Emily Hoover

With the demand for high quality fruit by consumers combined with the strong pressure to reduce chemical use, fruit growers must look to economically and environmentally sustainable management schemes of production. For instance, apple growers who want to stay profitable must establish high-density plantings with smaller trees using new cultivars. These high-density plantings cost 10 to 20 times more per land area to establish than lower-density plantings, thus greatly enhancing economic risk. Potential returns of high-density plantings, however, far exceed those of low-density plantings, particularly during the first 10 years. The central component of a high-density system is the rootstock, the part of the tree determining final tree height thus allowing for closer tree spacing and greater number of trees per land area. As part of the tree, the rootstock influences many factors in addition to tree size, particularly productivity, fruit quality, pest resistance, stress tolerance, and ultimately profitability. Continued tree losses due to cold temperature injury, disease, scion incompatibility, and poor soil conditions are an economic cost for the industry that can be ameliorated by improving rootstock choices for growers. Current research at the University of Minnesota is part of a national project, NC140, evaluating apple rootstocks in USDA hardiness zone 4 to determine suitability for growers in cold climates. 

Availability of locally grown strawberries is extremely limited in the Upper Midwest, due to the short growing season and cultivars with short harvest windows. While there is an expressed interest in having greater access to locally grown strawberries, lack of knowledge of production systems using new cultivars has limited growers from being able to fulfill this need in our region. Partnering with Steve Poppe at the West Central Research and Outreach Center in Morris MN, we have performed a number of experiments beginning in 2014 to develop sustainable, organic methods for growing day-neutral strawberries with the goal of extending the season. These studies began as part of Dr. Andrew Petran’s Ph.D. thesis. He replicated experiments done in warmer climates with cultivars grown on raised beds with white-on-black plastic mulch proving that growing day-neutral strawberries on plastic under low tunnels with organic practices are economically sustainable for Upper Midwest growers. The research has continued with studies by Jared Rubenstein discovering the application of mycorrhizal fungi at planting did not give a significant yield boost.  Nathan Hecht’s research determined that flies play a large role in pollinating day-neutral strawberries and adding a floral resource for pollinators may increase the number of floral visitors to these flowers.