The late winter cold front in early February 1989 brought significant snowfall and low temperatures to all of Oregon viticulture and caused considerable vine damage in the northeastern and in some western valleys of Oregon. The lateness of this winter freeze was unusual since most winter damage in the Pacific...
Minimal pruning is a vine management system developed in Australia and now widely used for wine grape production around the world. Porter Lombard started a minimal pruning trial in Cabernet Sauvignon following his visit to Australia in 1988. A replicated trial in Chardonnay was established at Woodhall vineyard in the...
Traditional vineyard practices in Oregon are labor intensive and require large pools of available labor for pruning, shoot positioning, and harvest. A mechanized system of grape growing has been developed in Australia to eliminate almost all of the handwork involved with grape production. The cornerstone of this system is minimal...
The objective of this project has been to develop a method to reduce vegetative growth in grapevines. Excess growth and dense canopies reduce wine quality and increase disease incidence, specifically botrytis bunch rot. Over the last four years, we extensively tested a method of reducing vegetative growth by a technique...
Objectives:
1. To evaluate compositional changes and flavor development during ripening in order to develop better harvest indices, and to develop practical methods to evaluate optimal winegrape maturity.
2. To evaluate the effects of viticultural practices on winegrape maturation, juice and wine composition, and wine quality.
3. To evaluate new...
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. The treatments were: upright vertical, cane pruned (Guyot); upright vertical, spur pruned (Bi-lateral Cordon); Scott Henry, cane pruned; Lyre, cane pruned; and Geneva Double Curtain...
Pinot noir vines, trained to the Scott Henry trellising system were separated into four different quadrants: Bottom canopy, trained toward the ground; Top canopy, trained upwards; East orientation, receiving the morning sunlight; and West orientation, receiving afternoon sunlight. Yield components and fruit composition were measured for each canopy, orientation, and...
The phrase "canopy management" has recently become trendy in many New World grapegrowing areas. Interestingly enough, the concepts are not new and are generally acknowledged in Old World viticulture, though often these empirical observations are misinterpreted, as we will soon show. It was Nelson Shaulis of Cornell University who developed...
A factorial design was used to vary leaf canopy structure of mature Pinot noir grapevines during two consecutive seasons: shoot tipping at full bloom (yes or no), lateral shoot length (no laterals, laterals cut back to 4 leaves at full bloom, laterals allowed to grow undisturbed) and cluster zone leaf...
This year's late spring frost prompted a number of growers to call OSU with questions about the fruitfulness of secondary buds and about management alternatives for frost damaged vines. In response to this concern three experiments were established in Willamette Valley vineyards. At Chateau Benoit Vineyard ten vines of MollerThurgau...
Plant-pathogenic nematodes that cause yield loss in California and European vineyards are found in over 85 % of Oregon vineyards. Population densities of Xiphinema americanun (dagger nematode) and Criconemella xenoplax (ring nematode) were found in 37% of vineyards at levels reported to cause > 10-25% loss in California vineyards. However,...
Crown gall can develop on grapevines wounded by freezing temperatures, mechanical damage or grafting. Increased demand for grape varieties grafted to phylloxera resistant rootstocks has led to increased incidence of crown gall at graft unions. Therefore a search for plant material that is resistant to crown gall has been undertaken....
One of the goals of the Integrated Production approach is an overall reduction of pesticide use, including the application of fungicides for disease control. Powdery mildew is the most frequently sprayed disease in Oregon vineyards. Losses to powdery mildew vary from year to year, but may be substantial. Because little...
The easiest way to introduce phylloxera to a site is by infested plant material. If a grower can effectively remove any existing phylloxera on new plants, the rate of spread of phylloxera. in Oregon vineyards will be significantly decreased.
The objectives of this study are to determine methods for dipping...
Agrobacterium vitis is a bacterium that causes crown gall in grapevines. Plant injury from freezing temperatures or mechanical damage during cultivation often provide wounds required for infection to occur. Crown gall may kill grapevines and a new shoot is often brought up from the root to replace dead vines. Discovery...
Crown gall can develop on grapevines wounded by freezing temperatures, mechanical damage or grafting. Pathogenic agrobacteria residing within the vascular system are able to initiate tumor growth in damaged plant cells. Sampling from 21 sites in Oregon vineyards and nurseries yielded diverse populations of pathogenic agrobacteria. Most of the pathogenic...