Association of chemical and mechanical weed control methods during the pre-harvest of coffee crops

Abstract Background: Weed control in the pre-harvest of the coffee crop is essential to enable mechanized coffee harvesting. Objective: Testing the efficacy of pre-emergent herbicides, applied after brush shredder or desiccation operations, on the weed control during the coffee crop’s pre-harvest. Methods: Two separate trials were accomplished in commercial Coffea arabica crops in the Cerrado Mineiro Region. In the first one, oxyfluorfen and sulfentrazone were applied after either brush shredder or burndown operation; in the second, they were tested as a tank mixture with glyphosate. Results: In the first assay, the brush shredder use, associated to the rains that follow, stimulated a sharp weed infestation during the pre-harvest, which was not observed in desiccated plots. A sole application of oxyfluorfen or sulfentrazone, following either brush shedder or desiccation operation, effectively controlled the weeds; however, the sequential applications on burndown areas may be needless. The applied herbicides did not intoxicate the coffee plants nor affect their growth. In the second assay, both herbicide mixtures were highly efficient on the weed control through post-emergence application during the pre-harvest, what was not observed with a sole application of glyphosate. In both experiments, a dry period during winter, associated to the operations to gather fallen coffee fruit, collectively contributed to control weeds. Differently from oxyfluorfen, the residual effect of sulfentrazone was high enough to control weed even in the beginning of the rainy season. Conclusion: Sulfentrazone and oxyfluorfen were effective on the weed control in the pre-harvest of the coffee crop, mainly when applied after brush shedder operations.摘要 背景：咖啡作物收获前的杂草防控是实现机械化咖啡采收的必要条件。 研究目标：评估在灌木粉碎或灭生性除草操作后施用的苗前除草剂（pre-emergent herbicides），对咖啡作物收获前阶段杂草防控的效果。 方法：在塞拉多米内罗（Cerrado Mineiro）区域的商业化阿拉伯咖啡（Coffea arabica）种植园开展两项独立试验。第一项试验中，分别在灌木粉碎或灭生性除草操作后喷施乙氧氟草醚（oxyfluorfen）与磺酰唑草酮（sulfentrazone）；第二项试验中，将两种除草剂与草甘膦（glyphosate）进行桶混后开展施用测试。 结果：第一项试验显示，配合后续降雨的灌木粉碎操作，在收获前阶段引发了严重的杂草滋生，而枯株干燥处理地块未出现该现象。单独喷施乙氧氟草醚或磺酰唑草酮，无论配合灌木粉碎还是灭生性除草操作，均可有效防控杂草，但在灭生性除草区域后续重复喷施可能并无必要。供试除草剂未对咖啡植株造成药害，亦未影响其生长。第二项试验中，两种除草剂与草甘膦的桶混制剂在收获前的苗后喷施（post-emergence application）阶段均表现出优异的杂草防控效果，而单独喷施草甘膦未达到同等效果。两项试验中，冬季干旱期配合捡拾落果作业，共同助力了杂草防控。与乙氧氟草醚不同，磺酰唑草酮的持效残效期足够长，甚至在雨季初期仍可实现杂草防控。 结论：磺酰唑草酮与乙氧氟草醚均可有效实现咖啡作物收获前的杂草防控，尤其在配合灌木粉碎操作施用时效果更为突出。