The Integrated Managements Of Tobacco Black Shank In Zibo

Tobacco black shank,caused by Phytophthora nicotianae var.nicotianae Breda de Haan,is one of the main destructive diseases of tobacco in the world as well as in Zibo,a very important area in Shandong province.The disease was aggravated in Zibo recently owing to the growing continuous cropping tobacco field acreage and increasing continuous cropping fixed number of years.If the disease occurs on tobacco and is not managed on time,it will lead to serious economy loss.To do the preventive treatment of tobacco black shank in Zibo,we carried out the researches.They mainly included the analysis of virulence of disease germs of P.nicotianae var.nicotianae in Zibo,the selection of disinfector against P.nicotianae var.nicotianae,the preventive result of black shank by several disinfectants,the resistance of different tobacco cultivar to black shank,the influence of intercropping of tobacco and yam bean.An integrated preventive treatment method on tobacco was obtained.The main results are listed as follows:1.The results showed that the Disease Index of P.nicotianae var. nicotianae in Zibo is between 60-80 through pathogenic testing of the 15 strains from different counties of Zibo,and all belongs to the middle level in pothogenicity.In the 15 strains,strain of bs1 from Boshan county was more virulent than that of yy1 from Yiyuan county.The results also showed that inoculation of the seedling stems with mycelia was the best method to test the pathogenicity ofP.nicotianae var.nicotianae.2.Solutions of 150-300mg/L Bleaching powder,50-100 mg/L Benzalkonium Bromide and 50-100mg/L all had very good effects either on inhibition of mycelia growth or on sporangium formation among the 10 chemical disinfectants.3.Among the 10 cultivars that are being used in Zibo,Yunyan87 and Honghuadajinyuan are very susceptible to strains of P.nicotianae var. nicotianae.The others such as K326,K346,NC89 and NC82 et als all had high resistance to the pathogen.4.We found that liquids of 4,000 times hymexazol plus 600 times mancozeb is the best fungisides in controlling black shank in the field. Because the fungisides can control the disease for a long time than others.5.According to the cropping module in Zibo,we analyzed the controlling effects of intercropping between tobacco and sweet potato on the disease.The results showed that this kind of cropping module had some effect on inhibit of the disease.6.According to the results above and the cropping reality of Zibo,We found that the integrated measures are very effective not only in controlling the disease but in improving the tobacco quality in Zibo.