Evaluation of herbicides on newly-planted 'Hecker' and 'Bounty' strawberries
Rowan, Susan Colleen
For successful strawberry production, weed control in the first four to six weeks after planting is essential to avoid reductions in vegetative growth and fruit yield from weed competition. The day-neutral strawberry has the potential as a commercial crop, but applied research into weed control is needed to determine tolerance to herbicides. Field experiments were conducted in 1984 and 1985 to evaluate the effects of herbicides (alone or in combination) on growth and development of two strawberry types, 'Hecker' (day-neutral) and 'Bounty' (June-bearer). All herbicide application rates are given as kilogram active ingredient per hectare (kgÂ·ha-1). Trifluralin (1.1, 2.2 kgÂ·ha-1); pendimethalin (1.5,3.0 kgÂ·ha-1); napropamide (4.5 kgÂ·ha-1) were preplant incorporated (PPI). Simazine (0.5,1.0 kgÂ·ha-1); terbacil (0.25/0.15 kgÂ·ha-1, 0.5/0.25 kgÂ·ha-1); metolachlor (1.68, 2.64 kgÂ·ha-1), sethoxydim (0.25, 0.35 kgÂ·ha-1); chloroxuron (5.6 kgÂ·ha-1) were applied four and eight weeks after planting, respectively. Two combinations included were trifluralin (PPI)/ terbacil (POST) applied at 1.1/0.5 kgÂ·ha-1 and napropamide (PPI)/ sethoxydim (POST) applied at 4.5/0.25 kgÂ·ha-1. Trifluralin applied at 2.2 kgÂ·ha-1, napropamide/sethoxydim (4.5/0.25 kgÂ·ha-1), pendimethalin applied at 3.0 kgÂ·ha-1, chloroxuron applied at 5.6 kgÂ·ha-1; both rates of simazine, terbacil, metolachlor, and sethoxydim in 1984 reduced 'Hecker' fruit yield. No significant reductions in 'Hecker' fruit yield occurred in 1985 when compared to the untreated control. Trifluralin applied at 2.2 kgÂ·ha-1 caused reductions in Bounty fruit yield. No significant reductions in 'Hecker' runner growth occurred in 1984, however, reductions occurred in all treated plots in 1985. Significant reductions in 'Bounty' fruit yield resulted from plots treated with trifluralin applied at 2.2 kgÂ·ha-1. Significant reductions in 'Bounty' runner growth occurred in all treatment plots in 1984 except trifluralin/terbacil and terbacil (0. 25/0.15 kgÂ·ha-1) treatment plots. In 1985, significant reductions in runner growth resulted from napropamide (4.5 kgÂ·ha-1), napropamide/sethoxydim, and terbacil (0.25/0.15 kgÂ·ha-1) treatments. The most effective weed control results were obtained from napropamide and pendimethalin treatments. All treatments were safe on Bounty, however Hecker had a lower level of tolerance to all herbicide treatments. Unacceptable levels of terbacil residue were detected in 'Hecker' fruit. Note:Page vi is missing in the original thesis.