AusBonsai

My pre bonsai English Oak has a strange thing happening to its leaves. Only got it a few months ago from Necises, growing well, but I don't like the look of these grey patches. Any ideas??

Hi

That is Powdery Mildew.
http://en.wikipedia.org/wiki/Powdery_mildew
Typically a result of humid conditions.

Yep kep it in full sun and not on a crowded bench.
Give it its own space so that air can circulate around it.
None of mine have had any issues but i am in western sydney. if you are closer to the beaches you will be more humid.

Ken

Hi Ben I had the same problem I sprayed the tree with Fungo Rid twice, this did not help I then defoliated the tree completely and then sprayed with Lime Sulfur in three weeks new flush of leaves and no sign of Powdery mildew
Cheers John

I had it on two of my collected oaks. Defoliated the entire tree and didn't get it back with the new growth. I didn't actually spray anything, was going to but didn't get time to it but had no sign of it on the new growth so didn't bother I the end.

Josh

I gave up on growing Oak bonsai because this problem is a reoccurring one.

Just simply spay with a monthly dose of sulfur from when it first shoots in spring till end of summer. Also avoid wetting the foliage when watering and all will be fine. Same as vines or people in glass houses with zuchini and watermelon.

I have a couple of oak's growing in some grow beds..
I believe that they are certainly not in a humid location but this problem persists for my trees.
As they are simply growing on (and seemingly not affected) I've just let them go..

http://www.bonsai4me.com/SpeciesGuide/Quercus.html

thats a great website i visit often when researching new species. gives good advice on general care, and funnily enough emphasises good air circulation to stop mildew issues on oak.

kcpoole wrote:Yep kep it in full sun and not on a crowded bench.
Give it its own space so that air can circulate around it.
None of mine have had any issues but i am in western sydney. if you are closer to the beaches you will be more humid.

Ken

Thanks Ken. Im in North Ryde.
Space and sun it shall have!

Thanks for all the opinions. Will think on it, do something this weekend.
Im keen on not spraying, and its easy for me to give it more sun and space. Ill think on it at work over the rest of the week.
Cheers.

I get the same thing when watering in the evening. I've found that if you keep the water off the leaves or water earlier in the day so they can dry before the evening. Defoliation also has worked for me.

GoldfieldsBS wrote:I get the same thing when watering in the evening. I've found that if you keep the water off the leaves or water earlier in the day so they can dry before the evening. Defoliation also has worked for me.

Interesting thought there as I water by fixed sprayers, but @ 7 am so dry within a few short hours, and thus the rest of the day too.

Ken

I've had great success with milk spray . Simply mix milk with water 50/50 , spray all over both sides of leaves etc . Spray as needed or if it's a real problem every 4 to 5 days or after rain . Got this from Jackie French . The leaves tend to have a glossy look and sometimes you get a bit of milk residue . Cheap and safe can't go wrong .
Cheers Sno

You mentioned you got the oak tree from Necises, I have googled this and get nothing, I am trying to locate an english oak starter tree and would really appreciate any help.