Quercus robur sooty mould issue.

dr dendro

Hi everybody,
I am an arborist from Christchurch New Zealand.
Currently we have a problem with a protected tree (Quercus robur) that extends significantly out over the roof of a house. The tree is privately owned, but council protected. This species is prone to green aphid attack, and this year is no exception. The aphids as you know secrete a sugary substance which drips everywhere, and is a food source for black sooty mould.
The problem is, is the black sooty mould is all over the roof of the house, and the residents (understandibly) are not overly happy about it. They want to retain the tree, but do not want to have to wash the roof monthly.
So, my question is, what options do we have? We have considered confidor granules, which may be sprinkled around the root plate and eventually be taken up by the tree. The downside is that this will kill all of the invertibrates in the root zone. The tree is quite large, so I believe that foliar spraying isn't an option. Being one of the last places on earth to be free of many of the pests and diseases that trouble the rest of the world (even snakes), our biosecurity measures are almost neo-nazi in nature, so there is no predatory mites available for the control of aphid.
We are reluctant to inject the tree. The tree is very healthy, but injection isn't really the 'done' thing here, and I am reluctant to put holes into the stem of a large happy tree, just to avoid some discolouration of some old ladys' roof.
Your help is as always appreciated,
Matt.

pcarborist

horticultural oil.

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derwoodii

Natural ways
Aphids: 9 Natural Tips For Removal | DoItYourself.com

Chemical ways
Product Details
This last for three years+ in Elms with Elm beetle

Yellow sticky decoy traps if you can get em will assist

TrevMcRev

Don't sweat over injecting it. Silvashield wil do the job.

Most Oaks i've seen with heavy infestations are usually somewhat stressed already by other factors like drought or possum grazing.

On that note...anyone know what effect a Silvashield treated tree has on grazing possums??? Do they keep at it?

derwoodii

I done about 15 or so trees over 3 years & not seen any undesirable sentient creature or non target down sides. I will ask the chap whos done about 2000 trees over 5 years see whats he says. Likely not good for em, is that good or bad thing hmm depends on the day. ha it might just kill their fleas.

dr dendro

Thanks guys,
I will try silvashield. We were going to spray (somehow) confidor which is also imidacloprid. It's about time I got around to trying out tree injections, and it is assuring to know that this is a purpose made product.
On a side note, possums are a major pest here (some tool introduced them so that we could have a fledgling fur industry, but all we got was a medium sized tuberculosis problem instead) so killing as many as possible here is desirable.
Thanks!

derwoodii

Nope Silvasheild wont hurt a possum or other vertebrae critters. The chaps been trying to find an injectable compound to deter possum with no luck.
Silavsheild is expensive and you need specialized gear and expertise to use so you may need to get some help.

Jeff Darby

With silvashield you have to treat the affected trees post flowering as silvashield is highly toxic to bees.

The label states not to be used on trees likely to be used by commercial beehives. Just keep this in mind when you plan your treatments and all will be good.

I have lost count of the amount of trees I have injected let alone the the number of injections made...its a monotonus job which brings about a lot of public interest.

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