December 2003. A member asked about the control of nematodes in an area where the population was high.
A comprehensive list of measures were provided, including a range of methods to manage nematodes in different situations. These are all non-chemical methods which are generally recommended in today's agriculture but some crops, such as perennial tree crops, can benefit from use of nematicides.
NON-CHEMICAL NEMATODE MANAGEMENT METHODS
PREVENTING THE INTRODUCTION AND SPREAD OF NEMATODES
Use of nematode-free seed, other planting material or seedlings
1. Planting material naturally free of infestation
2. Physical removal of tissues infested with nematodes
3. Physical destruction of nematodes in planting material
4. Production of clean seedlings from nematode-free seedbeds
* burning plant debris on surface
* turning soil to expose nematodes to sun and drying
* solarization of beds with clear polyethylene sheets
CULTURAL AND PHYSICAL PRACTICES TO CONTROL NEMATODES
1. Rotation of crops
2. Resistant cultivars
4. Adjusting planting time/escape cropping
5. Antagonistic plants and trap crops
6. Burning stubble
7. Flooding: artificial and natural
8. Post harvest removal/destruction of infected crop residues
9. Cultivating/turning soil between crops
11. Organic soil amendments and biological control
12. Improved crop husbandry (compensation for damage)
1. Multiple cropping
2. Mixed cultivars
Another response was directed more towards management of root-knot nematodes:
Root-knot nematodes cannot be controlled in a sustainable manner. In other words, a short term solution will not help, and a longer term strategy has to be thought of. Often pesticides either don't work very well on root-knot nematodes or, if they do, give only a temporary reprieve.
But there are several strategies that can be adapted, first of them being the use of a suitable crop rotation. Several vegetable crops like tomato, eggplant, carrot, etc are highly susceptible to root-knot. They shoudl be followed with a choice from the list below:
- A cereal like sorghum, or flooded rice, or
- A cool season crop like cabbage (or any cruciferous vegetable), or
- Sunn hemp (a green manure crop - Crotalaria juncea), which can be ploughed back into the soil in about 40 days to benefit the next crop, or
- Marigold (Tagetes erecta) if it has commercial value in your region.
Along with crop rotation, some biocontrol agents can be used, which will not give immediate results but over a period of 3 or more crops, will establish itself well enough to render the soil suppressive to nematodes.
The three biocontrol agents are:
- Paecilomyces lilacinus, a nematophagus fungus, now commercially available in a spore formulation.
- Pochonia clamydosporia, is also a fungus. No products are available in the market as far as I know, but it can be cultured on a compost/grain medium in a small scale and is suitable for small holdings (This was a part of my PhD studies!)
- Pasteuria penetrans a form of bacteria that multiplies inside the rootknot nematode. I have heard of a recent product in the market, produced in Japan. I shall find out more details on this for you, shortly.
There are a few cultural methods to be adopted, that can prevent the spread of root knot.
- Root-knot typically occurs in patches, always introduced from external sources. Hence agricultural implements used in the affected areas should be washed before moving to a clean area. By simply hosing down all parts which have soil sticking to it (including tractor wheels) with water within the infested area, the spread can be prevented.
- In severly infested areas, fallowing would be a good method if a farmer can afford it.
- Resistant cultivars are a possibility. (A cultivar resistant in one part of the world may not be resistant in another!).
Later (September 2011), University of Arkansas Press Release (www.uaex.edu), recommended pelletised chicken litter. It has 4% nitrogen, 2% phosphorus and 3% potassium, and also contains calcium, magnesium and iron. It was used with good results for sweetpotato, especially in reducing the effects of soil nematodes.