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Corn+Soybean Digest

Cotton Pests Think Garlic Treatments Stink

Walk past Tommy Pointer's pickup and you'll guess he had Italian for lunch. Investigate a little more and you'll find that empty garlic oil containers are producing that pungent smell.

Why? Pointer, of Cotton Center, TX, uses garlic oil as a cotton insect repellent. He's as much a believer in the stenchy stuff for controlling thrips and bollworms as Larry King is in garlic tabs for lowering cholesterol.

"Snake oil" first comes to mind when garlic oil is discussed as a pesticide. But using garlic oil to manage bad bugs is more and more common in cotton-growing areas.

"We see good nematode and thrip control," says Brad Aycock, a Parma, MO, crop consultant.

Garlic Barrier, made by Garlic Research Labs, Glendale, CA, is no more of a snake oil than commercial insecticides, says Pointer. Neither is the Fish Agra "fish oil" he applies with it to guarantee that it sticks to the plants.

"Some people still laugh at using garlic oil instead of chemicals for pest control," he says. "But we have used it three years ... and it has worked every time. It won't hurt beneficials, is safer to apply and won't contaminate water."

Pointer banded about 3 oz of garlic oil mixed with about 3 oz of fish oil per acre just after emergence on part of his '98 irrigated cotton. At prebloom in June, he broadcast 6.5 oz of each. The applications are mixed with 5-10 gallons of water per acre.

In past years he applied both oils through his center pivots.

"We have good control and haven't had to apply any insecticides. But all of my neighbors have had to spray for bollworms. That's all I have to go by."

How does it work? The garlic oil is absorbed systemically. That drives hungry insects away.

"The plant tastes and smells like garlic," says Pointer, "and the bugs don't like it. Beneficial insects aren't affected because they don't feed on the plants."

One drawback of the garlic oil treatments is that growers have to apply them before they know they need them. "If you wait until there is a problem, it's too late," says Pointer.

Crop consultants Aycock and his brother, Barry, work with numerous growers in southeastern Missouri and northeastern Arkansas. Up to 20% of their clients' acres receive garlic oil applications.

"Our farmers band on garlic oil early for thrip and aphid control," says Aycock. "As the cotton gets taller, we use a garlic oil and pyrethroid application for better bollworm control. We also receive good residual from the garlic in a continuous cotton program."

The Aycocks tested Garlic Barrier against chemical treatments. Garlic oil was applied at 12.8 oz/acre in-furrow at planting. At the sixth node stage, another 3.2 oz were banded on. A third 3.2-oz application was made 18 days later, and 6.4 oz were broadcast 30 days after that.

The garlic-treated field was compared to normal insecticide treatments of 5 oz/acre at planting, 4 oz at the sixth node, 2 oz later on and another 1 pint later for boll weevils.

Yields were slightly higher on the garlic-treated field: 1,069 lbs an acre vs. 1,048 lbs. Garlic also did a better job on nematodes. Bollworm and thrip control were the same in the two fields, but the garlic proved more efficient against aphids.

Aycock estimates the average cost for Garlic Barrier is about $14/acre.

Carl Patrick, Texas extension entomologist, says garlic may be a feasible insect repellent. He plans to research it on corn and wheat, where some growers have seen sound greenbug control.

"If growers want to try it, I suggest they evaluate it on part of their fields and leave some untreated," says Patrick.

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