The Plant Analysis Laboratory in the Department of Horticulture at Oregon State University is currently revising tissue standards and fertilizer recommendations for wine grapes. These revisions are the result of a research program that was sponsored by the Wine Advisory board beginning in 1985. We have utilized data collected during...
Three different green cover treatments were compared in their effect on leaf gas-exchange, vine growth, yield and fruit composition. The treatments were: grass cover, resident plants, and an insectary plant mixture. Photosynthesis, transpiration, and water use efficiency were lower for vines with a grass cover. Leaf area and shoot growth...
Five different trellis and training systems were compared in their effect on yield components, fruit composition, fruit set, and shoot morphology in Pinot noir grapevines in 1996 and 1997. This trial was performed on established vines planted on a low-vigor valley floor site, in the Willamette Valley of Oregon. The...
A broad range of factors influence wine grape quality and manipulation of these factors has stimulated interest among grape growers, wine makers, and research scientists alike. One such factor affecting wine grape quality is crop level, particularly for Pinot noir. Since the capacity of a vine to ripen fruit depends...
The connection between the fruit-set disorder Inflorescence Necrosis (IN) and high ammonium (NI14+) in affected tissues has led to an investigation of NH4+ assimilation enzymes (principally glutamine synthetase (GS) and glutamate synthase) in grape tissues. Previous work in this department has suggested that toxic levels of NH4+ build up in...
Inflorescence Necrosis (IN) has been an unpredictable problem for grape growers in Oregon. The
industry has seen significant losses due to this fruit set disorder in several out of the eight years since its
first description in 1988, particularly in Pinot noir. Little is known of how to prevent the...
For this trial, established Pinot noir vines, located on the valley floor of the Umpqua Valley in Oregon
were used. In 1996 and 1997 sixteen vines trained to the Scott Henry trellising system were separated
into four different quadrants, determined by shoot orientation: Bottom canopy, shoots trained toward the
ground;...
Phenolic compounds are key quality components of wine affecting sensory characteristics, wine color, and wine stability. Phenolics are responsible for much of the mouth flavor of wines affecting astringency, bitterness, and the "length" of the flavor impression on the palate. The color in both red and white wine is due...
Yeast strains used in wine production are known to differ in some fermentation characteristics, including rates of fermentation, alcohol tolerance, degree of foaming, temperature tolerances, volatile acid production, and hydrogen sulfide production. There may also be significant sensory differences in aroma and flavor in wines fermented with different yeast strains....
We have studied commercial fermentation practices for three vintages in order to learn how they affect
extraction and stability of anthocyanin pigments and other phenolic compounds in Pinot noir. Wines
were monitored during fermentation, processing, and aging for anthocyanin and phenolic content, color
intensity, and for phenolic profiles using high...