Mike,
To add my two cents, we have had an on again off again problem with
Lucostoma (Cytosopora) canker on McIntosh here at the Peninsular
Research Station on both RedMax and Marshall, not yet on Pioneer. At
least 4 blocks of various ages (Redmax/M26 20 yrs, Marshall/M26 10
yrs) showed symptoms. It even moved to an Empire/M26 block adjacent
to one of the McIntosh blocks, but did not spread as quickly. Your
description of symptoms, leaves hanging on through winter and major
limb and leader die back sounds similar to what we saw. We have also
seen greater symptom expression after cool wet extended falls. Our
pathology lab did not always have success in isolating the causal
agent and would often only find secondary fungi like Alteraria in
samples. Lucostoma is apparently a week pathogen, but can enter
trough wounds such as pruning cuts and branch stubs. We had the best
luck isolating that fungus right around budbreak or late in the
season around harvest. Diane Brown, a former MS student of Dr. Patt
McMmanus UW Pathology, dabble with it a few years back, she had
trouble isolating it from cankers. If I remember right, her IDs were
mostly from fruiting bodies that yielded spores. But only a subset of
the cankers had fruiting bodies, at least at any given time. She
also only had limited success trying to inoculate health trees as
part of here research.
Matt J. Stasiak, Researcher
University of Wisconsin - Madison
Peninsular Agricultural Research Station
4312 Hwy 42
Sturgeon Bay, WI 54235-9620
Phone: 920-743-5406
Fax: 920-743-1080
cell: 920-559-0529
e-mail: mstas...@wisc.edu
http://www.cals.wisc.edu/ars/peninsular/
