Symptoms of a Tomato Pest

Leaf Damage

• Many tomato pests feed upon the foliage and stems of the plant. They leave behind ragged edges, holes or discolored spots. Hornworms may strip the leaves completely from the plant or chew through the tomato plant stems. Pests, such as mites and aphids, typically feed on the underside of the leaves so damage is not always immediately apparent. Inspect the underside of the leaves for visible insects or discolored areas that indicate pests are feeding on the plant.

Honeydew

• Sap-sucking pests, such as aphids, mites and whiteflies, exude a sticky substance called honeydew as they feed. It appears as a slick, shiny trail on the surface of the leaves and stems of affected plants. Ants harvest the honeydew so infested plants may have ants crawling over them. The honeydew also provides a breeding ground for sooty mold, which resembles dark spots or a fuzzy dark growth on the leaves. Sooty mold is typically a symptom of a major pest infestation on the plant.

Wilt

• Several causes of wilt exist, and not all are tied to pest problems. Heat and water stress are the most common causes, but severe stress from an insect infestation may also cause the leaves to droop and wilt on the tomato plant. Pest-caused wilt is usually accompanied by other symptoms, such as leaf damage. The pests weaken the plant so it cannot absorb the necessary energy from the sun and the leaves begin to wilt. Pests may also spread bacterial diseases or viruses that lead to wilt or plant dieback.

Fruit Damage

• Fruit damage from pests can quickly decimate your crop on plants that were previously healthy. Fruitworms bore into developing tomatoes and feed upon them. Hornworms feed upon unripe fruit so that fruits that were developing one day are gone the next. Stinkbugs pose another issue. Their feeding may completely destroy the tomato or may only appear as a green or yellow discoloration under the skin of the ripened tomato. They may also cause the fruit to become sunken in the area where the pests fed most heavily.