Describes azalea disease, salt burn damage, a common disease in azalea plants. Find out what it is and what to do.
What is it?
A common problem in areas of low rainfall that occurs in soil with poor drainage and where an excess of fertilizer has been applied. Excess salt accumulates in tissues and causes damage.
What does it look like?
Leaf edges are dead and brown. This usually takes place in the eldest leaves first. This is key in distinguishing salt burn from windburn, as windburn develops first on young leaves. Leaves with salt burn damage may be a lighter green than normal and in severe cases drop off entirely.
How does it manifest?
Excess salts accumulate in the soil and travel to leaf edges where tissue is killed off. Salts also interfere with water uptake in the plants. Because of this, when fertilizer is applied in excess (many fertilizers are made up of soluble salts) they accumulate in the soil and do not dissolve as they normally would. This can also happen if fertilizer applied in correct amounts is not diluted somewhat by a thorough watering after the treatment.
What can you do about it?
Salt burn damage will not disappear from damaged leaves, but you can avoid further future damage. In areas of low rainfall, use heavy irrigation about once a month to leach accumulated salts from the soil. Improve drainage around the plants. This can be done by removing plants, and adding soil amendments prior to transplanting. In severely damaged plants, you must destroy and replace them. Always follow label directions when utilizing fertilizer and water thoroughly once you apply the fertilizer. Bagged steer manure contains large amounts of salt, and is best avoided entirely when fertilizing your azalea plants.