Azaleas grown in constant sunlight will have shorter stems, and more blooms which will not last as long. If the leaves show signs over-exposure to sunlight,round brown spots on the leaf tips and edges or the blooms fading quickly, move the plant to a more shady area. In full shade, the stems will grow longer as they reach for sunlight. They may not produce as many blooms in this condition, but the blooms will last longer. If water stagnates on the petals of azaleas, fungus starts to spread causing the flower to decay and wither. One of the diseases affecting azaleas is the rust disease which is most common during monsoon. The symptoms of this disease include the appearance of grey spots on the stem of the plant which can be treated by applying a mixture of two gram insecticide in one liter of water.
Aphid attack can lead to leaf roll in azalea. They live beneath azalea leaves and survive on nutrition in the leaves, thus causing a change in leaf color and subsequent shedding. One insecticide that can be used for aphids is the pesticide called sulphix. Three grams of sulphix mixed in one lite of water can serve as an antidote for leaf roll.
If the leaves starts turning yellow then we can conclude that the water used for irrigation is acidic in nature. This is relatively easy to diagnose. Azalea prefers moist, well-drained soil with a pH between 4.5 and 6.0. So if the water is found to be acidic, balance the pH by adding some decayed leaf powder to the soil mixture.
Even though Azalea is prone to a number of problems like infections, insect and pest attacks and weather fluctuations, they can easily be resolved.