Roller vs. Herbicides: an Alternative Kill Method for Cover Crops

Identifying more cost effective and perceived environmentally friendly techniques for cover crop management can increase their use. This study was conducted to determine the effectiveness and economic viability of using a mechanical rollercrimper as an alternativekillmethod for cover crops. Three cover crops, rye (Secale cereale L.), wheat (Triticum aestivum L.), and black oat (Avena strigosa Schreb.) were evaluated in terms of ease of kill and optimum time of kill using a roller-crimper, two herbicides (paraquat and glyphosate), and two reduced chemical rate (half label rate) combinations with the roller. During 1998-1999, the study took place at two locationsin east-centralAlabama, using a split-split plot experimental design with four replications. ThreeFeekes' scale growth stages were used to determine optimum time of kill: 8.0 (flag leaf), 10.51 (anthesis), and 11.2 (soft dough). Percent kill measurements were taken 14 d after treatment application. Black oat reached maximum biomass at anthesis (7660lb/A), while rye and wheat continued to increase biomass significantly through soft dough (8480 and 9340 lb/A, respectively). There was a significant interaction between growth stage and kill method; by soft dough, kill methods were equally effective due to accelerating plant senescence(95%mean kill acrosskill methods). The label rate of glyphosate and 1/2 label rate+roller combination produced the best kill mean, 91 and 89%, respectively, at all growth stage levels across all cover crops. However, at anthesis, the label rate of paraquat and 1/2 label rate+roller combination were as effective (mean 89% kill) as glyphosate. This study shows that it is possible to reduce the use of herbicides and implement effective alternative kill methods for cover crops.