DUST BUSTER
Agronomist Patents Fungicide Carrier Made from Sunflower Hulls

By Dan Lemke

Waseca, Minn. — Paul Kresge says his good dust will help snuff out bad dust and be good for potatoes and farmers to boot.

An agronomy consultant from Forest Lake, Minn., Kresge holds a provisional patent for a “diluent” powder made from sunflower hulls, which he developed with the help of AURI technical services specialist Alan Doering.

Diluents are diluting agents used, in this case, for farm herbicides and pesticides. For liquid chemicals, water is the chief diluent, but dry pesticides require something else.

“A lot of powdered pesticides put on active ingredients at a very low rate, so something is needed as a carrier,” says Kresge, who holds a Ph.D. in soil fertility. “You want a dry diluent, but you also don’t want fugitive or nuisance dust that can be respirable.”

Nuisance dust from dry pesticides can be released into the air when handled, creating a potential health concern for applicators. “Someone has to apply the fungicide, but you don’t want respirable dust. You don’t want it released into the air,” Kresge says.

Potato powder
Powdered pesticides are especially common in the potato industry. The majority of farmers in the western United States and Midwest plant potato seed pieces rather than whole potatoes. The cut surfaces are perfect entry points for disease-causing fungus. To prevent fungal diseases from causing the potatoes to rot in the ground, cut pieces are sprinkled with dry fungicides. The pieces are then stored for about 10 days while a new skin naturally forms over the cut.

Currently, talc and powdered alder bark are the primary diluent ingredients used in potato fungicides, but as the supply of alder dwindles, new ingredients are needed.

In 2003, Kresge and Doering started experimenting with a wide range of ag fibers that could be ground finely enough to work as a carrier. After nearly two years of evaluation, they developed a powder with sunflower hulls as the key ingredient because the hulls’ high-oil content reduces dust. The shredded fiber’s shape also helps hold on to small particles.

The dust-reducing quality of the diluent was tested and received high marks from the USDA Agricultural Research Service laboratory in Lubbock, Texas.

Spud Tested
Kresge tested the ag-based carrier on several plots in Oregon last year. Three more plots have been planted this year. But the fiber carrier has moved beyond testing as 7 tons of demonstration products have already been produced and another 20 to 30 tons will be made by the end of summer for potato markets in Colorado, Florida and the Red River Valley.

Kresge, who was raised in Northeast California’s potato-growing region and has 25 years experience in agriculture as an agronomist, knows there is significant market potential for his fiber carrier in all the potato-growing states. Idaho leads the nation in potato production, followed by Washington, North Dakota and Wisconsin. Minnesota ranks 7th.

“Potato growers are the target market because the growers are the end user,” Kresge says. “The seed-piece fungicide market exceeds 4,000 tons per year.”

Doering says the ag-fiber carrier development is good for Minnesota because the sunflower hulls are sourced and processed here. “It reduces dust, plus it utilizes what is typically viewed as a waste product.”

While potato-seed treatment is the initial market, future opportunities include flea
and tick powders as well as livestock insecticides.