Evaluation of corn gluten meal for preemergence weed management in cranberry

Corn gluten meal (CGM) is a natural product that is typically used as a fertilizer (8-0-0), but also has reported herbicidal activity against germinating seeds. Its use as a method of preemergence weed control on cranberry farms was evaluated. The use of CGM in cranberry is a novel approach, therefore a greenhouse study was conducted to evaluate any potential phytotoxicity or harmful effects of CGM on cranberry plants prior to the establishment of a field study. With assistance from the grower, the field study was established at two sites on a recently planted organic cranberry farm in southeastern Massachusetts to evaluate if CGM suppressed new weeds. The results of this study showed that CGM was not an effective weed control on new cranberry beds, and that the addition of CGM actually led to an increase in weed biomass. Four months after the initiation on the experiment, untreated plots had an average weed biomass of 19.1 g/m2, while plots which received CGM treatments averaged 109.4 g/m2 (a range of 67.1 – 156.2 based on treatment). However, cranberry plants that received CGM showed a significant increase in growth, presumably from the additional nitrogen. Untreated plots had an average cranberry biomass of 3.4 g/ft2, while plots which received CGM treatments averaged 7.3 g/ft2 (range of 6.7 to 9.2 based on treatment). Providing adequate nutrition to organic cranberry beds is a challenge, and CGM may offer organic growers a good fertilizer option, especially when establishing new vines.