Innovative methods of weed management for Long Island vineyards

Innovative methods of weed management for Long Island vineyards

Summary

Control of vegetation in the strip under the trellis is a standard practice in the management of vineyards in the northeast. The goal is to minimize competition at key vine phonological stages. Excessive weed growth can impair fruit quality and quantity. Typically, weed control in this area is achieved through the use of herbicides. The infiltration of herbicides into groundwater has motivated growers to seek other less intrusive methods. Cultivation has gained favor though it has distinct disadvantages in a perennial cropping system. We have begun evaluation of two less common methods of managing the area under the trellis. In one vineyard, we established two sets of plots examining the impacts of repeated mowing of vegetation under the trellis. Treatments include mowing alone and mowing in combination with glyphosate applications. Weed counts, vine nutrient status and harvest (yield and fruit quality) data will help judge the long term feasibility of this management technique. At the Cornell research vineyard and in two commercial vineyards, a mixture of winter annual weeds such as knawel and perennial clover were seeded in replicated plots. These groundcovers ideally minimize invasion of weeds while remaining minimally competitive with vines during the growing season. Our goal is to determine the feasibility of these alternative methods for management of under trellis vegetation. The impacts of these strategies on vine productivity and fruit quality must also be quantified. It is important to ensure that these methods maintain or enhance vine health and productivity.

Objectives/Performance Targets

Under trellis mowing: our goal is to ensure that the long term maintenance of weed cover under the trellis will not be detrimental to vines. If the mowing treatment turns out to be harmful, we are hopeful that minimal use of glyphosate will mitigate competition at key stages of grapevine growth and development.

Three groundcover sites: We intend to conduct weed surveys as well as document horticultural effects by evaluating measurements such as vine size.

Accomplishments/Milestones

Under trellis mowing: Mowing under the trellis as a means of weed control does facilitate the establishment of a solid stand of low growing weeds such as dandelions. Nutrient testing and harvest data did not indicate any major differences between treatments. It is likely that, if differences exist, they will be manifested over the long term. We will continue treatments and data collection in both plots. 2007 will represent year 3 for one set of plots and year 2 for the other. Next job is collection of vine pruning weights, a gauge of growth in 2006.

Three groundcover sites: Late March, evaluate winter survival. Spring, evaluate competition with winter annual then summer annual weeds. Glyphosate to be applied 3x over season to one treatment. Fall, evaluate weeds and status of groundcover, harvest grapes to gauge yield, collect berry samples to gauge fruit quality. Our ultimate goal is to establish groundcovers that a) will establish and maintain under the trellis; b) will provide some competition to invading weeds; and c) will tolerate low rates of herbicides designed to reduce or eliminate winter and summer annual weeds that invade.

Impacts and Contributions/Outcomes

Preliminary results will be presented as part of a talk on alternative weed management at Viticulture 2007, a regional grape industry meeting February 2007 in Rochester, NY. Attendance at individual sessions ranges from 30-100 people. As groundcover plots were established in fall 06, growers will have an opportunity to view plots at LIHREC at the summer field meeting in July 07. Typical attendance ranges from 10-15. Though subject to change, we are currently planning on presenting more comprehensive results January 2008 at the Viticulture Session of the Long Island Agricultural Forum. Typical attendance, 20-30. This work is long term and given preliminary results, it is not yet possible to gauge impact on the industry or the degree to which practices have been changed.

Collaborators: