I have what appears to be burns, but sticky, on the leaves of my shrubs. I live beside fields of beans and wheat and wonder if th
e farmers have sprayed something as it is very random? There are no signs whatsoever or any bugs or insects. See pictures and note the dark area is now like paper.
Certified GKH Gardening Expert
This seems more like a severe fungal or bacterial infection. You can either use dolomitic lime, and wettable sulfur to treat this, or a copper based fungicide. There are many diseases that are not able to be cured, but these two methods will take care of anything that can be cured.
Take care not to over water, and with most shrubs will like a dry period between watering anyway. Overwatering is the most common cause of fungal/bacterial infections.