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
