husband has cancer and because I don't want to use any chemicals
in my garden, I have been trying to manage my plants organically.
The roses were looking pretty good but over the last two weeks they
have been attacked by black spot. I'm picking off the worst leaves
and hoping for the best, but do you have any ideas for organic ways
to prevent black spot (and rust too, which I usually have to contend
with later in summer). Thank you very much.
spot is most prevalent in wet humid weather, while rust usually
is more of a problem later in summer when the weather is drier.
In your case the best way to minimise the effect of both diseases
(as well as powdery mildew, which can also be a problem on roses)
is a combination of good gardening practice and the use of organic
sprays. Try the following:
- In winter, when pruning,
collect up all fallen leaves and prunings - burn or put in the
rubbish, don't compost them.
- Make sure your plants
are well spaced or prune them to allow lots of air flow through
and around the plants.
- Before new growth
starts in spring, spray the plants thoroughly with a copper fungicide
such as Super Copper or copper oxychloride.
- During the growing
season, keep them well-watered and fed. Use a specific rose fertiliser
in order to avoid soft lush growth. And avoid wetting the leaves
- As soon as black spot
appears, pick off affected leaves to reduce its spread.
- For mildew and black
spot, try spraying during the growing season with an organic spray
such as Nature's Way Fungus Spray.
- Plant disease-resistant
varieties, like the Flower Carpet series.
Gardener, Issue 136, 2003, Page 35
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.