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Is Powdery Mildew Curable, or Does it Come Back Like Apple Scab?

4 years ago

Hi all,

I was wondering if powdery mildew is curable? Or, is it like apple scab where once a shrub gets it, it will always come back each year?

Thank you.

Featured Answer

gardengal48 (PNW Z8/9)

4 years ago

There are hundreds of species of powdery mildew, some very host specific, others much more generalized. One thing they have in common is that they tend to be quite weather related. Most appear late in the growing season when temps remain quite warm, soils are dry and the dewpoint high - those are ideal conditions for the incubation of PM spores. Cultural conditions also play a role - crowding, lack of good air movement, too much shade and poor garden sanitation can all contribute.

Is it curable? No. Will it come back every year? If the conditions are appropriate and you make no attempt to deter with preventative spraying, it could. But it is not necessarily a guaranteed phenomenon.

btw, apple scab is also very closely aligned to weather conditions. If not just the right combination of factors, that can also skip a season. Doesn't mean the plant is cured - just that the conditions were not favorable for the pathogen's development.

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Comments (7)

unclehippie
Original Author
4 years ago
Thanks, gardengal. If you were trying to grow a five foot tall privet hedge and the young shrubs became heavily infected with powdery mildew, would you dig them up and replace them with something else such as Hicks Yew?
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gardengal48 (PNW Z8/9)
4 years ago
I would :-) But then I dislike privet in any form....most are invasive to some degree, the flowers stink and the berries are toxic. And they are prone to a range of insect and disease issues.

Just not a very good plant :-)
unclehippie
Original Author
4 years ago
Thanks again, gardengal. It was a lot of work to plant them, but I don't want to be bothered spraying every year. I think part of the reason they got infected was that until about a month ago we had a large fence directly behind them; the air probably did not circulate too well.

I think a yew hedge would screen out the view of our woodpile better, but they are so much slower growing than privet, not to mention expensive (especially at box stores and nurseries).
ken_adrian Adrian MI cold Z5
4 years ago
you ought to link to the other post .... maybe i will later ...

plagues come and go ... and if i recall .. this is your first year ...

i guess i would give it a another year or two ... before i came to any conclusions ....

i would also add.. to my things in the other post [wood pile.. and fall cleanup] ... that this is a very good reason ... to avoid planting a monoculture ... the problem being.. when something happens... it happens to all of them ...

so one option.. would be to say ... remove every third one ... and interplant something other than a privet ... and as those grow to size.. keep removing more privet ...

also ... why 5 feet tall ... are you attempting a sight block.. or just hiding the wood pile ... with sight blocks.. you can often much more.. faster.. if you dont limit your planting to just at the property line ... a couple large trees between the house.. and the property line.. can block a lot more space/view ... .. than if it need all be done out at the line ...

ken
mad_gallica (z5 Eastern NY)
4 years ago
Reveal your location. This will help attract people near you to answer the question.
NHBabs z4b-5a NH
4 years ago
I also dislike privet for all the reasons GG48 mentioned. Even if they aren’t a pest in your yard, there is a high chance that birds will spread them to other areas. I remember removing privet seedlings from the garden as a kid and the nearest privets were several houses away.

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