This is important with the large leaved rhododendrons as it encourages strength to go toward more bud production and improves the following year's bloom. Otherwise this effort would go into seed production. Azaleas and elipidotes should flower well without deadheading. One of my rhododendrons is wilting even though the soil is moist. The cause is most likely phytophthora root rot or some other type of root damage.
Root rot is a fungus disease that causes the entire plant to wilt and die.
It usually affects smaller plants that have recently been transplanted. There is no cure. The entire plant should be removed and disposed of in the garbage. The leaves on a couple of my plants are very pale with little veins visible. This is probably an iron or magnesium deficiency, most likely due to the pH of the soil being too high.