Q.mildew on roses
What is the best thing to treat mildew on roses
I am assuming you are speaking of powdery mildew. Both Scotts and Bayer make "fungus fighters" but repeat applications are usually necessary. Make sure the product is rated safe for roses and follow instructions thoroughly. Make sure to clean up any plant material that falls to limit the hazard of repeat infection next year. If you use a mulch, consider removing it at the end of the growing season as it might be harboring spores. Powdery mildew usually strikes during hot, dry weather especially when roses are not getting an inch or more of water weekly. Unlike household mildew, it is not a result of humid weather. Make sure your rose is in full sun, that watering is at the root level and that you prune annually to "open up" the rose's center and improve air circulation. Early next spring, start a mildew prevention program, perhaps with Neem oil. Homemade recipes are available to treat powdery mildew but I can't confirm their effectiveness. Here is one: to one gallon of water, add 1 Tbl baking soda and 2 Tbl Safer SunSpray (fine agricultural oil) with or without anti-transpirant. (Anti-transpirant keeps fungal spores from spreading.) Coat both sides of leaves every 3 days x 3. Avoid using dish soap and kitchen oils which some recipes include.
https://www.gardeningknowhow.com/ornamental/flowers/roses/roses-powdery-mildew.htm
