The blackening of the leaf tips may be due to a light case of fire blight. This is primarily a spring disease and nothing need be done now. If entire shoots are black you can prune them out below the blackened areas but don't do anything if it is just the leaves.
It may also be due to some root problems especially if the tree is a new planting. Dry soil or soggy wet soil conditions or excessive fertilization can cause root death and leaf tip burn. Keep the soil just moist not soggy and new growth should be fine.
The brown hard stuff on the leaf rib is probably nothing to worry over. You could take some leaves with the problem to your Hays county Extension Office south of San Marcos to see if they can take a look and determine if it is an insect or not. There is no charge for this service at the Extension Office.
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