Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 22, 2002
Publication Date: August 1, 2002
Citation: Shrefler, J., Webber III, C.L., Faulkenberry, O.L. 2002. Effect of preemergence herbicides on early seeded watermelon [abstract]. HortScience. 37(5):747. Technical Abstract: Herbicides approved for watermelon may result in crop injury under cool or wet conditions. To obtain market prices associated with early harvest, planting may occur when conditions are sub optimal for seed germination and plant growth. Consequently, early planting may contribute to crop injury from herbicides. Field trials were conducted to compare existing and possible new herbicides for crop injury potential with early planting. A split-plot design was used with planting dates as the main plots and herbicide treatments as subplots. Yearly, 4 watermelon (cv. Allsweet) plantings were made every 2 weeks beginning mid April on fine sandy loam soil in 1999 and very fine sandy loam in 2000 and 2001. Herbicides and base rates (in lbs. active ingredient per acre) were ethalflualin at 1.125 lb ai/a, a mixture of bensulide at 4 lb ai/a and naptalam at 4 lb ai/a, a mixture of ethalfluralin at 0.8 lb ai/a and clomazone at 0.25 lb ai/a, and halosulfuron-methyl at 0.025 lb ai/a. Herbicide treatments included an untreated check, base rates of herbicides, base rates x 2 of herbicides and the base rate x 3 of halosulfuron-methyl. Stand counts and plant weights were determined when 50% of plants had a first female flower in 2000 and 2001. Stand counts were made at 63 days after planting in 1999. In 1999 no interactions were detected between planting date and herbicides. In 2000 and 2001, significant P<0.05 interactions occurred between plant date and treatment for stand only and no significant decreases in stand or plant weight resulted from 1x rate treatments as compared to the untreated control. For the 3x rate of halosulfuron-methyl and the 2x rate of ethalfluralin + clomazone, instances occurred when stand and plant weight were significantly lower than for the respective 1x rates.