Healthy tomatoes withstand infestations better than unhealthy plants.

How to Apply Malathion to Tomatoes

by Marylee Gowans

A versatile insecticide, malathion controls several pests on tomato plants (Lycopersicon esculentum), including aphids, spider mites and stinkbugs. Malathion pesticide interferes with the nervous system of the pest, causing it to stop breathing. Malathion can be used up to 24 hours before harvesting but can harm beneficial insects. Improper use of malathion insecticide can cause discolored and wilted leaves on the tomato plant. It is extremely important to apply malathion properly to tomatoes.

Put on chemical-proof rubber gloves and safety glasses to protect yourself when working with insecticides. Wear a long-sleeved shirt, long pants, shoes and socks when applying this pesticide because it can be absorbed through the skin.

Pour 1 gallon of water in a clean bucket. Add 1/2 to 2 fluid ounces of malathion-containing insecticide to the water. This mixture will treat a 1,000- to 3,500-square-foot area.

Transfer the solution into a watering can or pump sprayer. Water the tomato foliage with the solution gently until the leaves are wet with the diluted insecticide.

Repeat the treatment up to four times per year allowing for at least five days between each treatment.

Items you will need

  • Chemical-proof rubber gloves
  • Safety goggles
  • Long-sleeved shirt, long pants, shoes and socks
  • Bucket
  • Watering can or pump sprayer


  • Don't treat tomatoes with more than 2 fluid ounces of the malathion-containing insecticide in one single application.


  • Follow the instructions on the insecticide carefully to avoid damaging your tomato plants.

About the Author

Marylee Gowans has written about gardening for both online and print publications. She attended the University of Akron, graduating with a Master of Fine Arts in creative writing. In 2009, she received master gardener certification from the Master Gardeners of Summit County, Ohio.

Photo Credits

  • Digital Vision./Digital Vision/Getty Images