black blobs on plum branches

mikeinsantarosaFebruary 1, 2012

As soon as my 4yr old Santa Rosa Plum sprouts leaves and blossoms these soft black blobs show up on some of the branches and on these same branches lots of ants show up. What's wrong with my plum tree?

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fruitnut Z7 4500ft SW TX

mike:

Do these blobs move around? Do you know what aphids look like? Aphids typically show up at the time you are having trouble. They can be easily be controlled with insecticides or even a strong spray of water helps some. Some say controlling the ants helps but the aphids are easier to kill.

    Bookmark   February 1, 2012 at 12:06PM
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mikeinsantarosa

I'll check to see if they move around. thanks

    Bookmark   February 1, 2012 at 12:28PM
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fruitnut Z7 4500ft SW TX

Aphids mostly stand in one spot and suck juices. But they have legs and can move slowly. Scale is more like a blob. They only move when young and then so slowly you can't notice.

    Bookmark   February 1, 2012 at 1:12PM
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wizzard419

If it's a blob that looks like bead of dried sap, but the shell breaks when poked with a toothpick, then it's probably an older scale bug.

The best tool to use on them is something like all seasons horticultural oil (the hose kind) and just soak the tree, reapply each week (as they are tough to kill) and possibly go over the surface, scraping the bugs off, if the tree is small enough.

    Bookmark   February 1, 2012 at 6:05PM
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jean001a(Portland OR 7b)

Any chance of pictures? That would clarify the issue at hand.

    Bookmark   February 1, 2012 at 10:02PM
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mikeinsantarosa

*thought I just posted (sorry if redundant)*
I cheched for movement and they must be from last year because they were hollow and the side attached to the bark was open. Look like the butt end of a black widow.
I did take some pics. How do I post them here?

Thanks
Mike

    Bookmark   February 2, 2012 at 11:46AM
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fruitnut Z7 4500ft SW TX

Mike:

Those are last years scale. A picture would still help identify what type of scale. Some are much more damaging than others. A spray of dormant oil is a good starting point.

    Bookmark   February 2, 2012 at 12:00PM
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ramble

Google Black Knot. Maybe it's that fungus.

    Bookmark   February 2, 2012 at 2:41PM
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mikeinsantarosa

Here's a picture of a blob

    Bookmark   February 2, 2012 at 8:35PM
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mikeinsantarosa

here's a close-up of the bark:

    Bookmark   February 2, 2012 at 8:45PM
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fruitnut Z7 4500ft SW TX

The blobs are scale. Spray dormant oil asap unless you are already budding and leafing out. If later you may need a summer oil.

    Bookmark   February 2, 2012 at 10:56PM
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mikeinsantarosa

So is the blob the shell of a critter or is that the sap leaking from the branch?
The blobs I knocked off and inspected were thin shelled & hollow.
The 2nd pic has small oval shaped light colored objects all over it. Are those critters?
Scale is some kind of live infestation, right?

    Bookmark   February 3, 2012 at 9:17AM
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fruitnut Z7 4500ft SW TX

The blob is the hollow shell of a now dead scale from last year. The smaller oval disk may well be the young that will grow into the adult scale this year. Now is the time to smother the young with oil.

San Jose scale is the most damaging. Below, I hope, is a picture of one that looks something like yours and mine.

Here is a link that might be useful: scale

    Bookmark   February 3, 2012 at 11:24AM
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mikeinsantarosa

Hey fruit, that link looks pretty darn close to what I have. I soaked/saturated the tree with hort oil yesterday and will hit it again in a week or 2 if it isn't all bloomed out.

I've seen threads on this site where people knock them off with water spray or by hand. You ever try that?

    Bookmark   February 3, 2012 at 1:33PM
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fruitnut Z7 4500ft SW TX

Mike:

I mush all I find by hand. The first sign is usually honeydew on the leaves near and below the scale. Not sure I've ever eliminated them but mine are easy to kill with malathion in summer and oil in winter. Either I don't kill all or they come back. And this is in the greenhouse. Not sure how they get in.

Mine are European Fruit Lecanium scale I think.

Here is a link that might be useful: European Fruit Lecanium

    Bookmark   February 3, 2012 at 2:12PM
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vfrawley71

Can anyone identify these black dots on our santa rosa plum tree? I am not sure how old the tree is or how long the tree has had this trouble, but they seem to be everywhere on the lower branches and it's really grossing me out! Please tell me it is a curable problem and that we aren't going to lose this beautiful tree! :)

    Bookmark   June 17, 2012 at 2:04PM
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