Research On Apple Canker In Shaanxi And Controltechniques Of No-Agricultural Chemical Residue

Shaanxi province is one of the biggest optimized zones for apple industry in China, which is also the only district where many indexes tested measure up to the level of the most optimized region. In 2003, the apple cultural area in Shan xi province occupied the first place among all regions, and the yield also held the lead place ,only surpassed by Shandong province. Recently, apple canker occurs seriously, and the range of infection are very broad, including young or senescence trees; The disease even can result in imperil of whole apple orchard. In order to provide available measurement, we carry out the systemic research on apple canker, including the distribution and the condition of occurance or infestation; pathogen sources; The correlation between some agences and the development of apple canker; The evaluation of Nuisance free control technology against apple canker was also one of major tasks. The result was:1 .From South to North, and From East to West, the infection of apple canker in shaanxi province becomes more serious. The general situation of the development of the disease In the Weibei plateau was: the most seriously in Weibei drought donga ,more seriously in west of Weibei plateau and seriously in east of Weibei plateau.2. Varied part of different kinds of tree age can be infected by the pathogen in shaanxi province, the major symptoms are canker and branch dried up, the former occurs more frequently; Two pathogen strains are isolated from 15 counties where produce apple. Identification according to the principle of Koch's postulates showed that the major pathogens which lead to apple canker in shaanxi province are Cytospora sp.and C.carphosperma Fr.3.Two pinnacle of the occurance of the disease of apple canker, In Mar, new infected spot appear and expand with the available condition. The first pinnacle comes forth from May to June, but the amount of spectacles decrease abruptly in July. The second pinnacle emerge in August and September, and the spread of the disease nearly come to a standstill in October.