Weed Management Via Crop Competition
b'Home gardeners know the benefits of mulch in suppressing weeds, but researchers are also encouraging broadacre grain producers to deprive weeds of sunlight and space and take the pressure off herbicides as the \\u2018heavy lifters\\u2019 of in-crop weed control.\\n\\nWhile defeating weeds through crop competition isn\\u2019t new, Queensland trials have shown that crop density and narrow row spacing have significantly suppressed the prevalent weeds common sowthistle and fleabane in the northern region.\\n\\nThe Queensland Department of Agriculture and Fisheries (QDAF) and the University of Queensland (UQ) are currently testing other non-chemical controls such as varietal differences and fertiliser placement for their impact on weed growth and seed production.\\n\\nQDAF project leader Dr Michael Widderick says narrow row spacing has so far shown the clearest benefit in limiting weeds.\\n\\nThe tactic suppressed sowthistle and fleabane quite dramatically, but in trials testing control of feathertop Rhodes grass and awnless barnyard grass, the feathertop was quick growing and competed very well against sorghum and mung beans which didn\\u2019t suppress it as much as barnyard grass, which isn\\u2019t as robust a plant.\\n\\nBoth awnless barnyard grass and common sowthistle no have glyphosate resistant populations and sowthistle is becoming an all year round weed issue.\\n\\nThe trials showed that:\\n\\nGrowing a competitive crop can significantly reduce weed numbers, biomass and seed production in crop while providing increases in grain yield.\\n\\nGrowing faba beans and chickpea at a narrow row spacing of 25cm and a high plant density of 70 and 80 plants/m2 respectively significantly reduced sowthistle biomass and seed production while increasing crop yield.\\n\\nGrowing wheat at narrow row spacing of 25cm and a high density of 120 plants/m2 significantly reduced awnless barnyard grass density, biomass and seed production while increasing crop yield.\\n\\nNarrow row spacing (25cm) in mung bean and soybean can reduce weed growth and increased crop yield. The critical time of weed removal in mung bean and soybean occurs at later stages of crop growth in narrow (25cm) compared to wide rows (75cm).\\n\\nMichael says these key weeds are increasingly emerging later and affecting winter crops at a growth stage when residual chemistries are no longer persistent in the soil and when in\\u2010crop herbicides are either unavailable or can no longer be applied.\\n\\nBut by purposefully using crop competition alongside in-crop residual and knockdown herbicides, producers can delay herbicide resistance and limit future weed populations by reducing seed set.\\n\\nFurther information:\\nDr Michael Widderick\\nLeslie Research Facility\\nQueensland Department of Agriculture & Fisheries Toowoomba, Qld\\n07 4529 1325\\nmichael.widderick@daf.qld.gov.au\\n\\nGRDC project code: US00084 https://grdc.com.au/resources-and-publications/grdc-update-papers/tab-content/grdc-update-papers/2018/03/deprive-weeds-of-sunlight-and-space-crop-competition-research\\nLearn more about your ad choices. Visit megaphone.fm/adchoices'