I have a beautiful climbing hydrangea that is twenty-five years old and probably as many feet tall. It is on the north side of my brick house and just this morning (late November), my son noticed white spots on the leaves from about eye level to the ground. He thought it was a fungus, but it looks like (indoor) mealybugs, although I do not have any houseplants at the moment. I haven't introduced any new plants. Should I (1) spray with something; (2) fortify the soil with a product; (3) remove all diseased leaves; (4) cut it down, and if so, how short and how can I help it heal from the shock at this late date in the Northeast (NJ)? I also have an 80-year-old rhododendron in the area that I would be crushed to have get sick from this plant. And lastly, the 25-year-old purple wisteria that covers the trellis is there too. Help, please!!
Climbing Hydrangea Has What Appears to Be Mealybugs / White Spots on Leaves
Certified GKH Gardening Expert
Most of the time, diseases are plant specific. Usually these will not cross over to another species. The best thing to do would be to apply wettable sulfur to the area. This will kill off any infection to the soil. Here is a link that will give you more ways to make your own pesticides at home: https://www.gardeningknowhow.com/special/organic/