Common Rose Diseases—Know What To Look For

There are a few rose diseases that you should always be vigilant to find early and eradicate from your rose plants.

Downy Mildew

Downy mildew affects roses throughout the United States.

It starts on immature plant growth, and thrives in wet, cool conditions (spring, anyone?).

The rose bush's leaves grow dark purplish to dark brown spots, which may look like chemical toxicity burns.

Rust

Rust is found on roses just about everywhere. It's consistently a problem in the western US.

Spores infect leaves if fog, dew or rain happens at temperatures from 55 to 75 degrees F (13 to 24 degrees C).

Symptoms

• Yellow rust spots on the upper side of leaves during cool climate in spring or late fall.
• Leaves twisted around and dry.

Powdery Mildew

Powdery mildew and black spot are the 1-2 blow on roses. It commonly appears on new growth, in times of warm, rainless days followed by cool, wet nights. It affects roses in all parts of the United States.

Symptoms

• New leaves may curl or twist, and the shoots will appear badly distorted.
• The top surface of the leaves may seem natural, but there's fungus growth on the underside of the leaves.

If you live in an area where this rose disease occurs, don't place roses in shaded spots.

Black Spot

This rose disease also affects other plants, although roses are the primary target.

Black spot spreads rapidly in moist or humid, warm climate. Disease spores are broadcasted by rain and irrigation.

Symptoms

• Lower leaves of nonresistant plants become covered with brownish-black spots; finally the leaves yellow and fall off.
• Complete defoliation of the rose bush in a period of weeks.

Suggestions

• Don't wet your rose bush foliage. Use drip irrigation instead.
• Prune the plant to permit good air circulation between branches.

If this page was valuable for you, please share your new knowledge. Click Like...