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Armyworms a new threat for farmers

July 25, 1997

BROOKINGS, S.D. (AP) _ Armyworms are marching through South Dakota fields in what one insect specialist said could be the largest outbreak in almost 30 years.

Swarms of moth larvae began a feeding frenzy in Brookings, Hamlin and Deuel counties over the weekend. One farmer, Alvin Hartmann, lost a 24-acre field of barley overnight.

He could see them moving onto a nearby pasture _ so many that it looked as if the ground had come alive. ``They move pretty fast,″ said Hartmann, who farms north of Brookings. ``If there’s nothing left to eat, they keep moving.″

Last weekend they spread in a matter of hours over a 3-square-mile area north of Brookings before farmers contained them with insecticides. Isolated outbreaks are being reported this week in fields throughout Hamlin and Deuel counties.

``Where they are, the damage is pretty extensive,″ said Deuel County Extension agent Warren Rusche. ``Farmers are concerned about having enough feed for the winter.″

Parasitic wasps typically curb armyworm outbreaks. But cooler night temperatures earlier this summer immobilized the warmth-loving wasps and allowed the larvae to thrive. Foliage that had been beaten down by hail also provided ideal protection for the armyworm moth eggs north of Brookings.

When first hatched, the worms are easily overlooked because they burrow underground during the day and grow only to 1 1/2 inches long.

``You don’t know whether you have them unless you check,″ said entomologist Ben Kantack. ``Nobody knows how widespread this is.″

When hatched from moth eggs, the armyworms remain in the larval stage for three to four weeks, beginning their ravenous feeding during the last week of the cycle.

The worms can eat an entire field within a few hours, Kantack said.

``I’ve seen them wipe out a cornfield overnight,″ he said. ``The farmer didn’t even know he had them, and in the morning he went out and found only a field of midribs,″ the central leaves of corn plants.

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STONEVILLE, Miss. (AP) _ Researchers are using electron microscopes to detect flaws in cotton fibers that cost the industry up to $200 million a year.

Bill Meredith, who does field work at the Agriculture Department’s Agricultural Research Service division in Stoneville, Miss., said one area of research is on white-speck neps. They are pesky tangles of fiber that virtually cannot be dyed _ a sign that the fiber was not able to mature properly in the field.

Meredith said neps show up as tiny white specks on dyed clothing, for example.

While Meredith studies the problem through field work with cotton plants at Stoneville, scientist at USDA’s Southern Regional Research Center in New Orleans also use electron microscopes to study the fiber up close.

``Neps can sneak up on mills: The money is spent to dye the fabric, and it comes out spattered with white specks where the dye didn’t take,″ said Wilton R. Goynes, one of several cotton scientists at the New Orleans center.

His study of white-speck neps was published in the May issue of Agricultural Research magazine.

Goynes, a chemist, used a scanning electron microscope to confirm what researchers had suspected since the 1940s _ that the neps are the result of underdeveloped cotton.

With the device, researchers have been able to find out which dyes react best with different fibers and which enzyme treatments are most effective in dealing with neps.

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