These are close up photos of a grouping of 8 azaleas which have always been healthy. Two months ago their leaves yellowed and started dropping. They now have bronze color on both sides. I have sprayed with Malathion myself and Trugreen sprayed for insect and disease control. (8/14/19). All 8 plants are uniformly affected, the last photo is the same plant in a different area which is healthy. I have also fertilized with Hollytone. Can you please evaluate and give suggestions Thanks,
The original yellowing this spring may have been natural dropping of extra leaves when a plant has put out a lot of foliage in ideal (wet) conditions, but then conditions change (drought). Azaleas are very shallow-rooted and easily affected by changing conditions.
Since we don't see the yellowing, we cannot say for sure what caused it. Also be aware of delayed impact from sidewalk salts put down in the winter.
At the moment, the leaves look burned. This could be phytotoxicity from the malathion and other sprays, especially if they were applied during hot breezy (drying) droughty weather.