Zinc deficiency-Grapevines

Symptoms
Symptoms of zinc deficiency appear on young leaves first. A light green, mosaic-like chlorosis appears in the interveinal areas and continues to pale over time. Along the veins, a dark green border remains. The leaf blades are small and asymmetrical; one half of a leaf is always larger than the other. The main vein runs in a slight curve with the tip leading towards the small half.

Causes
Zinc deficiency At high P excess, Zn will combine with phosphate into the nearly water-insoluble Zn phosphate so that the roots cannot absorb it. Phosphate absorbed in excess leads to a partial inactivation of Zn, especially its specific function in the synthesis of auxins. Magnesium deficiency produces similar chlorosis, but starts on older leaves.

Symptoms
Leaves show a light green, mosaic-like chlorosis in the interveinal areas. Later interveinal fields turn pale. A dark green border remains along the veins. With further development, the chlorotic parts die off and the leaves roll in. Symptoms of zinc deficiency increase from older leaves to shoot tip. The bunches of grapes are small. Only a few berries set. Most of them are small and seedless.

Causes
Severe Zinc deficiency At high P excess, Zn will combine with phosphate into the nearly water-insoluble Zn phosphate so that the roots cannot absorb it. Phosphate absorbed in excess leads to a partial inactivation of Zn, especially its specific function in the synthesis of auxins. Magnesium deficiency produces similar chlorosis, but starts on older leaves.

Symptoms
With severe zinc deficiency the bunches of grapes are small. Only a few berries set. Most of them are small and seedless. First leaves show a light green, mosaic-like chlorosis in the interveinal areas. Later interveinal fields turn pale. A dark green border remains along the veins. With further development, the chlorotic parts die off and the leaves roll in. Symptoms of zinc deficiency increase from older leaves to shoot tip.

Causes
Severe Zinc deficiency Low zinc levels are associated with sandy soils or those with a high pH or high phosphorus levels. Clays with high magnesium content can also be deficient. At high P excess, Zn will combine with phosphate into the nearly water-insoluble Zn phosphate so that the roots cannot absorb it. Phosphate absorbed in excess leads to a partial inactivation of Zn, especially its specific function in the synthesis of auxins. Magnesium deficiency produces similar chlorosis, but starts on older leaves.

Symptoms
The symptoms appear on younger leaves first. They show intercostal chlorosis with veins remaining green. The leaf blades are small ('little leaf') and show wide open petiolar sinuses and a sharply dentated margin. Furthermore, the leaf blades appear uplifted. At further development, the chlorotic parts of the leaves die off and the leaves roll in.

Causes
Zinc deficiency At high P excess, Zn will combine with phosphate into the nearly water-insoluble Zn phosphate so that the roots cannot absorb it. Phosphate absorbed in excess leads to a partial inactivation of Zn, especially its specific function in the synthesis of auxins. Magnesium deficiency produces similar chlorosis, but starts on older leaves.

Symptoms
The symptoms appear on younger leaves first. They show intercostal chlorosis with veins remaining green. The leaf blades are small ('little leaf') and show wide open petiolar sinuses and a sharply dentated margin. Furthermore, the leaf blades appear uplifted. At further development, the chlorotic parts of the leaves show necrotic spots, die off and the leaves roll in.

Causes
Zinc deficiency At high P excess, Zn will combine with phosphate into the nearly water-insoluble Zn phosphate so that the roots cannot absorb it. Phosphate absorbed in excess leads to a partial inactivation of Zn, especially its specific function in the synthesis of auxins. Magnesium deficiency produces similar chlorosis, but starts on older leaves.