MCAREC Demonstration Vineyard

History
The MCAREC demonstration vineyard was planted in 1986 with wine grape varieties obtained from Porter Lombard at Oregon State University. The block was established to evaluate the suitability of these varieties for production in the Mid-Columbia region. Wine grape research has not been a focus of the overall program at MCAREC. Nonetheless, the MCAREC demonstration vineyard serves as an educational resource for Mid-Columbia wine grape growers. Pruning and training systems, canopy management practices, and pest management practices that could be used in this region for the production of high quality fruit are being demonstrated.

Varieties
The original planting included 13 different varieties. Background information for each variety is included in Table 1. This information was collected from various sources and should be considered preliminary under Mid-Columbia conditions. Characteristics such as vigor and yield depend on local conditions and management.

Each variety was planted in two four-vine plots, with each plot making up a half row (see vineyard map). The vines are own-rooted and planted at a spacing of 7’ x 11’. In 2005, the bottom vine row was removed to make room for the High Density Pear block. In 2006, several varieties were removed because of excessively late fruit maturity or otherwise poor fruit quality. The space will be refilled with vines of better adapted varieties.

It should be noted that the vineyard is located over a septic drainfield servicing the Experiment Station office and laboratory building. Due to the increased water and nutrient availability, some of the vines are extremely vigorous. This is most noticeable in the top half of the vineyard. The performance of the vines located in the bottom half of the vineyard is considered to be more representative of the potential for this site.

Cool Climate Viticulture
The Pacific Northwest, including the Mid-Columbia area, is considered to be a cool climate viticulture region. Cool climate viticulture areas are generally considered to have fewer than 2700 growing degree-days (° F). Wines produced in cool climate viticulture areas are often considered to have the greatest potential for achieving high quality. This is probably related to lower temperatures during ripening in the fall, which allow slow maturation of fruit with gradual accumulation of sugar, better balance of sugar and acids, and greater development of aroma and flavor constituents. Growing conditions may be more challenging, however, resulting in less than optimum fruit maturity in some years and generally lower yields.

Site Selection
In cool climate areas, the regional climate (macroclimate) may be well suited to the production of high quality fruit. Many potential vineyard sites, however, may be unsuitable for the successful production of high quality fruit on a consistent basis due to limitations of the site climate (mesoclimate). Because the vineyard mesoclimate is affected by several factors, careful attention to vineyard site selection becomes critical in cool climate areas.

Moderately productive, well-drained soils are often favored over deep, fertile, highly productive soils in order to balance vegetative growth and fruit production and quality. Sloping ground with southern or southwestern exposure contributes to good air drainage for frost avoidance and high interception of solar radiation for photosynthetic activity. Low to moderate elevation sites are chosen over high elevation sites because the latter may result in insufficient heat units for fruit maturation.

Canopy Management
Vertical canopies are often chosen in cool climate areas for their desirable canopy characteristics (canopy microclimate), such as a high potential for intercepting sunlight. Light is important for efficient photosynthetic activity and the initiation of flower primordia for fruit production in the following season. Light also affects fruit composition, especially the phenolic profile, which can have very significant impacts on wine style and quality. Open canopies also promote air circulation around fruit and foliage, which can help reduce disease development. Exposure of up to 80% of foliage and 60% of fruit may be desirable in cool climate vineyards.

Canopy management practices may help to achieve open, balanced vine canopies. Shoot density is one of the main factors that determine canopy density. Shoot density is controlled during dormant pruning and by choosing an appropriate training system. Shoot thinning may be necessary for those varieties that regularly produce more than one shoot per node.

Shoot positioning may be necessary for achieving the desired shoot distribution. Leaf removal in the cluster zone can improve fruit exposure to light and increase air circulation through the canopy. Excessive or poorly timed leaf removal, however, can result in sun burning of fruit and delayed fruit maturity from reduced photosynthetic activity. Shoot tipping and hedging can reduce shade in excessively vigorous canopies. Cluster thinning may result in earlier and more uniform ripening of fruit.

In early 2001, a multi-year process of vineyard renovation was initiated. The trellis system was retrofitted to accommodate different training systems. The main objective was to allow more effective canopy management aimed at balancing vine growth and improving disease management. Prior to 2001, all of the varieties had been cordon trained and spur pruned regardless of their fruiting habit. Part of the renovation process was to renew the cordons for spur-pruned vines. New vine heads were established for head-trained-cane-pruned varieties.

Two vertical canopy training systems are being used in the demonstration vineyard (see Figure 2). For low to moderate vigor varieties, the Guyot system with a single upright curtain of foliage is used. For more vigorous varieties, the Scott Henry system is used. This system has two curtains: one with the shoots trained upwards and the other with shoots trained downwards. The Scott Henry system allows the retention of up to twice as many buds per unit of row length without excessive shoot density. Along with balance pruning during dormant pruning, the choice of training system was made to strive for vine balance by matching the site x variety potential with an appropriate training system.

Vineyard Floor Management
Cover crops are planted between vine rows in hillside vineyards to reduce surface water runoff and soil erosion. The cover crop may also play an important role in regulating arthropod pests (insects and mites) in the vineyard. Increased botanical diversity contributed by the cover crop may result in greater abundance of beneficial arthropods that help keep pest populations in check.

Cover crop management can be an important tool in achieving a balanced, efficient canopy. During the summer, cover crops are mowed or alternate drive-rows may be eliminated to reduce competition with vines for water and nutrients. On high potential sites, deep-rooted covers may be used to reduce excessive vine vigor by reducing water and nutrients available to vines.

Irrigation Management
Some form of irrigation is usually necessary in the early life of a vineyard for vine establishment. Many Oregon vineyards are not irrigated beyond the establishment phase. Judicious use of nitrogen fertilizer and supplemental irrigation may, however, be important in achieving a balanced, efficient canopy.

Pest Management
Relatively few diseases or insects require regular treatment in Mid-Columbia vineyards. Powdery mildew, caused by the fung us Uncinula necator, however, does require a well planned and executed control program. There is little or no tolerance in the winery for fruit infected with powdery mildew. Fortunately, available fungicides can be very effective in controlling mildew in wine grape vineyards.

Botrytis bunch rot, caused by the fungu s Botrytis cinerea, is another disease that can significantly impact fruit production and quality. This disease can be particularly troubling in years when fruit maturity is delayed or when fall rains start early and persist during the harvest period. In many seasons, bunch rot can be controlled through good canopy management. An efficient, open canopy promotes early fruit maturity. As discussed above, leaf removal can increase air circulation through the canopy, as well as improve spray distribution in the cluster zone. Both of these outcomes improve disease management. Chemical controls that are very effective against bunch rot are also available.

Although most Oregon vineyards are not regularly sprayed for insect or mite pests, one insect, the grape phylloxera (Daktulosphaira vitifoliae) is currently ravaging many vineyards in the Willamette Valley that were established with own-rooted vines. Grape phylloxera is a soil-borne insect that feeds on the roots of own-rooted European grapevines (most important wine grape varieties were selected from the European grape species, Vitis vinifera). Vines infested with phylloxera are usually debilitated and die from their weakened condition. Once a vineyard becomes infested with phylloxera, it is practically impossible to eradicate the pest. The main management strategy is planting vines grafted on phylloxera resistant rootstocks. This is not, however, a perfect solution because grafted vines come with a set of additional management considerations.