What could be the cause of rust spots and holes on the leaves of my Pluot tree? Other trees nearby do not have this. I'm guessing that those rust spots on the left leaf turn into the holes seen on the right leaf.
2 Answers
The left looks like damage, like hail or possibly a fungus, the one on the right looks like ants or wasps are eating it.
you should mark a leaf and photograph it to see if that is the actual progression, also look for bugs around it.
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They're off the same tree and I feel like the rust spots are becoming the holes in the right leaf. The trees have been clear of insects for a while and are being regularly sprayed.– GuyCommented May 10, 2014 at 0:21
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2well really you have 3 options... 1 disease, 2 something is eating it, 3 environmental: nutrient deficiency or damage... the damage on the right looks like bits are removed with clean edges and the thing on the left looks like the tissue dies and stays there... I don't know for sure, but it seems different to me. Commented May 10, 2014 at 0:27
Shot hole disease. It's difficult to control but use mancozeb in the early cover sprays followed by thiophanate methyl closer to harvest. It usually doesn't defoliate the tree. Some varieties are more resistant than others. My Methley rarely gets it but my AU Rubrum gets it every year and it's right beside the Methley.