My tomato leaves are covered with a sticky yellow substance. What is this?
Most likely you’re being visited by aphids, tiny insects whose main job is to suck the juice out of your tomato leaves. They give off this sticky substance, called honeydew, which attracts ants and causes mold to develop. Controlling these interlopers usually requires the use of an insecticidal soap spray. Consult your local nursery for the best option in your area.