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Re: purple coneflowers

Barry:

Your coneflowers (and, if you look around, maybe other composites 
such as ashy sunflower, rosin weed, etc.) are being chewed through by 
a small, black, nocturnally active weevil. It cuts into the stem, 
perhaps purposefully  introduces or at least allows the invasion of 
bacteria which ferment the pith and sap at the wound, in which 
nutitious goo the larvae of the weevil develop. At this season, 
these critters can cut a lot of flower heads, but they slow down 
later in summer and the plants re-flower. Unless you're growing the 
flowers for a cut flower or garden club type display, there is no 
reason to control the weevils, as they're just part of the prairie's 
biodiversity. They are more abundant some years than others. Last 
year they were very abundant here in the St. Louis area, but appear 
much less so this year. Cutting and destroying the damaged flower 
stalks at the base (below the developing larva) may reduce the 
population somewhat; insecticides, with their obvious deleterious 
effects on pollinators, would control the weevils, but at a cost.

Jmaes C. Trager -- Shaw Arboretum

> Date:          Mon, 12 Jul 1999 20:52:40 -0400
> To:            prairie@mallorn.com
> From:          Barry Schroeder <tandem@mail.erinet.com>
> Subject:       purple coneflowers
> Reply-to:      prairie@mallorn.com

> I was walking around my prairie today and noticed that a lot of the 
> purple coneflowers have been attached by something. Never seen this 
> before. Anywhere from 2-6" down from the flower head, they look like
> they been cut. The head are hanging there. Everything from a bud to 
> full bloom was attached. 
> 
> Anybody have a idea what is attaching them and how to stop it? 
> 
> Thanks for your help
> 
> Barry 
> tandem@erinet.com
> 
> 
>  
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