Eldon Everhart, Field Specialist-Horticulture, Southwest Area
Tomatoes are the second most valuable vegetable crops in the US. Most tomatoes growers in Iowa sell tomatoes on a seasonal basis. Buyers often want a year-around supply. Tomatoes started from seed in greenhouses can be grown in fields, greenhouses, and high tunnels.
A grant from the Iowa West Foundation funded two high tunnels, a greenhouse with an attached headhouse, equipment, supplies, and workshops at the ISU Armstrong Research & Demonstration Farm. The high tunnels are manufactured by FarmTek, Dyersville, Iowa. The Clearspan tunnels are 12 feet tall, 30 feet wide, 96 feet long. The tunnels were erected at the ISU Armstrong Farm and at the ISU Horticulture Research Farm. The same replicated research was conducted at both locations. The objective of the fresh market tomatoes research was to maintain a steady supply by evaluating variety selection, sequence of planting dates, and use of high tunnels, row covers, and polyethylene mulches. The cultural system consisted of olive wavelength Selective Reflective Mulch (SRM) and trickle irrigation. Transplants were set 18-inches in-row and rows 4.5 ft on center for the high tunnels and 6-foot on center for field production. Plants were staked, tied, and pruned to the first flower cluster. Tensiometers were used to schedule irrigation. Pest management for field production included herbicide, insecticide, and fungicide applications. In the high tunnels, no herbicide or fungicide was need and only two insecticide applications were made. Ten tomato varieties were evaluated. Yield data was collected weekly with fruit sorted into marketable and culls. The high tunnel effect on daily maximum and minimum temperatures was measured.
The best performing varieties at both sites were Mtn Spring, Mtn Fresh Plus, Fla91, and FL47R. Data showed that the advantage of the high tunnels early in the growing season was in raising the daily temperature to hasten growth and development. Marketable fruit and yields were higher in high tunnels than in the field plantings. Yield of marketable fruit in the high tunnels was at least 46% greater than in the field. A detailed report is included in the 2006 Annual Progress Reports of the ISU Research and Demonstration Farms. The report will also be available on the Internet at: www.ag.iastate.edu/farms/.
February 19, 2007
130 Horticulture: Commercial and Consumer
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February 23, 2007
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