Evaluation of Activated Charcoal as a Remedy for Soil Residual Herbicide Injury

An experiment was conducted in fall 2014 to evaluate activated charcoal as a remedy for residual soil herbicide injury on vegetable crops. The experiment consisted of 4 herbicides and a control as main blocks and 4 activated charcoal rates as sub-plots. Aminopyralid (Milestone), aminocyclopyrachlor (MAT28), and picloram (Tordon) were applied at suggested label rates. Activated charcoal was used at 0, 1/2X, 1X, and 2X rates with 1X equivalent to 300 lb/acre. Eight vegetable crops (tomato, cucumber, corn, bean, lettuce, okra, cabbage, and pepper) were evaluated for reduction of fresh harvest weight 30 days after treatment. In the absence of herbicides, the 2X rate of activated reduced fresh harvest weight of corn, but had little or no effect on the other crops evaluated. The 1X rate of activated charcoal had no significant reduction of fresh weight on all crops while the 1/2X rate increased fresh weight of cucumber, bean, lettuce, and cabbage. In the absence of activated charcoal, of the 3 herbicides tested, aminocyclopyrachlor resulted in the most reduction in fresh weight of cucumber, bean, lettuce, and cabbage. When activated charcoal was used, there were no consistent effects of increasing activated charcoal rates on cabbage or lettuce for all three herbicides. With aminopyralid, increasing rates of activated charcoal had a positive effect on fresh weight of tomato, pepper, and corn. With aminocyclopyrachlor and picloram, all rates of activated charcoal increased fresh weight of all crops, except for cabbage, cucumber, and pepper. Initial results are promising that soil residual herbicide injury can be ameliorated with activated charcoal. Additional field research is needed to determine the benefit of activated charcoal on yield.