Vegetable growers and pest control advisers (PCAs) in Arizona have four new insecticides registered for use in the low desert during the just started 2008-2009 winter vegetable season. The new products are already registered in California.
“The new insecticides join other effective insecticide products currently on the market providing growers and PCAs with great options for insect control in leafy green production,” says John Palumbo, University of Arizona research entomologist and Extension specialist, Yuma Agricultural Center (YAC), Yuma, Ariz.
The new insecticides include: Coragen (DuPont) for the control of lepidopterous (lep) larvae (caterpillars), leafminer, and whitefly in leafy vegetables, cole crops and cucurbits; Movento (Bayer CropScience) for aphid and whitefly control in leafy vegetables and cole crops; Radiant SC (Dow AgroSciences) for lep larvae, thrips, and leafminers in leafy vegetables and melons; and Synapse (Bayer CropScience) which targets lep larvae in leafy vegetables, cole crops, and cucurbits.
Lepidopterous insects are leaf eaters and only cause damage in the larval stage. The four new products have a reduced-risk toxicity profile determined by the Environmental Protection Agency.
Palumbo provided the results of several years of YAC research on the new insecticides, plus current insecticides on the market during a presentation to growers, pest control advisers, and others attending the Preseason Vegetable Workshop held in Yuma.
Coragen, with the active ingredient Rynaxypyr, includes the new class of chemistry Anthranilic diamides, a unique mode of action that disrupts the calcium balance at the insect's Ryanodine receptor. Coragen's route of activity can be foliar applied (translaminar) or systemic (soil uptake).
The most cost-effective rate for Coragen is 5 ounces per acre, Palumbo says. For lepidopterous, knockdown occurs in 1 to 3 days with residual action for 7 to 11 days, similar to the product Radiant.
“Coragen is a foliar-rotation alternative with Radiant, Proclaim (Syngenta), and other translaminar knockdown products. Coragen also provides some whitefly suppression when used at higher rates,” Palumbo says.
In head lettuce trials from 2004 to 2007 to control beet armyworms, Coragen at the 3.5 and 5.5 ounce rates, Radiant (5 oz.), plus the standard insecticides Success (5 oz.) (Dow AgroSciences), Proclaim (3.2 oz.) and Avaunt (5.5 oz) (DuPont) provided consistent armyworm knockdown control. Coragen performed slightly better after seven days.
In head lettuce trials with the cabbage looper, Coragen provided fewer results. According to Palumbo, “I wouldn't say Coragen is weak on looper, but it wasn't as consistent compared to its armyworm control. The standard products performed quite well.”
Palumbo says Movento provides a slower rate of aphid and whitefly control due to its lipid biosynthesis inhibitor mode of action and the compound's foliar-systemic movement through the plant.
“I view Movento as an alternative to the neonicotinoids and the insect growth regulators (IGRs) for whiteflies and aphids. Movento is not a silver bullet, but it's an excellent product that has a good fit in desert vegetable production.”
The most effective Movento application rate is 4 to 5 ounces/acre. Knockdown occurs at about seven days with a 21 to 28 day residual depending on the pest and crop, Palumbo says.
Movento's efficacy is affected by field temperature, plant size, insect development, spray timing, and the use of adjuvants, products that enhance pesticide effectiveness. Cooler temperatures tend to slow down the plant's ability to translocate or systemically move the insecticide within the plant.
“Don't expect significant adult insect control with Movento,” Palumbo says. “I've seen very little control of winged aphids or whitefly adults.”
In spring field trials from 2005 to 2008, Movento and standard products were tested for knockdown and residual ability in all aphid species in head and romaine lettuce trials.
“The effectiveness of standard insecticides including Beleaf (FMC Agricultural Products), Assail (United Phosphorus, Inc.), Orthene (AMVAC Chemical Corp.), and other products provided a knockdown rate of about 80 percent at seven days,” Palumbo says. “Movento provided a similar knockdown and then control gradually increased; probably due to the systemic activity.”
Palumbo recommends Movento in a seasonal rotation with Beleaf, Assail, Fulfill, and similar products.
In eight spring trials with aphids in lettuce from 2005 to 2008, Movento scored equally with other insecticide sprays. Palumbo notes that relative to the commercial standard products, Movento is more effective against lettuce aphid and fox glove aphid than the green peach aphid. For best control, spray when the aphid population first shows up in the field and begins colonizing.
Using a penetrating adjuvant with Movento offers more consistent control especially on larger plants. In four trials this past spring, Movento alone significantly controlled aphids. Movento in combination with the adjuvant Dyne-Amic (Helena Chemical) provided exceptional control due to the adjuvant penetrating the insecticide further into the leaf tissue, Palumbo says.
Radiant's chemistry is a second generation Spinosyn that activates nicotinic acetylcholine receptors through foliar or systemic application. Palumbo supports a 5 ounce/acre rate of Radiant for lep, thrip, and leafminer control.
The knockdown takes 1 to 3 days with a residual impact of 10 to 14 days. Palumbo calls Radiant a “perfect fit” in desert-grown leafy vegetables and melons.
“Radiant will replace Success if it already hasn't in management programs.”
In 2005 to 2007 lettuce trials with cabbage looper, Radiant's effectiveness was proven after seven days of the application. Radiant use in armyworm trials provided a 95 percent-plus knockdown rate after three days and provided more control than Success after seven days.
Like Coragen, Synapse's mode of action is calcium disruption at the Ryanodine receptor. The product chemistry is Benzenedicarboximide.
Palumbo says Synapse is best applied through foliar contact with an effective rate of 2 to 3 ounces/acre, depending on the crop. Knockdown occurs in 2 to 3 days with residual benefits for 7 to 10 days.
Unlike the other new lep materials, Synapse is lep-specific with activity against a broad spectrum of lep species. It does not control other pests such as leafminers or whiteflies. Palumbo says Synapse is a good alternative to Intrepid and Avaunt.