Abstract

A major challenge in the production of butternut squash (Cucurbita moschata) is weed control without crop injury. Consequently, greenhouse studies in 2007 and 2008 were conducted to evaluate the tolerance of butternut squash to PRE and POST applications of halosulfuron-methyl at the following rates: 4.3, 8.6, 12.9, and 17.3 g ai/ha. Experimental design was a randomized factorial with three replications, and the factors were halosulfuron-methyl rate, application timing, and squash variety (Atlas, Betternut, and Waltham). Data collected included percent visual injury, and in PRE treatments only, plant heights and fresh weights. PRE rates at 4.3, 8.6, 12.9, and 17.3 g ai/ha provided 31, 32, 46, and 48% injury, respectively, when compared to the control. The same rates applied POST provided 15, 17, 19, and 22% squash injury, respectively. On average, plant heights were reduced 20% with no differences in fresh weights.

In 2007 and 2008, field studies examined butternut squash tolerance to PRE and POST applications of halosulfuron-methyl at 4.3, 8.6, and 17.3 g ai/ha. Experimental design was a factorial with four replications, evaluating Atlas and Betternut varieties. Data collected included percent visual injury and yields. PRE rates at 4.3, 8.6, and 17.3 g ai/ha provided 11, 25, and 52% injury, respectively. These rates applied POST injured squash 8, 19, and 27%, respectively, when compared to the control. Squash yields were reduced 15% with halosulfuron-methyl applied PRE (17.3 g ai/ha), and 11, 15, and 16%, respectively, with POST rates.

Field studies were also conducted to determine the competitive effects of common ragweed (AMBEL) on butternut squash. A randomized factorial design containing four replications was utilized, with ragweed density and squash presence as factors. Ragweed seedlings were transplanted into plots with and without Atlas squash at the following densities: 0.25, 0.5, 1.0, 2.0, and 4.0 per meter (m) of row. Data collected included squash yields and ragweed biomass and height. Ragweed density did not significantly decrease total weight or the number of squash harvested in either year. In both years, ragweed biomass collected from plots with squash resulted in significantly less biomass and no height differences in ragweed only plots.