Warm temperatures offer perfect breeding conditions for pests. In some hot, humid climates, an entire greenhouse crop of vegetables or ornamentals can be completely destroyed and, unless controlled, nearby houses are at risk of impending infestation. With health concerns resulting in the reduction of the use of chemical insecticides and pesticides, screening is the most effective, economical strategy available. The experts at Gothic Arch Greenhouses know all about Integrative Pest Management practices like screening that, if correctly selected, installed and maintained, dramatically reduce and control infestations that result in crop damage.

Integrative Pest Management (IPM) is defined by EPA as "an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices." W. H."Buzz" Sierke Jr., third generation president of Gothic Arch Greenhouses Inc. explains, "IPM doesn't use just one approach; its a problem-specific, natural approach to prevention and control." Growers have different needs. Some need complete eradication of pests while others just want them controlled, according to Sierke. He says IPM practices encourage growers to consider all aspects of the situation and then guides them to ways that are the most economical and least possible hazard to people, property and the environment. Sierke cites pests like aphids, flower thrips, leaf miners and whiteflies, as the top nemesis of growers everywhere. "They enter the greenhouse with the wind through any opening they can find. Keeping the little critters from coming inside the structure to begin with is best since once they take hold it's hard to get rid of them," Sierke explains. While screening does not guarantee a complete pest-free greenhouse, it can and does make a tremendous difference. But using screen over greenhouse vent inlets can be tricky since screens also affect airflow inside the greenhouse. Some of these bugs are mighty small. Screens create resistance which reduces airflow; the bigger the screen openings, the more air. The smaller the hole size, the greater the resistance.

A naturally ventilated greenhouse can be screened; it just takes more material as every opening must be covered for optimum outcome. But, if the greenhouse relies on artificial ventilation, it becomes more complicated. Improper screening can result in inadequate air exchange which means cooling equipment may not be able to work properly. Restricted air flow causes higher static pressure drops and increased energy consumption by the fans. Not only does this mean higher energy costs, it can result in overheating of cooling equipment eventually leading to higher greenhouse temperatures. So it's important to make sure the right screen is used to address each specific pest problem.

Insect pests microns inches mesh
leafminers 640 0.025 40
whiteflies 462 0.018 52
aphids* 340 0.013 78
flower thrips 192 0.0075 132

The folks at Gothic Arch Greenhouses are experts in their field with nearly70 years of experience in providing the horticulture industry with affordable, quality greenhouses and supplies. They know that not all insects are the same size and not all screens have the same hole sizes. They know the latest IPM strategies and the formulas to use to determine which size screen will work best. And, they have the most efficient and economical solutions for greenhouse owners.

A visit to Gothic Arch Greenhouses website will lead growers through the myriad of screens available to address most every bug problem:
  • Stainless steel mesh is woven like window screen. Long lasting but most expensive.
  • Plastics (polyethylene) woven monofilament (fishing line). Solid, rigid and strong. Or, film punched full of micro holes. Budget priced but weak construction, low UV protection, very restricted airflow and must be applied correct side out.
  • Polyethylene/acrylic is "multi-filament," meaning it's made up of many different fibres.
  • Nylon – low cost, short-term, light-duty applications; it too, is air flow restrictive.
Sierke says it all boils down to what the horticulturist needs. "Some see specific pests during certain periods of the growing season. For that, lighter-duty, less expensive temporary screens will work. But for handling multiple pests at different points throughout the year, a heavier duty screen is recommended." He adds that heavier, more rigid screens can also provide protection against sun, wind, rain and heavier wear and tear more.

And colour can make a big difference, again, depending upon which pest is the problem. Though thrips are small enough to fit through most screens with good airflow, they can be dramatically reduced using white screens designed for whiteflies, according to Sierke. He says scientists theorize that because of the color, the white screens are effective because the thrips don't see the material as something to feed on so they go elsewhere. Sierke suggests Econet T Insect Screen for its air flow reduction, light transmission ability, hole size, standard width and proven ability.

For screening to be effective against pests, it must be attached properly, according to the experts at Gothic Arch Greenhouses. While covering intake vents will produce dramatic results, make sure all greenhouse openings, including service doors (which should incorporate double screened doors), should be screened for best results. The goal, of course, is to keep it taunt to ensure good coverage. You can use poly fasteners, spring locks or lath.

Maintenance is critical to successful screening, Sierke reminds growers. The small holes can clog with dirt and dust which reduces your air flow. You must keep these clean for efficient air movement and overall plant health. He suggests investing in a manometer for measuring static air pressure to help keep tabs on air flow. "Just clean the screens by using a moderate pressure spray from the inside out. It's best to wait until the end of the day when natural ventilation has usually slowed. And remember; be gentle, as too much pressure can alter the holes.

Given the increased problems and costs associated with pesticides, using Integrative Pest Management practices like screening as a bug barrier is a must for every greenhouse. Correctly selected, installed and maintained, insect screening will prevent insect penetration, yet provide maximum possible air flow, essential for optimal crop yields.

For more information
Gothic Arch Greenhouses
T: +1 800-531-4769