Evaluation of Alternative Coverings for Year Long Utilization of Caterpillar Tunnels

Problem

Summer is the most productive and profitable time for any vegetable farm. Traditionally, caterpillar tunnels are covered in plastic and used primarily for season extension. I have seen others cover the tunnels with spun bound floating row cover for insect exclusion and have found enormous value in this method myself. The problem with using this fabric during a Missouri summer is that the cover builds up a lot of heat even on cloudy days and nearly eliminates air flow. Because insect exclusion is the primary goal, venting is not an option. This limits harvest or any other work that must be done inside to the very early morning. The combination of high temperatures, lack of air flow, and high humidity make it unsafe to spend any extended amount of time in them after 9:00 or 10:00 am during the summer. In addition, I have found the covers tear easily, and rips allow insects to enter and proliferate.

Year-round use of these tunnels can offer many benefits beyond season extension including decreasing soil erosion, providing windbreaks, preventing sunscald on fruits, decreasing irrigation needs, and reduction of pesticide application through pest exclusion. Even though they may not fully eliminate the use of pesticides, having the means to drastically reduce their need is important for the health and safety of farmers and farm workers and the general public as well. If caterpillar tunnels can be made more useful during the summer, the initial investment can be amortized over many more months of use and could contribute to higher productivity.

Solution

The solution to this problem would be to use a different cover. There are many types of shade cloth that could increase the usefulness of a caterpillar tunnel by decreasing internal tunnel temperatures, excluding pests, and increasing yields. Shade cloth is a woven material that is applied to greenhouses or hung over plants to decrease temperatures or lessen the amount of sunlight they are exposed to. It is graded by the percentage of light it blocks.

Four types of shade cloth with varying characteristics and costs will be compared in this project including black, white, reflective and red. Black shade cloth is the least expensive of these alternatives, however, the light- adsorbing nature of the dark colored cloth may not result in an improvement in the temperature inside the tunnel. White shade cloth is more expensive than the black cloth, however, it may be more efficient at cooling the tunnel for worker comfort and increased yields. Similar in construction to both the white and black cloths, but significantly more expensive, is reflective shade cloth. It is hoped the reflective cloth will be even more efficient at cooling the tunnel and further increasing yields. The most expensive option is the red shade cloth. The manufacturer claims it increases yields by managing the light spectrum, but I have been unable to find any research to prove this claim. If it performs as advertised the increase in yields could pay for the cover or even the entire structure over time; it is unknown how temperatures may be affected within the tunnel.