WHAT TO DO ABOUT POWDERY MILDEW
Rinse Spores from Leaves
Leaf washes can be effective at killing and removing powdery
mildew spores. Powdery mildew spores don’t germinate from
surface water on the leaves, so spores can be washed off all
the way to the day of harvest. Allow adequate time for the
leaves to dry so other fungi aren’t encouraged to form.
Spray Yucca Extracts
Yucca, a natural surfactant that can be safely added
to any foliar spray, is said to have natural fungicidal
properties. Instead of the water beading up on the waxy
surface of the leaves, the spray will spread out in a thin
film for better coverage.
“
At the first sign of powdery
mildew, carefully remove
infected leaves and discard
them from the growroom.
”
Add Silica
When plants are under attack from
powdery mildew and other fungi, they
mobilize silica to the point of infection,
which forms a callus around the
surrounding cells. The silica will help
prevent the disease from spreading.
Spray with Potassium Bicarbonate
Potassium bicarbonate additives can help kill
powdery mildew spores on contact, while also
increasing the pH level on the surface of the leaves. A pH
level above 8.3 on the surface of the leaves discourages fungi.
Use Botanical Oils
Alternate Treatments
Some horticultural oils and essential oils improve the
effectiveness of fungicidal sprays, just be careful not to
combine oils with sulfur treatments.
If you must use fungicides, it’s always best to follow up with
treatments that have different modes of action. If you use the
same active ingredient too many times, the treatment may
start to lose its effectiveness over time.
Treat with Biologicals
Source Quality Plant Stock
Some micro-organisms produce natural plant-protection
agents against pathogenic fungi. Inoculate your soil with a
good “maintenance” blend of plant growth-promoting rhizobacteria, and occasionally spray your plants with products
containing streptomyces lidicus or other beneficial microbes.
Apply Systemic Fungicides
Most organic controls for powdery mildew only help slow
down or contain the fungi, but systemic fungicides kill
powdery mildew at the source. Make sure the chemical
fungicide is rated for consumable crops and carefully follow
all application instructions.
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Maximum Yield USA | November 2015
Choose seeds and clones from well-respected breeders. The
best breeders choose stock plants that are naturally resistant
to powdery mildew and other pathogens, and do their best to
maintain a disease-free environment.
Once a crop is infected with powdery mildew, it is always a
battle to knock it down and keep it under control. The best
defense is growing strong, healthy, disease-resistant crops.
If you provide your plants with a healthy environment and
feed them a balanced blend of nutrients and organic biostimulants, you can help your plants reach their true genetic
potential. It’s also a lot more fun.