Mark, you may already know that David Rosenberger of Cornell's Hudson Valley Lab has suspected that glyphosate may be one culprit in the type of injury you describe.
We have seen unexplained tree decline and eventual death in several Massachusetts (and Connecticut) orchards (individual or groups of trees) over the years, trees typically range in age from 10-20 years. Macoun is often afflicted. (Not generally grown in Michigan.) Symptoms similar to what you describe. We have sometimes chalked it up to site, herbicide use (thanks Dave), and/or general environmental conditions. Climate change? General fungicide programs ought to keep black rot, suppressed, I suspect it would be far worse otherwise. I doubt there is a silver bullet, at least no one has offered me one. That would be too easy. The problems always seem to stand out in contrast to the successes. Remember that every individual is a product of heredity and the environment. Hope you are doing well. Jon On Wed, Nov 11, 2009 at 3:30 PM, Mark Longstroth <longs...@msu.edu> wrote: > I visited a grower this fall who asked help in determining what was wrong in > several of his apple plantings. > He had young trees which were dying a slow death. They had cankers on the > trunks, some were basal, some below and some among the scaffold limbs. The > grower used a used a mixture of several residual herbicides with glyphosate > in the spring and followed up with a band application of glyphosate in the > summer for escapes. The sick trees were located in patches that > corresponded to poorer sandy ground. the varieties involved were, Cameo, > McIntosh, Fuji and Empire on M26 or M9 roots. > > I suspected that the glyphosate was causing the problem but was at a loss to > explain the cankers higher on the trunk and around the scaffolds. Some of > the cankers had the papery bark I associate with black rot and the MSU plant > diagnostic lab isolated black rot but no other pathogens from samples. > > My question is what can the grower do to suppress the black rot. Is cutting > out all the infected trees his best course? > Would a fungicide such as one of the phosphite materials help? Generally > the sanitation in his orchards looks very good and he prunes heavily so the > trees are open. > > ----------------------------------------- > Mark Longstroth > SW Michigan District Fruit Educator > Van Buren County MSU Extension > Email - longs...@msu.edu > http://web1.msue.msu.edu/vanburen/disthort.htm > ----------------------------------------- > > > > -------------------------------------------------------------------------- > > The 'Apple-Crop' LISTSERV is sponsored by the Virtual Orchard > <http://www.virtualorchard.net> and managed by Win Cowgill and Jon > Clements <webmas...@virtualorchard.net>. > > Apple-Crop is not moderated. Therefore, the statements do not represent > "official" opinions and the Virtual Orchard takes no responsibility for > the content. > > > > > > -- JMCEXTMAN Jon Clements cleme...@umext.umass.edu aka 'Mr Liberty' aka 'Mr Honeycrisp' IM mrhoneycrisp 413.478.7219 -------------------------------------------------------------------------- The 'Apple-Crop' LISTSERV is sponsored by the Virtual Orchard <http://www.virtualorchard.net> and managed by Win Cowgill and Jon Clements <webmas...@virtualorchard.net>. Apple-Crop is not moderated. Therefore, the statements do not represent "official" opinions and the Virtual Orchard takes no responsibility for the content.
