Saturday, May 26, 2012

treating powdery mildew

Early this spring we planted pole beans in the greenhouse, and we were just starting to harvest.  The beans were delicious: crunchy and just sweet enough to eat them raw straight off the vine. We went away to the beach last weekend, and took a big bag of beans with us for road trip snacking.  Four days is ages in bean years, and we expected a bounty when we got home.

But sphaerotheca fuliginea got the best of our plants. Sphaerotheca fuliginea is a jerk-face and a powdery mildew that affects beans. I should have taken pictures, but it looked kind of gross (and who wants to document their giant failures)? By the time we caught it, it was too late to treat, since the (non-toxic) suggested remedies are really just prevention tools. We were able to salvage the beans that were ready for picking but had to clear out the plants, because the leaves were already yellow and dying. Apparently this mildew thrives in contained gardens, so our greenhouse was heaven.  For the sake of everything else planted there, I'm thanking the good Lord who makes the garden grow that powdery mildews only affect specific plantssphaerotheca fuliginea for beans, erysiphe lycopersici for tomatoes, erysiphe pisi for peas.  (Mildew better not even think about my sweet snap peas!)

Next time I'll be ready. There are lots of natural preventers that sound cheap and not too hard. Most are teas, which makes this more fun to discuss with a British accent. Who doesn't love a good cuppa:
  • Compost tea, not to be confused with your evening chamomile.
  • ACV tea: Apple Cider Vinegar is also an acidic fertilizer.  1-2 TBS of apple cider vinegar in a gallon of water, sprayed on plant leaves (but in moderation: too much could kill the plant, too)
  • Corn meal tea: The cornmeal should be dissolved in water (1 cup : 1 gallon) and then should stand until it has a yeasty, sweet smell. It should then be strained and sprayed onto the plants starting when they reach their second leaf stage. Since I'm the lazy type of gardener, apparently you can also sprinkle cornmeal straight on the base of plants, although this is probably less effective. (Side benefit: corn bread!)
  • Garlic tea: made from several cloves of garlic steeped in a gallon of water.
  • ...and it's not tea, but neem oil and jojoba oil are also reportedly useful (no more than 1 cup per gallon of water.
As a bonus Reader Rock-Out Challenge, would someone please rewrite the Aerosmith classic: "Don't Wanna Miss a Thing" to cover powdery mildew prevention? Thanks.

even after ACV, and the garlic tea that's on your leaves, I'll still eat you, babies, 'cause I don't wanna miss a bean...


  1. I read this just after crushing some garlic cloves and setting them in mineral oil to steep overnight. (Those tomato aphids better start planning their funerals, 'cause tomorrow they will be dead buggers - although not with a British accent.) Achaa for your yummy beans, though. I feel your pain as I look at my minimal basil harvest (cut way back because of basil bad guys.)

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