Still Raising a Stink Over the BMSB
At a recent cut flower field day in Maryland, we asked growers if they had any problems with weeds and insects this season. One grower wryly commented that he did not have a problem—weeds and insects were both flourishing in his operation this year. We know that 33 states were in major drought conditions this season. Many plants shriveled up and died this summer, solving many weed and insect problems. This obviously is a rather surgically blunt method of taking out these pests.
Cut flower growers are eternally optimistic and will be back next year trying it again. Unfortunately, so will the bugs and weeds. I write this not to depress you but to make sure you are well prepared and equipped when they show up at their dinner table (a metaphor for your cut flower plots). Not being a weed guy I will talk about the bugs instead.
In past articles I wrote about the brown marmorated stink bug. This pest is still busy spreading across America and into Canada and establishing itself very nicely. Here in one of the six epicenter states (Maryland and 5 adjacent states) we are getting lots of experience with this pest and now understanding a lot about its life cycle and plant preferences.
The BMSB overwinter outdoors under the bark of dead trees. They do not like fallen trees since the moisture level is too high. Dead standing trees appears to be an ideal overwintering site. So, if you have dead standing trees near your susceptible plants, drop them to the forest floor to cut down on overwintering sites.
The really great thing is that local parasitoids are starting to adapt to this invasive bug from China and trying it out as a food source. This year we were seeing 20-25% parasitism of BMSB egg masses from native wasp species. This is great news and reason for optimism.
I have spent time this late summer wandering about commercial cut flower growers’ fields looking for BMSB on cut flowers. The good news is BMSB appear somewhat selective and prefer to feed on just a couple major cut flower species. David Dowling of Farmhouse Flowers and Plants (and past President of the ASCFG) helped me focus on one particular plant—amaranth. He reported BMSB were all over the flowers. I observed nymphs and adult in mid-August and a large part of the population was on the flowers, on which they were feeding. I found nymphs and adults feeding on the foliage. The extent of damage was really not detectable. Amaranth appears to be a good trap plant for this pest and you might consider growing it just so you will know when they are active in your local area.
I also found nymphs and adults feeding on the ray petals of cut sunflowers. The damage appeared as spots on the petals. The population was not nearly as high as what was found on the amaranth but the damage is more evident on sunflower.
Dahlias are also a host. Nymphs and adults were feeding on the flower heads and some were found on the foliage but none seemed to be actually feeding on the leaves.
Presently I am working with OESCO Company on the efficacy of a woven insect barrier. We installed it on the side and end walls of high tunnels and are observing whether it can exclude this pest from susceptible plant species. It is looking very promising to date.
We will continue to do our research and share the results with you as our knowledge base grows. Meanwhile, keep your chin up: this crazy season will pass and it will be brighter in 2013.
Stanton Gill is an extension specialist (professor-ranked principal agent) in IPM and entomology with the University of Maryland Extension, based at the Central Maryland Research and Education Center in Ellicott City. He is also a professor in the Landscape Technology Program at the Germantown Campus of Montgomery College. Contact him at [email protected]