Tham khảo tài liệu 'fungicides for plant and animal diseases part 16', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Use of Cu Fungicides in Vineyards and Olive Groves 291 infection the leaf skin detaches from the epidermis causing the spots to turn white Photo 2 . In rare cases the symptoms of the disease also occur on the undersides of leaves as well as on stems and fruits. Photo 2. Symptoms of the disease Damage caused by olive leaf spot is manifested in yield reduction of infected trees as a consequence of a great loss in leaf mass. The fungus penetrates below the leaf epidermis spreading into and in between cells. It feeds itself and releases toxins which disturb the creation of starch necessary for normal plant functions which consequently leads to the falling off of the sick leaves. Since the leaves fall after the flower buds have been formed they become insufficient for an adequate diet of flowers which consequently remain under grown and do not bear fruit. In the case of a serious autumn and subsequently a serious spring infection leaves fall off massively. Consequently the trees become partially or completely defoliated. In older olive grove reoccurrence of the disease for several consecutive years can cause defoliation and destruction of individual trees Photo 3 . The damage is greater if the disease spreads in a young olive grove as then all olive trees can be destroyed Miller 1949 Azeri 1993 Katalinic et al. 2009 . Fruit infection can cause unacceptable blemishes on table olives and when it occurs on oil-producing cultivars infection may cause a delay in ripening and a decrease in oil yields Verona Gambogi 1964 . Use of copper fungicides against olive leaf spot and possible copper traces in olive oil Application of copper-based fungicides is the main method of olive leaf spot control throughout olive-growing regions of the world Teviotdale et al. 1989 Graniti 1993 Katalinic et al. 2009 . For effective olive protection several applications of copper fungicides are necessary in one year. For a long time it was thought that olive leaf spot infection could 292 .
