Rose Buitenhuis

Greenhouse Management: What should greenhouse IPM managers be on the lookout for during this time of year?

Rose Buitenhuis: It depends on what crops you’re growing. There are definitely some crop-specific challenges. Here in Canada, for some of the more tropical crops like mandevilla, we’re now really on the lookout for Thrips parvispinus. That’s the new invasive thrips that flies under the radar early in the fall, but then over the course of the winter, it seems to pop up when the weather warms up. This is a new species, and it’s difficult to get rid of. Because Thrips parvispinus is not exactly the same as other thrips species, we don’t know exactly what works best against it yet, but it’s already becoming resistant against several insecticides, so that’s one of the bigger problems in tropical ornamentals. Of course, other crops have other challenges, but that’s one example.

GM: What are some other problems growers can expect to face with other common plants?

RB: An ongoing challenge, I would say, is that bedding plants are going to start up soon, so making sure that the crop is started clean is always a nice challenge. You have to make sure to get on top of aphids before they get out of hand, especially in the colder weather. Of course, in the greenhouse, it’s not super cold, but a lot of biocontrol agents still have lower efficacy in the winter because they may slow down. So you have really have to be aware of that and choose the ones that are adapted to the conditions that you want them to perform in.

GM: What new developments are happening right now in the biological control space?

RB: Here in Canada, there are two new biological control agents that have hit the market. The first one is a predatory mite called Anystis sp. The company Applied Bio-nomics in Canada calls it Crazee Mite. And the other one is Nabis sp. There are still some regulatory hurdles to get those accepted in all of North America, but those were developed because here in North America, we were really missing some generalist predators that just eat everything and can give that baseline control together with the more specialized biocontrol agents. And this becomes really important in a preventative strategy because you want the biocontrol agents present before the pest comes in. But if a specialized predatory insect has nothing to eat, like if they only eat spider mites and the spider mites are not there, they die. So you have to release them every week as a preventative measure, at least generally, so they will survive in the fall and be there when the pests actually pop up.