Water berry, Short berry, Pink berry and Mummification of Grapes

Introduction Grapes are cultivated in many countries of the world. India produces only about 2.77 per cent of the total world production. However, in productivity India stands first with 23.5 t/ha. As grape is cultivated in tropical regions against its natural habitat, the vine physiology undergoes change. When environmental factors exceed their optimal conditions, grapevine undergoes stress and exhibits certain disorders. Grape disorders can be grouped into ecological, physiological, eco-physiological and disorders of unknown etiology.

Important grape disorders are Physiological: It is caused by disturbances in normal metabolic functions of the vine by an unknown or complex factors Water berry Shot berry Mummification Eco-physiological: Due to physiological disturbances under the influence of unfavourable environment Pink berry

Water Berries The condition of berries wherein they lack normal sugar, colour, flavour and keeping quality is referred as water berries. It is associated with fruit ripening and most often begins to develop shortly after berry softening (Veraison). The affected berries become watery, soft, and flabby when ripe (almost normal in size but their flesh is not firm) and shrivel and dry by the time of harvest. Such berries mostly confine to the tip of the main rachis or its branches.

Potash application during berry growth period. Reasons for this disorder: It occurs due to high nitrogen status vine, canopy shading, and cool weather during fruit veraison and ripening. How to manage?. Excessive irrigation and nitrogenous fertilizers should be avoided during berry development to reduce the water-berry formation. Potash application during berry growth period. Trimming off affected berries during harvest is a common practice, although labour intensive. Coutesy: Dr. Jagdev Sharma, NRC-Grapes

2. Mummification Though the etiology of mummification in grapes is not known (due to complex factors), the affected water berries in severe cases, shrivel and dry at the time of harvest leads to mummification. Coutesy: Dr. D. S.Yadav NRC-Grapes Mummified berries on a cluster (Photo: T. Zabadal)

3. Shot Berries Shot berries are smaller, sweeter, round and seedless as compared to normal berries in a cluster. Boron deficiency is the main cause of this disorder. Affected leaves show spotty yellowing and tend to be undersized and cupped. Affected clusters may totally abort or develop a few small berries, often with many small, green “shot” berries. Occurs either due to poor pollination and fertilization or due to inadequate flow of carbohydrates into the set berries. A yellowing cupped leaf and an affected cluster with green short berries (Photo: T. Zabadal)

Reasons for the disorder: Boron deficiency, incorrect stages of GA application and girdling are the known reasons for shot-berry formation. In the event of boron or Zinc deficiencies, ovary fertilization is impaired due to restricted growth of pollen tube. How to manage?. Boron or Zinc deficiencies should be corrected. Prebloom application of GA (Gibrellic acid) at proper stage should be ensured. Coutesy: Dr. D. S.Yadav NRC-Grapes

4.Pink Berry In recent years, pink berry disorder is a wide spread problem seen in all most all grape growing regions of the country, whose cause is unknown. This is a serious problem of Thompson Seedless in Maharashtra. As the bunch approaches maturity some berries becomes pink colour at random. The pink colour changes to dull red colour rendering the bunch unattractive. These berries become watery and collapse within a few days after harvest and can not stand storage and transport.

Reasons: This disorder is seen after Vines suffered prolong moisture stress after veraison. Spray of calcium given after berry softening. How to manage? Avoid soil moisture stress from berry softening. Give adequate dose of potash. Avoid indiscriminate use of Etherel. Coutesy: Dr. D. S.Yadav NRC-Grapes

Let’s sum up As grape is cultivated in tropical regions against its natural habitat, the vine physiology undergoes change. When environmental factors exceed their optimal conditions, grapevine undergoes stress and exhibits certain disorders. Water berry, Shot berry and mummification in grapes are caused by disturbances in normal metabolic functions by unknown or complex factors, whereas pink berry occurs under unfavourable environment. Proper care must be taken to avoid damage to grape vineyards caused by various physiological disorders.