Nematodes
Arkansas Nematode Diagnostic Clinic Laboratory
What are plant parasitic nematodes?
Who is most likely to benefit from service
Services and Fees
How to collect a sample
Shipping samples to
the laboratory
Retrieving assay results
The Arkansas Nematode Diagnostic Laboratory is the central facility in
the state for receiving samples submitted for nematode diagnostic assay. The
lab is part of the University of Arkansas Cooperative Extension Service and
is located at the Southwest Research and Extension Center, Hope, Arkansas.
The diagnostic clinic provides service to anyone who suspects they may have
a nematode problem.
What are plant-parasitic
nematodes?
Plant-parasitic nematodes are microscopic worms that live in the soil and
feed on the roots of plants. Damage from nematodes is sometimes incorrectly
diagnosed as a nutrient deficiency. Although nutrients may be plentiful,
root damage caused by nematodes may prevent absorption essential for plant
growth and good economic yield. A soil analyses performed by trained
professionals is the best method to determine if plant-parasitic nematodes
are present. Reniform, root-knot, and soybean cyst nematode are 3 common
nematode species of concern in Arkansas. Reniform nematode is a serious and
spreading problem in cotton. Root-knot nematode is the most widespread and
is a problem in cotton, soybeans, and sometimes corn. The soybean cyst
nematode is also a problem in soybean fields. Additional information on
nematodes in cotton and soybeans are available in U of A factsheets.
Nematodes of Cotton in Arkansas
Soybean Nematodes in Arkansas
Who
is most likely to use the Nematode Diagnostic Service?
Commercial growers, producers and farmers
Crop consultants
Cooperative extension agents
Greenhouse owners or operators
Landscape and Turf
Nursery
Homeowners and/or gardeners
Services and Fees:
Soil and plant samples are processed for determining the number of
plant-parasitic nematodes present in soil or plant material. Soil nematodes
are reported as number present in a pint of soil. Recommendations for
control are made for nematodes with a population higher than the threshold.
Threshold levels requiring control action are different for each crop,
nematode found, and the number of nematodes present.
General nematode assay - $10.00: Includes assay for all plant-parasitic
nematodes. This assay is appropriate for all soil living nematodes. Soils
currently in row crop production, turf or golf courses, horticulture crops,
and forestry are a few crops currently being represented by soil samples
received for assay. The fee for an out-of-state general nematode assay is
$20.00.
Soybean assay - $20.00: Includes a general nematode assay. Some soybean
varieties are resistant to certain races of the nematode, but susceptible to
others. A soybean cyst race assay is only needed when soybeans will be
planted and the soybean cyst nematode (SCN) is present. Unless otherwise
requested, all soybean samples with a sufficient SCN level will be
automatically tested for race. A bill will be sent based on results
received. If no SCN are found, we will only bill for a general assay and the
fee will only be $10.00. The fee for an out-of-state soybean assay is
$50.00.
Nursery stock - $25.00: This is usually not necessary unless soil and
plant material is crossing state lines. Certain states have strict
quarantine and regulatory requirements for shipping plant material into
their states. The Arkansas Plant Board can provide details of sampling
procedures. Both soil and root samples may be necessary.
Rice grain-certified-$75.00 per lot, generally there will be 3 samples
per lot. Rice is tested for the presence of the white tip nematode in a
special test. Large quantities of rice, such as a barge, may need to be
tested before shipping to certain overseas markets. Because this test is for
a large quantity, it will not likely be requested by individual rice
producers in the state. Guidelines for sampling rice have been determined by
the Arkansas Plant Board. Contact the Arkansas Plant Board for details. The
price for rice grain for single samples from a grower is $25.00.
How to collect a sample
The late summer and fall are the best times for sampling, when nematode
populations will be at their highest level. The end of the growing season is
the best time to identify problem areas within a field. Areas of the most
injury should be most evident at this time. Sampling at the end of the
growing season is in preparation for next years crop and not all fields
will need to be sampled every year. Sampling 1 out of every 3 years may be
sufficient.
