Reducing Herbicide Inputs in Vegetable Production
Sustainable Agriculture
Dwayne Joseph
Agriculture Educator
University of Maryland
Chestertown
Abstract
An integrated weed management (IWM) approach is crucial in vegetable production due to the limited availability of herbicides registered for use in vegetables compared to row crops. Moreover, many herbicides do not offer full-season weed control, posing an increased risk of crop injury if not applied according to label instructions. This presentation addresses these challenges by highlighting two ongoing research projects focused on reducing herbicide inputs by growers through the implementation of IWM tactics. The first project investigates biosolarization, a soil disinfection technique similar to solarization but involving the addition of organic soil amendments before the solar heating process. Biosolarization has been shown to increase weed seed mortality and decrease soil pathogens. The study included four replicated treatments comprising of eggplant: 1) grown in living mulch + no-till, 2) interplanted with cover crops, 3) grown in solarized soil, or 4) interplanted with a cover crop and grown in biosolarized soil. Results indicated that biosolarized plots had the lowest mean number of broadleaf weeds throughout the growing season, suggesting effective weed seed inactivation. However, biosolarization was not effective against vegetatively reproducing weeds like yellow nutsedge. The second study evaluated the weed-suppressing potential of a spring-seeded cover crop between plastic-mulched rows. Along with the weed control benefits, seeding a cover crop after bed formation offers growers more flexibility in cover crop adoption. The study consisted of a three-factor factorial, split-split plot design with four replications. The whole plot consisted of cover crop management method (clethodim, paraquat, roller-crimped). Subplots consisted of cover crop species (cereal rye, spring oats, cereal rye + spring oats, no cover crop), and sub-subplots consisted of residual herbicide treatment (fomesafen + S-metolachlor) or no residual herbicide. Results indicated that the presence of cover crops significantly reduced the mean number of weeds compared to plots without cover crops. Additionally, the presence of cover crops substantially increased cash crop yield, and the addition of a residual herbicide significantly increased full-season weed control. The preliminary results from both projects underscore the effectiveness of the evaluated IWM techniques. However, further research is necessary before making recommendations for grower adoption.
Authors: Dwayne Joseph
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Dwayne Joseph Agriculture Educator, University of Maryland Extension, Maryland, 21620