The goal of integrated pest management (IPM) is the prevention and control of pests, and to lessen the use of plant protection products to ecologically healthy levels.

That was the definition of IPM given by Erich N. Schoeller, Ph.D., Department of Entomology, University of Georgia, during his presentation “Enhancing Biological Control with Banker Plants and Supplemental Foods” at the most recent Great Lakes Expo.

There are some IPM challenges in the controlled environment agriculture growing of ornamentals, however, beginning with aesthetics. Schoeller noted that floriculture and nursery products are primarily grown for their aesthetic value.

Those growing in greenhouses and nursery spaces are often dealing with diverse crops and cultivars too, so control measures may not work equally on all plants.

Many plants mean many potential pests too. Some pesticides are not compatible with certain crops and a pest’s natural enemies.

On top of all that, a lot of these are semi-closed systems, which makes it difficult for natural enemies to migrate in when their food sources are scarce. Still, biological control is an option to consider.

“Biological control is control, not eradication,” Schoeller emphasized. “The ultimate goal is to reduce pest populations to below economically important levels without pesticides. This is not achieved very often.”

He explained there are three types of biological control: Classical (the introduction of nonnative species); conservation (supporting existing native or nonnative agent populations with resources); and augmentative (inoculative or inundative).

Whichever option (or combination of options) is used, the biocontrol agents need a food source. That’s where banker plants come into play.

Banker plants directly or indirectly provide resources, such as food, prey or hosts, to natural enemies deliberately released into cropping systems. They support natural enemy populations by supplying alternative food – often non-pest hosts – providing protection, promoting reproduction and offering a persistent habitat.

“They offer something your cash-making plants don’t to lure pests,” Schoeller said.

As an example, he talked about whiteflies, which excrete honeydew, which leads to mold. Most often seen are the sweet potato whitefly and the greenhouse whitefly. These pests have natural enemies like parasitoids and Delphastus beetles and predatory “bugs,” like Orius insidiosus (minute pirate bug) and Dicyphus hesperus.

But these predatory bugs can struggle without supplemental resources (like flowers and pollen in the case of Orius or mullein sap for Dicyphus). The best results are often achieved when they’re used in conjunction with other biological control agents such as parasitoids/mites. Schoeller recommended releasing these particular biocontrols every other week.

To boost these biocontrol agents, certain banker plants work really well. Ornamental peppers offer prolific flower and pollen production; grow leaves with domatia (tiny chambers that house arthropods) that protect adults and promote egg production; are attractive in the landscape; are readily available and easy to grow; and have many varieties available. Schoeller said they’re working really well as banker plants.

In another example, aphids of many varieties (including potato, green peach, melon and foxglove) were discussed. The first line of biocontrol defense for these pests is often parasitoids.

There are 17 species of Aphidius parasitoid wasps to handle aphids, as well as the bird cherry-oat aphid. One of the good guys, this aphid only eats cherry trees and oats or wheat – it won’t eat your ornamental crops. Grow a tiny patch of oats as banker plants in your CEA system to reap their benefits.

Banker plants are critical for biocontrol because they offer supplemental food sources to enhance predator populations. “The problem is that large predators sometimes eliminate prey populations then starve,” Schoeller said. “Then pest populations reemerge after predators disappear, which means more labor and material costs. You need to keep predators around during periods of low prey densities.”

In addition to the banker plants themselves, growers can offer biocontrol agents food sources. Schoeller listed cattail pollen as an option – and you can make your own – but cautioned users to not actively feed their pests while doing so. Brine shrimp cysts (aka sea monkey eggs) are another option, and they are inexpensive and have a long shelf life.