Lubbock, Texas
September 4, 2007
Inquiring minds want to know. The
supermarket headlines tell us so.
Inquiring Texas research minds want to know more about cotton
fleahoppers - a tiny, sometimes obscure pest that can damage
plants during their early growth.
"Fleahoppers are a threat to young cotton for about four weeks,"
said Dr. Megha Parajulee, Texas
Agricultural Experiment Station entomologist based at
Lubbock. "They feed on new plant growth, primarily the first
small squares. This damage can delay plant maturity, leaving the
crop open to damage from other pests later in the growing
season."
But these tiny pests aren't all bad. After cotton reaches peak
bloom, this tiny critter is considered a beneficial insect û
living out its relatively short life as both a predator and prey
species.
"Fleahoppers prey on bollworm eggs after peak bloom," Parajulee
said. "They also serve as a food source for other predatory
beneficial insects as the growing season progresses. But we
really don't know much about this
pest. We know it is only a cotton pest in Texas and Arkansas,
but there is more we don't know."
For instance:
- Can cotton plants compensate for fruit/square loss caused by
fleahoppers and still produce acceptable yields?
- What threshold of fleahopper numbers or feeding damage should
trigger a chemical control?
- What pesticides work best against fleahoppers without damaging
beneficial insects?
A three-year study begun in 2006 by Parajulee and other
scientists at the Texas A&M University System Agricultural
Research and Extension Center at Lubbock may provide answers to
these questions.
"We raise fleahoppers here in our 'nursery' and place them on
drip- and furrow-irrigated cotton plants/plots." Parajulee said.
"We vary the number of fleahoppers, and we watch them closely
through peak bloom to determine where they live and feed on the
plants. This will help us develop effective scouting methods for
this pest."
Plants in these fleahopper-infected plots are compared to those
not seeded with fleahoppers (naturally-occurring insect
populations) and to plants chemically treated for fleahopper
damage.
"2006 was not a good year for our study. It was very hot and
dry," Parajulee said. "Even so, we learned that cotton plants
can compensate for fleahopper damage. These plants incurred up
to 25 percent fruit loss from
as many as three fleahoppers per plant and still produced almost
800 pounds of lint per acre.
"Their yield compared favorably to plants treated for
fleahoppers, and untreated plants left to naturally-occurring
insect populations."
Parajulee hopes 2007 data from this study will help generate a
fruit (square) loss treatement threshold. By 2008, the
scientists hope to add specific chemical control tips to their
arsenal of fleahopper knowledge.
Parajulee is also contributing to another study designed to
survey fleahopper biology, behavior and movement statewide, and
generate management recommendations for cotton producers.
That study began in 2007 and is led by Dr. Chris Sansone, Texas
Cooperative Extension entomologist at San Angelo. Other
contributors are Dr. Raul Medina, Experiment Station research
entomologist at College Station; Dr. Charles Suh, U.S.
Department of Agriculture Agricultural Research Service
entomologist at College Station; John Westbrook, USDA
Agricultural Research Service meteorologist at College Station;
several Extension integrated pest management agents, and Apurba
Barman, an entomology doctoral student at Texas A&M University.
"For many years, we entomologists have worked under the
assumption that fleahoppers build up in wild host plants and
then move into cotton prior to squaring," Parajulee said. "In
the eastern part of Texas, fleahopper
migration into cotton from wild host plants is pretty constant.
Producers there can spray two to four times a season to control
them.
"In the Rolling Plains, lack of rainfall limits wild host plants
and makes fleahoppers an occasional cotton pest. Producers there
rarely need more than one control treatment. On the High Plains,
where we have an ocean of cotton and islands of wild host
plants, it takes longer for fleahopper populations to build up
to damaging levels. But once that level is reached, they can
severely impact a lot of cotton by delaying fruiting."
The statewide survey will identify wild host plants that harbor
fleahoppers, how and when this pest moves from host plants to
cotton, and determine if fleahopper populations from wild host
plants and cotton are biologically the same, he said.
"With this knowledge we can recommend cultural practices
(plant/weed control), scouting methods, economic thresholds for
treatment, and pesticides and application rates to help keep
fleahoppers in check," Parajulee said.
Both studies are funded by Cotton Incorporated's Texas State
Support Committee. |
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