Disappearance of rye cover crop residue and allelochemicals from rye residue were evaluated in a field study at Clayton, NC, in 1992 and 1993. The aerial portion of rye biomass declined linearly over time with 50% of the residue disappearing by 105 d after clipping. Extrapolations indicated all residue would disappear approximately 200 d after rye clipping. Total content of DIBOA and two related compounds, DIBOA-glucoside and BOA, in the residue also was measured over time. Fifty percent of the 0-d content of the compounds disappeared from residue 10 and 12 d after kill for 1992 and 1993, respectively. Extrapolations indicated content reached 0121 and 168 d after kill for 1992 and 1993, respectively. Reported duration of weed suppression by rye cover crops more closely follows disappearance of allelochemicals from rye residue than disappearance of the residue.
