Lack of nitrogen is the most common reason for pale green leaves and heavy rainfall could be leaching the nitrogen from the soil. I would try fertilizing now with a complete plant food like Osmocote. Check the soil when you work in the fertilizer. Poor drainage can also cause pale foliage. If the soil feels wet than you may have clay in the soil keeping it too moist. Adding organic matter and dolomite will help loosen clay soil over time. Building raised beds for your roses would be the answer to clay soil if the roses continue to decline. Keep growing, Marianne Binetti