I have a cherished coreopsis that did spectacularly this summer, but then started looking sickly. The leaves are silvery gray and the flowers have stopped coming. I'd hate to lose this plant. Here's a photo:
Thanks.
-F
Kinda looks like it is coated with powdery mildew, though I've never seen it get THAT bad. If that's not a powdery coating then it's not powdery mildew. But if that IS what it is, it won't necessarily kill the clump if it was otherwise going to perennialize. But you'll have to clip the infected plant to the ground, discard rather than compost the infected leaves, clean up the area super-well, trim back surrounding plants to permit better air circulation & better sun exposure, & water from the ground rather than with overhead sprinklers. Spray any autumn regrowth with dilute milk to keep the powdery mildew at bay, & in spring when the clump returns in earnest, give it another milky spraying, which works far better than do chemical fungicides on powdery mildew.
-paghat the ratgirl
Thanks Paghat! Looking around my garden, it would appear that I have more of this stuff on my boston ivy. Where does this stuff come from and how is it spread from place to place in my garden? Is there any way to eradicate it once and for all?
-Fleemo
Thanks Paghat! Looking around my garden, it would appear that I have more of this stuff on my boston ivy. Where does this stuff come from and how is it spread from place to place in my garden? Is there any way to eradicate it once and for all?
-Fleemo
Powdery mildew likes especially perennials & deciduous shrubs & vines, though it's not totally adverse to certain evergreens, such as euonymous. It gets started best where air circulation is poor & plants are watered from overhead, where plants are too shaded or crowded, or generally stressed in imperfect conditions. Mildew spoors are all around us all the time. They tend to take hold on plants that are for some reason stressed, or which are notably susceptible, like phloxes & beebalms.
Clipping & pruning for better circulation & to remove infected leaves, & watering the ground only, is often all it takes to control it. If it only gets to plants in autumn it may only mean cutting things back that were going to drop leaves or die back soon anyway. If it only reaches the lower leaves of a deciduous shrub late in autumn, it's not worth worrying about, except to clean up the fallen leaves in order to dispose of the spoors.
Fallen leaves & clippings should be discarded, not composted or kept for sake of leafmold, as the spoors are harbored in leaf particles & end up in the soil through winter until time to start up again on the plant the following year. Neem or other horticulatural oil can be sprayed on the ground around infected plants, as that will bind the mildew spores to the soil. New spring foliage can be sprayed with dilute milk which keeps the mildew from getting restarted.
-paghat the ratgirl
Once again, Paghat, thank you for sharing your wisdom. :)
-Fleemo
Powdery mildew is ubiquitous in drier climates where overhead watering is common - but usually only in late spring and early fall, when the nights are cooler (into the 40's). It has always fascinated me that in the East, with its high relative humidity, and mold and mildew so common that the smell of it is found in nearly every building, bread is slow to mold, whereas in the dry climates of the west, bread without chemicals can get moldy within 3 days after opening the package. My theory is that the mold and mildew spores are "looking" for a moist environment to latch onto, since the air is too dry to support them, which, in the west means they will latch onto watered foliage and bread.......
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