Weed control in organic watermelon variety trials

Authors: Webber Iii, Charles; Davis, Angela; SHREFLER, JAMES - OSU - LANE, OK; Perkins Veazie, Penelope; Russo, Vincent; EDELSON, JONATHAN - OKLAHOMA STATE UNIV.

Submitted to: Proceedings of Horticultural Industry Show
Publication Type: Proceedings
Publication Acceptance Date: 12/30/2005
Publication Date: 1/9/2006
Citation: Webber III, C.L., Davis, A.R., Shrefler, J.W., Perkins Veazie, P.M., Russo, V.M., Edelson, J.V. 2006. Weed control in organic watermelon variety trials. In: Dollins, D., Brendenberger, L., editors. Proceedings of the 25th Annual Horticultural Industry Show, January 6-7, 2005, Tulsa, Oklahoma. p. 124-127.

Interpretive Summary: The increasing perception by consumers that organic food tastes better and is healthier continues to expand the demand for organically produced crops. More information concerning the impact of different organic production systems on watermelon (Citrullus lanatus var. lanatus) is needed. In addition, weed control is often cited as the number one pest problem in organic vegetable production systems. The objective of these experiments was to investigate the impact of different weed control systems on yields of watermelon varieties grown organically. Six watermelon varieties were transplanted at two locations (Lane, OK and Center Point, OK). The six varieties included three seeded varieties ('Early Moonbeam,' 'Sugar Baby,' and 'Allsweet') and three seedless varieties ('Triple Crown,' 'Triple Prize,' and 'Triple Star'). The weed control system at Lane utilized black plastic mulch on the crop row, while the area between rows was cultivated to control weeds. The no-till organic system at Center Point used a mowed rye and vetch cover crop, hand weeding, and vinegar (5% acetic acid) for weed control. When averaged across watermelon varieties, the organic production system at Lane produced significantly more fruit per plant (4.2 vs. 2.3 fruit/plant), greater marketable yields (35.2 vs. 18.5 lb/plants), and higher average marketable weight per fruit (13.4 vs. 8.9 lb) than at Center Point. Plants at Center Point produced a greater percentage of marketable fruit, 92%, compared to plants at Lane, 63%. When comparison was made between locations, four of six varieties had significantly greater numbers of fruit per plant and higher marketable yields at Lane than at Center Point. Except for 'Early Moonbeam,' all other varieties produced significantly heavier fruit at Lane than at Center Point. In contrast, the Center Point location produced a greater percentage of marketable fruit for all varieties except 'Allsweet.' The plastic mulch and cultivation between crop rows was a successful method of weed control at the Lane location and provided a stronger weed barrier to prevent than the cover crop mulch at Center Point. In conjunction with this research, fruit quality evaluations (lycopene and brix) determined that the fruit quality was as good or better when harvested from the weedier Center Point location. Fruit quality differences between locations may be a reflection of weed pressure, other production factors, or a combination of both. Further research will specifically investigate the impact of weed competition on watermelon fruit quality.

Technical Abstract: Consumer interest and increasing demand for organically produced crops continues to grow in the U.S. More information concerning the impact of different organic production systems on watermelon (Citrullus lanatus var. lanatus) is needed. In addition, weed control is often cited as the number one pest problem in organic vegetable production systems. The objective of these experiments was to investigate the impact of different weed control systems on yields of watermelon varieties grown organically. Six watermelon varieties were transplanted at two locations (Lane, OK and Center Point, OK), into randomized complete block designed experiments with four replications. The six varieties included three seeded varieties ('Early Moonbeam,' 'Sugar Baby,' and 'Allsweet') and three seedless varieties ('Triple Crown,' 'Triple Prize,' and 'Triple Star'). The weed control system at Lane utilized black plastic mulch on the crop row, while the area between rows was cultivated to control weeds. The no-till organic system at Center Point used a mowed rye and vetch cover crop, hand weeding, and vinegar (5% acetic acid) for weed control. When averaged across watermelon varieties, the organic production system at Lane produced significantly more fruit per plant (4.2 vs. 2.3 fruit/plant), greater marketable yields (35.2 vs. 18.5 lb/plants), and higher average marketable weight per fruit (13.4 vs. 8.9 lb) than at Center Point. Plants at Center Point produced a greater percentage of marketable fruit, 92%, compared to plants at Lane, 63%. When comparison was made between locations, four of six varieties had significantly greater numbers of fruit per plant and higher marketable yields at Lane than at Center Point. Except for 'Early Moonbeam,' all other varieties produced significantly heavier fruit at Lane than at Center Point. In contrast, the Center Point location produced a greater percentage of marketable fruit for all varieties except 'Allsweet.' The plastic mulch and cultivation between crop rows was a successful method of weed control at the Lane location and provided a stronger weed barrier to prevent than the cover crop mulch at Center Point. In conjunction with this research, fruit quality evaluations (lycopene and brix) determined that the fruit quality was as good or better when harvested from the weedier Center Point location. Fruit quality differences between locations may be a reflection of weed pressure, other production factors, or a combination of both. Further research will specifically investigate the impact of weed competition on watermelon fruit quality.