36 August 4, 2010
If you are going to grow any one vegetable plant, it probably is going to be the tomato. After a winter of eating cardboard tasting tomatoes, there is nothing better than going to your garden and picking a ripe tomato to eat. However, you are not the only one who likes to eat your tomatoes. There is a garden pest who has made its appearance on tomato plants throughout the area.
At this time of the year, your tomato plants have reached a decent size. Yet one day when you go out to the garden, you realize that something is wrong. It may take you a few seconds but soon you realize that the tomato plants are much smaller than they were last week. If you look closely at the tomato plant, you will see the monster responsible for eating most of your tomato plant in just a few days. Welcome to the world of the tomato hornworm.
There is a large moth that lays eggs on your tomato plant leaves. This moth usually visits your garden in the evening. I have only seen the moth once and it is huge. The eggs hatch out and the tomato hornworm begins its feeding cycle.
The tomato hornworm is light to medium green in color. Its coloration allows it to blend in with the leaves it is eating, making it hard for you to see them until they get big enough not to ignore. They have white stripes on their body. They have a rows of dots on their sides that resemble eyes. They also have a prominent horn, thus the name tomato hornworm. When they are disturbed, they tend to rear up in a menacing posture. When they are big they make for a scary scene when you encounter them on your tomato plants. Yes, they do get big! They can reach 4 inches in length and they can be as big around as your small finger.
There are several methods for controlling this tomato monster. An application of an organic product called Bt will quickly kill the caterpillar when they are small. Bt only kills caterpillars. It can be applied as a dust or you can dilute down a liquid concentrate and spray it onto the leaves. There is also a product called Rotenone. It can be applied as a dust or you can mix it with water and spray it onto the leaves. This product will kill the caterpillar at all sizes. Neem should also work to control the tomato hornworm. Sevin is a chemical alternative that will kill the caterpillars at all stages of growth. Sevin can be applied as a dust or you can buy a liquid form and spray it onto the leaves. Sevin should not be applied when bees are present because it is harmful to bees.
If you are less squeamish, you can hand pick the caterpillars off the plants and give them a squish with your shoe. However, no matter what control method you choose, if you see white rice-like structures sticking out of the back of the hornworm, don’t kill the hornworm. The white rice on their back is from eggs laid by a parasitic wasp. The eggs of the wasp will hatch and feed on the caterpillar and quickly kill the caterpillar. Mother nature in all of her irony!
Speaking of tomatoes, you need to be keeping up with fertilizing your tomato plants if you want those tomatoes to ripen. Tomatoes use lots of potassium to ripen those tomatoes. If you don’t keep up with the fertilizing, you will wind up with lots of green tomatoes that won’t ripen. Tomato plants need to be fertilized right up until the time that the frost kills the plants.
Well, that’s all for this week. I’ll talk to you again next week.