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Martin, Engineer
Category: General
Satisfied Customers: 4764
Experience:  i'm 41 and i never stopped studying and experimenting
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My plum tree bears yellowish, green wonderful tasting fruit,

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My plum tree bears yellowish, green wonderful tasting fruit, but only about 4 or 5 each season. It is about 11 years old now, but has been transplanted from a big container directly into the ground in our backyard. Since planting it in the ground, every year it loses most of its leaves. First, a little worm starts eating on the leaves and the worm gets covered in a black, slimey substance. In fact, we thought the worms were little baby slugs or something until I rinsed one off with water and found it to be a little, green inch-worm-looking caterpillar. Next, the leaves all turn yellow, with bright-green circles all over them, and then they just fall off the tree. We need help. We give our tree Miracle Gro and water it, but it's the same story year after year since we moved to our present location in 2007. Can you solve our mystery? Thank you!!!
Submitted: 5 years ago.
Category: General
Expert:  Anna replied 5 years ago.
Hello Connie,

I apologize that no one has responded to your question earlier. Different experts come online at various times; I just came online and saw your question. Some additional information will be helpful.

In what state do you live?

Is this your only plum tree?

Is this what the leaves look like?


Thank you.


Expert:  Martin replied 5 years ago.
Hi Connie. Those are pear slug (but indeed no slug at all) coming from the pear sawfly: You will see that on cherry and plum and pear but never apples.

I no longer have a single one in my orchard this year and i suspect it have to do with the earwig infestation that started last year (they were not present at all before). If you can put some in the tree they will do wonder, just know that they are omnivore and can damage pear and apricot fruit if you have those also.

Before i used to have pear slug. I manually controlled them by pressing them on the leaf (this give a peculiar sweet odor). I also raked and kept short the grass under the trees as they fall there for the winter (i even put some wood ash to make it less fun for them).

When they were too many to control by hand i used dish soap diluted in water and sprayed that 2 days before a big rain forecast (note that those can be on top and bottom of leafs).
Expert:  Martin replied 5 years ago.
I am repasting the question here as you should continue communication in the original post.

Thank you, XXXXX XXXXX the info on pear slug. Can you explain the yellow leaves with green circles, too? Is that also a result of the pear slugs?

Already Tried:
I have sprayed with soapy water and a little Murphy's oil and ammonia mixed in. Sometimes it helps a little, but it's hard to get all of them.

As for the the yellow leaf, this is not directly related to pear slug as those usually eat the top surface of leaf only and don't even get the leafs veins. That said if this was severe infestation it may indirectly cause the problem.

Seeing a picture would help to identify this but such a pattern look like a fungus of some kind coming from a weakness in the tree that may affect it's immune system. You can always look for signs of borer larvae.

A tree that fruit just like that mean that it grew too tall, was not pruned often enough, is not in an appropriate soil or is over fertilized (too much nitrogen can deplete other element causing long time with lack of other mineral like sulfur, phosphorus and potash. Some variety of plum also perform better with other pollenizer around. Usually a plum tree is very hardy and require no special fertilizer.

If you have dead wood close to the plum tree, try to remove as much as you can. And try to apply a bit of sulfur.
Martin, Engineer
Category: General
Satisfied Customers: 4764
Experience: i'm 41 and i never stopped studying and experimenting
Martin and 62 other General Specialists are ready to help you
Customer: replied 5 years ago.

I just wanted to thank Martin. I will take his advice. Again, thank you, Martin!!!!

Connie :)

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