Roses: A Guide to Care and Treatment
Commonly known simply as The Black Spot, the small circular black spots with fringed edges cause leaves to yellow, and being that they are signs of a disease. Leaving the affected leaves on the plant can allow the disease to spread, so you should remove the infected foliage and pick up any fallen leaves around the rose. Artificial sprays may be used to prevent or treat it.
If you notice that the leaves on your rose plants start to curl and turn purple, you should check the leaves and canes for a white powder, as these may be signs of a fungal infection known as powdery mildew. Spread by the wind, it may cause the canes to become stunted or malformed. Treat using Funginex or Benomyl.
Known as rust, this disease is characterized by orange-red blisters that turn black in fall. It can survive the winter and will then attack new sprouts in the spring. Collect and discard leaves that are infected in fall. A Benomyl or Funginex spray every 7-10 days may help.
If you notice that the leaves and flowers on the plant are stunted or malformed, then chances are there are spider mites on the plant. They are tiny yellow, red or green spiders found on the underside of leaves where they suck juices. The application of Orthene or Isotox may help in treating this infestation.
If you see small red, green, or brown bugs under your plants, you have an infestation of aphids. Tell-tale signs of an infestation are mottled leaves and small white webs underneath the leaves. Oft-times the bugs will be found clustered under leaves or near the tender buds, where they will suck the juices. You can use Diazinon or Malathion to clear the infestation.
If your flowers appear deformed when they open, or if they don’t open at all, you could have Thrips at the source of the problem. The slender brown-yellow bugs with fringed wings can also be found sucking away at the juices of the leaves. Use Malathion and Orthene to treat.
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