Silvery Spots on Tomato Plant Leaves

Planting

• Place tomato plants in the garden once spring soils have warmed to 60 degrees Fahrenheit, usually in April or May. Potential frost may stunt tomato growth and damage plants even before they begin to grow. Tomato plants must be well-spaced to ensure good air circulation, which lessens the risk of diseases and damage that may causes silvery spots on tomato leaves, among other symptoms. Place each tomato plant 24 to 36 inches apart, and provide a stake or support structure for each individual plant to improve fruit quality. Unstaked plants droop and drag on the ground, and as such are more prone to disease. You can also use wire cages to provide support. Proper planting of tomatoes establishes healthy growing conditions early, reducing the risk of diseases and pests that may compromise the fruit.

Fungus

• Septoria leaf spot creates white, gray or silver spots on tomato plant leaves that are lined with a black or brown edge. Powdery mildew, another fungal disease, also creates white-gray or silvery spots on the surface of leaves. Poor air circulation and moist soil conditions encourage fungal problems. Keep plants pruned of dead foliage, well-spaced and soil evenly moist -- not wet -- to promote good health and prevent fungus problems with tomato plants.

Pests

• Pests feed on tomato leaves and commonly turn foliage yellow, but both whiteflies and aphids leave behind a shiny residue that may look silvery in the light. The substance makes leaves shiny and feel sticky to the touch. Both whiteflies and aphids cause minimal damage, if any, to tomato fruits when present, though they may cause wilting and early leaf drop.

Control

• Control fungal problems on tomato leaves with fungicide. Prune away all affected leaves to prevent the spread of the problem and treat the remaining plant with sulfur sprays and other fungicidal treatments. Aphids and other pests may be wiped right off tomato plants with insecticidal soap, which won't damage the foliage or the fruits.