Author
|
Submitted to: American Society of Horticulture Science Meeting
Publication Type: Proceedings Publication Acceptance Date: 5/17/2010 Publication Date: 10/17/2010 Citation: Johnson, W.C. 2010. Integrated systems of weed management in organic 'Vidalia' onion. American Society of Horticulture Science Meeting. Hortscience. 45(supplement):S136-5137. Interpretive Summary: Current weed management systems in organic Vidalia® onion depend heavily on costly handweeding. Trials were conducted in southeastern Georgia to develop integrated systems of weed management in organic Vidalia® onion that do not depend on handweeding.. Treatments were all possible combinations of summer solarization, cultivation with a tine weeder, and herbicides appropriate for use in certified organic production systems. Plots were solarized with clear plastic during the summer months prior to transplanting onion, with the mulch removed in October. Cultivation treatments were twice at 2-wk intervals, four times at 2-wk intervals, and non-cultivated. Herbicides were clove oil plus vinegar, clove oil plus a petroleum oil insecticide used as an adjuvant, and a non-treated control. Preplant solarization during the previous summer did not control the cool-season weeds present in these trials, along with no effect on onion yield. Cultivation with a tine weeder twice at two-week intervals was equally effective in controlling cutleaf eveningprimrose and swinecress as four cultivations, with both cultivation regimes increasing onion yield compared to the non-cultivated control. Cultivation with a tine weeder neither damaged nor bruised onion bulbs sufficiently to increase incidence of diseases in stored onion. Clove oil herbicide treatments provided minimal weed control and had no effect on onion yield. These data show that cultivation with a tine weeder effectively controlled weeds in transplanted onion and protected yield without the need for handweeding. Cultivation with a tine weeder can be immediately adapted by organic growers for use in transplanted onion. Technical Abstract: Trials were conducted in southeastern Georgia to develop integrated systems of weed management in organic Vidalia® onion. Treatments were a factorial arrangement of summer solarization, cultivation, and herbicides appropriate for use in certified organic production systems. Plots were solarized with clear plastic during the summer months prior to transplanting onion, with the mulch removed in October. Cultivation treatments used a tine weeder, with cultivation twice at 2-wk intervals, four times at 2-wk intervals, and non-cultivated. Herbicides were clove oil plus vinegar, clove oil plus a petroleum oil insecticide used as an adjuvant, and a non-treated control. Preplant solarization during the previous summer did not control the cool-season weeds present in these trials, along with no effect on onion yield. It is theorized that dormant, cool-season weed seed are immune from solarization during the previous summer. Cultivation with a tine weeder twice at two-week intervals was equally effective in controlling cutleaf eveningprimrose and swinecress as four cultivations, with both cultivation regimes increasing onion yield compared to the non-cultivated control. Cultivation with a tine weeder neither damaged nor bruised onion bulbs sufficiently to increase incidence of diseases in stored onion. Clove oil herbicide treatments provided minimal weed control and had no effect on onion yield. These data show that cultivation with a tine weeder effectively controlled weeds in transplanted onion and protected yield without the need for handweeding. Cultivation with the tine weeder did not damage the onion bulbs and there was no increase in diseases of stored onion. Cultivation with a tine weeder can be immediately adapted by organic growers for use in transplanted onion. |
