Nematology 100 Field
Trip
Rev
10/09/08
Purpose: Field symptoms, field extraction and observation,
discussion of practical detection, assessment and management issues:
Each group takes two samples from stratified area or group of
plants. Cores from a stratum are bulked, mixed and a subsample taken for
extraction of nematodes.
We will be visiting several sites. Please clean
equipment between sites.
Extraction:
-
decanting and sieving for large nematodes
-
direct observation for nematodes that
exhibit signs or symptoms
-
Seinhorst 2-flask method and sugar-centrifugation for
less mobile nematodes.
Where a coarse screen is used in the extraction, is there any
correlation with the amount of root detected in the sample and the presence of
nematodes?
Purpose: To demonstrate the tools available for sampling to
detect and quantify nematode populations. To test the reliability and
precision of sampling procedures.
1. Demonstration of sampling tools and
their use.
- Oakfield 2.5 cm diam soil tube - varying lengths and designs,
including automatic bagging and foot attachments.
- Veihmeyer sampling tube.
- Auger
- Gasoline powered auger.
- Shovel.
2. Effect of extraction method on determination of species
presence/abundance.
- Work in pairs.
- In the grape rootstock trial, from one replicate plot of St. George
rootstock, take a core of soil to a depth of
18 inches from each of three vines. Sample under a dripper and composite
the cores.
- One group extract nematodes from the soil by decanting and sieving with a
100 mesh sieve, followed by direct observation.
- One group extract nematodes from the soil by the Seinhorst 2-flask method
followed by sugar-centrifugation (we will do this later on campus).
- Are there differences in the types and abundance of nematodes detected?
3. Reliability of population estimates.
- Work in pairs.
- Use the 30 cm x 2.5 cm diam. Oakfield tube to sample a uniform stand of
alfalfa.
- Each student sample the field by taking 10 cores of soil from the root zones of plants as a composite
sample to represent the alfalfa field.
- Clearly label your samples and store in an insulated box.
- Class will work together during a scheduled laboratory session to extract nematodes from
250cc soil subsamples by decanting, sieving and Baermann funnel techniques
- At the next laboratory period, each group will identify and count the predominant species of
plant-parasitic nematode in their samples
- Determine the reliability of a single composite sample from the field on
the basis of the range and variance of individual sample estimates.
4. Sampling nematodes associated with
plant tissue.
- Sample walnut trees at the drip line.
- Wash samples through a screen into a 2-liter Ehrlenmeyer flask.
Collect the roots caught on the screen for mist extraction in the laboratory
to determine presence and abundance of migratory endoparasitic nematodes.
- Use Seinhorst 2-flask method followed by sugar-centrifugation to determine
presence and abundance of migratory endoparasitic nematodes in the soil.
5. NEMAPLEX Exercise
Main Menu:
Select...Methodology
Select...Sampling
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