One half of our peach-plum is dying suddenly. On closer inspection today we saw all parts of the trunk (yes) and branches covered in green aphids (yes) on the move. A few of the leaves on the healthy part of the tree have aphids and there are a few ladybugs around. I sprayed it hard with water to wash most of them off. Could the aphids have killed the damaged half of the tree? Why only half the tree? I've never seen aphids moving like that and I know they generally stay put unless they've become winged. Has anyone seen anything like this or have any explanation?
Sudden death of a Prunus doesn't sound like something that would come from aphids. Potentially fungal? Any pics to share?
You might be right. We had to cut a branch off a couple years ago. I'm attaching a couple of pictures (I hope) Here's a picture of the tree
Hmm, hmm. Who has been doing the pruning? Were the secateurs sterilized after being used to prune a diseased tree?
My husband pruned...not sure about sterilization. I'm most curious about the aphid activity because I've never seen them move like this. The previous picture just shows a couple on the trunk after we sprayed them off with water, but there are hoards of them all climbing determinedly upwards on the trunk. Seems very odd.
Whatever the problem is, it would be a good idea to cut off all of the dying part of the tree, hopefully well below the dying portion. If the disease has not spread to the main trunk, you should be able to save the tree.