Answer: There's a disease (Phytophthora megasperma) that causes wilt when roses are planted in poorly drained areas. The stems near the soil surface become water-soaked, dark green, and finally dark brown. New shoots wilt and die. Some cultivars are more susceptible than others. Check the drainage of the soil -- if water puddles or takes a long time to perc down to the roots of your rose bush, you may want to dig up the plant this fall and move it to a spot with better drainage.
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