| Flutolanil is affiliated to the succinate dehydrogenase inhibitor fungicide (Succinate Dehydrogenase Inhibitors, SDHIs), it mainly inhibits the succinate dehydrogenase activity of fungal pathogens, and thus interfere with their respiration. Flutolanil had a very strong inhibition on the mycelial growth of R. solani, Thanatephorus cucumeris, R. solani and R. cerealis, the average EC50values were0.1058,0.1068,0.1210and0.3428μg/mL, respectively. Followed by the inhibitory effect of Sclerotinia sclerotiorum, the average EC50value was1.8583μg/mL. However, it has poor inhibitory effect on Fusarium fujikuroi, Botrytis cinerea, Stemphylium solani and F. graminearum, with the average EC50value30.1134,38.1259,77.8034and98.1082μg/mL respectively. Both the baseline sensitivity curves of137R. cerealis isolates and112R. solani isolates were unimodal, with an average EC50value of0.2870±0.1725μg/mL and0.0736±0.0331μg/mL for inhibition of mycelial growth. The baseline sensitivity curves were approximately normally distributed, no resistant group were appeared, and all the strains were wild-sensitive to flutolanil. So these EC50values of R. cerealis and R. solani could be used as baseline sensitivity to flutolanil. Flutolanil had good protective and curative activity in controling rice sheath blight, protective effect of the disease was100%when flutolanil was200mg a.i./L, and curative effect was85.16%when flutolanil was800mg a.i./L; and flutolanil exhibited excellent acropetal movement in the leaves and roots of rice.The growth curve of Bacillus subtilis NJ-18strain was consistent with the regularity of general bacterial growth cycle, and its bacteria turbidity or the number of viable cells reached the maximum when cultured at48-60h. NJ-18showed strong antagonistic activity against mycelium growth of R. cerealis and R. solani, the oxford cup method demonstrated its inhibition zone diameter to R. cerealis and R. solani was23.5mm and16.6mm, and the determination of crossed method showed its inhibition zone length against them was35.5mm and28.4mm. NJ-18also had strong inhibitory effect on growth amount of R. cerealis and R. solani. NJ-18strain could grow normally both on LBA tablet and LB culture medium, which contained flutolanil at the concentration of500～1000μg/mL and400～1200μg/mL respectively. And the growth of its viable cells was not inhibited by flutolanil. Meanwhile, flutolanil could not suppress the viability of NJ-18endospore on surface of wheat grain, and promoted its growth. Flutolanil had good compatibility with NJ-18, so they were mixed to control R. cerealis and R. solani in greenhouse and filed.(1) The results of synergism of flutolanil and endospore powder (109cfu/g) of B. subtilis NJ-18strain by seed dressing showed that:in greenhouse, the mixture of flutolanil and NJ-18at two ratios, i.e.,[NJ-18300g+flutolanil50g] and [NJ-18300g+flutolanil100g] were applied respectively to coat100kg wheat seeds, offered47.96%and64.98%control efficiency on wheat sharp eye spot investigated at jointing stage, and control efficiency of the two mixtures was significantly higher than that of the single component; in field trial, both control efficiency and wheat thousand kernel weights of the mixture seed dressing treatments increased significantly. The mixed/single dressing treatments of flutolanil and endospore powder of NJ-18were proved to be safe for wheat growth.(2) The results of synergism of flutolanil and culture solution (10cfu/mL) of B.subtilis NJ-18strain by spraying during2011-2012showed that:in greenhouse, control effect of NJ-18(108cfu/mL) on this disease was ranged from30.92%to38.71%; control effect of flutolanil (20%WP) at single-dose usage of100-400g/acres on the disease was22.42～54.26%, while control efficiency of the two mixtures was significantly higher than that of the single component, and thousand kernel weights of wheat were increased significantly; under field conditions, control efficiency of the two mixtures was increased from43.37%to76.77%, which was significantly higher than the single-dose.(3) Both flutolanil and culture solution of NJ-18showed strong inhibitory effect against R. solani, and could completely inhibit the growth of R. solani when they were at a concentration of1000mg a.i./L and10cfu/mL respectively. Field trials in2011and2012indicated that flutolanil and NJ-18had good control effect on rice sheath blight, and their combined effects were significantly improved. Flutolanil provided the control efficacy ranging from59.62～88.88%when used at a dosage of50g/acres. And control efficacy of NJ-18(10cfu/mL) was ranged from47.80-54.21%, which was about the same with Jinggangmycin. The control effect on the disease was significantly increased when co-utilizing flutolanil (50g/acres) and NJ-18(108cfu/mL), which was up to81.10～97.87%. |
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