In my area, we have mildew through June. Some bushes worse than others. I just ignore it. It won't be an issue when June gloom goes away.

I never heard of mildew going away after june. I am concerned because some recently planted europena and Dublin Bay both have mildew problems. I was going to go after it with spray this weekend or toss the roses. They are both located in the same corner where I had America growing last year and it was filled with mildew and never went away. I welcome all advice. Judith P.

Both Chrysler Imperial and Europeana are well known for their mildew issues here in California. Mildew can be caused by several factors, as well as combinations of any and all of them. First is the genetic proclivity of the variety to mildew. Those genetically susceptible to mildew will require spraying for it in most climates. Immature plants are often more susceptible to diseases, so some may (or may not) out grow them. Weather conditions/time of year can trigger mildew (rust and/or black spot) if you go through short periods where the conditions are more favorable to foster the fungal growth. Siting plays a huge part in many cases. Not providing sufficient air flow or sunlight can create micro climates where diseases proliferate. If you can keep the air flowing (without creating a wind tunnel), and at least five to six hours of sunlight (here in the west, particularly), you may help alleviate the issue. One of the most unbelieved causes of mildew (and other diseases) is water stress. If you don't seem able to eliminate the issue, check the water to make sure the plant is receiving enough. I can force just about any rose in my garden to rust or mildew just by keeping it chronically too dry. If you've corrected all the other possibilities and the plant still offends, and you don't want to spray, change the rose variety for one which is known to be more resistant to the particular disease. Kim