in the environment, it's better not to consume the fruit of a plant immediately after chemical exposure.

Managing 2,4-D Exposure

• Never mulch tomato plants with lawn clippings unless you're absolutely certain that the lawn was not sprayed with herbicides. Avoid herbicide drift by following the label directions and applying herbicides on calm days when the temperature is below 85 degrees Fahrenheit. On windy days, herbicide drift may land on nontarget plants, porches, patio furniture, playground equipment, people and other surfaces. In fact, it's estimated that 95 to 98 percent of pesticides applied are dispersed onto nontarget surfaces. Pesticides may evaporate into the air on hot days, also affecting nontarget plants.