Minimising bunch stem necrosis in wine grapes

Bunch stem necrosis (water berry) in grapes affects fruit set and fruit ripening. It can occur around the bloom, in which case it is called early bunch stem necrosis, at veraison or later. The occurrence of it is associated with weather conditions and crop nutrition.

During bloom, the symptoms of bunch stem necrosis begins as the pedicle elongates. It can become necrotic, resulting in the dropping of the flower buds. Later, entire sections of the inflorescence can shrivel and die, and may or may not drop off. The symptoms appear as necrotic patches on the rachis or pedicle. As a result, the supply of water and nutrients are limited, leading to wine grape berries with less sugar, remain sour and eventually shrivel.

Crop Nutrition and bunch stem Necrosis in Wine Grape


Bunch stem necrosis is often associated with a magnesium deficiency and the imbalance of magnesium and nitrogen. Research suggests that low levels of sugars in storage organs and fruit lead to nitrate accumulation, particularly during cold weather during maturation. Two to three foliar applications of magnesium starting just before veraison minimise the problem.

Recommended Yara fertilisers for grapevines

Grapevine fertigation and nutrition advice
Grapevine fertigation and nutrition advice

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