2019 ASHS Annual Conference

Combinational applications of labeled herbicide chemistries is a strategy to enhance weed control in strawberry production. The objective of this study was to assess the benefits of combinational herbicide treatments in terms of strawberry yield and berry size of ‘Camarosa’ strawberries in hill plasticulture. Pre-emergent herbicides Prowl H₂O and Dual Magnum were applied individually and in combination with Devrinol 50-DF, Sinbar, or Spartan 4F. The latter-mentioned herbicides were applied individually also along with a control. Yield was calculated as mean yield per harvest. Berry weight was determined from the weight of 25 berries divided by 25. The study was a randomized complete block design with repeated measures over dates. The treatment design was a two-way factorial of herbicide treatment and date. Differences among cultivar least squares means were tested using the simulate method. Differences between single applied herbicide treatments to each of their respective combinational treatments were estimated using the simulated method. All significances were at α = 0.05. There were no interactions between treatment and harvest date in yield or berry size. Dual Magnum and Prowl H₂O produced yields that were statistically similar to their respective combinational treatments. Though not significant, Devrinol 50-DF + Prowl H₂O combinational treatment produced the largest berries, while Sinbar + Dual Magnum produced berries that were smaller than the control. Pairwise comparisons of Dual Magnum to its combinational treatments showed that there was a benefit provided to yield by combining Sinbar and Dual Magnum (p=0.0183), however, Sinbar + Dual Magnum produced the lowest yield numerically and significantly lower than both Prowl H₂O and Prowl H₂O combinational treatments. Conversely, efficacy of Prowl H₂O was not enhanced when combined with Devrinol 50-DF, Sinbar, or Spartan 4F. Berry size of Prowl H₂O and its combinational treatments were greater than other treatments but these differences were not significant. Overall, Prowl H₂O as a stand-alone treatment was the most effective in enhancing strawberry yield and berry size.