From the pages of Agricultural Research magazine Compression Puts the Squeeze on Hay Pests Tightly compressed bales of freshly harvested hay destined for dairy cows, beef cattle, or racehorses in Japan can now move swiftly through agricultural inspections there, thanks to studies by Agricultural Research Service scientists. Tests conducted for the past 6 years by entomologist Victoria Y. Yokoyama with ARS at Fresno, California, showed that compressing standard bales, then fumigating them with hydrogen phosphide for 7 days at 68 o F, kills any Hessian flies that might be hiding inside. Japan has recently approved this safe, practical quarantine procedure, ensuring that Hessian fly can't sneak into the country in baled hay. The new procedure applies to compressed bales of American-grown timothy, alfalfa, oat, bermudagrass, and sudangrass.
Hessian fly is one of the worst insect enemies of wheat.
It's believed the pesky insect hitchhiked to North America during the Revolutionary War, traveling inside straw mattresses used by Hessian mercenaries. Yokoyama's tests with West Coast hay were the first to show that merely compressing the bales at 1,136 pounds of pressure per square inch killed a large proportion of the test insects concealed within the bales. For her experiments, Yokoyama and colleagues reared more than 630,000 Hessian flies. Hydrogen phosphide fumigation provides an extra measure of pest control. The fumigation takes place inside cargo containers, after which American agricultural inspectors affix a sticker indicating that the containers' contents have been properly treated.