Integrated Weed Control in Transplanted Pepper: Evaluating the Use of Between-Row Cultivation Tools with Banded In-row Applications of 200-grain Vinegar 2010
Project Leader: Robin Bellinder, Horticulture Dept., Cornell University
Cooperator: Glenn Evans, Horticulture Dept., Cornell University
Abstract: Vinegar, an organic herbicide, can supplement the existing intra-row weed control options of organic farmers. However, there are two primary limitations to its use in vegetable crops. First, it is expensive. Second, vinegar applications that contact the crop can cause injury and yield loss. The aim of this research was to use vinegar to control intra-row weeds in bell pepper in a way that product costs would be reduced and crop injury would be minimized. Vinegar was banded in-row to reduce product volume and expense. Applications were shielded and directed below the crop canopy to minimize contact with crop foliage. Stem protectants, organic paints applied to crop stems, were included and evaluated as potential physical barriers to crop stem injury. A tractor mounted sprayer/cultivator was constructed to apply a 25 cm-wide band of vinegar at the base of two crop rows, while the inter-row areas were simultaneously cultivated. Two trials were conducted in transplanted bell pepper. A single application of 200-grain vinegar (20% acetic acid) at 700 L/ha was applied when weeds were in the cotyledon to six-leaf stage. Applications were made with the lower stems coated in one of two organic paints (linseed oil and clay-based) or left uncoated. Handweeded and weedy in-row treatments were included for comparison. One day after vinegar application, in-row weed control was 100% in both pepper trials. Two weeks after application, there were 75% fewer weeds germinating in the vinegar treated areas, as compared to the areas which were handweeded. With vinegar, there was minimal soil disturbance, so the potential to stimulate latent weed seed germination was significantly reduced. Neither stem paint prevented crop injury; the clay paint flaked off within 2 weeks while the linseed oil was phytotoxic. Despite pepper foliar injury of less than 5%, stem injury by 2 weeks post-application contributed to a measurable reduction in yield. With vinegar, high levels of weed control, and the extended duration of that control relative to handweeding, could facilitate improved organic intra-row weed control. However, crop injury must be reliably reduced beyond the levels found in these studies. More research will be needed to assess the value of alternative stem protectant materials.