Aphids on an immature soybean (photo courtesy of the Union Grove Co-op). To learn more about the exotic aphids see these websites: http://www.plantpath.wisc.edu/soyhealth/newaphid.htm, http://www.unitedsoybean.org/soystats2000/page_17.htm
Great Lakes scientists have now identified a foreign insect thatthreatens to cause major damage to the region’s soybean crops. Itapparently came from China and has so far been found in crops in atleast four Great Lakes states. The insect is causing concern amongscientists in the region, where more than 40 percent of the nation’ssoybeans are grown. The Great Lakes Radio Consortium’s Mary Jo Wagnerreports:
Transcript
Great Lakes scientists have now identified a foreign insect that threatens to cause major
damage to the region’s soybean crops. It apparently came from China and has so far been found
in crops in at least four Great Lakes states. The insect is causing concern among scientists
in the region, where more than 40-percent of the nation’s soybeans are grown. The Great Lakes
Radio Consortium’s Mary Jo Wagner reports.
The soybean aphid, which is native to China, has been a big problem for that
country’s crops. But until now it had not been seen in the United States.
University of Wisconsin scientists first discovered the pin-head sized aphid
sucking on soybean leaves in university test plots this spring…then
farmers started calling in with questions about what was causing their
soybean leaves to crinkle and turn yellow. University entomologist John
Wedberg says the aphids were so thick in some Wisconsin fields where
students were working, their legs would be covered by a sticky substance
researchers call “honey dew”. It’s a waste product excreted by the aphids.
Wedberg says the pest probably got into the country on some type of
ornamental plant.
“We’re convinced it didn’t come in on soybean seeds or something of that nature. And
to have the infestation we have over most of southern Wisconsin, and now we find southern
Michigan, northern Illinois and perhaps a little bit in southern Minnesota, it had to have been
here more than a year.”
Wedberg says the aphid doesn’t destroy the plant but it can hurt the
plant’s yield. A crop consultant in southern Wisconsin has seen the aphid
damage firsthand while walking through soybean fields.
“I’m very worried about this aphid”
Paul Haag says that’s because there are no pesticides right now designed
specifically to kill the soybean aphid – the ones farmers are using appear
to kill many, but not all of the pests. However, the chemicals are expensive
and they can also kill potential natural predators that may prey on the
bug. The good news is there are some natural predators at work right
now. One is a fungal disease that resides in the soil. Researchers have
found that when the weather is hot and humid, it destroys aphids. Another
enemy of the aphid is the ladybug. Haag says in some unsprayed spots there
is a “mini-war” going on between the ladybugs, the fungal predator and the
non-native aphid.
“We had thousands and thousands of ladybugs out in the fields – as the numbers went up, the
ladybug population came up behind them. The predators were trying, they just couldn’t keep up.”
Haag says the extent of the crop loss won’t be known until harvest time
this fall. Meanwhile, there’s concern about the extent of the problem
next year. That’s because the aphid produces wings during a portion of its
life cycle and could fly to uninfested locations where it would survive
winter by latching onto woody plants like the buckthorn.
That’s not good news for farmers, struggling to pay bills with record low
prices caused by a glut of soybeans around the world. If the aphid reduces
their soybean yield, the government guaranteed cash payment, that’s
available when prices are low, will be cut back.
A spokesperson for the American Soybean Association in St. Louis says from
what he’s heard, concern about the soybean aphid’s potential to hurt the
soybean supply is exaggerated. Instead, Paul Callinan says it’s a regional
problem, like a flood or severe dry weather. He says any yield loss in the
northern bean belt would not have a major effect on the huge soybean
crop expected this fall.
“Producers in the United States and in South America during the last 2 or 3 years have
produced bumper crops…they’ve had good weather…and although soy demand has continued to grow
during this period, the production supply has exceeded the demand in each of the last 3 years.”
In fact Callinan says his organization wants the government to give a
billion dollars worth of soybeans to foreign food aid programs.
Still scientists are worried about damage the soybean aphid could cause in
the future since the U.S. produces half these world’s crop of soybeans.
Wisconsin entomologist Wedberg says the U.S. Department of Agriculture
has given up any plans to quarantine or destroy fields because the aphid has
spread so far. And he says efforts to find other means to control the aphid
have been slowed because its natural home is China – so all the research
conducted on the pest so far is written in Chinese.
For the great lakes radio consortium, I’m Mary Jo Wagner.