FERTILISER GUIDELINES FOR THE WINE INDUSTRY

Certain leafhoppers also cause chlorosis symptoms that strongly resemble Kdeficiencies. These can be distinguished, however, because the colouration of the leaf ends sharply against a secondary or tertiary vein in some areas.

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FIGURE 9: Leaf edge colouration and necrosis due to leafhopper damage.

Leafroll virus infection also cause red or yellow colouration of leaves, but is readily distinguished from leaves affected by Kdeficiencies and result in a high K-content of the leaves. The leaf analysis norms for K are indicated in Table 14. Once again the same precautions regarding the use thereof, as for N, are applicable as explained on p.43.

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