by Marilyn Odneal, Horticulture Adviser
We have been working with our high tunnel at the State Fruit Experiment Station since 2011. A high tunnel, or hoop house, is a structure similar to a greenhouse, except that it is not actively heated or cooled – the side walls are opened and closed to cool and heat the tunnel as needed. This allows growers to moderate the climate and extend the season to earlier production in the spring and later production in the fall. Our tunnel in Mountain Grove presently has perennial crops that include raspberries and peonies. Annual crops so far this year include lettuce, cauliflower, broccoli, cabbage, onions, potatoes and beans.
We planted lettuce and cole crops on February 18 and 19. Even though the side walls were closed when the temperature was 45 degrees F or below, we covered the crops with 1.5 ounce row cover for extra protection when the temperature was predicted to drop down in the teens or 20s. These protective blankets are also used in high tunnel production of winter greens. Later, on March 14, we planted onions. On April 8 we harvested the first of the lettuce and planted potatoes. We will plant beans soon.
Benefits of using high tunnels in crop production include greater and higher yield, season extension, and disease reduction. One of the reasons that high tunnels decrease the incidence of several diseases is that rain does not wet the plants and promote fungal diseases. Of course, we need to irrigate all of the crops in the high tunnel since they are not exposed to rain.
The number one commercial crop in Missouri high tunnels is fresh market tomatoes – the earlier tunnel tomatoes command a higher price than field grown ones. Other crops grown in tunnels include cucumbers, greens and herbs. Fruit crops like strawberries and raspberries are also grown in tunnels.
Primocane bearing raspberries are a highly perishable perennial fruit that sets a crop on first year growth. In several research projects, high tunnel grown primocane raspberries have demonstrated increased marketable yield, higher quality fruit, an extended growing season, and longer shelf life when compared to field grown raspberries.
At the experiment station, we planted three varieties of raspberries both inside and outside the high tunnel. Primocane-bearing raspberries have done well in our high tunnel and outperformed those that we planted outside in the field for comparison. Josephine, with its bigger berry, was preferred over Heritage and Caroline in our demonstrational study based on data recorded 2011-13. We did not have any production problems until 2013 when the spotted wing drosophila arrived in our state for the first time. This pest necessitated weekly pesticide sprays be applied to the hedgerows. To help manage the pest, we are going to reduce the canopy of the raspberries by thinning the hedgerow to 1 foot wide, and then thinning the emerging primocanes to 3-5 per square foot.
Although the perennial raspberry crop does well in the high tunnel, the problem with is that they occupy that space year round so other annual crops cannot be rotated into it. Next week we will talk about a new project at the State Fruit Experiment Station that addresses this problem. Until then, enjoy spring!
Direct comments or questions concerning this column to Marilyn Odneal via email at MarilynOdneal@missouristate.edu; write to Missouri State Fruit Experiment Station, 9740 Red Spring Road, Mountain Grove, Mo. 65711; or call (417) 547-7500. Visit our website at http://mtngrv.missouristate.edu.