FERTILISER GUIDELINES FOR THE WINE INDUSTRY

The norms for leaf contents of B for grapevines, are indicated in Table 18.

TABLE 18: Norms for B-contents (mg kg -1 ) of leaf blades and petioles of grapevines.

Fruit set

Leaf blade

Petiole

Deficiency Sufficient

High Toxic

Deficiency Sufficient

High Toxic

<15

30-80 >100 >250

<25

30-70 >100 >120

Veraison

Leaf blade

Petiole

Deficiency Sufficient

High Toxic

Deficiency Sufficient

High Toxic

<25

30-80 >100 >250

<25

30-80 >100 >150

Foliar spraying with B can be done using a 0.2-0.3-Na-borate (Solubor) solu tion, but soil applications are more permanent and, although risky on sandy soil, it can be applied according to the amounts indicated in Table 19. Due to the sensitivity of grapevines towards B-toxicities, it should be applied in solution across the entire soil surface to ensure even distribution and also preferably after harvest in existing vineyards without wetting the canopy. In the case of new plantings soil application can be done as aforementioned, just before the making of planting holes.

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TABLE 19: Soil application of B according to level of deficiency symptoms or soil type.

Amount (kg ha -1 )

Level of deficiency or soil type

Borax* (11.5% B)

Solubor** (20% B)

Light symptoms on sandy soil

15-18

8-10

General leaf symptoms on sandy clay loam soil

30-45

15-20

Serious bunch symptoms on clay soil

60

30

* Na 2 B 4 O 7 .10H 2 O ** Na 2 B 4 O 7 .3H 2 O

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