SOIL AND MANAGEMENT PATTERNS

Consider a field that, following a long history of root knot nematode infection, is widely infested with this nematode. The dominant soil texture is sandy loam, but a large irregular sandy streak occurs across the field. The field has established grapevines susceptible to root knot nematode attack, and the grower has a single irrigation line across the field. Discrete areas of poor vine growth, visible in the field area, are predominantly confined to the sandy soil streak. Additionally, the individual vines adjacent to the irrigation line show improved growth within the sandy area. Poor growth in the sandy area is related to the low water holding capacity of the sandy soil, which compounds stress on the infected plants by further limiting the root systems' uptake of water and nutrients. The improved growth near the concrete irrigation line is due to water leakage or availability that enhances the frequency of water supply to nearby plants, thereby reducing stress on those vines. This indicates that improved frequency of irrigation can alleviate some plant stress in this damaged area. Although nematode populations may be higher in sandy areas in a field such as this, the example illustrates that a different set of factors - in this case, soil and management factors - can influence the pattern of nematode incidence and plant damage within a field.

From: McKenry, M.V. and P. A. Roberts. 1985. Phytonematology Study Guide. University of California, Division of Agriculture and Natural Resources.

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