1. Good Organic Gardening - January-February 2016

PLANT HEALTH | Disease distress
Sooty mould on an orange — a
telltale sign that there are other
pests infesting the tree, more
than likely scale
Make sure you are giving your plants the
right growing conditions with the required
hours of sun a day and good airflow. This
will help prevent fungal problems.
Powdery mildew on silver beet
Rust spores starting on the
underside of frangipani leaf
Powdery mildew
This fungal disease attacks a wide range
of plants and spreads like a white or grey
powdery mould on the leaves, stems and
flower buds.
Powdery mildew is an aggressive fungal
disease that can easily kill smaller plants and
set back larger specimens as it affects the
plants’ ability to photosynthesise.
Plants commonly attacked include
zucchini, squash, mustard, mint, roses,
hydrangeas, peas, gerberas and more. It can
appear because the plant species is being
grown in too much shade, there’s insufficient
airflow, the weather is cool and humid,
especially at night, or the plant is stressed
due to being grown out of season or having
inadequate nutrition and/or water.
Control
Spray plants as soon as possible with a
fungicide such as Eco-fungicide. This
fungicide is curative as well as preventive.
Spray susceptible plants with a solution
of one part full-cream milk to nine parts
water — particularly effective before
mildew appears.
Wettable sulphur can also be used under
organic certification.
Foliar sprays and in-ground applications
of seaweed will strengthen plants’ cell
walls and make them more resistant to
mildew attack.
Be sure your plants have good airflow.
Don’t water overhead, especially at the
end of the day.
56 | Good Organic Gardening