The defiant dozen - 12 roses can resist the 3 common diseases

The defiant dozen If you've ever grown roses, the chances are good that you're familiar with one or all of the troublesome trio of diseases pictured above. Black spot, powdery mildew, and rust are three fungus that not only make plants look bad, but also rob roses of their energy.

What can you do to prevent these diseases? You could undertake an intensive spray program. Better yet, you could plant disease-resistant varieties to start with, then follow up with the good cultural practices described in "Heading off the rose diseases," later in this issue.

To determine which roses are most resistant overall, we focused on the popular floribundas, hybrid teas, and grandifloras, then surveyed curators of public rose gardens and more than 300 members of the American Rose Society around the West (we thank the participants for their generous responses). The 12 winning varieties appear at right. You'll find them for sale bare-root in nurseries and mail-order catalogs this month.

A host of roses and their rankings

In our survey, we found that some roses resisted one fungus but not another. Here, we list the three diseases and roses that rebuff them best (some of these missed the top 12). Varieties appear in order from least to most susceptible, with 'Olympiad' coming out strongest.

Black spot. 'Olympiad', 'Brandy', 'Iceberg', 'Pristine', 'Gold Medal', 'Fragrant Cloud', and 'Queen Elizabeth'.

Powdery mildew. 'Olympiad', 'Gold Medal', 'Pristine', 'Honor', 'Voodoo', 'Iceberg', 'Queen Elizabeth', 'Peace', 'Sunsprite', 'French Lace', 'Playboy', and 'Color Magic'.

Rust. 'Olympiad', 'Gold Medal', 'Honor', 'Pristine', 'Iceberg', 'Voodoo', 'Precious Platinum', 'French Lace', 'Sunsprite', and 'Sunflare'.

To spray or not to spray

Most rose society members who responded do spray their plants to control diseases. Some, however, do not spray at all, and many said they are trying to reduce the amount of chemicals they use. Even with a spray program, almost all respondents had experience with these diseases. The list of top disease-resistant roses showed very little difference between those who spray and those who don't.