I agree re moisture as well as temperature being needed.
I did say earlier re a moist spring. This seems essential for their survival after hatching, or for hatching.
Chuck
-----Original Message-----
From: gary white in2iris@yahoo.com [iris-species] <iris-species@yahoogroups.com>
To: iris-species@yahoogroups.com <iris-species@yahoogroups.com>
Sent: Wed, Mar 11, 2020 11:09 pm
Subject: Re: [iris-species] iris borer, Iris tectorum
I believe its a combination of cold weather and moisture level. The whole state of Nebraska usually has very cold winters (most years there are a few days when our high temperature is zero or below). The difference between eastern Nebraska and western Nebraska is moisture. In eastern NE, our average annual rainfall is about 30 inches per year. In western Nebraska it is only about 15 inches per year. At an invisible line north to south, the average soil moisture and/or humidity drops to a level that is not conducive for a viable life-cycle of the borer. I would expect that the line extends south into Kansas and north into South Dakota. By the way, many other natural populations change along that north-south line as well. A number of eastern and midwestern birds disappear and western birds are noticed. Plant populations change as well, transitioning from the tall-grass prairie to short-grass prairie, etc..
Gary White
On Wednesday, March 11, 2020, 09:36:28 PM CDT, Chuck Chapman irischapman@aim.com [iris-species] <iris-species@yahoogroups.com> wrote:
Threre are many climates where iris do well, but the borer taps out sooner. Seems to be even more dependent on cold weather. But don't forget, it was born in Canada.
Chuck
-----Original Message-----
From: Rodney Barton rbartontx@yahoo.com [iris-species] <iris-species@yahoogroups.com>
To: Mark Cook hemerocallis1962@gmail.com [iris-species] <iris-species@yahoogroups.com>
Sent: Wed, Mar 11, 2020 10:15 pm
Subject: Re: [iris-species] iris borer, Iris tectorum
We don't iris borer here in North Texas but TBs do just fine.
R
On Wednesday, March 11, 2020, 7:11:29 PM CDT, Mark Cook hemerocallis1962@gmail.com [iris-species] <iris-species@yahoogroups.com> wrote:
That would explain the absence of borers. Florida for instance has some
cold snaps, but they are not prolonged. The spring is extremely dry.
I wonder if the southern limit of the Iris Borer would be very similar
to the southern limit of Tall Bearded Irises?
Mark A. Cook
On 3/11/2020 8:19 AM, Chuck Chapman irischapman@aim.com [iris-species]
wrote:
> It has to do with winter weather. AS part of their life cycle they need specific weather. A cold period follower by humid spring. They hatch under a change from cold weather to time with initiation of growth of new foliage in iris in spring.
>
> Without these specific climate conditions they don't survive. They evolved with iris. Much the same way there is a southern limit for survival of iris.
>
> Chuck
>
