Mildew?

11 years ago

Over the last week or so, my Mexican primroses have become covered with a silvery coating, which I assume to be some type of mildew. They are in a bed that is mostly shaded, but gets full midday sun. I also have a large aloe, dwarf tropical bird of paradise, and dwarf natal plum in the same bed. The natal plum looks like it has a few leaves that may be affected, but the others plants don't seem to have any. Everything still looks healthy. Does anyone have any experience with this? How can I get rid of it before it kills everything and/or spreads?

Featured Answer

Phil Peck

11 years ago

I have used the 'baking soda, organic soap (like Dr. Bronners), oil (I use a Summer oil rather than dormant oil-More effective and less likely to damage). Sometimes I omit the soap as the Summer oils contain a surfactant already. Very easy to use and safe.

My other goto for non-edibles is a 'sanitizing rinse' I buy at Smart and Final. It's used widely as a bar rinse. The active ingredient is a quaternary ammonia. Quats are amazing virucides, bactericides and fungi/mold killers. They are USDA approved for use in slaughterhouses. The rinse from S&F is cheap and safe for most anything. As a retired chemist, I worked with the leader in producing then years ago. I have used quats occasionally on severe infections on edibles like tomatoes. I have used it as a soil sterilant after a Tobacco Mosaic and Fusarium outbreak in veggie gardens. It breaks down quickly in warm weather. You do have to be very careful to get the good guy cultures going again. 1 Tbs/gal is the use rate.

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Comments (6)

joncongaroo
11 years ago
Looks like powdery mildew to me. This might help: powdery mildew control
LeslieM peoria az
Original Author
11 years ago
Thank you! According to thatt article, it looks like I don't have to worry about it spreading to other plants, and since its ready to bloom and still looks healthy maybe I'll just leave it for now and pull it all up after it finishes blooming. I saw a spray that is supposed to kill powdery mildew, but it included an insecticide and miticide. I don't want to go all scorched earth on my planting bed, so I left it on the shelf.
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grant_in_arizona
11 years ago
Definitely powdery mildew. Make sure the plant isn't getting watered from overhead often--that definitely encourages powdery mildew. I like your approach; let it bloom and then either pull it or hack it back afterward. Great article, Jon, I LOVE that gardening show (on PBS). Let us kinow what you do and how it works out, Leslie. Happy gardening!
LeslieM peoria az
Original Author
11 years ago
Never gets overhead water. I throw the hose on the ground and let it trickle in so it gets a good deep soak, then it usually gets pretty dry in between waterings.So far everything seems pretty happy with that, except for my pigmy date palm that did great for years, and then up and died on me last year.
grant_in_arizona
11 years ago
Interesting! Good that you're not over head watering it. I noticed a tiny bit of mildew on some desert penstemons in my garden. They'll either get over it, croak, or get pulled, hah. Keep us posted, happy gardening!