Studied On Pathogen Of Onion Fusarium Basale Plate Rot And Chemical Control In Jiayuguan

The Basal plate rot of onion was surveyed in Xinchen Town, Jiayuguan City,Gansu Province. The pathogen that caused the disease were Fusarium oxysporum . Meanwhile, the resistance of different varieties to this disease was conducted and several fungicides were screened in the laboratory. And chemical control experiment was also maken in the field.F. oxysporum caused Basal plate rot of onion. The beneath leaves showed yellowing, wilting or bending in the early stage. The disease developed at the base of the bulb, causing it to become soft. A semi-watery decay progresses from the base of the scales upward.All of leaves overground became wilt seriously, and bulb scales discolored brown and died. Meanwhile, white and grey white mildew were found interscales when air became humidity. The diseased tissue became purple during the Basal plate condition. F.oxysporum was widely spread and accounted for the highest percent of 69.66, while F.solani and F.moniliforme were relatively lower 21.99 and 8.35 percent, respectively. Pathogenic testing in the laboratory showed that Fusarium oxysporum the pathogen of the disease. the disease indexwas 60.2.Evaluated the 10 onion cultivars resistance for the disease with plate method.The results showed that cultirars resistant for the disease was difference, among which Mutong and Jinmei F1 showed middle resistance for F.oxysporum, Taiyanggelin and Xiongshi middle susceptible, Ouzhoubao 1 high susceptible,and Hongsejindian,Hongpi 08, Huangpi 02, Zijin505F and Hongbao 911F1 susceptible, respectively.The inhibition effect of 4 kinds of fungicides to 3 Fusarium had difference, in whch EC50 of Carbendazim,Chlorothalnil,Emeifu and Shijunke for F.oxysporum was 69.58,158.12,143.13,6.03μg/mL, respectively. For F.solani was 5.87,152.76,35.75,70.12μg/mL,respectively. And for F.moniliforme was 49.53,2.11,4.48,126 .61μg/mL, respectively. The inhibition effect of Shijunke demonstrated the strongest place and Carbendazim took second ,while Chlorothalnil showed the weakest one. The correlation coefficient of 4 fungicides was over 0.98 . And positive correlation were found between pharmaceutical concentration and inhibition effect.Seven kinds of fungicides were used for chemical control experiment in Xincheng Town of Jayuguan City and made field plots trial. The plots were designed randomly, and duplicated 4 times. After a comprehensive evaluation of each plots of incidence rate,disease index and yield, the results showed that the best effect of 15% Avermectin.Toxin 1500X and 1000X were 84.79% and 81.11%. The onion treated with 15% Avermectin.Toxin 500 X and 1500 X demonstrated increase production,which came to 14.23% and 8.54%,while 40% Phoxim EC 800 X decreased by 6.64%. However,no significant difference of production treated with 90% Trichlorfon 0.6g/acreas or 1.2g/acreas and 40% Phoxim EC 400 X were found.