Failure to control aphids can make plants unmarketable

"The first problem is that they can become active in temperatures as low as 50°F," Bogash says. "On top of that, there are very few crops that they don't like."

Greenhouse vegetable crops such as tomatoes, peppers, and cucumbers can be targets for aphids, and because petunias are close relatives of tomatoes and peppers, they are also susceptible. Once they colonize, aphids will reproduce quickly, Bogash says. While viruses vectoring can be an issue, the main problem is that as aphids feed, they quickly deplete the plant's resources.

"The honeydew they leave on the plant then becomes a breeding ground for sooty mold, which makes the plants and fruit impossible to sell," Bogash says.

Building a Rotation Plan

While installing fine mesh screening and basic reminders to your team about keeping doors closed at all times can help keep aphids out of the greenhouse, true control of aphid populations comes down to a mix of conventional and biological tools.

Grandevo and Venerate are two products from Marrone Bio Innovations that should be part of a rotation program. While they can help with managing other pests as well, such as Western flower thrips and spider mites, Bogash says they are suppressive in nature and shouldn't be used as stand-alone options for aphid control, as aphids can be tough to manage.

The program Bogash recommends starts with a tank-mix of either Grandevo or Venerate and a pyrethroid to knock out early populations, followed by rotating between these two products and an azadiractin or insecticidal soap-type of material.

"The idea is that you are walloping them with so many different modes of action that all have efficacy for control that it's very difficult for the aphids to develop resistance," Bogash says. "You're not hitting them with the same material every time, and you can also incorporate a biocontrol agent to further manage resistance."

Continue reading.

Photo created by aleksandarlittlewolf - www.freepik.com

Source: Greenhouse Grower