Warren County Agriculture

In late summer, two common late-season pests often need control on homegrown tomatoes. The first are caterpillars, which chew small to large holes in the fruit with their mouthparts. The second are stink bugs, which cause discolored, tough spots under the fruit skin by piercing and sucking. Continue reading to learn more about these pests and control options.

Among late-season tomato pests, caterpillars are a common threat in Kentucky, including:

• Yellow-striped armyworm,
• Tomato fruit worm, which is also known as the corn earworm, and
• Hornworms.

There are many insecticide options available, including OMRI-approved organic insecticides. This wide range of choices not only helps home gardeners control pests effectively but also supports their environmental values. 

Tomato Pests: Stink Bugs

Stink bugs are another common cause of insect damage to tomatoes in Kentucky. They pierce the fruit with their mouthparts, suck out the juices, and inject enzymes to feed on it. This results in hard, corky areas beneath the skin that lack proper color development. These injuries, called ‘cloud spots’, are marked by their whitish look and irregular shape.  

Both green stink bugs and brown marmorated stink bugs can cause this type of damage. It is essential to understand that damage can happen before the tomatoes ripen. This early damage emphasizes the need for early detection and proactive management, helping gardeners to take action before the problem gets worse. 

Blossom End Rot on Tomatoes

Another issue that occurs in late summer is blossom end rot. This condition results from calcium deficiency in tomato fruit. The affected area appears grey and water-soaked on the blossom end of the tomato. As the fruit ripens, the damage becomes more concerning for homeowners. 

Home gardeners should conduct a soil test to check calcium levels. Another tip is to provide consistent moisture to the plants during the growing season and to lay down a 2- to 4-inch layer of mulch at the base of the plants. To learn more about blossom end-rot, be sure to visit our Extension publication at: https://ccd.uky.edu/sites/default/files/2024-12/ccd-fs-11_blossom_end_rot.pdf.

To hear more about late-season pests of tomatoes, check out this short video from our Warren County Agriculture YouTube Channel.

For more information about controls and other recommendations for your garden, contact the Warren County Extension Office at (270) 842-1681 if you live in Warren County, Kentucky, or reach out to the Extension Office in your area.

Happy Gardening!