FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

CHAPTER 5

deficiency (the so-called spring fever of the Californians) and high levels of nitrate accumulation in leaves, which can lead to shiny blemishes and leaf edge necrosis (Figure 3). Bright yellow leaves, wherein the chlorophyll has broken down on account of insufficient sunlight penetration, will also be noticed on the bottom side of excessively dense canopies, induced by an over-supply of N (Figure 4). Long, flat internodes, bunch abortion and shattering of berries are further symptoms, as in the case of growth arrest phenomenon, found on N rich soils along the Lower Orange River.

FIGURE 2: Light green colour/yellowing of grapevine leaves, associated with N deficiency (right) (Photo: P. Raath).

FIGURE 3: Excessive N nutrition induce temporary K deficiency (left), as well as shiny blemishes and leaf edge necrosis (right), due to high levels of nitrate accumulation in leaves (Photo’s: Phosyn (left); D. Saayman (right).

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