Aptly observed by Carol at May Dreams Gardens, certain things are missing so far this summer. In my garden, powdery mildew is conspicuous in its absence. In the past it has descended on my garden early in the season, around June (when it murdered the monardas), and later, in August (last year in the aster attack).
But I'm not letting down my guard. We had months of soggy weather capped by deluges a couple weeks ago; now it hasn't rained in over a week (10 days? Almost two weeks? I lost track). I'm concerned that these adverse conditions could give the dreaded mildew an opportunity to maim the confused and struggling plants. So on the advice of some extremely helpful readers/bloggers, I am applying the proverbial ounce of prevention.
I have complained about my battles with powdery mildew in the past, and based on the comments from that post I have devised a little experiment with my new monardas (M. fistulosa) and smooth blue asters (Symphyotrichum laevis).
Garden Girl did some research and discovered that a milk/water mixture is recommended for mildew problems. I took a one quart spray bottle and made a 1:3 mixture of milk and water. I used 2% milk. Here's a look at a milk-mixture-sprayed aster.
I also sprayed one of the monardas with this mixture.
Gail suggested a recipe she learned courtesy of P. Allen Smith. I whipped it together and sprayed it on a second aster and a second monarda.
(This aster has ominous brown spots, now coated with dormant oil mix. My apologies for the harsh afternoon lighting.)
In one gallon of water, I mixed 1 heaping tablespoon of baking soda, one tablespoon of vegetable oil and one teaspoon of dish soap.
(Here is the monarda with an oil-illuminated spider web in the bottom left.)
Of course, any experiment must have a control, so I left my third smooth blue aster un-sprayed, as well as my other two monardas. What will I learn? Well, it could be a lot or nothing at all. Maybe one mixture will prove effective and the plants sprayed with the other will succumb to the mildew. Maybe both sprays will help and the controls will go down. Maybe every plant will survive unscathed because powdery mildew never gets near my garden this year (yeah, right). We'll have to see what happens!
(Milky monarda with spider web. Both mixtures look similar when sprayed, as the soap resembles the watered-down milk.)
On a side note, the baking soda-oil-soap mix was recommended to prevent insect damage, which is also a problem here. The asters are being eaten by a rabbit, but the monardas are suffering from some insect pest, I haven't figured out exactly what (likely earwigs since japanese beetles have been nowhere to be found). So I will also be watching to see if this "dormant oil" application cuts down on the bug damage!
And just for kicks, here's a gratuitous picture of my astilbe, which is blooming for the first time in two years! It's proof that for every challenge in the garden, there is another reward waiting!