Heading off Hornworms in the Tomatoes

Created on 5/22/2009

Tomatoes are the queens of the summer. They’re a staple in most every garden – partly because they’re best eaten fresh and partly for bragging rights. I know many gardeners who have friendly competitions with each other on who can grow the largest tomato, while others strive for the earliest harvest, particularly in northern climates where the season is abbreviated. I’m the one in the early harvest category, although this year I am trying my hand at growing a large slicer that will mature in our short season.

Our two-year old, Samuel, helped me plant our tomatoes in the Wall-O-Waters the other day. Normally, I’d have them in the ground weeks earlier since the Wall-O-Waters do a fantastic job of protecting them even from spring – or summer – snowstorms, but two-feet of snow in late April knocked off my traditional schedule.

Regardless of when you plant your tomatoes, one of the most important decisions is where to put them. This is one plant where crop rotation is critical to help avoid pests that overwinter in the soil. When you plant the same crop in the same spot for subsequent years, you’re basically providing a quick trip to the buffet line for any tomato-loving pests that stayed in the area during the winter.

The one I dislike the most is the tomato hornworm. It’s a nasty looking caterpillar that is roughly the diameter of a finger with a horn on its posterior. It’s bright green coloration blends in very well on the tomato stems and leaves, making it very disconcerting when you touch the plant and it moves! There’s also the tobacco hornworm that looks similar, but instead of the horn, it has diagonal stripes. Both give me the heebies. Both feed on the leaves of tomatoes, and can do considerable damage.

The first line of defense is planting your tomatoes in a three year rotation plan so you have at least a couple of winters to weed out any hornworms from the previous year. And even with moving plants each season, hornworms are fairly common throughout the country.

If they’re serious enough, you can apply Bt or chemical products, but keep in mind birds will eat hornworms. Plus, you hate to knock out beneficial insects in the process.

Unless you have acres of tomatoes, one of the easiest methods of control is hand-picking. If you do find some on the plants, simply pick them off and destroy them. When I notice them in the summer I’ll try to cruise through the tomato row a few times per week with pruners in hand. When I find one, I snip it in two. Gruesome, but effective. Who knows, hornworms are probably a delicacy in another country, but I’ll pass, thank you very much.