From observing all of the photos, I would agree with Amanda. The discolored leaves and subsequent early leaf fall could be a lack of nutrients getting to those branches. If the branches are on the same side of the tree as the trunk damage, the likelihood of borers is greater. to check for the borers, look for brown frass (looks like wet brown sawdust clumped together) along the bottom of the trunk at ground level. The look for small pin holes in the trunk around the broken bark areas. The likely borers would be dogwood borers. The bark itself would still be alive as you suggested, probably getting broken away at the soil line from the thawing and freezing of ice . this makes an ideal habitat for borers to lay eggs. Then the little boogers hatch and eat away at the cambium layer and on into the good wood. i have seen them completely girdle a 6 to 8" tree to the point that only about an inch or two of good wood was left to get nutrients to the rest of the tree. The result was all of the leaves discoloring, just as your, and the tree eventually snapping off at the point of borer entry.
I also noticed in the third photo ( http://im1.shutterfly.com/procserv/47b8df24b3127cceb36cc2efdbc900000036103AaNmrJi4Ze ) the fruits seem to have quite a bit of russet, so I would like to share the following information about this disorder from our plant pathologist at the University of Illinois.
Fruit russet is a condition in which the peel becomes corky due to untimely divisions of the epidermal cells. It develops as a result of healing of the tissue from the injury. Several factors have been shown to cause russet, including genetics, tree health, cultural practices, diseases, insects, yeasts, chemicals, and environmental conditions. Some apple varieties such as Golden Russet, Golden Delicious, Cox Orange Pippin, spur type Delicious, and Bosc pear are more prone to heavy russet. Fruits from trees on sub-dwarfing rootstocks like M.27, and P.22 and extremely vigorous trees are also more susceptible to russet than fruit from moderately growing trees. Tree health is also important in that diseased and poorly pruned trees are more likely to have russet fruits than healthy ones. Fruit growth stage at the time of injury is also important; fruits are most susceptible to russet between petal fall and three weeks later than at any other time during development, although hail and heavy rain may cause fruit russet later on in the season in some cultivars. Russet damage occurs early during the fruit growth, but symptoms may not become visible until several weeks later when the corky tissue dries out.
Other types of injuries that have been shown to cause russet include powdery mildew, mite damage, and crop protection products such surfactants and carbamates. Sevin in particular can cause russet when used as a thinner in cold weather. Some combinations of chemicals may increase russet incidence, so read the label and try any new combinations on a small scale first. Weather is probably the most critical factor in russet development. Look for more russet on lateral than on terminal fruits and on exposed than on shaded fruits. In 1980, L. L. Creasy from the Department of Pomology at Cornell University in New York looked at the correlation between weather conditions and russet development in Golden Delicious. He found that humidity, and to a lesser extent rainfall, correlated very well with russet development. He found that the most sensitive time is between petal fall and 16 to 20 days after full bloom. Prolonged fruit wetness in general can increase the chances of russet and for this reason it is best to spray pesticides during times of quick drying, to avoid using wetting agents, and to use concentrate rather than dilute spray during the critical periods. Water quality may also be important in russet development. High iron and calcium water have been suspected to increase russet incidence. For this reason water quality should be monitored and also avoid spraying micronutrients during two weeks after petal fall.
In conclusion, russet can be serious in some years when the weather is bad early in the growing season or when the fruit is injured or exposed to prolonged wetting periods. Other than cosmetic appearance, russet has no effect on the quality of the fruit and it does not penetrate deep into the tissue.
Mosbah Kushad (217-244-5691; kushad@uiuc.edu)
Hope this helps!
Dennis Norton
Royal Oak Farm
Orchard
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
http://www.revivalhymn.com
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