Pesticides Screening And The Reduction-synergy Effects Of Synergists On The Control Of Grape Powdery Mildew And Arboridia Kokawana

Effects of different pesticides on the control of grape powdery mildew and Arboridia kokawana,and the reduction-synergy effects of five synergists including Silwet 636,Agrospred 960,Silwet 806,Y-20079,and ethoxy-modified polytrisiloxane were evaluated mixed with 29%Isopyrazam·azoxystrobin SC and 25%thiamethoxam SC for the control of grape powdery mildew and Arboridia kokawana.The key results are as follows:1.10 fungicides were screened for the control of grape powdery mildew,the better effects were observed in treatments of 20%Pydiflumetofen·difenoconazole SC and 29%isopyrazam·azoxystrobin SC with control effects of 75.82%and 63.95%,respectively.There are significant synergistic effects in treatments of four synergists,such as Silwet 636,Silwet 806,Y-20079,and ethoxy modified trisiloxane,mixed with 29%isopyrazam·azoxystrobin SC at the recommended doses,and Silwet 636 performs the best.There are equal or even better effects were achieved by reducing 30%doses or liquid volume in treatments of 29%isopyrazam·azoxystrobin SC mixed with 4 synergists than that of fungicide single treatment at the recommended dose.It is recommended to apply 20%pydiflumetofen·difenoconazole SC agent 1500 times solution and 29%isopyrazam·azoxystrobin SC agent 2000 times solution to control grape powdery mildew in the field.Under the 30%reduction of dosage or liquid volume,the combination of 29%isopyrazam·azoxystrobin SC with synergists of Silwet 636,Silwet 806,Y-20079,and ethoxy modified trisiloxane can achieve the same or better prevention effect.2.The leaf-dipping bioassay was used to determine the toxicities of seven pesticides in the laboratory,Arboridia kokawana is still susceptive to all of tested insecticides,but the susceptibilities to emamectin benzoate and avermectin decreaseed with the RR values of 3.57-fold and 4.07-fold,respectively.thiamethoxam and acetamiprid insecticides showed high insecticidal activity against A rboridia kokawana.3.The synergistic ratios of thiamethoxam mixed with 5 synergists including Silwet 636,Agrospred 960,Silwet 806,Y-20079,and ethoxylated polytrisiloxanes are 1.96,3.93,5.12,3.87 and 4.16,respectively,to the third instar nymph of Arboridia kokawana.Adding different synergists can reduce the dosages by 50%～75%without reducing the toxicity.4.25%thiamethoxam SC,40%acetamiprid WP,and 22%sulfoxaflor SC all showed high control effects on Arboridia kokvawana in field efficacy test,and the control effects are all over 90%after 21st days of treatment.Under the 30%、50%reduction of dosages or 30%reduction of the liquid volume,the combination of 25%thiamethoxam SC with 4 synergists including Silwet 636,Silwet 806,Y-20079,and ethoxy modified trisiloxane can achieve the same or better control effect in comparison with the single treatment of 25%thiamethoxam SC at the recommended dose,the efficacy could be maintained above 90%after 21st days of treatment.There are no significant decrease in the control effects of treatments with 30%to 50%dosage reducing by adding a synergist.