Abstract: The work was corducted during 1982-1985.The dodder (Cuscuta Chinensis Lam and C. australis R.Br. ) are the mose noxious and parasitic of annualweek of soybean filds in Henan province, distring widely in soybean production area of whole province. There are about 140 thousand hactares of domaged area and cause yild losses can be very severe. The application of biotic pesticide" Lubao-1 " is limiting by weather conditions,and therefore is not very effective.This study about some biological characteristics of the sovbean dodder has been observed in details, the finy ouc effective pesticide and optimum pcriond of applying herbicids. The peseicidc usually shoud be used before sowing or before emergence of the sofore emergence of the soybean seedling and spraying should be done when the seedling are in three to five leave stage. Sue Such as 25% amiprophos and 4% d ibaralla seryed separately or mixedly on the surface of ground and whole plane geve effeets more than 90-95% could be gotten, and also with similar effects on coatrolling of the other weeds. Alarge scaie demonstration of production practices, and the great results of increasing yield were obtained.

Key words: Dodder, Biological characteristics, Ami prop hos, Did uratin