Traverse City Record-Eagle

November 3, 2012

Ag Forum: Researchers assess grape varieties

Evaluating vine survival, fruit production, quality, flavor and marketability


---- — Riesling and chardonnay grapes account for a large portion of northwest Michigan's wine production. However, wine grapes with names like Pinot Gris, Pinot Noir and Cabernet Franc have become well-known in the last 10 years.

What will the next 10 years bring? The answer to that question may be in the making at the Northwest Michigan Horticultural Research Station in Leelanau County, where over 30 "new" grape cultivars are currently being evaluated. These varieties are new to our area, but some are old and well known in Europe.

Over the next few years, MSU researchers will be assessing the suitability of these cultivars for use in the region by looking at numerous characteristics, including vine survival, fruit production and quality. Wines made from these new varieties will be evaluated for flavor components and marketability.

During harvest, fruit samples from each cultivar are collected for laboratory testing that provides information on important fruit chemistry characteristics. The number of clusters of fruit and weight of fruit are recorded separately for each vine.

This fall, the harvest team at the station picked more than 36,000 clusters, weighing in at over three tons, from 500-plus experimental vines.

Trends in our data over subsequent years will help to identify vine health changes or needs to modify horticultural practices to "tune in" a cultivar to our growing conditions. In this same way, we can determine if a cultivar is not suitable for northwest Michigan.

Fruit quality and quantity are not the only important factors. Other vine and fruit characteristics can make or break a variety. Cultivars may differ quite a bit in their susceptibility to insects and diseases, or their attractiveness to birds. We have already learned a tremendous amount from working with the new cultivars, and we have established some early favorite varieties, but there is a lot more to learn before we can declare "winners."

Sometimes a seemingly insignificant factor ends up making a big difference in the acceptability of a grape cultivar in commercial production, and these may only be noticeable in years with weather variability.

For instance, one might think that large clusters of fruit would be a desirable trait, but this can make harvest difficult if the fruit cluster hangs down and is bound into the lower shoots and tendrils of the vine.

Vines with numerous or strong tendrils on their shoots are easier to train into the wire trellis, but are much more difficult when clearing the trimmings from the trellis during pruning. Vines with weak or few tendrils are a snap to prune, but the weight of the fruit can easily dislodge the shoots of the vine from the trellis during the growing season.

Dare I reveal my early favorites? GrunerVeltliner and Zweigelt.

However, we will have to wait and see how my picks turn out after a few more years.

in the experimental vineyard.

Erwin "Duke" Elsner is an agricultural educator for Michigan State University Extension in Grand Traverse County.