Crop scientist targeting fungus threatening pumpkins, peppers
Jim
Barlow, Life Sciences Editor
(217) 333-5802; b-james3@illinois.edu
8/6/02
CHAMPAIGN, Ill. —
New strategies emerging from research at the University of Illinois at Urbana-Champaign
are saving many of the state's vegetable crops from a fungus that nearly put
an end to pumpkin and pepper production.
The culprit, Phytophthora capsici, has become a threat to many crops nationwide.
First detected in Illinois in the 1990s, it seriously threatened the production
of pie-pumpkin production near Morton and forced pepper growers near Shawneetown
to move into other fields. The loss of pumpkin crops would have dealt a serious
economic blow to Illinois, the nation’s leading pumpkin-producing state.
"There are approximately 20,000 acres of pumpkins grown each year in Illinois,
8,000 to 10,000 for processing and 10,000 to 12,000 acres for jack-o-lanterns,"
said Mohammad Babadoost, a professor in the department of crop sciences. Illinois
growers account for 70 percent of all commercial-processing pumpkins in the
nation.
"We are making progress," Babadoost said. "We have the disease
contained. A walk through pumpkin fields in the Morton-Pekin area late last
month showed that the disease is still there, but not spreading as it used to
be doing."
Babadoost is studying both immediate and long-term strategies to fight the pathogen,
which has struck pumpkins, cucumbers, eggplants, melons, peppers, squashes,
tomatoes, watermelons and zucchinis with seedling death, foliar blight and fruit
rot. Crop losses of 100 percent had been recorded in 1999 and 2000 in Illinois
following periods of frequent and sometimes heavy rainfall. Without intervention,
a crop can be lost in a week.
Babadoost reported on some of his work in the July issue of the journal HortScience
and in a late July presentation to the American Phytopathological Society annual
meeting in Milwaukee. Another paper has been accepted by the journal Plant Disease.
In 2000, Babadoost's team tested 14 fungicides before narrowing their choice
to Acrobat MZ, with approval from the U.S. Environmental Protection Agency,
for field experiments on pumpkins in 2001. While results were positive, they
found MZ to be too costly. This year, they are using Acrobat 50WP alone, again
with EPA approval, applying 6.4 ounces per acre where the fungus is spotted.
Growers mix it with a copper compound.
At the APS meeting, Babadoost and postdoctoral associate Sayed Zahirul Islam
reported that three of 56 varieties of peppers – Emerald Isle, Paladin
and Reinger – are resistant to the pathogen in Illinois.
In HortScience, Babadoost, Islam and Y. Honda, a researcher at Japan's Shimane
University, documented that starting peppers, pumpkins and tomatoes under red
light in a greenhouse offers protection against P. capsici. Less than 36 percent
of the plants exposed to the fungus after four weeks of red-light treatment
became infected, while between 78 percent to 100 percent of control plants started
under traditional white light died.
Peppers transplanted into the field after red-light treatment are showing resistance
in ongoing tests near Shawneetown, Babadoost said. Pumpkin transplants in experimental
fields near Pekin are being evaluated. If red-light treatment offers season-long
protection, he said, chemical applications eventually might be unnecessary.
Using red light may not be readily agreeable to pumpkin growers, Babadoost said,
because pumpkins traditionally are grown directly from seed in the field rather
than started in a greenhouse, a change that would involve extra costs. However,
red-light treatment for other cucurbit crops such as cucumbers, melons and squashes
would be readily available.
Another long-term solution showing promise is the use of a fungicide on seeds.
In their Plant Disease paper, Babadoost and Islam detail how the fungicide mefenoxam
(Apron), when applied to seeds, offers systematic protection to pumpkin plants
in early growth stages, delaying the development of Phytophthora disease.
Since Apron is already registered for use on cucurbit plants, pumpkin growers
may choose to use it and later apply Acrobat, if necessary, on affected plants,
he said.