DE provides organic method for controlling many pests

Diatomaceous earth, a cousin to the stuff used in a pool filter, is being touted as an effective weapon on a wide range of pests because it creates a situation in which those pests are "crawling across cut glass."

That's how Tome Martin-Duvall, senior director of research with Caltec Ag Inc, characterized the damage done to pests with the material.

She spoke at a grower education field day for the San Joaquin Valley Winegrowers Association. The event was held at the Kings River Winery in Sanger.

The product is AgDE-cide, a diatomaceous earth insecticide. It comprises fossilized remains of tiny aquatic organisms called diatoms and contains a primarily amorphous silicon dioxide, along with small amounts of crystalline silicon dioxide. It was first registered for use as an insecticide in 1960.

The organic mineral insecticide controls vine mealybugs, gill's mealybug and other soft-bodied insects including scale, mites, aphids, black widow spiders, thrips, white flies, psyllids and ants.

The material kills the pests by scarring the insect body, causing dehydration and eventually death. It can be applied up to the day of harvest and has a 12-hour re-entry level.

It has no effect on powdery mildew, Martin-Duvall said.

She said there are no residue issues on harvested crops. The material remains effective for weeks after application and is available in both dust and spray formulations. It can be washed off fruit.

The material's mode of action is not subject to development of resistance.

Martin-Duvall listed a wide range of crops on which the material can be used. They included—in addition to wine, table and raisin grapes—almonds, walnuts, pistachios, citrus, blueberries, tomatoes, potatoes, alfalfa, rice, beans, leafy greens, onions, garlic and seed grass.

The product is OMRI-listed by the Organic Materials Review Institute, meaning it's suitable for use by organic growers.

Martin-Duvall said its chief active ingredient is silicon dioxide at 85%.

She warned it can cause moderate eye irritation and said it's best to avoid contact with eyes or clothing.

"Wash thoroughly with soap and water after handling," she added.

Martin-Duvall said users should avoid breathing dust and make sure there is adequate ventilation. "Wear a suitable dust mask when using this product during prolonged exposure," she said.

She added that respirators fitted with filters certified to standard 42 CFR 84 and meeting N95 efficiency are suitable.

Martin-Duvall said those using the product should wear personal protective equipment that includes a long-sleeve shirt, long pants, shoes and socks and a suitable dust mask.

She warned against using the material when bees are pollinating crops because they fall prey to death when they encounter it.

"You don't want to kill off all your bees," she said.

The same risk applies to beneficial insects.

Beyond controlling agricultural pests, the product can be used for flea and tick control, on bed bugs, in skin care products, in toothpaste and water filters and many other applications, Martin-Duvall said.

"I've personally used it for ticks on my dogs and cats and it works great," she said.

The liquid application requires strong agitation and can be abrasive to nozzles and pumps, Martin-Duvall said. The dust application, on the other hand, causes no damage to application equipment.

"A sulfur duster works great," Martin-Duvall said, "but it does billow for miles and miles."

She cited research in 2018 that shows effective use of the product for gill mealybug control in pistachios and for navel orangeworm control in almonds.

She said the product is mined, not manufactured, and then ground to "whatever your specifications are."

Workshop participants also heard a presentation on workers compensation and pesticide application safety from representatives of the Leavitt Group insurance company, whose office locations include Visalia and Fresno.

Presenters were Elsa Lara, a Leavitt agent, and Jake Newman, an account executive.

Lara talked of return-to-work programs for injured workers that can mitigate the cost of workers compensation claims.

She and Newman also talked of pesticide application safety and the need for protective gear, having detergent or soap before you mix chemicals and an adequate supply of water.

They recommended learning the early symptoms of poisoning and first aid procedures for the pesticide being handles.

"Do not work alone," Lara said. "Never eat, drink, smoke or use the bathroom without first washing your hands."

They recommended having emergency contact information on site and having an eye wash station.

Martin-Duvall, who has conducted pesticide safety classes in Madera County, said it is important to read pesticide labels.

Lara said it's not a matter of "one mask fits all." Each applicator, she said, should be "fit tested."

"Each person needs to have their own respirator," Martin-Duvall said, adding, "Make sure you're using the right pesticide for the right target."

She said someone needs to check periodically on the welfare of the applicators.

(Dennis Pollock is a reporter in Fresno. He may be contacted at agcompollock@yahoo.com.)