Soil Analysis Directed Ground Cover Approaches to Excessive Canopy and Weed Control in Southern Vineyards

View the project final report

• 2012 annual report

Commodities

• Fruits: grapes

Practices

• Pest Management: weed ecology
• Soil Management: soil analysis

After ten growing years the two major problems I have faced are canopy management due in large part to excessive vigor and weed control fostered by summer rains. The approaches taken to the former have included altered pruning methods, abstinence from fertilization, and altering trellis systems. Means utilized to address the latter include use of a Weed Badger and a gamut of (agriculture specialists directed) herbicides, both pre- and post-emergent. Excessive canopy alters the cluster microclimate which determines sunlight quality and quantity, temperature, humidity, wind speed and evaporation. This threatens sustainability of our vineyard by reducing quality due to excessive acidity, low brix and reduced varietal character, or yield (including total crop loss) due to mildew and/or rot. Soil nitrogen mineralized from soil organic matter (SOM) can promote excessive vegetative canopy growth in grapes. Weed control of species such as morning glories (local nemesis in Kentucky) poses an expensive challenge both in chemicals and labor costs with failure further contributing to excessive shading as these foreign vines climb across and add to the dense canopy. For a vineyard and winery to remain viable, production needs must be met with quality product. This problem is common to other vineyards across the state and must be addressed for the industry as a whole.
issues plaguing sustainable grape production for wine. Upon completion of the research, the best management practices found to lower soil nitrogen content will be employed thus increasing both quality and quantity of grapes grown for wine production. Materials with carbon to nitrogen (C:N) ratios greater than 25:1 are known to immobilize soil nitrogen. We want to evaluate the role of ground covers as they impact excessive canopy by nitrogen utilization as well as their efficacy in weed suppression. More specifically to evaluate a three-inch wood mulch application, wheat straw, and a Cereal Rye cover crop compared to more traditional pre- and post-emergent herbicide application. The Cereal Rye cover crop would be broken down into two treatments – one that is killed chemically before seed formation, the other allowed to terminate on its own. Both proposed mechanisms (mulch and cover crops) are well known to immobilize or utilize plant available nitrogen and reduce the incidence of weed pressure during the growing season. They should allow for grape growth to proceed unhindered by unneeded nitrogen during the early growing season. Each treatment will be replicated 4 times within a variety on similar slope, aspect, and soil type

Project would proceed as follows:
1. Soil analysis spring 2012
2. Woodchip mulch, wheat straw and rye grass
application prior to bud break
3. UK agriculture specialist supervised pruning
4. Late July petiole analysis
5. Canopy assessment at harvest
6. Harvest yield and quality assessments
7. Soil analysis post harvest
8. Sequence repeated the following year