How to check the nematode population in soil?

Question

How to check the nematode population in soil?

Answer 1

There is a well defined procedure for extracting most nematode populations from soil samples defined in "Principles of Nematology" be Gerald Thorne, 1961.  I used this technique for years to evaluate the potential for damage from nematodes on crops, and recommended various methods of control based on counts of plant parasitic nematods in soils.  I beleive there is a similar technique for extracting nematodes or nematode eggs from fecal matter to evaluate animal parasitism.  Very breifly the soil extraction is based on dispersing a soil sample in water, screening most of the soil of by use of seives and collecting the nematodes on a 100 mesh (or smaller) screen and then allowing the live nematodes to migrate thru a filter medium to collect in the bottom of a funnel.  The nematodes are slightly heavier than water and settle into the tip of the funnel where they can be withdrawn and evaluated microscopically.  Different nematodes affect different crops.  This technique is good for free roaming nematodes (those that attack a root from the outside) and less effective for nematodes that penetrate the roots and live inside the crop.

Answer 2

Pre-Plant Soil Testing for Nematodes:

Soil samples should be taken in the early fall from the root zone of the previous crop shortly after the last irrigation. For an adequate test, a composite of 15 sub-samples should be taken from root zone randomly through the field. Sample depth should be 8-12 inches. The soil should be mixed and about 1 quart placed in a zip-lock bag. During transportation and storage, the soil should remain close to the temperature and moisture level in the field. If the soil gets too hot or cold, the nematodes are killed and cannot be recovered from the sample.  Most Extension services will test the soil sample or you can contact a private nematode lab to do the tests.  They cost about $15 per sample.

http://www.ipm.iastate.edu/ipm/icm/node/...

Answer 3

As I am not sure what country you are in, I am not sure what you have available for soil testing and evaluation services. Unless one is well trained, even with a microscope one could not determine which species are beneficials and which are problems.

1) Nematode problems can be spotted as they occur with a daily walk around of your crop, paying attention to root areas and looking for any tell tale signs, especially if you have had a problem before. As with any crop that you grow, especially in monoculture where rotation of crops is not practiced, you need to look closely on a daily basis to find any possible pest, disease, or nutrient problems, to include plant roots. Notes need to be taken on important issues in the crop and watched day to day and this information needs to be kept in a calendar like event document and referred to daily, and used year after year so that noted cycles can be anticipated. You need to keep a map of each area with enough room to make notes and keep plant markers in your pocket and a way to record info on the markers, then place them with the plant.

2)Change your crop. If you have had a nematode problem before, you need to address the issue as it only gets worse. We are talking obviously about the bad nematodes. If you can not change your crop to one that will not be damaged by nematodes and the disease they bring in with them, then you have a number of ways to fight them. Organic solutions first.

3) In areas where you have a problem, let the field sit for a season with nothing in it and let it get dry. If it starts to get  weeds, keep them turned under so the nematodes have no where to go and the sun gets to kill the eggs. If you can split your area up into 3 or 4 blocks and use only one for the problem planting and switch every season.

4) Follow up the fallow stage above with solarizing, or at least solarize if that is all you can do. This helps with a great number of disease problems as well as some weed problems. The soil needs to be tilled deep, to one foot. After that it needs to be wet down so that it is really soaked, much more than just watering. Then let it sit over night. The next day it needs to be tightly covered with clear plastic sheet, and the edges of the sheet need to be buried to seal it tightly. It must stay this way for 4 to 6 weeks. If it rains, DO NOT poke holes in the plastic, but you can carefully use a soft broom to get the puddles. Those puddles will leave spots that will not be solarized, so they must be removed. If you have a rainy season or a period of time when it is rainy, then that is probably not a good time to do this. And plastic must be clear or it will not produce the heat needed to kill problem pests, and this will just be wasted time and materials. When the plastic is finally removed, DO NOT till or move the soil around much. Plant in it as is. But one thing you might do is the following...

5) Use a really heavy mulch. This will encourage the regrowth of the beneficial soil bacterias and fungi which are the natural enemies of nematodes. The best products to use are leaf mold, the rotting and decomposing leaf vegetation, and if you are near the sea, seaweed mulches and compost. Both leaf mulch and seaweed have their own ways to battle nematodes and they also are great in the nutrients they provide for plants. If available and inexpensive, use kelp meal also.

6) Other things to try, at a greater cost of space and money are trap crops of Castor beans, which they will go for first, and antagonists that lower the population like asparagus, french marigolds (Tagetes patula) and chrysanthemum (C. coccineum and C. pyrethrum. In a really bad area, you can plant the whole patch with marigolds. Find a restaurant, flower shop or vendor, or anyway to make a little money on cut flowers so as not to be a complete waste, but at the end of the season you must plow the root and plant under and into the soil. When they have decomposed the chemicals will keep the nematodes from reproducing, even if a few still get into your plants.

7) And keep everything clean. Remove and burn any infected plants, even to the point of removing all the roots and leaves of the plants at the end of the season. Keep tools clean with bleach.

8) If you just wish to use chemicals they are available but only are used if you have a real bad problem and the cost of using it will be justified with the crop, but all will depend on the crop and the nematode type, so you will have to have a test to be sure. For the soil/ root nematode there are things like ethylene dibromide (EDB) and dichloropropene (D-D or Telone). If that sounds really scary, they are. If you have to use it your better off planting something else. I know nothing about them, or how to use them, and for me personally, I would not and will not use them because there are other things to grow that will not have problems

Select a crop or a variety of crop that is nematode resistant, and if you need some more info on that send me an email and I'll help out. Good Luck.

Answer 4

You can go to this   site @  http://edis.ifas.ufl.edu/NG039 ;  for information.  

"...More than 15,000 species and 2,200 genera of nematodes had been described by the mid-1980s.  Soil is an excellent habitat for nematodes, and 100 cc of soil may contain several thousand of them.

   Nematodes are found in almost all habitats, but are often overlooked because most of them are microscopic in size. For instance, a square yard of woodland or agricultural habitat may contain several million nematodes. "  ..................

  "... The only reliable way to determine if plant-parasitic nematodes are involved in a grass problem is by having a nematode assay conducted by a professional nematode diagnostic lab. The Florida Nematode Assay Lab is such a facility and will assay nematode samples for a cost that is currently $20 for each sample from Florida and $25 for each sample from outside of Florida. Nematode sample kits containing everything needed to collect and submit a sample, along with instructions, are available at your local county Cooperative Extension office. "  

"Because plant-parasitic nematodes live in soil or roots, the pesticides used to kill them tend to be very toxic and are water soluble. Because of health risks and environmental concerns there are currently no toxic nematicides that are labeled for use on established home lawns.

  At present, the best management strategies for nematodes in the home lawn are aimed at increasing the grass' ability to tolerate nematode damage.

   Free-living nematodes are very important and beneficial in the decomposition of organic material and the recycling of nutrients in soil. Nematode bacterivores and fungivores do not feed directly on soil organic matter, but on the bacteria and fungi which decompose organic matter.

Answer 5

get the sample of the soil and go to the lab.. coz they are invisible.. gud luck....