Re: When do borers hatch?
- To: Multiple recipients of list <i*@rt66.com>
- Subject: Re: When do borers hatch?
- From: C* M* <c*@tiac.net>
- Date: Tue, 4 Mar 1997 10:18:37 -0700 (MST)
>
>In 1993 the University of Massachusetts's Garden Calendar explored the idea
>of "Growing Degree Days" as markers for insect emergence. The idea was to
>average the high and low temperature of a day. You then kept an accumulated
>seasonal total of the amount by which that average exceeded 50 degrees, ie
>((H+L)/2)-50. (If the figure was negative you did not add it to the
>accumulating total.) The theory: "most insects and mites, as well as weeds
>and diseases, have generally predictable life cycles that depend on
>temperature, or more accurately, the accumulation of heat." In other words,
>different types of pests emerge when the accumulated degree days hit a
>species-specific figure. I've not read anything else about that research,
>but it might be an interesting approach for iris growers to pursue. It
>would take several years to come to any conclusions, but....
>
>---------
>Kathy Marble <cmarble@tiac.net>
I left out an important step: you must observe when you first see the borer
and link that to the GDD of that day. This would be confirmed (hopefully)
in subsequent years. The desired result is the ability to predict when they
would emerge. Would the GDD/borer day be the same for different
areas...that's the question.
---------
Kathy Marble <cmarble@tiac.net>
Harvard, MA
zone 5
