Study on maize rough dwarf virus incidence law and its integrated control technique.

The incidence of maize rough dwarf virus(MRDV) has some law.Around May 25,the first generation of gray flies fly to maize fields to suck maize sap and spread virus,which is the root cause caused the incidence of MRDV.It is very efficient for preventing maize from MRDV to spray insecticide at the proper time(May 23-27).It is also an efficient measure to use resistant varieties and adjust the sowing time.