Technical Information Bulletin

SUBJECT: Pest Control with Insect Screening

Interest in pest exclusion screening is growing rapidly in the commercial greenhouse industry. This interest stems from increasing government regulations on insecticide use, decreasing effectiveness and availability of certain pesticides, worker safety concerns and public scrutiny. Insect screening offers a clean and practical alternative to traditional chemical control programs.

When developing a screening project, consider the following key points:

1. Select a material with the appropriate mesh.
   Make a list of the crops to be grown in the greenhouse and the pests of each crop. The screen chosen must have holes small enough to exclude the smallest pest on your list (see Table 1). Research published by Jim Bethke of the University of California, Riverside, explains an interaction between the hole size and the barrier composition. A 0.018” hole size will exclude most insects. It has been determined that a fabric hole size of 0.0075” or smaller is required to effectively exclude Western Flower Thrips since thrips are much smaller than other insects. Other factors influencing the final selection of material will be fabric type, fabric longevity and cost (see Table 2).

Screen Sources
Duragreen, 436 E. Fifth Ave., Mount Dora, FL 32757, (904) 383-8811, fax (904) 735-2688.
Green-Tek Inc., 407 N. Main St., Edgerton, WI 53534; (608) 884-9454; fax (608) 884-9459.
LS Americas, 1813-E Associates Lane, Charlotte, NC 28219; (704) 357-0457; fax (704) 357-0460.
Lumite, P.O. Box 977, Gainesville, GA 30503; (404) 449-4960; fax (404) 449-0054.
Naz-Dar Co., 1087 N. Branch St., Chicago, IL 60622; (312) 943-8338; fax (312) 943-8215.

2. Design for adequate air flow:
It is important to consider air movement before installing the material. Tacking screen material over the existing greenhouse may exclude insects but may also create an unfavorable growing environment. Air temperature and humidity escalate due to restricted airflow when facilities are screened. Modifications will most likely be required to increase the surface area to improve airflow. Consult an agricultural engineer for assistance in designing an effective system that meets the specifications of the given structure.

3. Build a double door entryway:
To ensure the continued exclusion of insects, the method of entry must be addressed. Insects targeted for exclusion may enter the screened environment when outside greenhouse doors are opened. Once the screening is in place, a simple but sizable entry area is best for maintaining easy labor and equipment access to the greenhouse.

4. Add positive airflow:
Once the double-door entry system is installed, add positive airflow to further discourage insects from entering the greenhouse. One simple design places louvers on the greenhouse side of the entryway. When the exterior door to the entryway is open, an exhaust fan is triggered to blow greenhouse air out against this door. Outside insects are unable to fly against the air stream, thereby excluding entry.

5. Start with clean plant material:
Ensure that the newly screened greenhouse is clean from the start. Before bringing new plants into the greenhouse, remove weeds and plant debris and apply an insecticidal smoke to rid the structure of insects.

Carefully examine plant material before introducing it into the greenhouse. If insects are present, rogue infested plants, dip them in an insecticide, or simply remove infested leaves.

6. Establish routine scouting:
Insect management requires constant vigilance and attention to details. Monitor the crop regularly for insects by examining leaves and yellow sticky cards. Quickly treat any infested areas with an insecticide to prevent the problem from spreading.

Insect screening can be a dramatically effective tool in your integrated pest management program. While zero tolerance is difficult to achieve, we can create a safe, healthy environment for ourselves and our crop through aggressive, proactive approaches.

DOUBLE ENTRY AIR LOCK A large fan is activated each time the outer greenhouse doors are opened. Air flows from the greenhouse to the outside through the entryway area causing positive air pressure. The air stream blowing from the entryway area prevents the insects from entering the greenhouse.

©1999 Paul Ecke Ranch All Rights Reserved	.
We hope the information provided will be helpful. It is based upon data and knowledge ( including information provided by the recipient) considered to be true and accurate, but without independent investigation and is offered for the recipient's consideration, investigation and verification, but we do not warrant the results to be obtained. Please read all statement, recommendations, or suggestions in conjunction with any conditions of sale or use which apply to any products, or systems recommended by us. No statement, recommendation, or suggestion is intended for any use which would infringe any patent/copyright.