| NEMATODE: | RATE OF DECLINE/ YEAR | YEARS OF FALLOW |
| ROOT-KNOT | 85% | 0.25 - 2 |
| SUGAR BEET CYST | 25-50 % | 4-8 |
| STEM AND BULB | 4 | |
| DAGGER (X. INDEX) | 10 | |
| LESION | ???? | ???? |
| CITRUS | ???? | ???? |
| STUBBY ROOT | ???? | ???? |
| FOLIAR | ???? | ???? |
| RING | ???? | ???? |
| DAGGER (X. AMERICANUM) | ???? | ???? |
| NEEDLE | ???? | ???? |
| SHEATH | ???? | ???? |
The basic principle behind utilizing fallow to manage nematodes is that nematodes will starve to death in the absence of a host crop.
For some important nematodes such as root-knot, sugarbeet cyst, stem and bulb and X. index, relatively good information is available on the length of time nematodes must be without a host in order for this to occur. For other nematodes, this type of information has not been developed.
In some cases, fallow is not successful in practice because the importance of weeds as hosts is not taken seriously.
The length of time that roots remaining in the ground are able to serve as hosts for nematodes in the absence of above ground plant growth is often overlooked.
Efforts to reduce populations of stem and bulb nematode on alfalfa, garlic, and daffodils, and root-knot nematode on potatoes have been confounded by the presence of "volunteers" surviving around the edges of fields or as "weeds" within the field.
There is conflicting evidence in the literature as to whether dry or wet fallow is of greater usefulness. The particular nematodes of interest, soil type, climatic conditions, and other variables are likely to all play a role.
Research by Ferris and others indicates that soil disturbance (e.g. plowing or rototilling) a field during fallow will increase the rate of nematode decline (as well as add to the cost of the fallow procedure).
The usefulness of fallow is limited at the present time because of our inability to predict when it would be economically beneficial for growers to fallow ground to reduce nematode populations rather than to plant a susceptible crop.