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Troup extension agent: Trap cropping — A case of fatal attraction, pt. 1

By Brian Maddy

Contributing columnist

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One of the most discouraging aspects of vegetable gardening is to go out one morning and find that your summer squash vines are all dying or that hornworms are in the process of gobbling up your tomato plants.

You might wonder why not use insecticides to control these pests? One of the downsides of using insecticides is that they kill not only the guilty but innocent as well. There are many beneficial insects in the garden and when you eliminate the good predator insects such as ladybugs, you can actually increase the population of the bad ones such as aphids. Over time insects can also become resistance to the same pesticide.

It’s a good thing that some folks can think outside the box. It has come to the attention of some growers and researchers that some of these pesky insects prefer certain cultivars of our vegetable species. They do to such an extent that they’ll ignore other varieties and concentrate on their favorite.

The principle of trap cropping is that the preferred host plants attract insects away from the main crop during a critical time period. Most insects are attracted to plants in the reproductive stage of growth as opposed to the vegetative stage of growth. The host plants are sacrificed in order to protect the main crop. The target insect then is controlled in the trap crop by timely applications of an insecticide or by mechanical removal.

Gardeners can implement trap cropping by using two methods. The first is to use the same plant cultivar as the main crop and the trap crop. The trap crop must be planted much earlier so that it can be in the reproductive stage and the main crop in the vegetative stage. Planting an early maturing variety of tomatoes as a trap crop for a later maturing variety is an example.

The second method is that the main crop and trap crop are entirely different species. An example of this is to plant sorghum as a trap crop for stink bugs which damage many kinds of vegetables.

How effective is trap cropping? Planting Blue Hubbard squash as a trap crop for cucurbit crops such as yellow squash, pumpkins and cucumbers has proven to be highly attractive to striped cucumber beetles. Ninety four percent of the cucumber beetles were in the trap crop. This reduced the infestation in the main crop to less than 7 percent.

Trap crops are not a “silver bullet” solution to controlling pests. It requires more pest management skills and knowledge of insect behavior. There are also insects not controlled with trap crops.

Next week: How do we implement a trap crop strategy?

What’s going on in Extension?

Become a Master Naturalist: The program begins March 31. It will run through June 6. Cost of the program is $175. Call the Extension office for more information and the registration packet.

March 11: Small Ruminant Training FAMACHA training and nutrition and March 24, reproduction, lambing, marketing, hoof trimming. Call Susan James, Meriwether County Extension, 706-672-4235 for registration information.

March 15: TCCA Meeting, 7 p.m. meal, $ 6. Program begins at 7:30 p.m. Guest speaker: Mark Slay, “Managing Your Fertilizer Needs.”

March 18: Equipment maintenance workshop, 9 a.m. to 3 p.m., Ag Center.

March 23: Farm to Market Food Safety Workshop. Become a certified food safety provider. Call the Extension office for more details.

Tree seedlings can be ordered from the Georgia Forestry Commission, 706-845-4122.

Brian Maddy is the ANR Agent for Troup County Extension. The Troup County Extension office is located at 114 Church St. in LaGrange and may be reached at 706-883-1675, Monday–Friday 8 a.m.–noon and 15 p.m.