Influence of Glyphosate on Resprouting of Parent Tubers ofCyperus esculentus

Yellow nutsedge ( Cyperus esculentus L. # CYPES) was treated with unlabeled and 14 C-labeled glyphosate [ N -(phosphonomethyl)glycine] to study the toxicity and translocation of glyphosate into parent tubers of this weed. When plants of 2 and 4 weeks of age were treated with 0.6 kg ai/ha of glyphosate, fewer parent tubers from treated plants resprouted (14 and 32%) than tubers from control plants (73 and 59%, respectively) of equal age. Also, fewer tubers resprouted from 2-week than from 4-week-old treated plants. The radioactivity of parent tubers from plants treated at 2 weeks of age, which exceeded that of tubers from plants of 4 and 6 weeks of age, indicated that translocation of 14 C into parent tubers decreased as the treated plants increased in age. The differential amounts of 14 C translocated appear to explain why applications of glyphosate were more effective in suppressing resprouting of parent tubers from 2-week than 4-week-old plants.