Roses have this nasty reputation for needing lots of fussing and chemicals to thrive. More disease-resistant varieties are available, and that’s great if you’re adding a rose to your garden. But what if you already own a few?
I inherited a garden with several dozen roses. Some are shrub roses, but most are hybrid teas, the kind most of us picture when we think “rose.” Last season the leaves on these high-maintenance beauty queens were covered with – horrors – black spot.
I’ll use a chemical if I absolutely have to, but I’d rather not. So I was thrilled to see a list of chemical alternatives from The National Gardening Association. Here’s what they suggest:
Neem oil: Controls black spot, powdery mildew, rust and many insects and mites. Made from a tropical tree. The downside: It can harm the good bugs like bees.
Bacillus subtilis: A bacterium that attacks fungi that cause diseases such as powdery mildew and black spot.
Sulfur-based fungicides: Can help control fungal disease.
Homemade brew: Baking soda, horticultural oil and water can help control powdery mildew. The recipe: 1 rounded tablespoon of baking soda and 1 tablespoon of horticultural oil mixed with 1 gallon of water. Spray on a weekly basis. More effective commercial solutions made with potassium bicarbonate are available.
Anti-transpirants: These are normally used to protect plants from drying out. May help control fungus by coating the leaves and preventing fungal spores from infecting the leaves.
For pests, blast aphids with a jet of water from the garden hose. The downside is wet leaves can contribute to plant diseases such as black spot, so do it early in the day so leaves can dry.
Bt (Bacillus thuringiensis): Kills only moth and butterfly larvae, but it doesn’t discriminate between the pesky caterpillars and the desirable butterflies.
Horticultural oil: Controls many pests including spider mites, whitefly and aphids.
Insecticidal soaps: One of the least toxic options for fighting soft-body insects such as aphids, leafhoppers, mites, thrips and whiteflies.
Keeping roses beautiful involves a lot more than what you spray on them. A healthy, strong plant will do a better job of fighting diseases and pests. I’ve put some rose care tips on my blog online at www.heraldnet.com.
What I’d like to know is how effective are these less toxic treatments? If you’ve tried these, tell me how they worked by visiting my blog and posting a response. You also can e-mail photos of your garden and your rose care tips to me.
Also, we’re interested in writing about coleus. If you’ve fallen in love with this flower, please contact me.
Reporter Debra Smith: 425-339-3197 or dsmith@heraldnet.com.
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