Greenhouse Management: What are ornamental growers dealing with right now from a pest perspective?
Suzanne Wainwright-Evans: Broad mites are still a huge issue in a handfull of crops like new guinea impatiens. They've been pretty bad for several years. This fall, lewis mites were pretty bad on poinsettias and were easy to miss when the populations were low. That was a real issue. On the horizon, we're very concerned about Thrips parvispinus because it’s popping up in more places in North America and I don't think it's getting the [attention] it deserves. It is being called the tropical tobacco thrips but it’s a pest on many ornamental crops. It can be challening because the damage can resemble broad mite feeding. The economic threshold is very low. It was found in Florida a few years ago and now can be found in the NE US and Canada. It is a tropical thrips species and seems to be moving on tropicals like Schefflera arboricola and mandevilla.
GM: How can people combat parvispinus and what does the damage look like?
SWE: Again, the damage can look like broad mite damage, which I think leads to mistaken identities leading to wrong control measures. This is why having a qualified person who can correctly identify your problems is very important. Being it's so new that there isn't an easy answer yet for management. They are doing research in Canada at OMAFRA trying to figure out how to manage it. Any of the work I know [about parvispinus] is coming out of Canada.
GM: What can growers do to better deal with broad mites and other pest issues?
SWE: With broad mites, it's often coming in on offshore cuttings. It goes back to the same conversation we've been having for many years. We know that if it comes in on cutting, it's affecting the rest of your greenhouse. ... There's some in the industry trying to focus on dipping, but the pushback I get is that they don't have time or they don't want to deal with the REIs. Another issue is lack of labeled products. But dipping is about the best way to stop the pests from coming in. Canada has done the research on how effective dipping cuttings can be. ... I think people only look at the economics of that day and don't look at the annual economics. Spending money up front of dipping can save you money in the long run. Same goes for the economics of biocontrol. People say biocontrol is too expensive, but it's because they are comparing the cost of a pesticide application to a shipment of beneficials without taking into consideration you might need to spray every three days versus applying beneficials every few weeks. Also with beneficials you do not have to stop work for application and there are no REI’s.
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