And just to make sure how often should I apply? And just spray infected areas or the whole plant?
The recipe formula mentioned is the original. The member who developed it has toned it down a touch but I still use the strong version just to get the job done as quickly as possible.
I would be recommending doing a spray at least once a day for 3 days. Spray everywhere you can from top to bottom, both sides of the leaves and even the buds. If it rains then spray again after the rainwater dries off. After the first 3 days of spraying I will spray every 3 or 4 days to kill off any new mildew that is still too small to be seen.
Two things will happen. One is that the citric acid kills the mildew within minutes. Where the spots of mildew were there often is a mark left on the leaf, kind of a white-gray color which is about impossible to rub off. Some of it is dead mildew and some is the damage done to the leaf while the mildew roots were attached. Those spots will stay and after awhile I have started to ignore the old spots and just look for the new spots showing up.
Spraying the buds might, and I mean it might, cause some of the stigma/pistils to pick up an off color. But, the plant continues to grow the buds and produce new stigma. Plus, the mildew is really good at being hidden inside all the little nooks and crannies in a bud which is why I spray them as part of my treatment.
The other thing that happens is that as the spray dries it leaves a coating of tiny citric acid crystals on the surface of the leaves which is an inhospitable environment to any new mildew spores that land there. It is often enough to repel the new spores from starting to grow.
Some people will get all excited and say that the drops of spray will cause spotting problems in the sun but no one has been able to prove that. There have been studies and experiments and the results are that it does not happen. No horticulture or agriculture universities or research centers have been able to cause the spots. We find anecdotal comments from people but they are often repeating something someone else said. None of the attempts to prove it with research has worked.
Plus if the water caused spots or burns in the leaves then why are thousands of farmers running their irrigation systems during bright sunny days?
