Studies on bunch stem necrosis disorder in grape in Maharashtra

摘要

Bunch stem necrosis disorder in grapevines occurs worldwide and is also called 'water berry' in California, 'shanking' in New Zealand and 'stiellahme' in Germany. Brown necrotic zones along the bunch stem (peduncle) are formed beyond which berries ripen poorly and whither. The large and unpredictable variations in bunch stem necrosis incidence occur between years and regions (Holzapfel and Coombe, 3). There are reports of severe yield losses (Theiler and Muller, 9) and lowered wine quality. The causes of the disorder are not fully understood yet and conflicting reports have been published from different parts of the world. Weinhaus (10) attributed the causes to Ca plus Mg deficiency using respiratory inhibitors like fluoro-acetic acid. Satyanarayana and Shikhamany (8) indicated that defective Ca assimilation by fruits is responsible for this disorder in Anab-e-Shahi grape. Kassimatis (4) concluded that this condition was directly related to occlusion of xylem vessels in pedicel to become necroticand dying up of berries. Recently, this disorder has also become a serious problem in Maharashtra, causing yield losses up to 30-40 percent. Therefore, studies were undertaken to find out the causes of bunch stem necrosis.