Evaluation of common buckwheat tolerance to two preemergence herbicides at Hettinger, ND, 2024
(Research Report, Hettinger REC, December 2024)A trial was conducted near Hettinger, ND, to evaluated the effects of two preemergence herbicides, in common buckwheat. As neither of these herbicides are labelled for use in buckwheat, they will only be identified as Herbicide 1 and 2. Buckwheat was planted on June 12, 2024 at a depth of 2 inches using a John Deere no-till drill with 7.5 inch row spacings. Herbicide treatments (Table 1) were applied on June 13, 2024 using a tractor-mounted research plot sprayer (Table 2). In the 10 days after herbicide treatments were applied, 1.16 inches of rainfall occurred. Buckwheat emerged on June 18. Buckwheat was visually evaluated for injury (bleaching or stunting) at 2, 3, and 5 weeks after treatment (WAT) at a rate from 0 to 100%, where 0% is no injury and 100% is complete plant death (Table 1). Stand count was measured two weeks after buckwheat emergence (WAE) by counting all buckwheat plants within two randomly placed 0.5 m2 quadrats in each plot. Heights of 10 random buckwheat plants were measured within each plot 5 WAE. Buckwheat was swathed to dry down and then was harvested using a small plot combine on September 12, 2024.
Neither of the two herbicides evaluated caused visual injury exceeding 10% when evaluated 2, 3, and 5 weeks after treatment. The combination of both herbicides at the highest rates (treatment 9) resulted in injury of 11, 23, and 15%, at 2, 3, and 5 WAT, respectively. There was no significant reduction in buckwheat stand count when measured 2 weeks after emergence. Buckwheat height was lowest (69 to 70 cm) 5 WAE with Herbicide 2 alone (both rates) and with the combination of Herbicide 1 and 2, compared with Herbicide 1 applied alone at 1X, 2X, and 3X rates (77, 78, and 73 cm, respectively). However, buckwheat in the untreated control was also similar in height to treatments having the lowest buckwheat height. July and August of 2024 were hot and dry with only 50% of normal rainfall. These hot and dry conditions reduced buckwheat growth and yield potential. Yield of buckwheat was much lower than typical due to these growing conditions and was also quite variable (CV 29). Due to the low yield and variable yield, there were no significant differences in yield when comparing herbicide treatments. While yield differences were not significant, all herbicide treatments resulted in buckwheat yields that were numerically higher than the untreated control. Also, the two treatments where buckwheat height was reduced most (6 and 9) had the highest numerical yield of all treatments.
This trial demonstrates that buckwheat has good tolerance to both herbicides evaluated in this trial at this location, whether applied alone or in combination.
