Aberdeen, Idaho
September 25, 2007
An insecticide previously approved
only for field corn and non-crop uses is headed for release next
spring in potatoes, thanks to an integrated pest management
project for wireworm control led by
University of Idaho
entomologist Juan Manuel Alvarez.
The insecticide, fipronil, received U.S. Environmental
Protection Agency approval for use in potatoes this month
(September). While all other insecticides currently used against
wireworms are organophosphates and carbamates-older classes of
chemicals being scrutinized by the EPA-fipronil is in a newer
class of chemicals called phenylpyrazoles.
After four years of side-by-side comparisons at the University
of Idaho's Kimberly Research and Extension Center, Alvarez says
fipronil performed more effectively and consistently against
wireworms than any other chemicals evaluated. Not only did it
hold wireworm damage to the lowest percentage of affected tubers
and the lowest number of holes per tuber, it did so without
reducing the potatoes' highly valued size.
"We're excited about it," says Keith Esplin, executive director
of the Potato Growers of Idaho. "Although not perfect, it's a
better control and we're hoping it helps growers raise a larger
percentage of U.S. No. 1s-which will mean more money in their
pockets."
Control options are critical when it comes to battling these
crop-threatening larvae of the click beetle. Although click
beetle adults are innocuous to crops, their slender, hard-bodied
larvae feed on seed pieces and tunnel into tubers, affecting up
to a third of the potatoes in individual Idaho fields, Alvarez
says. After harvest, damaged tubers that look like they've been
studded with nail holes are downgraded or downright rejected,
and the processing industry has zero tolerance for the presence
of wireworms themselves in the raw product.
Wireworms have proved especially difficult to control because
their life cycle extends as long as six years and because they
spend much of it below the reach of the preventative chemicals
that growers routinely apply to soils at planting. Alvarez says
wireworms won't move toward soil surfaces until soil
temperatures reach 50 degrees Fahrenheit in spring, and they
return to cooler, lower soil levels during the dog days of
summer. He and his research partners have documented that most
wireworm damage in Idaho potatoes occurs after mid-June and that
the insects' activity actually peaks in mid- and late September.
The longer tubers remain in the ground, the higher the
percentage of wireworm injury.
"Wireworms return to the soil surface during the second half of
September when your nice tubers are ready for harvest," Alvarez
says. "By then, your insecticide is probably no longer
protecting the plant-it's run out of powder." Because of
concerns about insecticide residues in crops, no wireworm
chemicals are currently registered for use after planting,
leaving a complete control elusive.
Complicating concerns about wireworms is the insects' preference
for grassy fields-like the pastures that support Idaho's growing
livestock industries. "Once wireworms increase in those fields,
the adults can move and infest new fields," Alvarez says. Plus,
as pastures are rotated to other susceptible crops-which include
small grains, peas and beans as well as potatoes-farmers can
find themselves battling unexpectedly high populations.
At BASF, where fipronil is produced and sold as Regent,
technical service representative Jim Vandecoevering says the
chemical "has very good activity at much lower rates-about 3
ounces per acre-than other products on the market."
"I've probably been asked about this registration more than any
other product that we've had in the pipeline for 12 years," says
Vandecoevering. "It's something the industry has really lobbied
for, and I think they'll find it a very useful tool for their
production practices."
Funded largely by a grant from the Western Integrated Pest
Management Center, Alvarez and entomologist Tom Kuhar of
Virginia Tech are continuing to examine improved wireworm
monitoring technologies and to evaluate alternative control
tactics. Alvarez is also working with Rich Novy, a USDA
Agricultural Research Service potato breeder at Aberdeen, on
building wireworm resistance into new varieties.
University of Idaho agricultural research offers critical
expertise and assistance to the state's farm industry. For more
information on potatoes, visit the Idaho Center for Potato
Research and Education online at
http://www.ag.uidaho.edu/potato/.
Founded in 1889, the University of Idaho is the state's
flagship higher-education institution and its principal graduate
education and research university, bringing insight and
innovation to the state, the nation and the world. University
researchers attract nearly $100 million in research grants and
contracts each year; the University of Idaho is the only
institution in the state to earn the prestigious Carnegie
Foundation ranking for high research activity. The university's
student population includes first-generation college students
and ethnically diverse scholars. Offering more than 150 degree
options in 10 colleges, the university combines the strengths of
a large university with the intimacy of small learning
communities. |
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