FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

CHAPTER 5

FIGURE 8: Typical potassium deficiency symptoms that can be observed for table grapes (Photo: G. van der Merwe).

Certain leafhoppers also cause chlorosis symptoms that strongly resemble K deficiencies (Figure 9). These can be distinguished, however, because in some areas of the leaf the colouration ends sharply against the secondary or tertiary veining.

FIGURE 9: Coloration and necrosis caused by leafhoppers, can sometimes be confused with K deficiency (Photos: D. Saayman).

Leafroll virus infection also causes red or yellow colouration of the leaves but is easily distinguished from leaves affected by K deficiencies. Additionally, they result in a high K content of the leaves (Figure 10).

FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY | 53