Starting clean and controlling pests preventively are two keys to biological pest control in greenhouses, according to a speaker at the 2025 Oregon Association of Nurseries' Farwest Show, Aug. 20 in Portland. Karen Stever, a technical specialist with Griffin Greenhouse Supplies, also said the growers should know which pests are most likely to be a problem in a production cycle, scout regularly, consider layering biological control agents and be prepared to spray if necessary.
"Biocontrol requires making regular releases," she said. "It's a preventative program, it's not a reactive program. And it's extremely important that you scout the plants. That doesn't mean just doing a crop walk. It means turning the plants upside down, looking under the leaves, checking the stems.
"And while you're there, look at the roots, look for any leaf spots, look for anything going on with that plant," she said. "This is your opportunity to catch it and deal with it. Dealing with the problem early is a requirement for a successful program."
Stever, a Ph.D., said that it is important for growers to set realistic expectations when developing biological pest control programs for greenhouse production. "Set your expectations about what the biological control program can do for you," Stever said. "It is never 100 percent eradication."
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