Comparative Study on the Efficacies of 11 Chemical Agents against Taro Soft Rot Caused by Pectobacterium aroidearun

The agents were mainly screened for the prevention and control of P. carotovorum, while the agents specially for the prevention and control of P. aroidearum had not been screened. [...]in order to effectively control the occurrence and prevalence of taro soft rot, it is necessary to further screen the effective control agents against taro soft rot. According to the presence and size of inhibition zone, the agents with good fungicidal effects were screened. The determination results of original liquids of agents showed that thiosen copper, copper quinolate, thiediazole copper and garlic oil had certain fungicidal effect, but their fungicidal effects in the test were very poor, with the inhibition zone diameters of 0.4, 12.6, 4.2 and 4.7 mm, respectively. [...]tetramycin, bromothalonil, zhongshengmycin and zinc thiazole were selected for indoor toxicity determination. 2.2Indoor toxicity determination of effective agents The EC50 of 0.3% tetramycin AS was the smallest of 0.6 xg/mL, indicating that tetramycin had the largest toxicity and the best inhibitory effect against P. aroidearum; followed by 25% bromothalonil EC and 3% zhongshengmycin WP, with the EC50 of 2.57 and 97.72 xg/mL, respectively; the inhibitory effect of 30% zinc thiazole SC against P. aroidearum was the poorest (Table 3 and Fig.2). Within the test concentrations, the inhibitory effects of 0.3% tetramycin, 25% bromothalonil, 3% zhongshengmycin and 30% zinc thiazole against P. aroid(arum increased with the increase of mass concentration. [...]it is of important reference value to determine the EC50 of various agents for rational and accurate medication.