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;...
Grafted grapevines will become increasingly important in Oregon vineyards in order to prevent loss of plants to phylloxera infestations. Several rootstocks are now being evaluated in Oregon for horticultural traits and characteristics related to wine quality. Resistance or tolerance to other plant diseases affecting grapevines needs to be examined as...
The objectives of this study are to isolate and characterize pathogenic agrobacteria that cause crown gall in grapevines and test hot water dips as a method for eradicating the infectious bacteria . Crown gall is commonly found among Oregon vineyards and the causative agent, Agrobacterium vitis, is known to be...
Stuck and slow fermentations are a major concern of winemakers. If the levels of fermentable nitrogen in juice are too low, fermentations will be slower and may stop or 'stick' before all the fermentable sugar is utilized by the yeast. Sluggish and stuck fermentations are also sometimes accompanied by production...
Different fermentation practices are generally believed to affect wine composition and wine quality of Pinot noir. Oregon winemakers, for example, commonly attribute differences in color and phenolic extraction to differences in processing. There is, however, little information from replicated trials with controls demonstrating the cause and affect of these perceived...
Traditionally, winemakers have relied upon 'spontaneous' malolactic fermentation (MLF) from indigenous species which may take weeks or months to go to completion depending upon the wine and the cellar conditions. Control of MLF has increased with the development of pure MLF bacterial starter cultures. Pure cultures started from slants generally...
The new varietal trial at SOES was monitored during the growing season and during ripening by David Sugar and Porter Lombard (see Winegrape Variety Trial in Southern Oregon). The 1993 vintage was a late ripening season and not all the varieties developed sufficient maturity for experimental wine production. Tempranillo, Viognier,...