JessPlacerville
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Scale Treatment on Plum/Apple tree's?

Hello everyone, this is my first post here so I'll give you a quick bit of history.

We bought this property in Placerville, California about 8 years ago. On one of the hills is a small orchard with 2 Damson (I believe) plum trees, 2 wild plum trees a very tiny pear and two apple tree's. I'm very new to gardening and especially fruit tree care and it wasn't until recently that I decided to start looking after them as that hillside has grown a little wild.

Anyway, I just discovered I have a pretty serious scale infestation. All of my plums have it and at least one of the apples has it. I've been doing as much research as I can but I'm to the point where a little direction could help.

Based on my research I believe I have Kuno scale (Eulecanium kunoense)? I've read about the various treatments but the one thing I can't figure out is what to do if my tree's have fruit. None of the fruit is ripe yet so I'm worried if I spray my tree's if I'll hurt the fruit. Do I need to wait until winter to treat it?

Any help would be great, thanks!

Jess
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tomc
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Re: Scale Treatment on Plum/Apple tree's?

For scale, I'd mix up some dormant oil. Use the directions on the lime sulphur bottle, or research one you prefer from the web. It gets applied early in the spring before bud-break.

You won't be able to spray till early next spring before leaf buds open and before bloom.

Oil and something mildy caustic will asphyxiate the scale.
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ReptileAddiction
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Re: Scale Treatment on Plum/Apple tree's?

I agree. Wait until the trees are dormant and spray them with a dormant oil.

You also need to make sure that you keep the ground underneath the trees clear of any debris. Especially fallen leaves make excellent overwintering spots for insects.

JessPlacerville
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Re: Scale Treatment on Plum/Apple tree's?

Thanks for the replies!

@ReptileAddiction, I was told to cover the ground around them with mulch to help retain moisture in this drought, should I keep it clear? My soil here is basically clay that turns to brick when it dries, but I've noticed it seems to retain moisture pretty well as I've been trying to dig wells around them for watering.

JONA878
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Re: Scale Treatment on Plum/Apple tree's?

Re the scale infestation Jess.
there are horticultural oils available to spray in the growing season.. But you must follow the labels carefully.
never use oils when it's very hot.
never use them in conjunction with sulphur products.
If the scale is very bad then you may have to resort to a summer spray as they can do sever damage as we have found to our own costs.
I would suggest that you do a trial small area first though and check after a few days to see any detrimental effects on the leaves/fruit etc.

As regards the mulch. A good mulch is invaluable in dry summers. But...the ground must be completely soaked before applying.
Mulch applied to dry soil just acts as a thatch and can keep water off the ground.
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ReptileAddiction
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Re: Scale Treatment on Plum/Apple tree's?

JessPlacerville wrote: @ReptileAddiction, I was told to cover the ground around them with mulch to help retain moisture in this drought, should I keep it clear? My soil here is basically clay that turns to brick when it dries, but I've noticed it seems to retain moisture pretty well as I've been trying to dig wells around them for watering.

You should definitely mulch. Sorry that was unclear. Mulch can provide a way for the insects to overwinter but it is less likely to because it is not the plum/apple matter. Make sure you keep mulch away from the trunks though. It can hold moisture against the wood letting phytophthora in. Phytophthora is basically when the trunk off the tree is rotting. It is not good.

As to the growing season oils, I do not like them. I have seen them damage trees pretty severely and in my opinion it is much harder to spray the tree well enough so it is not just a waste of time. Especially large tree have so much foliage that it is just much easier to spray during the fall, winter, and spring.

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applestar
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Re: Scale Treatment on Plum/Apple tree's?

I realize we're talking tree -- as in big -- but couldn't you at least go out there with cotton swab and alcohol and take as many of the hard-shelled adult scales off as you have patience for?

Also, I believe ladybug and greenlacewing larvae will eat scale larvae and eggs. I know in my garden, some small birds like finches, kinglets, and chickadees, titmouse and nuthatches will work fruit trees over pretty thoroughly at certain times of the year looking for bugs. Maybe scales, too?
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ReptileAddiction
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Re: Scale Treatment on Plum/Apple tree's?

Ladybugs will eat scale. If you go to a local nursery and get a cup of ladybugs release them at dusk. Take the cup and put it into the tree as low to the ground as possible and release them. That would probably help.

I am not sure if small birds would eat the scale. You could try hanging a bird feeder near and see if that helps.

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Re: Scale Treatment on Plum/Apple tree's?

applestar wrote:I realize we're talking tree -- as in big -- but couldn't you at least go out there with cotton swab and alcohol and take as many of the hard-shelled adult scales off as you have patience for?
I tried that one year on a laurel tree, which is evergreen. and I painted scales with rubbing alcohol. This was only a two foot tall plant and it took a couple dozen hits to finally get them all.

So, I guess you could hit those trees with an alcohol-swab of death, but it might be after leaf-fall before you caught up.

I love my pump sprayer. Really i do.
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JessPlacerville
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Re: Scale Treatment on Plum/Apple tree's?

ReptileAddiction wrote:Ladybugs will eat scale. If you go to a local nursery and get a cup of ladybugs release them at dusk. Take the cup and put it into the tree as low to the ground as possible and release them. That would probably help.

I am not sure if small birds would eat the scale. You could try hanging a bird feeder near and see if that helps.
I'll try the Ladybugs for sure, thanks!

As for using a swab and alcohol, I could probably do that on the smaller tree's. The larger ones I'd never be able to finish, plus there isn't really level ground for a ladder. If I swab them, do I swab the black bulbs? I understand those are dead shells of the previous years scale?

NatureHillsNursery
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Re: Scale Treatment on Plum/Apple tree's?

We only use dormant oil in the spring on our fruit trees, and I tend to agree with the others that it’s the best practice. Now that it’s too late for you to do that this year however, I would be inclined to just wait it out. It seems to me that the kind of damage you can expect will depend upon the type of scale you have and the degree of infestation. It may be that your tree will only be weakened by the scale this year and still be able to recover next year (when you’ll be able to do a spring spraying). Of course, do the alcohol with a toothbrush thing now if you can, but I know with large trees this may be unrealistic. Best of luck with your fruit trees!

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