Black leaf curl on new pear tree
I planted a new D'angueu Pear tree in March. Just noticed many of the leaves have this black curl condition. Couldn't find pictures on the web that looked similar. Not sure whether it is an insect, bacteria, or fungus. Note: neighbor has 2 pear trees (older) about 20 feet from this one without the problem.
Diagnosis and advice appreciated. Note: This tree is new and has no fruit this year.
Davis County Utah
Thanks for including the great pictures.
Diagnosing this problem on pear is somewhat tricky, because pear are so sensitive to a variety of problems. So I have two guesses:
1. Spider mites. Spider mite damage on pear does not look like the typical injury on other trees. Often the leaves will look normal, but new leaves will be deformed and have blackened edges. You need a strong hand lens to see if you can find the mites on the undersides of the leaves. (Look at the oldest leaves closest to the ground.) Here is more info: http://www.ipm.ucdavis.edu/PMG/r603400211.html
2. Bacterial blight caused by Pseudomonas syringae. This is a disease that needs free water to spread. It does not severely harm plants in Utah, usually just a few leaves or twigs. The buds are not affected so next year, it should have healthy new growth. Here is more info: http://pnwhandbooks.org/plantdisease/pathogen-articles/pathogens-common-many-plants/bacteria-and-oth...
Again, something like this is hard to diagnose in an email, so you may want to consider sending a sample to the Utah Plant Pest Diagnostic Lab. Diagnoses are $7, and the form (and delivery address) can be found here: http://utahpests.usu.edu/uppdl/files/uploads/Submission_Form.pdf.