Why Biocontrol Agents May Fail in Your Vegetable Greenhouse
March 28, 2023 
Photo: Tom Ford, Penn State University
High tunnel and greenhouse-based production systems present different challenges for growers, but they both can be a source of great frustration when pest issues emerge. Most new entrants into vegetable production in protected culture systems are experienced vegetable producers that are experts when it comes to managing pests in the field. When these growers move vegetable production indoors, they realize almost immediately that their field-based approaches to pest management will not work well in the confines of a high tunnel or greenhouse. Once this realization takes place, some field-based growers will try to unsuccessfully meld their field-based pest management techniques with bio-based control practices with often disastrous results.
In a recent eGRO blog post, Penn State University Commercial Horticulture Educator Tom Ford recalls a discussion with a new greenhouse vegetable grower who released and quickly killed hundreds of dollars of biocontrol agents.
“He worked with a reputable biocontrol agent supplier and released the appropriate biocontrol agents for managing an assortment of pests (aphids, whiteflies, two-spotted spider mites, etc.),” Ford says. “But this grower never disclosed to the biocontrol agent supplier that he had applied an assortment of pesticides in the greenhouse (some of them off-label) to the tomato crop prior to the release of the biocontrols. When the biocontrol agents died, he quickly dialed the supplier and filed a complaint about the quality and efficacy of the biocontrol agents that he had purchased even though it was his pesticide usage that was clearly responsible. This grower did not realize that pesticide residues can persist for a very long time in the greenhouse environment and that their past usage may jeopardize the health and vigor of even the most robust biocontrol agent.”
When selecting pesticides for use with biocontrol agents, Ford says you must cross-reference every active ingredient in the pesticides that you wish to deploy with their potential side effects to the bicontrol agents that you wish to release.
“Pesticides that have no adverse side effects should be the primary materials in your chemical arsenal if you are going to deploy biocontrol agents in your greenhouse or high tunnel,” Ford says. “Biorational insecticides like horticultural oil and insecticidal soap are two broad-spectrum insecticides that can be used safely prior to the release of most bicontrol agents in the greenhouse and high tunnel.”
For additional information on utilizing biocontrol agents in protected culture systems with vegetable crops, click here to read the original blog post.
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