Movement and Activity of Glyphosate in Purple Nutsedge

Abstract

Tubers from purple nutsedge (Cyperus rotundusL.) plants grown in the greenhouse for 2 to 10 weeks did not germinate after foliar applications of 4 kg/ha glyphosate (N-(phosphonomethyl)glycine). Some tubers from 12- and 24-week-old purple nutsedge plants survived glyphosate application. Translocation of14C-glyphosate from treated purple nutsedge leaves to other plant parts increased from 5% of the amount applied at 1 day to 19% at 4 days after application. Specific activity of14C in tubers was greater than in leaves of plants 2- to 6-week-old. With increasing plant age, specific activity decreased in both tubers and leaves. As purple nutsedge grew older, total14C translocated increased in tubers, and decreased slightly in leaves. Thin layer chromatography showed no evidence of glyphosate metabolism in purple nutsedge.

Effects of humidity and moisture stress on glyphosate control of Cyperus rotundus L.*

“…The correlation coefficient between '•'C recovery and reduction in regrowth was 0-91, We did not identify the '''C-label as intact glyphosate. However, glyphosate appears to be quite stable in the plant during the time period involved in these studies, Zandstra & Nishimoto (1977) reported no evidence of metabolism of glyphosate in purple nutsedge leaves or tubers.…”

Herbicides for Natural Area Weed Management

“…Necrosis occurs several days after initial symptoms and complete plant death results in 21 to 35 days depending on species and maturity/size of treated plants. Glyphosate is extremely difficult to metabolize by plants and is readily translocated to areas of new growth [114]. This stability within plant tissues is the reason it has excellent activity on many perennial plants, allowing glyphosate to be 'stored' in overwintering tissues such rhizomes and rootstocks [115].…”

Effect of a Nalco-Trol® II on bioavailability of glyphosate in laboratory trials

“…The range of counting efficiency was 92 to 98%, and the data listed in Table 2 were corrected for this. Because few glyphosate metabolites have been reported in plants within 48 h after treatment (Devine and Bandeen 1983;Gottrup et al 1976;Zandstra and Nishimoto 1977), the radioactivity recovered will be referred to as C-glyphosate.…”