Answer: The brown areas you're describing could be sunburn, or they could be caused by root damage due to poor drainage. Watering as often as you do might keep the soil too moist. Rhodies must have acidic, well-draining soils. Keeping the soil constantly moist will cause root rot. It's better to water deeply once each week than to water every other day. Have your soil tested and feed with an acidified fertilizer if indicated by the soil test. Be sure to turn off your drip irrigation and water your rhodie by hand, soaking the soil slowly so moisture penetrates down to wet the entire rootmass. Don't water again until the top inch of soil is dry.
Curling, drooping leaves is a sure sign of phytophthora root rot - again caused by poor soil drainage, poor nutrition and improper soil pH. The disease will remain in the soil - don't replant a rhodie in the same spot or it will suffer the same fate. There is no cure - I'd remove the plant and put something else in its place.
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