3 min read
High Tunnel
This report is an update regarding the high tunnel pest exclusion (HTPE) system. This research was started in 2014 with USDA SARE program funds. The HTPE system uses woven black shade-cloth of various grades installed under the sidewalls and at end-walls as permanent pest exclusion system aimed at reducing several large moths and leaffooted bugs. Currently, we have seven on-farm HTPE demonstration locations that utilize a 40 or a 50 percent woven shade cloth from Poly-Tex (MN) or FarmTek (IA). Rapid laboratory-based behavior studies using high tunnel models enabled the quick transfer of information and sharing of interest with producers across Alabama. 2016 and 2017 have been notable years to compare the effectiveness of the HTPE system, especially considering the fact that 2016 was a drought year and 2017 was the exact opposite! Below is a summary of HTPE system based on experience from on-farm studies.

Overall benefits of HTPE based on multi-year study

There are remarkable differences between pest exclusion potential of a 40 or 50 percent fabric between a drought year (2016) and cool wet year (2017); refer to the data below. Overall, we had great success stopping cabbage and soybean loopers (range 40 to 97 percent) with no outbreaks in the field studies. Armyworms, major pests in open field crop in drought years, were reduced 43 to 70 percent. There have been no tomato hornworm issues inside the tunnels since the moths are very big and cannot go past the fabric. This system makes tomato production very profitable inside a netted tunnel.

Producers interested in growing squash and other cucurbits inside the tunnel will be delighted to know that squash vine borers can be reduced 80 to 90 percent inside a netted high tunnel. A 40 percent shade cloth allowed honey bees to pollinate the crop. For higher grades of shade cloth, producers may use a bumblebee box inside the high tunnel to pollinate cucurbit crops.

Shade cloth must be tightly installed and clamped on the sides to prevent insects from sneaking in. Many insects like leaffooted bugs and armyworms appear to be very good at exploiting any weakness in the fabric. We have seen them lay eggs on the fabric and small caterpillars migrating to crops by crawling in. If you see egg masses then remove them immediately!

There is a tremendous improvement in crop quality as a result of reduced caterpillar and sucking insect pest numbers by using a 40 or 50 percent shade cloth around the side and end walls. In a drought year, when insect outbreaks may occur early and pest pressures may be high (as seen in 2016), it is a good idea to use 50 percent woven shade cloth with wide openings to maximize pest exclusion. In a cool wet year, when the pest lifecycles are delayed and pest pressures are moderate, a 40 percent shade cloth may be sufficient to stop large moths and leaffooted bugs.

Since aphids and whiteflies remain a problem in netted tunnels (they are too small to stop), producers can use other light insect exclusion materials like Super Light Insect Barrier or AgroFabric Pro19 to prevent colonization.

We have only evaluated black shade cloths in present studies, since it is very commonly used for shading materials and readily available from many vendors. We have been purchasing custom-cut and finished woven fabric at 26 to 50 cent per square foot cost from Poly-Tex, MN. Producers can check with their local vendors for material availability.

We are working with additional producers statewide for IPM training and on-farm research, so stay connected with ACES for future updates regarding HTPE. We have recently added new IPM research and demonstration locations across Alabama in order to provide peer-to-peer learning opportunity for beginning farmers. If you want more information immediately, then contact the authors or checkout the HTPE webpage on Alabama Vegetable IPM. Producers can also refer to two HTPE bulletins on Southern SARE where preliminary research data was reported along with basic information on IPM tactics.

Did you find this helpful?