Nader Soltani, Robert E. Nurse, Peter H. Sikkema
Canadian Journal of Plant Science 96 (1), 160-164, (25 February 2016) https://doi.org/10.1139/cjps-2015-0175
KEYWORDS: Crop injury, Glycine max, pods per plant, seed per plants, sensitivity, tolerance, yield, dommages aux cultures, Glycine max, gousses par plant, graines par plant, sensibilité, tolérance, rendement
The anticipated availability of dicamba-resistant crops will increase the potential for crop injury to non-dicamba-resistant soybean due to dicamba spray tank contamination. A total of eight field trials were conducted at various locations in Ontario, Canada during 2012-2014 to determine the response of non-dicamba-resistant soybean to dicamba spray tank contamination at 0, 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha-1 applied postemergence (POST) at the V2-3 (2-3 trifoliate) or R1 (1st flower) stage. At one week after treatment (WAT), dicamba applied at 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha-1 at V2-3 caused 12, 18, 25, 31, 43, 53, and 66% visible injury in soybean, respectively. Injury increased at 2 and 4 WAT and decreased by 8 WAT with 68% visible injury observed at the highest dose. Dicamba applied at R1 caused 23, 28, 36, 40, 48, 61, and 73% visible injury in soybean at 0.75, 1.5, 3, 6, 15, 30, and 60 g a.e. ha-1, respectively. The predicted dose of dicamba to reduce soybean seed yield 1, 5, 10, 20 or 50% was 1.1, 5.8, 11.8, 25.2, and >60 g a.e. ha-1 when applied at V2-3 and <0.75, 1.0, 2.0, 4.3, and 11.5 g a.e. ha-1 when applied at R1, respectively. Results show that dicamba spray tank contamination of as little as 0.75 g a.e. ha-1 can cause significant crop injury in non-dicamba-resistant soybean when applied during the vegetative or reproductive stages.