PM is freakin herpes for weed....you can control it but it always comes backkiss-ass
Powdery Mildew (PM) is a systemic problem coming from within an infected plant. What you are seeing (the white powderey looking substance) on the leaves is the flowering body of the fungus- the hyphae live within the plant. By the time you can visually identify the problem it's already well established within the plant. No external treatment (like sulphur) can fix the problem.
PM proliferates in shaded and low-light areas of gardens where the humidity is raised; obviously countering these grow room conditions will slow the spread but it won't truly eliminate the fugus from the plants.
The same is true for sulphur applications; be it from a sulphur burner or from a solution such as Safer's Defender. Sulphur will prevent the growth of PM where it is present on the leaf, but the PM still exists within the plant.... not to mention sulphur applications negatively affect the taste of the final product; it seems to concentrate on the resins and an experienced or trained palate will always be able to tell if there was sulphur applied to the plants from how the hash smokes. I don't recommend using sulphur on vegging for flower or flowering plants
There is a product called Meltatox that is designed for application on ornamentals which gets into the plant and actually kills the PM. You should not spray this on plants that are going to be put into flower, or are in flowering. However, IMO it can safely be used to treat your veg state plants to eliminate the PM from your stock. I would suggest waiting at least 4 weeks before taking clones to be put into a veg/flower cycle.
Of course the MSDS is available online and anyone considering using the product should completely read the label instructions to inform themselves about the factors involved, how to properly spray and what precautions to take, the product half-life, etc before considering using.
It does work IME, and can be used as a part of a integrated approach that not only deals with eliminating all traces of spores from the growroom, but also removing the fungus from the plants themselves. Having either infected plants OR a spore infected growroom will ensure the problem persists as one will infect the other.
I would remove the plants, clean the room with industrial greenhouse cleaner, and use a sulphur burner before putting the plants back in the room. Then separately cut back the mothers and sterilize with Meltatox. If the plants are for consumption I'd then wait a month before getting back on schedule to take clones and veg out for the next crop... any remaining Meltatox in the plants would be negligible.
This product is not for everyone and is not safe to spray on flowering plants for consumption. I only recommend it's use to those that will use it responsibly and make themselves aware of the MSDS information available before choosing to use it.
Sulphur inhibits the growth on a cellular level by interfering with biological processes opf the fungus this is also well documented on the scientific literature.
A higher pH spray does help to slow the fungal growth, but this is not the reason sulphur and potassium bicarbonate are used to combat PM.
this product works really good.....
www.greencure.net ....ODERLESS....up to 14 days inbetween aplications...ORGANIC...Can be used up to harvest.
