Fighting Insecticide Resistance In South Florida

Pesticide rotation is particularly important in South Florida vegetable crops because of the continuous cropping practiced there, says Dr. Gregg Nuessly, associate professor for the University of Florida at the Everglades Research and Education Center in Belle Glade. Growers produce thousands of acres of Asian leafy brassica crops and spring mix-type vegetables such as arugula, mesuna and baby spinach in isolated areas throughout the Everglades and South Florida.

“They basically create little islands of these crops,” says Nuessly, who works primarily with sweet corn, snap beans and leafy vegetable crops. “When you have an insect population living on that island, you are treating it over and over with insecticides. So you have very strong selection pressure for resistance development.”

In his quest to help the vegetable growers in his four-county area, Nuessly often conducts grower trials with new products. This spring, he selected Tom Yee, owner of Yee Farms, based in Boynton Beach for a trial using new Vetica Insecticide from Nichino America. Yee grows leafy vegetables on well-drained silica-based soils and has very high insect pressure.

“We have a number of problems with various types of worms, particularly beet armyworm and diamondback moth worm,” explains Yee. “We’ve found the rotation of different pesticide products helps to minimize resistance.”

Vetica contains flubendiamide, a new chemical specific to Lepidopteran insects, and buprofezin, a proven insect growth regulator that has excellent activity on Homopteran pests, including whiteflies and leafhoppers. Vetica is registered for use on cucurbits, head and stem brassicas and leafy and fruiting vegetables.

Both Tom Yee and Dr. Nuessly and were quite satisfied with the results of the Vetica trial. “We had nonstop rain the whole month of May,” Lee says. “But despite the weather, I was encouraged and impressed with the trial.” Nuessly explains: “If anything, this trial put the product through a greater test than if it happened during the normal growing season. It was fairly warm – in the high 80s and low 90s – and the area received heavy rains every day. From May 15th to May 31st, we had 16 inches of rain in that area – literally an inch of rain a day.”

Dr. Nuessly adds: “Radiant is the main product currently used by leafy vegetable growers for worm control and leafminer fly suppression. So we’re trying to encourage a rotational pattern where we save Radiant for thrips control and use other products for worms. We need to have another rotational partner. After this trial, I feel comfortable recommending Vetica as a rotational product for Lepidoptera pests. It performed very well.”

Further Trial Results
In the Homestead area, Dr. Dakshina Seal evaluated Vetica to control melonworm and pickleworm on cabbage and cucumbers last winter. Dr. Seal, an assistant research scientist at the Homestead Tropical Research and Education Center, is specialized in insect management of vegetable crops.

“Our insect problems on vegetables start at planting and continue all the way through harvest,” says Dr. Seal. “Worms are a key pest on all of our crops and we use a wide rotation of products to control them.”

In Seal’s cabbage trial at the Homestead research facility, he studied control of diamondback moth larvae. Vetica-treated larvae stopped feeding in six to 24 hours after exposure to the product. “Vetica significantly reduced diamondback moth larvae on cabbage,” he says.

The one-acre cucumber trial was conducted in a commercial field in Homestead. Dr. Seal compared Vetica to the grower’s standard treatment for melonworms, whitefly and thrips. “Melonworms were satisfactorily controlled by Vetica,” Seal notes. “We experienced fewer numbers of melon thrips in Vetica-treated plants than in the grower’s standard treatment, while Vetica and the grower’s field had similar levels of silverleaf whitefly control.”

Dr. Seal plans to recommend Vetica as part of a rotation program for worm control in Homestead-area vegetable crops. “The product provides us with another effective rotation partner for use in fighting worms and other insects in our vegetable acreage,” he adds.

Source: Nichino America