Winegrape Nutrition: Deficiency Symptoms and Micronutrient Response
Atypical visual symptoms are the first indicator of vineyard production problems. Nutritional deficiencies often appear as leaf discoloration, but can also appear as misshapen clusters, fruit, or discoloration of other tissues. As an added complexity, insect damage can often mimic certain nutrient deficiency symptoms. Deployment of the appropriate corrective measures is dependent on identifying the cause of the symptoms. However there are few published resources which aid in visual assessment of nutrient deficiencies.
Work to develop low end critical nutrient standards has been based on either field trials with specific nutrient levels or on tissue survey projects. As a result, the absolute low end of nutrient concentration in wine grape petioles and leaves is not based on induced deficiencies and may not fully represent truly deficient conditions. With this project, we propose to establish these low end levels under controlled conditions and will analyze all tissues to determine if fruit vs. leaf (blade or petiole) vs. some other tissue type would best reflect the status of a particular nutrient. In addition, this effort will produce visual guidelines for the evaluation of nutrient deficiency symptoms.
Can late season foliar nitrogen application reduce wine grape nitrogen nutrition stress?
Nitrogen (N) management is critical to successful grape production. When nitrogen is added to a vine with low nitrogen nutrition, nitrogen metabolism is stimulated causing an increase in protein synthesis. Based on recent whole plant nutritional analysis of grapevines in the Pacific Northwest, N is less available at a time when it is essential for fruit growth and development, and to build storage reserves for the following growing season. Research has also indicated that soil applications of N at veraison do not move to the appropriate organs for fruit development, thus these applications increase the risk of N leaching throughout the wet, winter months. This field experiment is being conducted using own-rooted Merlot and Riesling grapevines (Vitis vinifera L.). Twelve plots were designed in a four block pattern with each row serving as a block. Plots were replicated at each site. This two year study involves using a 6% solution of liquid urea applied at weekly intervals beginning at veraison, for five total applications (total of 6.8 kg N / ha). For the organic nitrogen a single rate of Biolink Vegan Nitrogen (6-0-0) was applied at the same rate for the same duration of time. The objective is to determine the effects of late season foliar N applications with both conventional and organic N sources on yield, yield components and vegetative growth in irrigated vineyards of Eastern Washington.
Developing a Site Selection GIS for Inland Pacific NW Grape Production
Absolutely quantifying terroir will likely never be possible. However, by scrutinizing major factors influencing grape vine growth, we can delineate areas for grape production ranging from suitable to ideal.
By compiling and analyzing climatic, topographic, soil and land use geospatial data in a geographic information system, we intend to develop a site selection model for grapes in the inland Pacific Northwest. Washington state is currently second only to California in wine grape production in the United States and it leads the nation in Concord grape production. The goal is to provide grape growers with recommendations of species and varieties in order to optimize the potential of the site and help push the region’s grape production toward continued success and excellence.