Elmer Swenson Legacy Collection: 2018 Update

By: Matthew Clark
Assistant Professor, Grape Breeding and Enology
Department of Horticultural Science

Elmer Swenson Legacy CollectionThis project aims to address the key components of sustainable production for grape growers and will benefit the expanding grape and wine industry in several ways. The identification of cultivars with disease and pest resistance will support human health, reduce environmental impacts through reduced spraying, enhance rural economies through new products, and improve profitability by reducing grower risk associated with weather events such as frost and low-temperature injury.

Elmer Swenson, a native of the Osceola area is often credited with pioneering grape breeding and viticulture in the upper Midwest. The Elmer Swenson Legacy Collection is an attempt to evaluate many of Swenson’s breeding lines that had been maintained at Seed Savers Exchange (SSE) in Decorah, Iowa. The goal of this project is to grow this diverse collection along with UMN varieties to examine them for resistance to insect pests and diseases in the organic vineyard setting. We hope to identify breeding lines that could become new cultivars, or be used as parents in the breeding program. Cold-climate grape growers are constantly seeking new grape products that reduce their inputs for disease and pest management and reduce risks associated with extreme weather events including (late) spring frosts, wide daily temperature variation, and low-temperature injury. Simultaneously, growers want varieties with consistent, high yields and high quality that fit into their portfolio of wine and table grape offerings. Cultivars with reduced spray programs can dramatically reduce operating costs and have favorable environmental and health benefits. Typical viticulture practices require insecticide and fungicidal sprays to obtain high-quality fruit. These spray programs can be disruptive to native pollinators. We plan to observe insect populations throughout the growing season, specifically during bloom and at harvest, to characterize the species that visit grapes.

This spring, Research Professional John Thull and I collected hardwood cuttings from the vineyard at (SSE) and brought those cuttings into the greenhouse for propagation. Grapes are generally easy to root from dormant cuttings, and with the assistance of some students, a heated greenhouse, and overhead misting, we had a very high success rate. After rooting the vines, plants were potted up and began to grow. We labeled the vines and brought out two replicates of each to the Horst Rechelbacher Site in Osceola, WI for planting.

Elmer Swenson Legacy Collection PlotOne of the hexi-plots was chosen for use as a hexi-vineyard. To our knowledge this is the first vineyard to take on this unique shape! With support from many staff, we staked out the vineyard, so we could determine where posts and plants would go. Nearly 270 vines were planted on June 28, during a very hot weather day! We had assistance from Associate Professor Julie Grossman’s research group, PlantEd Project Coordinator Lindsey Miller, and my lab group. The vines were planted, a bamboo stake was added for support, the vine attached to the stake, and a protective growtube placed around the plant. We have learned that the growtube has been instrumental to prevent deer from browsing on the vines. More specifically, it keeps the deer from chewing them all the way to the ground. The tops of the plants have been eaten off at the top of most of the tubes, at about 3 feet. This may seem dramatic, but during this establishment year, the plant is putting down lots of roots. With the harsh winters, many of these plants will experience winter damage down to this height or lower before the 2019 season. With the recurring rain events this summer, supplemental irrigation using a water cart was only needed a few times.

A critical next step in this project is installing the trellis system. The vines will need a support structure to grow on in 2019. We also have discussed changing the understory planting to different species that are pollinator and/or soil health friendly. We need to discuss and plan how to implement this. In 2019 we will also collect and analyze DNA from the population. This will help to identify any known genetic resistances already in the population. One of the biggest challenges is deer. We believe that the trellis design itself, with some minor manipulation will deter deer from browsing, and will be a key objective in 2019 as the vines continue to establish.