2013 Annual Report
1a.Objectives (from AD-416):
The objective of this cooperative research project is to determine the balance between canopy and crop level manipulation in vineyards, and to quantitatively assess the effects of so-called 'vine balance' on fruit chemistry.
1b.Approach (from AD-416):
A field-based approach will be taken, using mature wine grape vineyards. Crop load will be adjusted to within, above- and below- the wine industry's standard recommendations for the cultivar and production district. All other vineyard management will follow standard practices for the cultivar and production district. Canopy and fruit microclimates will be characterized quantitatively at physiologically important stages of vine and grape berry development. At commercial maturity, fruit will be analyzed for standard maturity indices, phenolics, and other compounds associated with quality.
This research was conducted in support of NP305 objective 1 "Determine effects of water management on wine grape productivity and fruit maturity" of the parent project. The research was conducted to address how plants can compete with each other for nitrogen (a plant nutrient) and its management in a vineyard with a moist, fertile soil. Soils with high amounts of nitrogen promote excessive grapevine growth, which is undesirable. Nitrogen levels in the grapevine also affect the quality of wine produced from the grapes. The research also addressed the problem of how many grapes, or the level of fruit, should be grown for premium wine grape production, particularly in Oregon. Many farmers deliberately remove fruit from the grapevines with an expectation of improving fruit quality at harvest. When grass was planted between rows of grapevines, it effectively reduced excessive growth of the vines by competing with the grapevines for nitrogen rather than for water, as had been previously thought. Including grass between rows of grapevines also reduces the potential for nitrogen to leach through the soil into groundwater. Managing nitrogen, grapevine growth, and fruit levels constitute significant costs to the farmer. We found that the natural level of grapes produced by the vine did not compromise fruit quality and by consequence, improved the profitability of the vineyard. The potential benefits of this research are to allow growers to reduce farming costs for grapevines that are planted in fertile, moist soils. By growing grass between the vine rows rather than tilling to bare soil, we estimate cost savings for growers to be $372 per acre, including reduced cost for removing excess shoots ($200 per acre); reduced need to cut the tops of excessively long shoots ($59 per acre); one less spray application for diseases as the shoots and leaves are less dense and thus less prone to disease ($46 per acre); and reduced need to remove excess leaves that shade the fruit ($67 per acre), which is undesirable for fruit quality. If growers can maintain more fruit on their vines by not removing what is thought to be excessive fruit, this equates to a savings of $270 per acre. In sum, these direct savings improve the economic viability of the vineyard operation.