In our area the three most common rose diseases are black spot, powdery mildew and rust. The worst of the three is black spot.

The first sign of trouble begins when dark spots appear on leaves. Then the infected leaves turn yellow and begin to fall. The result is an unsightly, weakened plant subject to dieback.

Powdery mildew looks like the leaves are covered with powdered sugar. It's not overly harmful to the plant, but it looks horrible and can weaken the plant by reducing photosynthesis.

Rust begins with orange or yellow pustules under the leaves. Once infected, the leaves turn an ugly brown before withering and falling off.

When it comes to these diseases, the best offense is a good defense. Replace highly susceptible roses with ones labeled as resistant. Plant your new rose in morning sun where foliage tends to dry sooner, and avoid wetting foliage when watering.

If you can't bear to part with a favorite rose that is prone to these blights, it may be necessary to apply protective sprays once per week to prevent these diseases from gaining a foothold, particularly in rainy weather.

Neem oil is an environmentally friendly product that is highly effective if applied before the leaves become infected. Store the neem oil somewhere sufficiently warm. When it's cold, the oil forms a blob that is extremely hard to mix with water in order to spray effectively.

Plant desert candles

to light mixed border

Eremurus, commonly known as foxtail lilies or desert candles, are some of the showiest plants available for the mixed border. They proudly strut their stuff in early summer. These lily relatives feature spectacular towering spikes of intensely colorful blooms.

Depending on the variety, the densely clad flowering spires can reach anywhere from 3 to 8 feet tall, and come in white, pink, orange or yellow.

I have an incredible collection of these winter-hardy beauties. All they require to stay looking great is well-drained soil and a sunny location. By now you're probably wondering where you can buy one of these magnificent plants.

The bad news is that they rarely show up as potted plants in your local nursery, and when they do, they're quickly snapped up.

The good news is that they are readily available to purchase as bulbs next spring at the Northwest Flower & Garden Show. Try pairing a few tall growing orange and yellow varieties with a dark blue Delphinium.

Private garden tours

What can be more fun than going on a garden tour? Not only will you visit magnificent private gardens rarely open to the public, you'll also discover new plants and plant combinations. On many tours, you'll meet the garden owners and learn what inspired them to create their beautiful garden.

A fun one coming up Saturday is the Secret Gardens of Lake Forest Park Garden Tour. The tour includes five private gardens with either an artist or a musician working or performing in each one.

Tickets for the 10 a.m. to 4 p.m. garden tour are $15 (or $12 in advance). Information at www.secretgardensoflakeforestpark.com

The event also includes a plant fair held in the Third Place Commons that is free and open to the public. There will also be a master-gardener clinic, and I'll be broadcasting my radio show from 10 a.m. to noon.

For a complete list of garden tours and information about them, visit the Elizabeth Miller Library website at depts.washington.edu/hortlib/calendar/tours_sales.php. Also keep an eye on my "Garden Events" section that I include here every week.

Ciscoe Morris: ciscoe@ciscoe.com; "Gardening with Ciscoe" airs at 10 a.m. Saturdays on KING-TV.