With the 2015-2016 winter produce season underway in the low desert, a large blip on the radar screens for growers and their crop advisers is pest threats.
Produce insect pests are broken down into eight categories, including whitefly, worms, leafminer, aphids, thrips, and others. Thanks to evolving chemical technology, the good news is the produce industry has a tool box full of effective insecticides to combat pests.
“It would be very difficult to grow quality produce in the desert without effective insecticides,” says John Palumbo, Extension entomologist with the University of Arizona, based at the Yuma Agricultural Center at Yuma.
The nation’s winter vegetable production is primarily based in California’s southern-most county, Imperial, and across the Colorado River in neighboring Yuma County, Ariz. Combined, this area produces 80-90 percent of the U.S. winter vegetable supply.
The first synthetic chemicals developed to fight pests were introduced about 70 years ago. Palumbo calls this first round ‘broadly toxic insecticides.’ This group began with organochlorines in 1945, followed by organophosphates a year later, carbamates in 1956, and pyrethroids in 1972.
Today’s modern insecticides are largely reduced-risk products which Palumbo says provide improved efficacy and are safer for people and the environment.
Reduced-risk products fall into 13 chemical classes: neonicotinoids, spinosyns, diacylhydrazine, pyridine, thiadiazine, oxadiazine, carbaximide, diamides, ketoenols, sulfoximine, pyrazol, and butenolinide.
Today, about 60 percent of all insecticide usage to control pests in Arizona produce is reduced-risk products.
Reduced-risk products offer multiple ways to protect plants from pests and farmers’ pocketbooks. For example, neonicotinoids are a highly effective soil systemic products and the spinosyn class uses translaminar (locally systemic) distribution of the chemical within plants.
Palumbo has conducted numerous insecticide efficacy trials over the years and recently shared the results from the most trials on some of the latest chemistry on the market registered for Arizona produce.
Active ingredient is flupyradifurone - effective spectrum includes whitefly and aphid.
2015 is the first year for Sivanto use in produce. Its main target is whitefly control in lettuce, cole crops, and melons.
“Sivanto does a great job of knocking the adult whitefly down,” said Palumbo based on his trials.
Sivanto is part of the new IRAC 4D group which uses translaminar (foliar applied) and systemic (soil applied) activity to suppress whitefly nymph development and buildup.
“My trials have shown that Sivanto is every bit as good as the products Venom and Scorpion as a soil application for whitefly control and for the suppression of cucurbit yellow stunting disorder virus in melons,” Palumbo said.
With the current tough regulatory climate, he says the Environmental Protection Agency views Sivanto as one of the most ‘bee safe’ products on the market.
“This is a big plus with aphids in crops during the bloom period in brassica seed crop production when bees are in the field,” Palumbo said.
When applied according to label instructions, Palumbo says Sivanto does a good job on aphid while maintaining bee health. The insecticide has short re-entry and pre-harvest intervals.
Exirel 0.83SC and Verimark 1.67SC
The active ingredient is cyantraniliprole – effective spectrum includes leps, leafminer, and whitefly in leafy vegetables, cole crops, and melons.
Introduced last year, these insecticides contain the same active ingredient and are second-generation anthranilic diamides. Exirel is the foliar version while Verimark is soil-applied.
These products provide cross-spectrum control for whitefly, leafminer, and all major lepidopteran pests in one swoop in lettuce and cole crops.
“In my Yuma Ag Center trials, Exirel looked great. I expect more growers to use Exirel and Verimark this fall in melons and produce crops,” said Palumbo.
Another benefit for these products is cross-spectrum control for sucking and chewing insects.
“On worms and leafminers, Exirel and Verimark are just as good as Radiant or Coragen, and just as good as Movento on whitefly.
Be aware, Palumbo says, that Exirel and Verimark are slower at adult knockdown.
“It’s a little bit slower but don’t be discouraged as it will eventually do the job in 2-3 days. It’s not a disadvantage - it’s more of a perception issue. PCAs should be aware of this.”
Exirel and Verimark have secondary activity on aphids, thrips, and flea beetles.
Palumbo says these insecticides provide an alternative and very effective mode of action to neonics for whitefly management in melons.
Active ingredient is sulfoximine - effective spectrum includes aphid, lygus, and whitefly.
The entomologist says the best fit for Sequoia in desert produce is for aphid control.
“Overall, Sequoia is a great addition to our aphid management program in the desert,” Palumbo said. “It’s a great product to rotate with Movento, Beleaf, and other neonicotinoids.”
Sequoia can be used in leafy vegetables and brassicas, spinach, and melon in Arizona.
Tolfenpyrad is the active ingredient and its effective spectrum includes thrips. It is a purely a contact material with no translaminar activity. It is currently registered on leafy vegetables.
“Torac’s big fit in the desert is for thrips control on lettuce.”
The product is a good fit as a tank mix partner with Radiant and methomyl to replace the pyrethroid.
“We use so much pyrethroid in this area that anything we can replace it with and take the pressure off the pyrethroid chemistry is a benefit.”
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Palumbo says chemical companies invest about $250 million dollars to bring a new insecticide to market.
New insecticides on the market provide growers with alternative products which in turn reduce the likelihood of insect resistance, he says. There is no documented pest resistance to any insecticide used in produce in Arizona.