Answer: Most researchers now say that there is no tangible benefit to treating tree pruning wounds. Small wounds heal quickly enough to not need it, and large wounds (like the one you mentioned) will not heal faster when coated. In fact, many of the wound dressings are a black, tar-like material that can collect heat from direct sun exposure on a hot summer day and discourage effective healing of the wound.
The only benefits of wound treatments are to discourage decay of the interior wood and to discourage borer attacks and canker infections of the wounded bark and cambium tissues. To gain the first benefit, wound treatments must be maintained annually, as they tend to crack, allowing moisture in. As for the insect and disease deterance, pecans in your area are not really prone to these problems.
Keep your tree healthy and vigorous, by fertilizing it and giving it a good soaking every week or so during the hot summer months. This will help it heal as quickly as possible.
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