Control Index of Alisma orientale(Sam.)Juzep.Damaged by Rhopalosiphum nymphaeae L and the Field Trial of the Pesticide Efficacy

Rhopalosiphum nymphaeae L is one of the important pests in Alisma orientale(Sam.) Juzep.The results of field trial for the pesticide efficacy showed that 2.5% Spinosad SC,1.5% Gamma-Cyhalothrin CS,25% Actara WG,3% Mospilan EC,20% Confidor EC had good effects on Rhopalosiphum nymphaeae L,useful in production of Alisma orientale(Sam.) Juzep.In addition,the relationship between the amount of Rhopalosiphum nymphaeae L and the yield loss rate of the tuber of Alisma orientale(Sam.) Juzep.was investigated,their relations fitted to the formula:Y=-0.331 8+0.397 8X(r=0.993~(**)),for earlier stage;Y=(0.041 2)+0.247 4X(r=0.950~*),for later period;Y=-0.003 6+0.113 9X(r= 0.922~*),at the later stage.According to the formula,the control indexes of differenf kinds of pesticides at different stages were finally determined.