Hi DAve,
It does look like PM to me. I have used Lysol on a few plants that had it and it did get rid of it. Just be aware that the spray will kill any blossoms on the plant. I have found the most effective method of getting rid of PM is to keep air circulating around your plants. I have a ceiling fan that runs 24/7 and has been on for over 13 years. When the lights are on I keep a fan blowing in the direction of the plants at a low speed. With all this happening I haven't seen PM in a long time.
Fred in NJ

Hi, Dave,

Yes, that sure looks like powdery mildew. When I get it on a plant, if it is just an isolated area or the plant is in bloom, I spray the lysol into the cap so I have the liquid. Take a q-tip, dip into the liquid, and 'paint' the affected area. If it is the whole plant, spray from a distance so the spray isn't quite so cold. And yes, it will damage the blossoms.

Barbara

I hadn't heard of using Lysol. When I see any powdery mildew, I just give the leaves a good rinse with warm water from the kitchen sprayer each time I water. Afterwards I use a napkin to dab out the crown and any big droplets. A few rinses and it's gone, especially if I keep the plant a bit warmer than it had been.

People who keep their collection on wicks-mats-trays setup - usually have Physan as part of their water preparation to control the algae. Physan is actually a pretty good fungicide. You can read the label -- something like a teaspoon per gallon - recommended for PM control.

The growers who had PM problem before - need to start a prevention treatment - neem oil spray works wonders as a prevention, not so good as a control of a full developed case.

IMHO - it very much depends on a setup - Fred resolved the issue by changing his conditions and creating an air movement in his grow area.
If it is the same area you grow and you didn't install a fan recently - you will be getting PM every spring and fall no matter what - and neem oil spray every 2 weeks probably is a good solution.

As far as I know the PM is a result of warm days cold nights contrast - when the temperature goes down, the humidity goes up and at some point we have miniscule drops of dew appearing on leaves - which helps PM spores penetrate the leaf "skin". It coincides with the time we are about ready to turn the furnace off for the summer. My best guess is that a fan makes the air move and prevents these cold dump pockets in a room especially on a lower shelves. The problem is if several plants are infected - they produce so many airborn spores - your whole collection goes down the drain. You need to stop PM at the very beginning - wash the infected plant, remove the affected leafes and flowers, spray it. Treat the whole collection. Some plants are PM magnets. You can drench them in Lysol - and PM still comes back.

I think it is time to spray...

irina