I am afraid my Blue Girl might have bigger problems than a little sunburn. It wasn't as bad as I thought since it was pretty much all the new growth. Unfortunately, in the process of removing the burned leaves, I noticed what looked like hard water spots on some of the other leaves and a few were starting to dry out the tips, which are curling and turning brown. Is this mildew? And if so, what's the best way to stop it? Blue girl has always been my favorite and this is my first time growing my own roses.
Rose Disease and Treatment Options
Certified GKH Gardening Expert
When roses get stressed out for any reason, it does open them up to some of the disease problems. Those markings could be just water spots and the delayed progression of the sunburn. However, they could be the start of mildew as well. You can use a product called Green Cure, an earth-friendly product that works great! You want to apply it early in the morning when it's cool so as to avoid any further burn problems. Fill a sprayer with water the night before application and let it sit to help clear out the chlorine. Then in the morning, add two scoops (big end of scoop) of Green Cure to each gallon of water. Spray it onto the rose bushes liberally. If you only want to spray the one rose bush, you can also mix some up in a 32 ounce hand sprayer by using two of the small scoops. Here is a link to their website and places to buy it on line: http://www.greencure.net/
You may also be able to find it locally at Ace Hardware stores. Some garden centers carry it as well.