Compression Puts the Squeeze on Hay
Entomologist Victoria Yokoyama
(left) and technician Gina Miller inspect wheat used to rear Hessian
flies for compressed hay experiments.
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.
U.S. growers export about $240 million worth of hay to Japan every year.
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 68oF, 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.
In the past, any unfumigated compressed bales with even a wisp of wheat--a
Hessian fly favorite--or perhaps a stray stem of a weed species known to harbor
the fly--would be rejected by Japanese agricultural inspectors to safeguard
Japan's farms from this pest. Inspectors could send back--at the American
shipper's expense--the entire container load.
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.
She did the work with Gina T. Miller and Preston L. Hartsell (now retired) at
Fresno and Jim H. Hatchett, an ARS entomologist at Manhattan, Kansas.
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. Compressed bales shipped in containers
that don't bear this "phytosanitary" certification are subject to
time-consuming dockside inspections in Japan and run a high risk of rejection.
The idea of fumigating bales to rid them of insect stowaways is not new.
Work at Manhattan by Hatchett and Charles L. Storey (now retired), for example,
won Japan's approval in 1978 for phosphine fumigation of standard-size timothy
hay bales. But Yokoyama's tests are the first to provide the extensive
documentation needed to garner Japan's okay of a combined compression and
fumigation technique for the increasingly popular compressed bales.
Only one-third the size of conventional bales, compressed bales are neat,
compact, and easier to handle. They save storage and shipping costs because
more of them can be squeezed into a barn, warehouse, or shipping container.
The National Hay Association, California Department of Food and Agriculture,
and the Organization of Kittitas County Timothy Hay Growers and Shippers in
Washington helped fund Yokoyama's research. By
Marcia Wood, Agricultural
Research Service Information Staff, 800 Buchanan St., Albany, CA 94710; phone
Victoria Y. Yokoyama is in
the USDA-ARS Commodity
Protection and Quarantine Insect Research Unit, Horticultural Crops
Research Laboratory, 2021 S. Peach Ave., Fresno, CA 93727; phone (209)
453-3026, fax (209) 453-3126.
Compression Puts the Squeeze on Hay Pests " was published in the
March 1998 issue of Agricultural Research magazine. Click here to see this
issue's table of contents.