Powdery mildew - Rudbeckia hirta and soil

Chapel Hill, NC(Zone 7b)

I have a huge number of self-sown R. hirtas (originally wintersown). I love them when they are healthy (of course) and in prolific bloom. BUT - after a while some of them start wilting, flowers shrivel, stems and leaves turn light brown and sort of fuzzy looking. I guess that is powdery mildew?

I am going to pull them all out. Now my question is: does the mildew remain in the soil and if so what can I do to get rid of it. If there is something that I can use (preferably nothing too toxic), can I immediately put in vincas, or should I just leave only mulch in those spots?

Has anyone heard of using milk spray? See the URL below

http://www.gardenguides.com/779-using-milk-control-powdery-mildew-garden-pest-tip.html

Thanks for your ideas,
Clementine

Pretoria, South Africa

Hi Clementine,

I used some of the milk spray on my Dahlias, with some success, but, as soon as they look better, I forget to spray them, and one has to continue doing so to keep the mildew from returning.

Elsa

Chapel Hill, NC(Zone 7b)

Elsa, thank you so much for responding. I am glad to hear that the milk spray seems to work some. How ever, as you say, it is just like with loosing weight - you have some success, and then you think you can have ice cream again. It is the "sticking with the program" that is so difficult.

I went and bought a quart of skim milk. I have already pulled out many of the plants, and there are more ( it is so terribly hot here, I can't be outside much). When I am done, I will spray the ground a couple of times, perhaps that will do something good. Then I will mulch and plant perhaps some vincas, which do ok in the heat and drought.

Have you used it on zinnias?

My sister just told me that she used milk spray on tomatoes for early blight, but I am not sure how well she did with that.

Thanks again, good luck with your gardening

Pretoria, South Africa

No, I haven't. Will give it a try this year - I started some seeds this past week...

Good luck,
Elsa

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