Answer: It sounds like your roses are having trouble recovering from being transplanted into their new home. Black spot is a common rose ailment on all but the most resistant of varieties. The brown edges however indicate a problem in the "plumbing system"; most likely a root problem. Common causes could include root burn from fertilizer placed in the planting hole or roots that were allowed to dry out prior to planting.
I wouldn't suggest additional pruning unless it is to remove dead branches. Make sure the soil was properly firmed around the roots and that the plants are kept moist but not too wet. They will likely outgrow the problem if the initial damage was not too severe. The black spot will require regular treatments if you have chosen a susceptible variety. Numerous fungicide options exist for roses, the most natural and low-tox of which are products containing "neem oil" (note: most neem products are insecticidal only, while those listing "neem oil" as the active ingredient have insect and disease controlling features).
For a tough, disease resistant shrub rose for humid southeast Texas look for the variety 'Nearly Wild' which is available in your area.
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