(一) 三棱草是莎草科多年生宿根性草本植物,主要依靠地下球茎繁殖。稻田一旦感染三棱草后,在两三年内就能扩展至全田,严重消耗稻田肥分,与稻苗争夺阳光,使稻苗由绿变黄,由壮变弱,生长发育迟缓,并且容易诱发稻瘟病,使水稻产量和品质显著降低。三棱草比水稻根多,主要分布在15厘米左右深 (A) Sanguancao is a sedge herbaceous Perennial herbivores, mainly rely on underground bulbs breeding. Once infected, the paddy field can be extended to the whole area within two to three years. The paddy field is severely depleted of fertilizer and competes with the rice seedlings for sunshine to make the rice seedling turn from green to yellow, from weak to strong, to slow growth and development. Induce rice blast, the yield and quality of rice significantly reduced. Trifolia more than rice roots, mainly distributed in about 15 cm deep