Phosphorus deficiency-Table Grape

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Nutrients

Wine Grape - Number reduced

Symptoms
P deficiency reduces fertility and fruit setting considerously, resulting in poor yield.

Reasons
Phosphorus deficiency

Wine Grape - Discolouration

Symptoms
P deficiency results in reduced growth and dark green leaves, often with some bronzing to purple lesions on the leaf blades. Discoloration starts at the margins and spreads over the interveinal areas. The leaves become hard and stiff. Dormant buds contain only small flower primordia what reduces the performance of the vines.

Reasons
Phosphorus deficiency Phosphorus deficiency occurs rather seldom in the fields.

Phosphorus deficiency made worse by

Acidic or very alkaline (calcareaus) soils
Low organic matter
Cold or wet conditions
Crops with a poorly developed root system
Soils with low P reserves
Soils with a high phosphate capacity
Iron rich soils

Phosphorus is important for

Healthy green foliage
Improved fruit set
Improved quality

Yara recommended fertilizers for Phosphorus

YaraVita CROP BOOST

Grapevines: 3 to 5 l/ha at flower buds visible, flower buds separated, fruit set, and early veraison (one month before harvest). Water rate: 200 l/ha.

YaraVita SENIPHOS

Grapevines: 10 l/ha at fruit set and repeated 2-3 times at 10-14 day intervals. Water rate: 500 l/ha.