I have had excellent results using milk, water and a little baking soda. Where i live big ole trees like maples, chestnuts etc get totally flocked with it. I ended up with my huge chestnut tree just white with mildew -- and it was upwind from my roses. It spread mildew everywhere- to my cherry, lilacs, roses -- i even had the weeds behind my ac unit all covered in it. I used the milk solution to kick it out of my rosebeds atleast. It's ugly but didnt really bother the rest. Google powdery mildew and milk and you'll see plenty of recipes and discussions regarding skim milk or whole, organic or not etc. I think i did 2 cups water, 1 cup milk (organic skim is what we keep in the refrig) and the soda amount was what they recommend if you make it with water. It's worth a try since its so easy and safe- you can drink it- LOL. My rockcress (aubrieta) grows this fuzzy mildew that literally billows off it when disturbed and i plan to try it on that thia year. (i read it was very effective in treating a peanut fungus like it).

Hi - In spring spray your gardens with 1 part skim milk to 9 parts water. Tests some years ago showed that this stops powdery mildew from forming - this has worked for me for years. This spring I didn't get around to spraying the gardens down and sure enough my monarda, asters, phlox, dahlias, lilacs and anything in the mint family got great coverings of powdery mildew! This also works wonders for keeping PM off grape vines. You can use only skim milk - it makes no difference using the higher fat content milk - except that it reeks! Here is the link to the original research in 1999. http://www.pioneerthinking.com/tv-mildew.html You can do a google search on this and find out more whenever you want. Cheers from Michigan Here is a link that might be useful: Powdery Mildew & Milk

It is interesting that most of the research on the milk has been done in Australia. Some now is going on in California among the grape growers. If it works like a wonder cure....sure is a nice safe way to zap powdery mildew. You are so right...makes a person feel a whole bunch better spraying foodstuff with milk or baking soda than with something that has a skull and crossbones on its label! The above link and other sources I googled indicate a 10% solution of milk. But I didn't read a lot of the google results....just four or five. 10% would be one part milk to 9 parts water. Sierra came across a 30% recipe. The only thing I found at 30% was when using Whey. Yup, they found milk by-products to be effective too. Interesting stuff. I wonder if milk would work on Black Spot on Roses? Here is another link.... Here is a link that might be useful: more on milk and PM

Digging up this post as BS is slowly taking over my new rose garden. First it was on one Emily Carr, now another Emily Carr, and now a miniature. No BS so far are Winnipeg Parks, Quadra, Rugela and Prairie Princess. But I have seen Winnipeg Parks infested at other garden centers.... I checked around today to see what was available, and this is what I came across: - the garden center I frequent said they dust "the Rose Doctor" on their roses to prevent blackspot. Contains Folpet - 5%, Malathion - 4%, Carbaryl - 5%. - other fungicide dusts I came across contained Captan Other fungicides also noted: - sulphur, liquid spray form - greenworks - powdered sulphur ("wettable?") - greenworks - lime sulphur - greenworks? - QST 713 strain of dried Bacillus substiis - Natria (by Bayer?) - copper sulphate in various sprays/dusts I also learned that anything systemic is not available in canada. I am currently testing powdered sulphur mixed with water, and also being vigilant in cutting off any leaves with blackspot and putting them in the garbage. I read bark mulch can be an issue. I have also read that cow or horse manure used instead of bark mulch can help as it acidifies. For powdery mildew, diluted milk, with frequent applications, has worked for me in the past on rosemary plants.