Identification and damage
As you can see Mildew comes in a white powdery mycelia and spore growth that forms on leaf surfaces and shoots and sometimes on flowers and fruits.These are the fruiting of the fungus.
It can severely effect woody plants as young sapping which would dwarfed.
Downey Mildew thrive in temperatures ranging from 50 to 60 degrees wuth humidity of 90%
It can be recognized by only being specific to the leaves & not like its other relation Powdery Mildew which effect the stalks as well.
And require the opposite it needs free water and temperatures ranging from
60 -80 degrees to germinate.
Prevention is the only way with this I’m afraid :-
- Make sure that the air is well circulated either out doors or inside
- water the plant in the morning and in the evening if necessary.
- apply fungicide at the first sign of attack and remove and dispose of infected leaves
- As it wind blown and dependent on climate make sure that the plant is planted in the right environment & that there isn’t any other plant that is infected with it near by .
- Plant a species that is immune to it if possible for example Rosa rogusa or a
As Mildew seem to thrive in shady moderate temperatures ( esp Powdery Mildew) place plants in a sunny area with good circulation
Avoid over feeding the plants with fertilizer as this will make sappy growth .giving the plant an over head watering will wash of the spores and kill them in the soil
In severe cases when roses and other woody plants are infected spraying with fungicide will be the only alternative.
These are classified as :-
These fungicides are applied to new growth before mildew has a chance to get a foot hold.
These include :-
- Horticultural oils like neem,jojoba (read My article on neem oil )
- Powders like sulphur , potasium bicarbonate
- and Biological with serenade
For Mild to heavy infestation spray with the plants natural product ie Neem oil. Becareful never to apply a oil spray within 2 weeks of sulphur spray or it will burn the leaves.
Also never apply oil sprays when the temperature has reached 90 degrees
Sulphur sprays have been used for centuries and rather ironic that in the days of the smug plant diseases never appeared cause the sulphur was believed to keep it at bay
The best sulphur to buy are the wettable kind cause the dust can be toxic to humans
Although copper has been used for ages as an effective fungicide when it mixed with a another formulation like lime it acts a bactericidal thus killing off leaf spot and fireblight
Vitax Bordeaux Mixture should be mixed with water and then applied, without drenching, as a fine spray to both sides of affected foliage. The actual dilution rates vary from plant to plant and full instructions are provided on the product label.
Contrary to the myth Sodium Bicarbonate found in Baking Soda actually restricts fungus growth due to its alkalinity & there fore only useful as a preventive measure.
Also available to licensed applicators only is a fungicide containing potassium bicarbonate (e.g., Kaligreen).
Sprays of potassium bicarbonate can injure the plant, so use these products with caution.overuse should be avoided because of possible negative effects (sodium accumulation and alkaline pH) on the soil
Biological fungicides (e.g., Serenade or UK Myclobutanil ) are commercially available beneficial microorganisms formulated into a product that, when sprayed on the plant, destroys fungal pathogens. The active ingredient in Serenade is a bacterium, Bacillus subtilis, that helps prevent the powdery mildew from infecting the plant.
Myclobutanil is a triazole chemical used as a fungicide. It is a steroid demethylation inhibitor, specifically inhibiting ergosterol biosynthesis. Ergosterol is a critical component of fungal cell membranes.
These products have some effect in killing the powdery mildew organism but are not as effective as the oils or sulphur in controlling it.
- Powdery mildew disease and recent advances in indian context (slideshare.net)
- A Natural Way to Eliminate Powdery Mildew (kitchencures.wordpress.com)
- Powdery Mildew (boomerempowerment.com)
- Luna Fungicide By Bayer CropScience Receives MRL Approval for Crops Bound for Japan (prweb.com)
- Downy mildew threat to cucurbits and watermelons (thetandd.com)