Submitted to: Georgia Organics Incorporated
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2010
Publication Date: N/A
Technical Abstract: Weed control in organic crop production is difficult and costly. Early studies on organic weed control in conservation tillage systems were disappointing. Research shifted to organic weed control in conventional tillage systems. Intense cultivation with a tine weeder was the most consistent method to control weeds in organic peanut and dry-bulb onion. Additional research trials evaluated row patterns, seeding rates, and duration of cultivation. Preliminary results showed that peanut seeded in wide rows (two rows, 91 cm apart), at a density of 20 seed/m, and cultivated weekly for at least 6-wk was the most effective regime evaluated. Weeds were not effectively controlled in peanut seeded in twin rows (two pairs of rows, each pair 46 cm apart with each row in the pair 17 cm apart) at a density of 10 seed/m. However, when peanut in twin-row patterns were seeded at 20 seed/m, weeds were controlled by intense cultivation with a tine weeder. These results suggest that in-row plant spacing is critical for successful weed control with cultivation and independent of row pattern. Peanut seeded at 20 seed/m improved crop competition with weeds and greatly facilitated overall weed control with cultivation. It was noted that cultivation needed to be initiated before weed emergence, which coincided with peanut emergence (‘cracking’). Weeds already emerged were not consistently controlled with the tine weeder, regardless of the duration or frequency of cultivation. These basic concepts were also proven to be effective in transition to organic production in plantings of millet and southern pea. The most effective cultivation regimes from these research trials were validated on certified organic farms in 2007 and 2009.