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Title: Organic weed control in certified organic watermelon production

item Webber Iii, Charles
item Davis, Angela

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/15/2009
Publication Date: 2/7/2009
Citation: Webber III, C.L., Davis, A.R., Shrefler, J.W. 2009. Organic weed control in certified organic watermelon production [abstract]. Joint 2009 Meeting, 49th Weed Science Society of America and 62nd Southern Weed Science Society. Paper No. 86.

Interpretive Summary:

Technical Abstract: The increasing perception by consumers that organic food tastes better and is healthier continues to expand the demand for organically produced crops. Field research was conducted in southeast Oklahoma to determine the impact of organic production systems on weed control and watermelon (Citrullus lanatus var. lanatus) yields. 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; 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%. 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. Plants at 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 weed emergence 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.