Abstract
A method of using cover crops for suppression of weeds in the row middles of organically grown oranges is being developed. However, weed control within tree rows is currently accomplished by cultivation, which is time consuming and tedious. Alternative weed management methods are being sought that would be less labor intensive and equally or more effective than cultivation. The objectives were to compare the efficacy of three nonsynthetic, postemergence, contact herbicides (Alldown, Matran 2, and Xpress) with that of corn gluten meal applied preemergence, and flaming for weed control in organic citrus production. Also of interest was whether weed control could be improved by a pretreatment of mowing or tillage. The response with mowing and no pretreatment differed from the response with tillage. The most effective treatment with mowing and no pretreatment was flaming with 97% control 1 week after application (WAA) and declining to 79% by 3 WAA. Alldown and a 20% concentration of Matran 2, provided better than 70% weed control within the first week, but decreased to less than 60% by 3 WAA. With tillage as a pretreatment, corn gluten meal, 20% Matran 2, and flaming provided the best weed suppression of 68 to 75%, during the 5 weeks after application. Inconsistent results obtained with Xpress may be due to separation of the component oils from other ingredients in the product.
