الفهرس | Only 14 pages are availabe for public view |
Abstract Grapevine (vitis vinefera L.) is one of the most important fruit crops all over the world, especially in tropical regions. It has many uses as it fresh eaten, non fermented or concentrated juice and dried into raisins. Fruits of the Egyptian grapes are very important both for local consumption and exportation. The cultivated area of grapes in Egypt reached (153956) Fadden which produced the average of (1531418) tons (Statistics Dept. Ministry of Agriculture, Egypt 2008). Grapevine trees are liable to the attack of many pathogens of which Uncinula necator (Schw.) Burr. causes powdery mildew disease is very distractive one. This fungus attacks buds, leaves and fruits causing considerable yield losses. Powdery mildew symptoms can be seen on foliage, fruit, flower parts and canes. Mildew usually appears first as whitish or greenish-white powdery patches on the undersides of basal leaves. It may cause mottling or distortion of severely infected leaves, as well as leaf curling and withering. Lateral shoots are very susceptible. Infected blossoms may fail to set fruits. Berries are most susceptible to infection during the first three to four weeks after bloom, but shoots, petioles and other cluster parts are susceptible all season. Infected berries may develop a netlike pattern of russet, and may crack open and dry up or never ripen at all. Old infections appear as reddish brown areas on dormant canes. |