Azaleas turning yellow, spreading to other azaleas
Hi, For the past 3-4 years, this one azalea has been struggling, getting more yellow and then last year, most branches were bare, but new leaves (but no flowers sprouted). Just recently, one bush right next to it, and another about 8 feet away (seperated by a garden) have started to turn yellow in certain spots, although there is bright new green growth that is not effected. Is this chlorosis? Someone thought lacewings? I have no idea what's going on. I did notice that the bare brances seem to have a fungus on them? Is there a fungus that could cause this? How do I remedy this? They are very old plants, probably 50-60 years. I sprayed them with neem oil. I've given then some raked in general fertilizer in the past week.
Baltimore County Maryland
We viewed your photos and do not see an insect or disease issue.
It is possible you may be dealing with a chlorosis problem. Your soil pH may have changed over time. The azaleas are located next to a brick wall with mortar and the cement walkway possilby leaching lime into the soil.
Azaleas grow best in a moist, well drained, acidic soil in morning sun and afternoon shade. They have a shallow root system.
If your soil pH is too high, the fertilizer that you applied might not be taken up if the pH is off. Azaleas grow best in a pH of 4.5-6. Do not spray unless you have identified the pest or disease and you know what you are spraying for.
At this point, test your soil. Results will give you pH and nutrient deficiencies.