Greenhouse Water Barrier

Final Report for FW04-302

Project Type: Professional + Producer
Funds awarded in 2004: $10,871.00
Projected End Date: 12/31/2006
Region: Western
State: Guam
Principal Investigator:
Pete Terlane
Guam Department of Agriculture
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Project Information


The purpose of this project was to determine if using a “greenhouse water barrier” on Guam would allow the continued growing of crops sensitive to excess moisture and rain during the rainy season or periods of extreme rains. From this project it has been determined that crops can flourish and the growing period can be extended using this farming method new to Guam. Crops that were grown in these types of greenhouses reached maturity quicker and produced fruits and vegetables of a better grade than those grown in an open area. However, because of the unforeseen and uncommonly frequent tropical storms and typhoons, many of the initial crop trials have been destroyed.

The framework for the greenhouses did survive the storms, and two of the bigger producers in the test project are now able to bring crops to market. Rick Guerrero, one of the two farmers able to secure greenhouse tarps from the Department of Agriculture, is now the lone supplier of cherry tomatoes in the Guam market. Ernie Wusstig’s Island View Farms, the second to secure tarps, will soon be supplying the market with tomatoes.

The immediate benefits are the ability to go to market with these crops when no other producers are competing, improving market prices as much as 200-300% during the rainy months.

The primary objective was to allow Guam farmers a way to market and grow crops sensitive to heavy rain and moisture during the rainy season using the “greenhouse water barrier.” The rainy period typically runs July through December.

The four participants in the trial were all willing to try to adopt the method using metal materials that hardware stores and other vendors had on hand. One chose to purchase commercially available piping from a canopy supply warehouse, which made for easy setup as the pieces simply had to be joined with prefabricated fasteners. The other three chose to build greenhouses from industrial metals, like rebar and steel piping, constructing them on the site of use. The method was time-consuming and labor-intensive as the participants wanted to make them sufficiently strong to withstand storms and typhoons. While the storms tore the tarps from the frames, the framing remained largely unaffected. The four plastic covers supplied by the Department of Agriculture for each greenhouse were 20 feet by 100 feet.

The trial crops were planted on the ground, as opposed to containers or beds, and the crops grew 7 to 12 inches longer than plantings of similar ages and varieties in open fields. However, the crops were lost when the storms ripped off the tarps, and no further data were collected.

Rick Guerrero and Ernie Wusstig, the only two farmers able to obtain tarps from the Department of Agriculture, decided to delay planting until the storm cycle passed to avoid losing the remaining tarps. Guerrero had started production of cherry and plum tomatoes in August 2005, and Wusstig planted in September.

The results of the two farms show that had the trials been allowed to reach maturity during the first phase of the rainy season in 2004 and early 2005, both farmers would have realized market success, based on current harvests, including higher prices that could be demanded because there was no competition from other farmers.

The most immediate and noticeable impact on farmers is that they are now able to supply produce to the market during the months of heavy rainfall, typically starting in July and ending in December or January. This has opened up another avenue for Guam farmers to be more economically self-sufficient. Tomatoes grown during the dry season from January to June sell at 50 cents a pound compared with $2-3 a pound during the rainy months.

Added benefits of this type of system are reduced pest populations and easier handling of existing populations compared with crops grown in an open environment. This saved farmers pesticide costs because of fewer pests and fewer applications. Wusstig reported savings of $100 in pesticide use and about $500 in labor costs for applications, weeding and fertilization. Guerrero reported identical savings in pesticide costs and about $200 savings in labor. Finally, wind damage was reduced because the crops had less exposure to the wind, which also resulted in higher production of flowers and fruits.

With the success of the two farms and a separate trial by the Department of Agriculture, several farmers were able to visit the greenhouses to learn how they could adopt the practice on their own farms. Jun Aguilar has ordered tarps from the Department of Agriculture and a supplier in Asia to convert his operations to greenhouse production from open fields. He was planning to plant peppers, cabbages and melons in the greenhouses. Brian Leon Guerrero, one of Guam’s largest producers of cucumbers and watermelons, had expressed interest in trying the practice and needed to figure out how to apply it on a large-scale operation like his.

The most common comment has been how easy it would be to adopt this on any farm on Guam and the benefits of growing in a semi-enclosed structure. When selecting farmers for the trial, both Wusstig and the Department of Agriculture wanted to be certain the methods could be easily adopted by farmers with both large and small incomes, requiring only minor investments. Some growers expressed in trying the method with herb production.

The construction of the greenhouses must be sufficiently strong to withstand minor storms. The tarps should be designed to allow for easy removal and storage when heavy storms are imminent. This was a problem in the trial because all of the tarps were permanently affixed in a way that precluded easy dismantling and storage. It would be interesting to see a project that attempts to obtain maximum production or capacity of crops grown under greenhouse cover. What is commercially viable without jeopardizing production?

Because all of the trials of participating farmers had been destroyed by the storms, none were able to demonstrate their use in late 2004 or early 2005. However, the Department of Agriculture set up a system in May 2005, demonstrating it for 65 people attending the “organic farm” opening. However, not until September 2005, in the middle of Guam’s rainy season, could the system be fully demonstrated. Guerrero was able to set up a tour with participants in the Cooperative Development Training Workshop on Guam Sept. 12-16. Fifteen participants from Guam, Saipan, Rota, Tinian and the islands of Micronesia toured the project and all said they were eager to try the system on farms on their own islands.

Also, in cooperation with the Guam Department of Agriculture, a flier was produced to notify people about the greenhouse trials and the potential for the greenhouses’ use on Guam.


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  • Ernie Wusstig


Participation Summary

Research Outcomes

No research outcomes
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.