FERTILISATION GUIDELINES FOR THE TABLE GRAPE INDUSTRY

The norms for leaf contents of B in grapevines are indicated in Table 26.

TABLE 26: Norms for the B contents (mg kg –1 ) of leaf blades and petioles of grapevines.

Fruit set

Leaf blades

Petioles

Minimum Sufficient

High

Toxic Minimum Sufficient

High

Toxic

15

30 – 80 100 > 150

25 30 – 60 70

> 100

Veraison

Leaf blades

Petioles

Minimum Sufficient

High

Toxic Minimum Sufficient

High

Toxic

25

30 – 80 100 > 200

25 30 – 80 100 > 150

Foliar spraying with B can be done using a 0.2 – 0.3% Na-borate solution (Solubor- solution), while soil applications may be considered according to Table 27, if the solution can be applied uniformly over the entire soil surface, because soil applications are regarded as risky due to the sensitivity of grapevines towards B toxicities. Applications must preferably be done before planting or after harvest and soil applications should rather not be done on sandy soils.

TABLE 27: Application of B agents to alleviate deficiencies.

Amount (kg ha –1 ) Borax Solubor

Level of B-deficiency symptoms or concentration in the soil (mg B kg –1 )

Light symptoms or 3 mg kg –1 in soil

14 – 18 7.5 – 9

General leaf symptoms or 2 – 3 mg kg –1 in soil

30 – 50 15 – 25

Serious symptoms or < 2 mg kg –1 in soil

60

30

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