Answer: If you're sure there's no sign of scab on the leaves, I can only wonder if borers have infested the tree. They are sometimes hard to detect, but if they're present, you should see their holes near the base of the trunk, with some sawdust underneath. There may also be a problem with roots being damaged by a high water table, mechanical damage (such as soil compaction due to heavy equipment use on the property), a leaky gas line, etc. Sometimes excess lawn fertilizer/herbicides can cause this type of damage. Also, if you have limed the lawn, it may have changed the pH enough to throw off nutrient availability. Let us know if you get closer to a specific cause, and we can help with a solution.
Do you have a regular feeding/pruning schedule for your crab? Generally, pruning should be done in late winter/early spring, before growth begins. For pruning diagrams, contact your county agricultural extension office (ph# 847/223-9288) for a pruning bulletin, or consult a book in the library. In spring, spread compost in a band 2' wide and 1" deep under the drip line of the tree. Feed the tree its "main meal" of nutrients in the fall (2.5 lbs each of rock phosphate, granite dust and greensand), and offer the tree supplemental foliar feedings with liquid kelp and fish emulsion (follow instructions on the product label). Hope this helps!
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