I had planted the tree in Nov of 2006. This spring the leaves came on and turned green but in mid July the leaves started turning brown around the outside of the leaf. On one tree the leaves have turned red and have started droping. What would cause the leaves to turn brown on the outside of the leaf? We have had alot of rain this spring and early summer.
The symptoms you describe are consistent with drought. Even with the rain you've had, it may still be too dry. A newly planted tree (I would rate yours as such) will not have spread its roots very far beyond the original rootball and may have actually been drying itself out with water uptake. Watering them 1/wk for the remainder of this summer & once every two weeks next summer will probably be enough to get them well established for a typical droughty Texas summer (I gather this summer is not typical?).
Newly planted stock may shed water to surrounding soil, amending of planting hole backfill often makes this worse. If precip. not at least 1 inch per week, not adequate. Might also have problem there with mineral salts, inquire locally.
