Troubles in High Tunnel Tomatoes

Jerry Brust, IPM Vegetable Specialist, University of Maryland;

After visiting a few high tunnels this past week I was struck by the amount of hornworm damage I was seeing in the tomatoes. I always see some damage, but there was some feeding damage across the entire high tunnel. In one HT the damage was extensive as the grower caught it too late and then had a hard time killing the hornworms–they were hand removed eventually. Not only were the tops of plants defoliated (Figure 1) but there also was extensive fruit feeding (Figure 2), which I do not see very often.

Aphids (mostly Potato aphids, which seem to be the most common aphid species I find in high tunnel tomatoes) were also in abundance in some of the HTs. There was some leaf curling and sooty mold on leaves (Figure 3) from their feeding. In Figure 3 you also can see a great number of exuviae or caste aphid skins; this is a sign that aphids are growing rapidly and heading quickly to adulthood when they will begin to give live-birth to more aphids. In one HT, predators (Syrphid fly larvae) and mummified aphids (parasitized aphids) (Figure 4) were also found.

Figure 1. Defoliation of tomato tops by hornworm

Figure 2. Tomato hornworm feeding on fruit

The growers who recognized these pests early on were able to control them with Entrust, oils, soaps or Beauveria bassiana applications – all organic controls. Growers who recognized the damage too late could not control the pests with organic products. It pays to scout your crop regularly and identify the pest damage you encounter so you can make management decisions quickly and accurately.

Figure 3. Sooty mold and leaf curling due to aphid feeding, along with exuviae (white dots)

Figure 4. Syrphid fly larva feeding on aphid (blue arrow) and mummified aphid (red arrow)