Of the various factors known to be important, temperature has been looked at in the greatest depth. Some examples of the length of time for a generation under optimum conditions are given in the table.
In a particular cropping system, there is often a single crop for which the grower receives the highest rate of return. The prime strategy then of the crop rotation program is to grow that crop as often as possible. In some areas of California, this would be cole crops, in others potatoes, tomatoes, or perhaps carrots, all of which can suffer serious nematode damage.
In a crop rotation program, it is advantageous to be able to plan several years in advance. If the expected rate of population increase is known, one can forecast what the population will be at harvest. This combined with knowing the expected rate of decline will allow forecasting when the most profitable crop can be planted once again and so forecast if the rotation chosen will be economical. One could also consider other possible options such as harvesting the crop early when nematode numbers might be lower which might then permit a shorter rotation period.