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Greenhouse Updates: Mar 25, 2020

Spring Brings Insect Pests
March 25, 2020

This week in the greenhouse brings upon us the start of aphid season. Green peach aphids (Myzus persicae) were detected on calibrachoa, fuchsia, and pansy. If you are using biocontrol agents (BCAs) for aphid management, deployment should have begun by this point in the season.

BCAs such as Aphidius colemani and A. matricariae tend to favor the smaller aphid species as prey so they are generally preferable for control of green peach aphid. For spring production, take note that A. matricariae are better adapted to lower temperatures than A. colemani. A. matricariae has the best population development between at 67-77 °F, but is less effective above 82 °F. A. colemani develops best between 65-72 °F, and is less effective above 86 °F.

Thrips were controlled in hotspots with Pylon (chlorfenapyr), which continues to be one of the go-to products for thrips management. Note that Pylon can be detrimental to some biocontrol agents, including Neoseiulus cucumeris and N. californicus. If you are using biocontrol organisms, consult the side-effects manual on your biocontrol supplier’s website before applying any pesticides.

Fungus gnat and shorefly levels remain low. An estimated 1/3 of growers are using beneficial nematodes (Steinernema feltiae) to manage these insects.

Scout greenhouses regularly for insect pests. Where aphids, thrips, or whiteflies are known to be active, be on the alert for symptoms typical of insect-vectored viruses such as leaf mottle, puckering, and stunting.


- Angela Madeiras and Geoffrey Njue, UMass Extension, with Jim Mussoni, Private IPM Scout