Diseased knockout

My disease resistant knock out rose has ceased resisting. What to do???
diseased knockout, gardening
  3 answers
  • Douglas Hunt Douglas Hunt on Sep 07, 2013
    It's hard to tell from your photo, but is there sort of a black film on the leaves? If so, that is probably sooty mold, caused by some type of suckering insect. Could be rose leafhopper or aphids. The good news is that it doesn' hurt your roses that much. Dispose of all the foliage when it falls in the winter. Next season, keep an eye out and use a commercial insecticidal soap if you sees signs of either.
    • Catherine Smith Catherine Smith on Sep 08, 2013
      @Douglas Hunt is right. Looks like a moderate fungal problem and given the amount of rain we've had this year it's not surprising. Easily fixable with some extra TLC. Clean the area around the roses throughly to remove any diseased leaves etc. Sprinkle some corn meal over the roses and the growing area to act as a fungus suppressant. Spray the plant with insecticidal soap either the commercial type or homemade, there are plenty of recipes for that on the web. And give this baby some organic fertilizer, ie worm castings. I am an organic gardener, and no fan of Bayer's chemical junk stuff. You want to encourage the microbes in the soil to reproduce to help your plant grab all the available nutrients. Chemical fungicides,insecticides and fertilizers kill those microbes and don't do the worms much good either. If you feed your soil rich organic matter it helps your plants to get long and strong, so they are much more resistant to both disease and insect pests. Knockouts are tough, so if you do the TLC now, you should be rewarded with a much healthier rose bush in a short time.
  • Kim Kim on Sep 08, 2013
    Bayer Advanced 3 in 1 Insect, Disease, and Fungus Control is a systemic liquid that you mix with water and pour on the base of the plant. I've had good success with this on Nearly Wild roses and think you'll also get good results. If you apply it in the spring as soon as the roses start leafing out, and repeat every six weeks, your roses should be healthy and insect free. As Douglas and Catherine have mentioned, do clean off infected foliage and dispose of it.
  • Anna Marie Gustafson Anna Marie Gustafson on Sep 08, 2013
    I trim off affected leaves...and there is something going around affecting roses and knockout roses as well this year. I heard it is good to cut back and dead head--unlike what folks said to do with these mostly carefree florals. I always cut back and dead head mine--no disease at all on mine this year and they are in their third main bloom now.
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