Many fields do not have nematode problems. Growers with medium textured soils, adequate rooting depth, proper irrigation management, and reasonable rotation practices are least likely to experience nematode problems. Nematodes are especially problematic when soils, irrigation practices, or management are marginal. Marginal soils may include the sand or clay soils, shallow soils, or highly stratified soils. Marginal irrigation practices are those that fail to provide water at the needed frequency or quantity.
Marginal management involves such decisions as crop rotation or cropping sequences.
A second example would be the removal of a perennial crop and the replanting of a similar perennial crop the following spring. These situations precede or aggravate nematode problems. Nematode problem areas are usually pocketed or irregular spots of poor growth. In Califonia's alluvial valley soils, damaged plants are frequently in sandy streaks across the field. Nematode incidence in a particular field may or may not be restricted to areas of poor growth.