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High Tunnels on the March

Posted: February 22, 2012

The crowds were very large at the 2012 Mid-Atlantic Fruit and Vegetable Conference with certain sessions very popular. Over the years, high tunnel talks and sessions have become a 'destination of choice' as growers utilize the technology to extend the growing season.
The roll-up sides of a high tunnel allow a grower to modify the interior temperatures by raising and lowering the plastic.

The roll-up sides of a high tunnel allow a grower to modify the interior temperatures by raising and lowering the plastic.

One can get an idea of trends within the horticulture world by looking at the Mid Atlantic Fruit (MAFVC) and Vegetable Conference program agenda of years past.  One area of increasing interest over the years is high tunnels.  High tunnels encompass a crop growing system that fits somewhere between row covers and greenhouses.  They do not offer the precision of conventional greenhouses for environmental control, but they do sufficiently modify the environment to enhance crop growth, yield, and quality.

Local grower and regular MAFVC attendee, Bryan Poorman of Poorman's Island Market, believes it is the way of the future.  “We planted tomatoes in April and had our last harvest Thanksgiving week”, says Poorman, “and I wouldn’t trade it for anything”.   His operation was able to harvest over 5500 pounds with this season extender and hopes to add an additional two with a goal of six structures to supply his roadside stand.

Six years ago, there were five talks throughout the three-day event that covered aspects of high tunnels.  One year later in 2007, only four presentations covered these structures.  Fast forward to this year’s MAFVC and high tunnel information was all over the place. 

There were two high tunnel sessions where presentations were made throughout the day covering a wide range of topics including marketing, issues with tunnel frames, vegetable trials, bramble production, capturing rainfall off a high tunnel, the high tunnel project occurring in inner city Philadelphia diseases, and bio-control measures. 

Even in other sessions, high tunnel topics were covered throughout the conference.  There was high tunnel pepper nutrient management in the Pepper session, high tunnel beets and carrots in the Root Crops session, and growing cut perennials in high tunnels in the Cut Flower session.  In fact, there was just not enough room to delve into high tunnel topics during the day that a special session was held one evening on bio-control issues in high tunnels.

All told, participants had fifteen different talks they could attend to gain information about various aspects of high tunnels. 

I did not have the chance to attend all these high tunnel sessions but was able to attend the use of bio-controls in high tunnels.  This topic intrigues me the most as growers are using predators and parasites to control insect problems instead of pesticides.

Carol Glenister of IPM Laboratories spoke to the audience on the variety of ‘good’ insects that can be utilized to take care of the ‘bad’ insects in high tunnels.  She was able to show research data that showed the effectiveness of this pest management method and a viable alternative to chemicals. 

Glenister showed several pictures of destruction these ’good’ insects leave behind.  One of the examples was the small parasitic wasp, Aphidius colemani.  This wasp does a great job of controlling certain species of aphids in vegetable crops.  The female will lay an egg inside an aphid which will hatch in several days.  When the egg hatches, the larvae will start feeding upon the aphid, eventually killing it.  The wasp larvae will pupate and swells the aphid's body and the adult wasp then exits the aphid body, leaving behind a hard brown shell called an aphid mummy.

High tunnels are not a fad and I expect many presentations in future Mid-Atlantic Fruit and Vegetable Conferences.