STONE FRUIT AND NUT TREE CROPS

On grapevines, aboveground symptoms of nematode damage are relatively nonspecific compared with most aboveground disease, soil, and management problems. However, aboveground symptoms do occur from damage on grapes by the more pathogenic nematodes species. These symptoms include reduced vine vigor, reduced yield, and occasional slight yellowing of leaves in both young and established vines. Vine death seldom occurs unless there are other stresses on the plant. Damaged vines are the first to show nitrogen or water deficiency, especially during peak growth or high temperature periods. Damaged vines often tend to be grouped together to form a poor growth area within a vineyard. However, within the poor growth area, plants may vary considerably in the amount of stunting and vigor loss that they show. Nematode damaged vines will show correspondingly less yield than will healthy vines, with the amount of yield reduction depending on the severity of nematode attack and on the tolerance of the particular cultivar or rootstock grown. Nevertheless, grape varieties of high vigor can be damaged as much as those of lower vigor. Heavy pruning may be used to minimize stress on the plant. This is a common means of minimizing nematode damage.

From: McKenry, M.V. and P. A. Roberts. 1985. Phytonematology Study Guide. University of California, Division of Agriculture and Natural Resources. Publication 4045.

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