Hey everyone. Just went and examined a few of my maples up close for the first time since fall, and I noticed these weird white spots whit darkish centers all over the bark on a few of them. I tried scratching them off, and turns I can. Any idea what it is?
Scales. In february/march white one’s are probably dead and easy to remove; brown shelled one’s are alive. But invisible eggs are ready for a new heavy infestation in spring/summer/autumn. It is a serious pest difficult to control along the year. You can try a soluble oil, dilute in water and paint with a brush.
I use Vaseline ‘solubilised’ oil (said emulsionable vaseline oil ); commercial name APHASIS EV from BHS in Europe Dilution: 20 ml for 1 litre water. You can pray woods or paint them with a brush. You can use it all the year. Exists also colza oil (rapeseed oil). Same dilution. Solubilised oils are effective against scales, mealybugs, aphids, must mite. You can use it on leaves. In winter it is used against eggs of all insects. Against aphids, i think it is best than diluted soap.
There will be some horticultural oils on the market in the USA, and they will likely be as effective. They are all variations of the same thing, oil, water and an emulsifier. Summer Oil, Dormant Oil, Horticultural Oil—What's the Difference?
I get prepared NEEM oil (just out a tablespoon in a quart of water and spray) at my local hardware store. It does the job for most every insect pest I've had including several kinds of scale (though this is the first time I've seen anything like this whatever-it-is).
Got it. Yeah, I wasn’t familiar with it, but some of my maples have it really bad. I actually think it may have killed my ‘Autumn Moon’ I grafted a few years ago. Has it all over and only a Bud or two looks like their may be any life left.
Is this White Scale too? I live in the states in Oregon so NEEM oil is readily available because of all the marijuana growers here, can I just spray the spots with NEEM oil after using a toothbrush to wipe them off? Thanks everyone!
Often branches are so weakened that they don’t grow at all, it is a pitty. I am happy you find ‘’horticultural oil’’, the light summer one . @maf. Thanks. You have to mix in water, the dilution is on the package/ box. The best you have to do is to paint the trunc and branches with a brush, without forgetting the underside of the branches . It will be useful to start again 1/2 an hour after and also in a week. After that, your trees can stay under rain It is possible that a few eggs (invisible) escape the 1st treatment, start again in may/june. Selled scales are a very résistant pest, reinfestations are commons in autumn/winter, particularly in greenhouses. When they are alive they are very difficult to see, hou have to look at with yours best reading glasses.
Fortunatly i don’t see any shelled scales on yours photos. The white dots are part of the bark of young’s cultivars. But the 3rd photo shows a wood in poor condition over a few centimeters .
Neem oil is not sufficient to eliminate scales and their eggs; that is my experience. --When you use a toothbrush to wipe off scales, you wipe off the dead one’s but the alive one’s stays. --Horticultural soluble oil coats their shells, so they can’t breath. --But they can lift themselves up and breathe throught their stomach. Half an hour after a first application of soluble horticultural oil, a second application will produce the best result.
I doubt this is white scale. I may be wrong. but if what you showed in pic #3 is a consequence of the rest, to me it's more like a kind of fungus : the white dots seem to be aligned, as if they followed the veins of sap. Not sure that scales would behave like that. And on all my maples, I've rarely, if never, had scales, white, or any other colour. So perhaps my experience it much too limited to put a diagnosis. But I would opt for a fungal disease and use the "magic treatment" : copper-based fungicide...
Don't ! First, I tried to use the conditional tense and words like "perhaps" and "seem to"... ;-) Secondly : Neem oil is a very efficient preventive treatment for trees that can have scales, mainly conifers (but also Fagus sylvatica) : I have several that had scales, It appears I got rid of them, but I'll use neem oil when the buds break so they won't be back. Anyway, Neem oil will prevent, not cure attacks of scales.