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Whiteflies have increasingly become one of the most common pests in the ornamental industry. In the battle of the whitefly, prevention is key to a clean greenhouse and a healthy crop.

Bemisia tabaci feeds on more than 600 host plants and vectors over 111 plant virus species, and is considered to be a major invasive species worldwide, says Dr. Lance Osborne, professor of entomology at University of Florida’s Mid-Florida Research & Education Center. Poinsettia crops are especially susceptible to whitefly infestation.

In 2016, there were multiple outbreaks reported of the Bemisia whitefly, specifically biotype Q. With a different genetic makeup than other species of whitefly, growers had to look for alternative solutions if the insecticide they were using did not control this specific type.

Also in 2016, Florida researchers found that the Q biotype had moved from being a greenhouse pest to a landscape pest. It was found in home landscapes, on weeds bordering fallow agricultural fields, and found on sweet potato crops in more northern counties, Osborne explains.

Grower education, coupled with providing more tools for an integrated pest management program, are key steps to helping growers prevent whitefly problems.

As a committed industry partner, Syngenta strives to introduce innovative, reliable products that meet growers’ needs, and has released Mainspring GNL, a systemic insecticide that works as a shield to prevent pest populations from building to damaging levels.

With Mainspring GNL insecticide, growers have the ability to control a wide range of chewing and sucking pests, including whitefly biotypes B and Q, with a non-neonicotinoid product.

Left: Control with B. tabaci Q biotype infestation. Right: Hibiscus treated with Mainspring GNL 8 fl. oz. drench.

The newly hatched crawlers and the adults are most susceptible to chemicals, but the waxy covering on the larger immatures makes them more difficult to cover thoroughly with spray material, says Osborne. Resistance is a problem, and every effort should be made to rotate chemicals each time an application is made. Don’t rely on any one product or chemical class for whitefly control, Osborne adds.

“We need ways to preserve the best pest control materials we have available,” Osborne says. “The industry has to protect these very valuable resources. Proper rotation, as well as using a combination of biologicals and chemicals, will help.”

(Editor’s note: For more information on rotation and agronomic programs, please see "Agronomic Program" in this publication.)

Mainspring GNL can provide control of Bemisia spp., as well as aphids, caterpillars and thrips, when used as part of a preventive pest management program. Drench applications offer long residual protection, shielding the crop for 8 to 12 weeks, depending on the rate used.

Mainspring GNL has a unique mode of action (MOA) in new IRAC Group 28, says Nancy Rechcigl, Technical Field Manager, Ornamentals at Syngenta.

“When you have a product with a new MOA, it helps with resistance management, giving growers a more robust integrated crop management program,” she says.

A trial at the University of Florida tested the effect of soil drenches of Mainspring GNL to control Bemisia tabaci Q biotype (right) on salvia, and its compatibility to Amblyseius swirskii (top).

Mainspring GNL provides both systemic and translaminar activity. As a spray, it penetrates the plant cuticle to form a reservoir within the plant tissue. In drench applications, Mainspring GNL is taken in by the roots and moves up throughout the plant canopy. For crops with shorter production time, such as 6 to 8 weeks, use it as a spray and make two applications on a 14-day interval, Rechcigl suggests. For crops that are in the greenhouse 10 weeks or longer, Rechcigl suggests using a drench application.

Compatibility with biocontrol agents

Mainspring GNL is an excellent option to incorporate into a biological control program. It has proven compatibility with many beneficial insects and mites, such as Amblyseius swirskii, which are recommended for whitefly control. A. swirskii is a predatory mite that feeds on thrips larvae, as well as whitefly eggs and larvae.

“We recognize that many growers have embraced and are using some of the biological components as part of their pest management strategy,” Rechcigl says. “It’s important to know how products interact with that type of program. We’ve performed trials to evaluate the compatibility of Mainspring on some biocontrol options that are used in production facilities today.”

Research on Q biotype, supported by the Floriculture Nursery Research Institute (FNRI), was conducted jointly by researchers at the University of Florida in Apopka, Fla. and the USDA-ARS in Ft. Pierce, Fla. Researchers tested the efficacy of Mainspring GNL to control Bemisia tabaci Q biotype on salvia and its compatibility with the predatory mite A. swirskii when used in an integrated program. Research by Osborne and his team, Dr. Cindy McKenzie and Dr. Vivek Kumar, revealed that Mainspring GNL controlled Q biotype and is compatible with A. swirskii, so the two can be used together in whitefly management programs. Osborne and his team infested 1-gallon salvia plants with 25 whitefly per plant three times on a weekly interval. The predatory mites (A. swirskii) were released one week after whitefly releases and prior to the Mainspring GNL drench (12 fl. oz.). Mites were released three times using 20 mites per plant. Eggs and mobile stages of A. swirskii could be found four weeks after the last release, indicating the compatibility of Mainspring GNL drench and the predatory mite releases, according to the research.

“When it comes to controlling whitefly, including the Q biotype, growers are shipping product into environments that are unfriendly to the use of neonicotinoids, and they need an alternative that is effective,” Osborne says. “Now we have the potential of a chemical compound that can be used that’s beneficial friendly and pollinator friendly, and it’s a non-neonicotinoid. That’s a game changer.”

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