Which fields or crops
should be sampled?
1. If the next crop will be cotton or soybeans, then the field should be
sampled if it is currently in cotton, soybeans, corn, or any vegetable.
2. If the next crop is to be corn or grain sorghum, a sample may not be
necessary. Some nematodes may be a problem in these crops. Root-knot
nematode may be a problem in some susceptible corn hybrids. Sampling these
fields may provide advanced warning to a potential problem.
3. There is no need to sample if next years crop will be rice.
Sampling and handling care.
1. A single sample should not represent more than 20 acres.
2. For crops grown in rows, samples should be collected from the root zone
of the crop to a depth of 8 to 12 inches. The best time to collect from
these crops is during the growing season or shortly after harvest.
3. Golf greens, lawns, and landscapes should be sampled to thoroughly
represent the area of concern. Each golf green should be represented by a
separate sample.
4. Fruit trees, small fruits, woody ornamentals, and other perennials should
be sampled to a depth of 12 inches in the root zone near the drip line.
5. For all samples, a minimum of 20 cores with a sampling tube or sampling
device should be collected randomly from the area to be tested. The cores
should be mixed together and 1 pint submitted for analyses.
Handle the samples with reasonable care. Package and label them
adequately and properly. Place the samples in a plastic bag immediately
after they have been collected. Regular freezer bags are the best type to
use for nematode soil samples. Zip Loc bags are satisfactory, however, these
types of bags may pop open during shipping and handling. The "zipper type"
bags stay closed the best. Keep the samples out of the sun. Exposing the
soil samples to excessive heat will kill the nematodes. Putting the soil
samples in a cooler without ice is the best method of protecting the
nematodes until shipping.
Bags should be labeled on the outside with a tag. Sharpie markers and
other waterproof markers are not a permanent method of identifying samples.
Many times the writing rubs off the plastic bag during transport, especially
if many samples are shipped in a box. Do not send too many samples in a box.
Ten samples per box is ideal. There is a direct correlation between the
number of samples in a box and the condition of the samples upon arrival.
Heavier boxes are the most likely to arrive damaged, with split sample bags
and sometimes missing 1 or more samples.
Fill out a sample submission form. Each sample must be accompanied by a
Nematode Sampling Submission Form. These forms may be obtained from your
local county Extension office or from the Arkansas Nematode Diagnostic
Laboratory. Completed forms should be included in the box with the soil, but
not inside a bag of soil. If sending more than one sample per box, place the
completed submission forms together on top of the soil. Do not stagger them
throughout the box.
Instructions for collecting samples determining if
Nursery stock is free of nematodes.
Collect fresh specimens and ship in a crush-proof container. Label
samples in a clear and concise manner.
Rice grain
The nematode lab will perform assays on
rice grain for presence of the white tip nematode (Aphelenchoides
besseyi). Rice must be declared free of this nematode before a shipment
will be accepted into certain overseas markets. This nematode was
historically a problem in the mid South. Guidelines for proper sampling of a
lot of grain are available from the Arkansas Plant Board.
Shipping samples to the
laboratory
Samples for nematode assay may be sent by any means to the nematode lab.
Mailing samples early in the week is preferable. Samples shipped early in
the week will generally arrive at the lab the same week and are less likely
to be subjected to a less than ideal environment for prolonged periods.
The mailing address and phone number are:
Arkansas Nematode Diagnostic Laboratory
362 Highway 174 North
Hope, Arkansas 71801
Phone: (870) 777-9702, Ext. 124, 130, or 140
Results of assays
Results of a general, nursery stock, or rice grain nematode assay will
usually be available within 1 week after the sample is received at the lab. A
soybean cyst race assay, when needed, requires about 40 days to complete and may
take longer if a greenhouse buildup is required. Clients will be e-mailed,
faxed, or regular mailed the results as soon as they are available.
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