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Home HortTechnology High Tunnel, Open Fields Compared for Cold Weather Raspberry Production
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EAST LANSING, MI—When it comes to raspberry production, growers in Midwestern and Northeastern states must contend with multiple challenges. While California raspberry producers have the advantages of longer growing seasons and favorable climates, growers in the Midwest must address issues such as shorter seasons and colder winters. Creating additional concerns, frequent summer rains and high humidity in these regions can promote fruit rots and reduce raspberry shelf life.

Researchers are looking to high tunnels—plastic-covered, unheated greenhouses—to help cold-weather raspberry growers produce more consistent crops. A study from researchers at Michigan State University compared production periods, yields, and fruit quality of raspberry cultivars in the open field and in three-season tunnels. The study, published in HortTechnology, provides valuable information for regional raspberry production. "High tunnels are expensive investments, and growers need more information on expected benefits and basic management options such as cultivar selection," explained author Eric Hanson.

The scientists established identical trials in 2005 in an open field and in an adjacent high tunnel at the Southwest Michigan Research and Extension Center in Benton Harbor, Michigan. Each trial contained primocane-fruiting cultivars (Autumn Britten, Caroline, Chinook, Heritage) and floricane-fruiting cultivars (Canby, Encore, Heritage, Nova). Berry yields and average weights were measured from 2005 to 2007 (for primocane) and from 2006 to 2008 (for floricane). Floricane fruiting plots of 'Heritage' were pruned to produce fruit on floricanes and primocanes (double cropping).

Results confirmed that the most productive cultivars in both environments were the floricane-fruiting 'Nova' and 'Canby', and primocane-fruiting 'Caroline' and 'Heritage'. 'Caroline' and 'Heritage' produced the highest yields of primocane fruit in the field and tunnel. 'Heritage' plots that were pruned to the ground so that they produced only primocane fruit yielded similar amounts of fall berries as 'Heritage' pruned for double cropping. 'Nova', which fruits primarily on floricanes, produced a small amount of primocane fruit in the fall. 'Nova' and 'Canby' produced the highest yields of floricane fruit in the tunnel, and 'Nova' was the most productive in the field.

The study also contained convincing evidence that high tunnels can effectively suppress mold and disease in raspberry crops; the scientists reported that overall mold incidence was 1% in the tunnel and 13% in the field. Leaf spot, cane anthracnose, spur blight, and botrytis cane blight were common in the field but absent in tunnel.

"Although the tunnel and field environments were not replicated and plants were managed differently in each, tunnels generally tended to lengthen harvest periods and promote plant vigor, yield and fruit quality," Hanson said. Tunnels also reduced the incidence of fruit, foliar, and cane diseases, but did not consistently affect berry phytonutritional contents.


The complete study and abstract are available on the ASHS HortTechnology electronic journal web site:

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at


Original Article:

High Tunnel and Open Field Production of Floricane- and Primocane-fruiting Raspberry Cultivars
Eric Hanson, Mike Von Weihe, Annemiek C. Schilder, Ann M. Chanon, and Joseph C. Scheerens
HortTechnology 21:412–418. [Abstract][Full Text][PDF]

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