Oak leaf Phylloxeran[Oak leaf aphids]

Hasaki

I'm posting this here to ask if any keeping Q. robur[English oak] or Q. garryana[Oregon white oak] as bonsai will see it and if they have found it on their trees.
This has become a problem on one of my Q. robur over the past two years and they[oak leaf aphids] have been found on another tree last year. I'm going to use a horticultural oil this spring as soaps have not worked.
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English oak (Quercus robur), both the regular and pyramidal variety, is affected by an insect called the Oak Leaf Phylloxera (Phylloxera sp., Phyllox-eridae). The key to recognizing this pest is to follow the progression of symptoms from spring to fall. Apparently, the insect overwinters on English oak in the egg stage, which are laid in bark crevices. The eggs should hatch near the time of leaf emergence. The nymphs walk to the leaves and start sucking sap from the lower side of the leaf. The insect is yellow and oval with a maximum size of approximately 2 mm. They often start sucking at the leaf edge and cause a very characteristic leaf roll. Each Phylloxera feeding site will result in a yellow spot showing on the upper side of the leaf. This damaged tissue will remain yellow for a period of time and then die, turning brown.
Left unchecked the whole leaf will turn brown and die, branches become defoliated.

Hasaki

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Hasaki

The dormant oil has eliminated almost all of the over wintering aphid egg population. They will defoliate branches leading to branch loss and weaken the tree so little secondary growth appears.
Now for some insecticidal soap!

Hasaki

joakimlinden

Is this "oil" available in regular nurseries or is it hard to get? I've begun to get the symptoms of small yellow bumpy spots - I'm not sure if this is the cause though. It increased from being on none of the few leaves I have to being on about half of them... I'm worried about this since I collected this tree in spring and it really doesn't need more stress.

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Best regards, Joakim

Aaron_K

Sorry to hijack this thread slightly, but it does pertain to Quercus Robur. I have a "problem" with ants and my oaks. I see ants on other trees - maybe one or two - but for some reason, they all love my two oaks. I must have shaken off about 50 ants from each tree earlier.

They don't appear to be doing any damage, and the trees seem to be doing fine, but its a bit unsightly. Anyone else have the same problem?

All the best,

Aaron

Ian_Homer

Hi Aaron,

I can instantly agree with your observation that Ants seem to have an attraction to Oaks. I first noticed this on a tree planted in the Garden when we moved to our current house 3 years ago. They were crawling up and down the trunk and along the branches. This tree is some way from my Bonsai benches, so never caused any concern. In these three years, my Bonsai Oaks have not been troubled. I can only put this down to the natural "fatty acids" insecticide I use. This type of hand-spray is readilly available for under £3 at B+Q and Wilco's. I tend to use them alternatively - just in case one gets some bugs better than the other.

Sprayed as a preventative every 2 weeks, that must be sufficient for Ants to to keep away, along with Blackfly, Greenfly and all the other normal pests. Last year the Oak in the garden suffered the same attacks of Ants at different times throughout the Summer, so this year, I have sprayed the lower 4 feet or so with the same products, and I have seen no re-occurrance.

Hasaki,
If you do not use this type of spray, give it a go.

I also thought about the spray type "Ant Guns" you now see as opposed to the normal white powder. As yet, I have not had reason to try this treatment on trees, just in case it is slightly systemic. It certainly works well on any Ant outbreaks on the patio and other areas of the garden. I wonder if anyone else has actually used this specific type of Ant control on Bonsai ?


Regards,
Ian.

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Aaron_K

Hi Ian,

I'll definitely have to consider getting some, as they are absolutely everywhere. As I was typing the post, I felt one of the little buggers crawling on my arm. They don't seem to be harming the tree as far as I can tell and was even wondering if they formed a natural symbiotic relationship? Does the tree secrete anything that the ants eat in return for protection from other pests?

If not... I'm gonna nuke 'em with the spray lol

All the best,

Aaron

Hasaki

The oil is just a 'dormant' oil, now refered to as a horticultural oil{97% mineral oil}. Sprayed before leaf emergence.
Not sure what you have but oak leaf phylloxera is a european aphid and can be seen on the underside of Q. robur leaves.
Not sure about the ants but if I find ants there are usually aphids on plants.
When I have an unidentified insect I'll take a sample to Pest Diagnostic Clinic, University of Guelph.
http://www.uoguelph.ca/pdc/

Hasaki

rockm

" have a "problem" with ants and my oaks. I see ants on other trees - maybe one or two - but for some reason, they all love my two oaks. I must have shaken off about 50 ants from each tree earlier."

Ants are usually a symptom, not the disease. Ants actively "farm" aphids and scale insects. They will move and tend these other insects to harvest the sugar-rich secretions produced by them. You might watch where those ants are going on the tree. They will usually move towards the ends of branches to tend their "farms" of sugar making critters.

Take a look on the twigs and stems of the oak for aphids (underneath leaves and on leaf stalks and especially new growth. Also look closely at the stems and thinner bark of new growth for scale (they look like little limpet mines). I'd bet you find either one or the other. If it's aphids, intesne blasts from a water hose from underneath the tree aimed upwards will dislodge them. The scale has to be picked off by hand. This can take some doing, since the ants will try to replace the insects you remove, but once you get most of them off the plant, the ants will mostly give up and move on.

Another thing you can do is to look around the base of the plant for the ants' home and destroy it.

joakimlinden

Hasaki, the bugs are/were on the underside of the leaves. Small, but perfectly visible, greenish, pale critters attached right in the middle of the yellow bumps. I did a coctail of soap, ethanol and pyretrine (I'm not sure about the english name for it, probably similar) and sprayed each leaf upside and underside by hand. I also sprayed the wigs and other hard to reach areas.
Today when I looked, all the little bugs had turned brown and wasn't moving. So I think I had success. I'll probably repeat this tomorrow or in two days.

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Best regards, Joakim