FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

TABLE 12: Vigour * (veraison to after harvest): guidelines for nitrogen fertilisation of table grapes with a production level of 30 ton ha –1 .

Nitrogen requirement (kg N ha –1 per season)

Vigour classification norms for grapevines

After bud break

After fruit set

After harvest

Total N

Very poor vigour • shoot length of 50 – 70 cm • shoots pencil thickness or thinner • tips of shoots did not ripen • short internodes (< 5 cm) • leaves have a light green colour • little or no effective growth before veraison • shoots on average pencil thickness • tips of shoots did not ripen properly • short internodes (5 – 6 cm) • little active growth before veraison Ideal vigour • shoot length 100 – 150 cm • 10 – 12 leaves per bunch • 20 – 30% active growth at veraison • shoots ripen properly • only light tipping of shoots necessary at veraison Above average vigour • shoot length 150 – 250 cm • internodes longer than 10 cm • > 50% van growing tips active at veraison • must be tipped twice before veraison • lateral shoots common • most shoots still growing after harvest Too much vigour • long, thick, flat shoots (up to 5 m) • necessary to cut open every two to three weeks • large, dark green leaves (become yellow underneath the canopy) • strong development of secondary shoots • shoots continue growing long after harvest Below average vigour • shoot length 80 – 100 cm

1

50

60

50

160

2

50

50

40

140

3

40 20 – 40**

40 100 – 120

4

20 – 30**

0 30 – 40** 50 – 70

5

0 – 10***

0

0 – 30 0 – 30

* Use the vigour of the previous year as guideline **These values must be adjusted after evaluation of the vegetative growth *** Experience will show whether this instalment should also be omitted.

48 | MAINTENANCE FERTILISATION