The Q&A Archives: Rust & Japanese Beetles On Roses

Question: It seems no matter what I do, by mid-summer my roses have been decimated by rust and Japanese beetles. The plants are practically bare by the end of the summer. I have followed advice of all kinds. Now please tell me the best way to keep this from happening next year.

Answer: If I had a list of things that should be eradicated from the face of the planet Japanese Beetles would be at the top of the list. I get especially angry when I remember they weren't even in this country until 1916 when they "immigrated" here as illegal aliens. I have a problem with them also, here are a few things I am doing/plan on trying this spring. First, you can try to control the population of grubs in your yard that will grow up and be Japanese beatles. Japanese beetle grubs are best controlled by spraying beneficial nematodes on the lawn and garden area. These microscopic worm-like creatures attack only the grubs in the soil and not plants, animals or humans. Spray them in spring when the temerpatures are above 55F and you should see a difference this summer. You can buy the beneficial nematodes from, Gardeners Supply Co, 128 Intervale Rd. Burlington, VT 05401 800-863-1700. <br><br>The bad news is, all of your neighbors probably aren't going to treat their lawns so you are only reducing the population, not eliminating it and where Japanese beetles are concerned, if you grow it, they will come. Fortunately, some gardeners have had luck deterring them with repellents. Gardens Alive (5100 Schenely Rd., Lawrenceburg, IN 47025; ph# 812-537-8650) offers an organic, Neem-based repellent. It's important to apply it before beetles show up. If they show up anyway, and as a very last resort, you can try spraying the plants with a stronger synthetic insecticide as soon as you startto see damage. If you spray a strong pesticide, it is especially important you follow instructions and are very careful during application. Be sure to keep children and pets away from sprayed area. These pesticides do reduce the honeybee (and other "good" guys) population. It's a decision you will need to make. Also, I have found at least 1 variety of rose which Japanese beetles don't seem to like. I have the climber "Dream Weaver" and while they decimated my entire flower garden, they didn't touch that rose. Maybe it was a fluke, but I am hoping I am on to something. Now for the rust, unfortunately there is no way to completely control this disease. At the first sign of rust, pick off and destroy the infected leaves and spray with a fungicide (such as a lime-sulfur spray or 'Rose Defence'). Carefully follow application instructions specific to your plant, generally this is every 7-14 days as long as conditions are favorable for infection (moist, foggy, 55-75degrees F). Practice good garden sanitation: rake up and destroy all infected leaves, prune off and destroy infected twigs. Also, look for roses that are resistant to rust such as 'Garden Party'.

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