Good Afternoon, My Acer Pictum - ‘Usugumo’ had scale last year but I noticed it later on. This year I see them all again but very small and just starting. I’d like to knock them back ASAP. Could anyone recommend a treatment? Also can they spread from maples to pines? Thank You.
There may be a chemical treatment but I was successful many years ago eliminating scale from a Corylus avellana 'Contorta' just by relentlessly scraping off the scales as they showed up. The tree didn't have leaves at the time of year I discovered the scale which could work in favour of your maple now. Sorry, I don't know if they can spread to pines.
Thank you. That sounds like a good idea. Since it’s not an infestation I’ll just scrub them with a nylon bonsai brush. It doesn’t seem like they care for pines too much from further reading. Certain thin bark maples seem to be a preference. Only buds at the moment so I’ll start scrubbing.
Are you dealing with a bonsai tree that currently has no leaves? If so you may want to use insecticidal soap sprays after the adult scales have been physically removed. I've done this in the past using an old, worn out toothbrush which I wet with the soap solution. There would be less chance of damaging the bark than from using a stiff brush. However I was dealing with soft scale; you may need a stiffer brush with hard shell scale. Soap sprays should be quite effective if there is no foliage to deal with.
It’s not a bonsai but a container tree. Just buds at the moment. The green brush is fairly soft but I could use an old toothbrush. That sounds gentler. The brushes I posted are more for moss removal. I’ve never tried soap and scrubbing at the same time. Just one or the other. The scale are squishy. Thanks for the suggestions.
The soap solution acts like a lubricant to further lessen chances of damaging the bark while at the same time it kills the juvenile scale, the ones you can't see.
I would agree with that for sure. I think the reason my strategy of flicking off the scale bumps as soon as they appeared was successful was that they didn't have the opportunity to produce any young'uns. Using a soap solution increases the likelihood of total eradication. Scale is a problem to take very seriously.
Depending on the size of the tree, you may want to use the brush on the entire bark surface. Then by applying a final spray of the buds you'll have covered all surface areas. You may not see them but young scale that have started to develop shells are nearly impossible to see because the shells are transparent at this young stage. Alas, the eradication is only temporary if this is an outdoor plant.
I think that depends . . . it has been at least 10 years since I ridded my Corylus avellana 'Contorta' of scale and have never had a recurrence.
@Margot They’re a single season insect so if you can get them all I think it’s possible. I’ve learned they hatch, reproduce and die in 1 year.
Come to think of it, you may also consider using a horticultural oil as this is an outdoor tree. I suspect it would be a more effective solution than using soap sprays. Scale Management Guidelines--UC IPM
I've not used oils before but I thought the advantage of oil is that it would smother all the scale, adult or otherwise, without having to scrape.
Good morning G, as you have had some excellent replies I will just add what I do. This is a soft tooth brush dipped in rubbing alcohol and remove every one. I find that by keeping a keen eye out every year for any new infestation is by far the best remedie. I don't spray with soap or oil afterwards btw. Good luck and don't miss any.
I recently used a mix of neem oil and dish soap, on both late aphids and scale. Seems to have worked.
