Multifunctional Intercropping as a Cultural Strategy to Reduce Weed Pressure for Organic Vegetable Production

A multi-layered canopy provided by intercropping multiple species can provide barriers for the spread of pests and diseases and can allow for a more efficient utilization of resources that reduce competition to target crops from weeds. As a result, intercropping can be an effective cultural control strategy for the management of weeds, pests, and diseases. Different combinations of peanut, watermelon, okra, cowpea, and pepper planted alone or in various intercropping combinations were investigated in a low-input organic system in Texas. Each species was selected to perform a specific function within the system. Watermelon was selected as a smother crop and significantly reduced total weed biomass when planted alone and in all intercropping combinations in 2011. Total weed biomass was reduced by 81, 83, 88 and 92% in treatments containing watermelon as compared to pepper, peanut, okra and cowpea grown in monoculture., pepper grown in monoculture had significantly higher weed biomass than all other treatments in 2012, with 46% more weed biomass than the next highest yielding treatment. Sedges were consistently most effectively reduced and pepper, cowpea, peanut and okra benefited most from intercropping in both years. Total above-ground plant biomass was not a significant predictor of weed biomass. Weed biomass was a significant predictor of total fruit yield, however, accounting for 39% of yield variability. These findings suggest that three and four species intercropping combinations, whereby each crop is selected to perform a specific function within the system, may provide small-scale sustainably-minded producers a model system for the management of weeds.