The orchard photos accompanying Doug’s July 23 email show resemblance to a problem I had two years ago in mature apple trees. Dr. David Rosenberger, Hudson Valley, NY fruit pathologist, photo-diagnosed that problem as likely to be Black Rot (Botryosphaeria). He noted that this common orchard disease usually affects foliage and fruit, but less often will infect woody tissue, particularly if the trees have been drought-stressed. My trees had been drought-stressed, and the symptoms did not appear until summer. Symptoms resembled winter damage, but the delayed appearance of symptoms would have been unlikely if winter injury were the cause. Some of the trees died, and some recovered.
David Kollas Kollas Orchard Tolland, Connecticut USA > On Jul 26, 2018, at 10:19 AM, Kushad, Mosbah M <kus...@illinois.edu> wrote: > > Hi Doug: > The graft union looks strong and there is no sign of bark peeling… It could > be phytophthora, but could be other causes as well (Doubt it’s fireblight > injury)... Did you see any root suckers in the affected trees? The bark > above the graft union appears to be much thinner than below the graft union > and so is the trunk diameter that appears to be much smaller.. Is that true > for the other trees? I did not see visible signs of dogwood or corn borers > or burrknots in the photo. Borers are usually more active close to the ground > surface, where burrknots are more common..… What is the history of herbicide > use? I have seen damage on tree trunks and scaffolds from spraying Rely > herbicide. Add to these mechanical injury and drought.. had several trees > started dying mostly at the graft union from the 2012 severe drought. > Interested to read other inputs. Mosbah Kushad, University of Illinois > > From: apple-crop-boun...@virtualorchard.com > <mailto:apple-crop-boun...@virtualorchard.com> > <apple-crop-boun...@virtualorchard.com > <mailto:apple-crop-boun...@virtualorchard.com>> On Behalf Of Doug Nelson > Sent: Monday, July 23, 2018 11:37 AM > To: Apple-Crop discussion list <email@example.com > <mailto:firstname.lastname@example.org>>; wincowg...@mac.com > <mailto:wincowg...@mac.com> > Subject: Re: [apple-crop-2] Photos of dying trees-fireblight- Doug - resent > and complete > > The row that is most affected is buckeye gala on M9 that is about 4 years > old. I removed one of the trees and cut back the bark around the graft union. > I found the graft union appeared to be dead with green tissue above and > below. The tree went from healthy to fully wilted within about 2 weeks. About > 20 trees around it in the same row appear to be doing the same thing. > <image002.jpg> > <image004.jpg> > <image006.jpg> > <image008.jpg> > <image009.jpg> > <image010.jpg>
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