Technical Bulletin
A publication of the LG Seeds Agronomy department
Issue 255: August 2015
Corn Nematodes
Matt Teply, Agronomist, CCA
The 2015 growing season will definitely be one to remember. There were a multitude of issues that have
affected the corn crop this year. Early cold and continued wet weather lead to increases in several disease
and insect issues. One issue that I noticed more this year than in the past was the severity of nematodes and
nematode damage. Every year we have one or two issues within the region with these damaging little
parasitic worms. Yet, this year it was relatively quiet; though as I drove around, I would see field after field
showing signs of nematode damage.
With the higher than average rain amounts across the region I heard a lot of people talking about the
leaching of early applied nitrogen being the cause of the unevenness within fields. The leaching was
probably one of the issues growers were seeing. But, the larger issue was root damage caused from
nematode feeding. Nematodes are extremely small parasitic worms that feed on and cause damage to corn
roots. Most are so small they can’t be seen with the naked eye. The early cold and wet weather wasn’t
conducive for the establishment of vigorous early root growth which is essential to outgrow damage caused
by nematodes. Symptoms of the feeding are bottle brushed and stunted roots, similar to damage from root
inhibitor herbicides.
Root Damage from corn nematode feeding
Picture courtesy of Matt Teply, LG Seeds
Root damage and stunted corn affects from
corn nematode damage
Picture courtesy of Matt Teply, LG Seeds
Root damage from corn nematodes in turn can stunt plant growth and development. This early added stress
causes tremendous loss in yield potential. There are also above ground symptoms can that be seen in some
circumstances. Symptoms could include stunted plants, yellowing or discoloration of plants, and in worse
cases plant death. These symptoms often mimic symptoms you would see with the ponding of water and
nutrient deficiencies. Most symptoms will show up in circular or irregular shaped patterns due to the varying
levels of nematodes within a given area.
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The most common nematode found throughout the Corn Belt is the lesion nematodes and are the nematode
related to most crop damage. Needle nematodes are probably the most devastating but are less frequently
found. Stunt, stubby, lance, dagger, spiral, stunt, pin, and ring are other types nematodes found across the
corn belt and are known to cause damage to corn.
There continues to be a rise in issues associated with nematodes and nematode populations. Several factors
lead into this. Farming practices continue to switch to more no-till and minimum till systems, thus disturbing
the soil less frequently. The introduction of traits to control insects such has rootworm has greatly decreased
the amount of soil-applied insecticides once used to control them. Counter and Counter 20CR were once
widely used to control rootworm and was the only, and still the only, soil-applied nematicide in the market.
Other issues that have led to the increased nematode populations include lack of crop rotations and the lack
of grass control in crops.
To help in the control and suppression of nematodes there are few options in corn. In the market today
there is still some availability to, and the use of, soil-applied insecticides and nematicides. Again, Counter
and Counter 20Cr are the only labeled soil-applied nematicides.
The other options are seed-applied products. LG Seeds decided several
years ago to use VOTiVO, a biological seed treatment offered by Bayer
Crop Sciences. Bacterial spores are applied to the seed. As the seed
germinates and the roots start to grow the bacteria begins its life cycle as
well. The bacterial spores grow and feed off exudates given off by the
roots as the corn plant grows. As the bacteria grows and feeds off the
exudates, it basically covers the root in a protective layer, thus reducing
the root surface area that nematodes have to feed on. With less root
surface area out in the open, the nematodes basically starve to death.
Picture courtesy of Bayer CropScience
The use of VOTiVO and its biological control is not only very consistent in its results, but is extremely safe
for humans and other non-target organisms. Chemical based compounds do not have these same attributes.
Some intense nematode pressure has been seen in western Kansas and Nebraska where the use of both a
soil-applied nematicide and a seed treatment are needed. Crop rotation is probably the best option in these
situations. But, the economics of irrigated acres in the high plains often lead back to corn-on-corn.
Nematode issues continue to spread across the Corn Belt and into various different soil types. Make sure
you looking closely at your fields. Misdiagnosis of the issue is easy. If you think you may have an issue take
samples to find out. It is important that when taking samples you send in both soil and root mass. Soil and
root mass need to be intact and together if possible because nematodes will be found in both. Universities
and labs are capable of diagnosing corn nematodes. This link to the University of Nebraska –Lincoln may help
and clarify the sampling procedures. UNL Nematology Diagnostic Lab - Sample Submission =
http://nematode.unl.edu/diagnostic_lab.htm
I recommend that all LG Seeds seed corn purchased be treated with PONCHO 500/VOTiVO. We continue
to find that year after year it just pays.
Sources and Additional Information:
1. Interactive Diagnostic Key to Plant Parasitic, Freeliving and Predaceous Nematodes.
http://nematode.unl.edu/key/nemakey.htm
2. Corn Nematodes. http://nematode.unl.edu/corn_nematodes.html
Counter is a registered trademark of AMVAC Chemical Corporation. VOTiVO and Poncho are registered trademarks of Bayer CropScience.
Note: The information in this issue is based upon field observations and third party information. Since variations in local conditions may affect the
information and suggestions contained in this issue, LG Seeds disclaims legal responsibility therefore. Always read and follow label instructions. LG
Seeds and design are trademarks of SCA Limagrain.
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