How to Overcome Fungus Diseases in Roses

The vast majority of rose diseases are caused by fungi. Regardless of which nasty fungus is attacking your roses, the treatment is pretty much the same: Cut off the affected parts of the plant and destroy them. To avoid spreading the disease, dip your shears in rubbing alcohol or peroxide after every cut. Then, to get the plants back on their feet, follow this routine.

Things You'll Need

• Well-cured Manure Or Commercial Organic Rose Food
• Pruning Shears
• Alcohol Or Peroxide
• Nondetergent Dishwashing Liquid Or Canola Oil
• Baking Soda

Instructions

1. Water the soil, not the plant. Moisture that clings to leaves, stems and flowers is an open invitation to fungi.

2. Keep the beds clean. Pick up and destroy plant litter as soon as you see it, especially at the base of the plant, where fungal spores thrive.

3. Cut off odd-looking leaves or canes the minute you see them. Then burn them as soon as you can or toss them out with the weekly trash. Don't add them to the compost pile, or you'll be asking for more trouble.

4. Prune with a vengeance. Each year, cut out all diseased or damaged canes, and any canes more than three years old. (Vigorous, new wood is far less vulnerable to diseases--and to pests.) Aim for a structure that lets air circulate to all parts of the plant, especially to the bud union, where new canes develop.

5. Be careful when you're working or playing around rose bushes. Nicked or broken canes are open doors to fungi.

6. Feed the plants heavily in early spring and again just after each big flowering. Roses thrive especially well on large quantities of well-cured manure.

7. Spray once a week with this fungicide developed at Cornell University: In 1 gallon (4 l) water, mix 3 tsp. baking soda and 1 tsp. nondetergent dishwashing liquid (such as Ivory) or 1 tsp. canola oil--not both.

8. Reduce fungal woes by planting disease-resistant varieties. You'll find them identified as such in garden catalogs, especially those that specialize in roses. (Bear in mind, though, that no rose--or any other plant--is guaranteed to be completely trouble-free.)

9. Keep in mind that fungi thrive in damp, humid weather. Roses growing in Seattle or Atlanta will always be more prone to problems than those in Tucson or Palm Springs.

Tips & Warnings

• With organic treatments, such as the Cornell fungicide (see step 7), the key to success is consistency. You need to spray every week without fail.