First of all I am Ontario, Canada. I noticed this morning my Burning Bush that the newer outer leaves are curling and a few of the leaves have pink spots. Now, we have had an incredible rainy spring now the humidity and heat are on the rise. However, I am concerned if it is developing a fungus or disease. I use sheep manure from time to time---it is planted about 2-3 feet away from zebra grass (which is still tiny) 2 feet from Clematis/ beans and and another 3-4 feet from Virginia Creeper all of which is screening the shed, fence and neighbour.
Certified GKH Gardening Expert
The cool rainy spring & sudden heat has brought about many fungal diseases and also insects. Try spraying your burning bush with neem oil. It is a fungicide and pesticide, with no harmful residues.