Greensboro, North Carolina
October 15, 2008
Source:
Syngenta Crop
Protection
Are your grower customers seeing
lower yields in corn fields that have the ability to produce
higher returns? Does their crop show little to no sign of damage
or stress? Have they considered corn nematodes as the culprit?
While these microscopic, thread-like round worms are invisible
to the human eye, corn nematodes can inflict major damage to
crops, which can lead to sizable yield losses. In recent years,
changing production practices have created an environment
conducive to nematode survival, making it especially crucial for
growers to understand how these pests can harm their fields and
their profits, as well as ways to safeguard against this threat.
Types of Nematodes
Corn can be attacked by at least two dozen species of nematodes.
“The most common nematode is the lesion or root-lesion
nematode,” said Dr. Terry Niblack, a nematologist at the
University of Illinois who has been studying nematodes for about
25 years. All soil types are at risk for the lesion nematode,
which is also one of the most damaging corn nematodes. In sandy
soils, Niblack notes that some of the most injurious and
commonly found corn nematodes are the needle, sting and
stubby-root nematodes.
Nematodes are classified into three major categories based on
their root-feeding characteristics: endoparasitic nematodes
completely enter the host as they feed from within and live
within the roots; semi-endoparasitic nematodes can feed from the
outside or partially enter the root to feed; and ectoparasitic
nematodes feed only from the outside and live mostly in the
soil.
A Hidden Pest
Often misdiagnosed and misunderstood, corn nematodes have become
a growing problem in the Midwest as a result of changes in
production practices. In recent decades, the widespread use of
soil-applied organophosphate and carbamate insecticides helped
inadvertently suppress corn nematode damage. Now, with the
switch to pyrethroid insecticides and the removal of in-furrow
insecticides due to the use of transgenic insect-resistant corn,
nematode pressure has become more evident as these products lack
the ability to suppress nematodes.
Additionally, some nematodes do not respond well to soil
disturbance; therefore, the increased trend in no-till and
reduced-tillage farming coupled with more corn-on-corn
production also has helped provide a more suitable environment
for these creatures to thrive.
While all fields can be vulnerable to corn nematodes, many
producers still underestimate the problem. “Most farmers do not
sample their soil for corn nematodes,” said Niblack, adding that
the symptoms of nematode damage are not easily recognized. Some
common signs of damage from corn nematodes include chlorosis,
reduction in stalk diameter and discoloration, which can mimic
other problems such as harsh environmental conditions or
herbicide injury. However, more often than not nematode damage
may be impacting crop yield even if visual symptoms are not
present. The only way to accurately diagnose nematode damage is
to collect and analyze soil and root samples. Several
universities and labs in the Midwest provide soil sample
analysis services for nematode damage. “Growers need to collect
samples to accurately find out what nematodes are in their
field, that’s the most important step,” Niblack said. For a list
of labs that can analyze soil and root samples for nematodes,
contact your local university extension office.
Syngenta Seed Care™ recognizes the threat that growers face with
corn nematodes and is working to receive registration for a corn
seed treatment nematicide. For more information, please contact
your Syngenta Seed Care sales representative.
Syngenta is a world-leading agribusiness committed to
sustainable agriculture through innovative research and
technology. The company is a leader in crop protection, and
ranks third in the high-value commercial seeds market. Sales in
2007 were approximately $9.2 billion. Syngenta employs over
21,000 people in more than 90 countries. Syngenta is listed on
the Swiss stock exchange (SYNN) and in New York (SYT). Further
information is available at
www.syngenta.com.
Syngenta Seed Care™ is a registered trademark of a Syngenta
Group Company. |
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