Aphids are common pests that infest tomatoes. These annoying insects are capable of reproducing without having to mate. That fact coupled with each aphid's ability to produce up to 100 offspring in less than a week's time can wreak havoc on a tomato lover's garden. Take precautions to prevent these pests whenever possible. If your garden becomes infested, treat the problem immediately to ensure that valuable crops are not lost.
Place aphid traps around the garden area in late February. Peel off the sticky backing from one side of the trap. Attach the wooden skewer to the sticky side of the trap, allowing 3 to 4 inches of the skewer to stick out from the end of the trap. Peel the backing off the other side of the trap. Place the aphid trap at the end of the row so the bottom of the trap is just above ground level.
Inspect your tomato plants at least once a week for signs of aphids. Lift up the leaves and look underneath for insects that are long and somewhat angular and tan, red, brown, yellow or black in color. Aphids also secrete honeydew, which promotes the growth of black mold on the leaves of the tomato plant.
Prepare a solution of one part insecticidal soap with four parts of water in a garden sprayer. Use the agitation of the spray to mix the soap and water together until it is of an even consistency. Open the top of the sprayer and pour 2 or 3 inches of the soapy solution into a metal coffee can with a lid. Pump the handle up and down again to prime the sprayer.
Begin spraying at the top of the tomato plant using a medium spray. Drench all of the leaves of the tomato plant from top to bottom. Work in a circular pattern around the plant to be sure you reach the leaves that are in the back.
Lift the leaves of the tomato plant. Use a fine mist to gently spray the underside of the plant. Work from the top to the bottom on the front side of the tomato plant. Repeat the process on the back side of the tomato plant, lifting only one leaf at a time. Pick off any aphids you may see while you are doing this and place into the coffee can filled with insecticidal soap solution.
Spray the base of the plant. Stand 2 to 3 feet away from the tomato plant and aim the spray attachment at the stem using a thin stream of solution. Wet only the stem and the base; do not allow the solution to penetrate the soil.
Spray tomato plants daily for the first week. Spray every other day the second week. Spray the tomato plants weekly after the third week.