Horticultural and entomological basics of high tunnel vegetable production

Sarah L Thompson, Purdue University

Abstract

High tunnels are a form of protected agriculture that aids in season extension by creating a favorable microclimate using trapped solar heat. Tunnel structure is similar to a simple greenhouse, usually comprised of stretched plastic over a large ribbed frame. High tunnels are used extensively around the world for the production of high value crops. In 2010, the USDA-NRCS initiated a high tunnel funding program that aided in the erection of 4,500 new high tunnels across the U.S. in 2010 and 2011. As high tunnel use continues to rise, basic research is needed in this production system to investigate its effectiveness and begin developing specialized IPM solutions to pest-related problems. This study involved production of three crops: tomato, broccoli, and cucumber in three high tunnels as well as three comparison field plots over the 2010 and 2011 growing seasons. Season extension, yield, and fruit quality (size and marketability) were compared among traditional field plots and three different production systems within the tunnels: traditional black plastic mulch, containerized soilless production, and rockwool; however, the rockwool system was quickly abandoned after several failed attempts to maintain plant quality. Season extension was the most dramatic for tomatoes—fruit was harvested in the high tunnels more than two months before the field. Tomato size was also larger in the tunnels and there was a greater percentage of marketable fruit compared to the field. Conversely yield was not significantly different between production systems in the tunnel and the field for tomatoes. There was no significant difference in the broccoli or cucumber size between the high tunnel and the field; however, high tunnel yield was significantly greater for cucumbers and broccoli. There was no significant difference in the cucumber marketability, but broccoli marketability was significantly higher in the field. The containerized soilless production within the tunnel showed no significant advantages--decreased yields, smaller fruit, and lower fruit marketability. Pest density was also compared between the high tunnel and the field. Greenhouse pests were more prevalent in the high tunnels throughout the season. Common field pests such as hornworms and cucumber beetles were not significantly different between the high tunnel and the field; however the crucifer caterpillar complex including imported cabbageworms, diamond back moths, and cabbage loopers was significantly denser within the high tunnels. Multiple insecticide treatments were made in the high tunnels for various pests throughout the season. These results show that pest density is not significantly different in high tunnels compared to the field—implementing integrated pest management techniques is necessary in high tunnels just as it is in the field; however components may need optimized for this specialized form of production. Further research should aid in developing IPM decision making protocols for high tunnel producers.

Degree

M.S.

Advisors

Weller, Purdue University.

Subject Area

Entomology|Horticulture|Agriculture

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