Help ID this plant malady

Maybe its powdery mildew, maybe not.. I've seen powdery mildew on my cucumber and squash plants but it looks powdery, while this stuff looks stained, as if it were bird droppings, but its not, most of my plants have a couple leaves with a stain or two, and i promptly remove them.

The 2nd photo shows a pretty good example of something, i think its the same thing as the stains in the first pic, you can see the grey stuff converged at the center of the leaf.

Ive had problems with bud rot last year, buds turning brown. Its outdoor not super confined and we get breezes, its not high humidity, i am in the east bay in the Bay Area, about a couple miles from the bay, moderate temps. I do not wet the plants at night, unless i foliar the plants with compost tea or neem seed meal/insect frass every 3 weeks or so.

I've done a number of compost tea foliar sprays this season and i am really hoping to avoid bud rot, but seeing this stuff pop up again, as it did last year, worries me! Any advice on an ID and/or organic treatment? The plants otherwise look fine and are doing well, IMO.

WPM / White Powdery Mildew

Remove affected leaves as best as possible (bag and throw away, I dont even compost these even if people say its okay)

Spray with 3% hydrogen peroxide 2x weekly until gone.

Promote airflow by defoliating as necessary and if possible, get a fan out there.

Yeah. Last year i had a lot of leaves that i let accumulate around the edges of the "yard" and i allowed to rot to help the soil. Some of it probably was wet last year and must have created some spores...I was sure to clean all that up this spring to avoid the WPM!

But, I have a lot of fruit trees in the space and immature persimmons that fall and rot, I didn't get rid of the all the dropped fruit until a couple weeks ago. Probably doesn't help. Live and learn !

dunphy
I have a question about your suggestion to remove the powder, when you mention spraying the plant, is that only the effected plant or all plants in the garden?.

Thanks

To me it doesn't look like wpm it looks like dry water spots. Ive seen it before.

I get what you are saying about dry water spots! I think there is truth to that happening on some leaves, but that 2nd pic is some sort of fungal activity. I also know i had bud rot last year, for whatever reason, and im definitely not experiencing extreme enviornmental moisture or temperature factors but its starting from somewhere. I think ill try to attach with the peroxide, i don't have any other great options.

@garybo

I spray the whole crop down if I find it, but i only got a legal op going right now with less than 12 plants, so it only takes me about an hour to hit everything thoroughly, and the h202 is cheap enough where hitting everything isnt an issue of cost. The way I look at it is those spores could've gotten anywhere, and instead of doing it all over again in a day when I find some more on another plant, I may as well just mix up a big batch in the sprayer and go to town. Now, if I think I just caught the beginning of it, or didnt have time or something, or wanted to avoid spraying for some reason, I would just grab a paper towel and wet it then blot the area thoroughly making sure to get under the leaves as well, Mostly Ill find it on a fan leave that I can afford to lose, so ill carefully just cut it out of there, and try to not bump into anything, then throw it far away from the plot, skip composting anything with disease/mold/etc... Then give the area a good spray as well as a once over of the plot, then just try to be more vigilant moving forward.

Good luck.

Lost coast plant therapy, never used it for that problem but it says it works for that. And you can spray it up until the day of harvest.

It's not cheap but compared to losing a crop it's not that bad I think this bottle cost me like 80-90 bucks.

@Apalchen
Bro please dont buy that stuff... Look at the ingredients list... thats what theyre charging you 80-90 bucks for? soybean oil, water, Rubbing alcohol soap and peppermint oil.. Shit I was just talking about how the cannabis growing community is overrun with these shitty companies marketing products to growers for ridiculous amounts of money... Complete rip off my friend Im sorry..

Just buy a gallon of this for 10 bucks and call it day..

dunphy said:

@garybo

I spray the whole crop down if I find it, but i only got a legal op going right now with less than 12 plants, so it only takes me about an hour to hit everything thoroughly, and the h202 is cheap enough where hitting everything isnt an issue of cost. The way I look at it is those spores could've gotten anywhere, and instead of doing it all over again in a day when I find some more on another plant, I may as well just mix up a big batch in the sprayer and go to town. Now, if I think I just caught the beginning of it, or didnt have time or something, or wanted to avoid spraying for some reason, I would just grab a paper towel and wet it then blot the area thoroughly making sure to get under the leaves as well, Mostly Ill find it on a fan leave that I can afford to lose, so ill carefully just cut it out of there, and try to not bump into anything, then throw it far away from the plot, skip composting anything with disease/mold/etc... Then give the area a good spray as well as a once over of the plot, then just try to be more vigilant moving forward.

Good luck.

Click to expand...

Great advice, thanks dunphy.

I sprayed down with a bottle of hydrogen peroxide and a little bit of the dr bronners organic peppermint soap that i already had in the shower, ha.

Havent noticed any new spots, thanks dunphy! Except for the ash that is collecting on my plants due to these fires

I may spray down again but i'd first like to know of any detrimental effects of H2O2/peppermint soap on buds, the plant pictured is the most far along in the garden, probably 4-5 weeks to go, not sure since it is a new cross.

Np, Glad I could help,

My only concern with spraying it on buds would be the same concern as getting them wet, 3% peroxide is 97% water, the peroxide itself wont harm the bud at that concentration, In fact there are people who wash their buds with it after harvesting theyll wet trim, and dunk them in a bucket of water/peroxide or lemon juice for its antibacterial properties, or baking soda, etc. So if your worried about it hurting the buds its fine at that low concentration, But I would avoid it as best you can at least getting the dense buds wet unless they have enough time to dry out... But even if they did get wet like that, its better for it to be peroxide vs. rain at least because it will help keep any fungal activity down.

Ive sprayed weekly, and have gone from having a worse outbreak than you had, to nothing, and finishing out the season never seeing it again. Like I was saying in the other post, if you see any area that has a bunch you can give it a little more attention and/or blot it with a wet paper towel instead of spraying.

Good luck! Plants look great.