had a lovely display from my bedding dahlias, but now some are coming
down with a bad attack of mildew. Any tips for stopping its spread?
this time of year a wide range of plants show symptoms of attack
by powdery mildews - a group of fungi diseases that all have similar
symptoms. Late in the season, when plant growth is slowing down
and the disease has spread to form large whitish patches or covers
entire leaves, it's really too late to do anything. But if you spot
the problem early enough in the season, when there are just a few
small white powdery spots on the leaves, spraying with a fungicide
such as Bravo, Super Sulphur or Nature's Way Fungus Spray will help
reduce its spread.
Unlike most other fungal
diseases, it tends to be worse in dry conditions, so regularly watering
the foliage and keeping the soil moist will help. Weekly sprays
of a teaspoon of baking soda in one litre of water plus a few drops
of dishwashing detergent have proved to be a useful deterrent and
some gardeners swear by regular applications of fish fertiliser
to the leaves.
Next year, be on the
lookout for first signs of the disease and act early - or take precautions
before it shows up.
Gardener, Issue 168, 2005, Page 24
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.