Powdery oak mildew

[MattyF]

I have a few hundred young oaks that have this , amongst hundreds more in a young wood and open spaces that over the years I’ve been planting.

They have all come from different sources but it seems that trees planted in 2021 are all badly effected , every single one intact and now they are crossing in to ones that have been planted a year or two after .. putting this down to they where infected in the nursery as they have looked rubbish from the start but it was almost impossible to get trees that year. 

Last few years I’ve put down the stunted growth and die back to frost damage but this year it was quite clear what it was. 
My question is if it’s treated in some way what is the best treatment... or should I this winter just remove the infected trees and burn them. 
im concerned as last year we planted a lot more than usual, they where high quality cell grown trees that have thrived with nearly 100% success and I don’t want them to get infected. 

[Peasgood]

My understanding of mildew is that it is a surface infection rather than one that enters the plant. Having said that the infected shoots are certainly a source for new infections next year and are best pruned, taken away and burnt in the dormant season to reduce that overwintered primary infection.

It also requires specific conditions to thrive, temperature, humidity, air movement etc and not likely to infect a plantation dependant on what year they were planted/ propagated.

I don't know of any spray specific for oak but potassium bicarb plus a wetting agent is well known to kill mildew as well as being as environmentally friendly as you can. I use Maxicrop Triple as the wetting agent as it is effective and also as benign as possible. I does require repeated sprays and does rely on sunlight to do the killing. It is more of an application targeted at the leaves during the growing season that you start early in the year with.

I would remove the infected shoots and burn them but I wouldn't be taking the whole tree out. I know it can look a mess but it doesn't kill the tree.

 

My knowledge is based on mildew in apples but I cannot think why it wouldn't apply to oak too.

[MattyF]

That photo is of a good tree , it just clearly shows the fungus…most are shocking with multiple dead leaders.. my thought and evidence is that it’s progressing across the stand, I think these where definitely infected in the nursery I just didn’t catch on , partly because the where levelled by dear in the first year too. 
if spraying will work I will do that but if it’s short term and the trees have been too damaged the cell grown small trees I got this year have amazed me and would be happy to replace the stunted wrecked trees and assess whats salvageable and spray. 

[MattyF]

Anyone have experiences of it in mature trees ? 

[Stere]

Mature trees less affected as lammas growth that gets it and they have less % of it versus seedlings.

 

Its seedlings and coppice that get it worse i think.

 

Alot of  in depth info here:

 

 

European oak powdery mildew: impact on trees, effects of environmental factors, and potential effects of climate change | Annals of Forest Science | Full Text

ANNFORSCI.BIOMEDCENTRAL.COM

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• Context Powdery mildew is one of the most common diseases of oaks in Europe. After alarming reports in the beginning of...

 

Don't think theres any easy  fixes esp with climate change probably making it worse.

 

I wouldn't blame the nursery as its being knocking about  for over 100yrs.

 

Though theese things evolve new more virulent strains that nuseries  general and international trade etc may help spread about  faster than previously.....if trees were all sourced local...

 

Edited October 8 by Stere

[daltontrees]

22 minutes ago, Stere said:

 European oak powdery mildew: impact on trees, effects of environmental factors, and potential effects of climate change | Annals of Forest Science | Full Text

ANNFORSCI.BIOMEDCENTRAL.COM

---

• Context Powdery mildew is one of the most common diseases of oaks in Europe. After alarming reports in the beginning of...

Good article thanks