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Pear tree & shrub have curling leaves with black edges and brown/black spots #462408

Asked June 14, 2018, 4:20 PM EDT

I have a chanticleer pear tree and a shrub on the other side of a fence that have both developed curling leaves with black on the edges that are curled. They also have black and brown spots on the leaves. On the tree it tends to be the branches toward the bottom of the tree and up higher it's the outside branches. We lost our honey locust tree as it didn't come back this year and it had similar issues. We tried trimming the branches on that tree but it continued to spread and died. We regularly use Bayers protect and feed on all the trees and shrubs. Late this spring I put down Adonis on the trees and shrubs at the direction of the extension last summer when the locust had issues. The pear tree and shrubs still started developing the same symptoms despite the Adonis so I used sevin spray. The belief was that aphids had gotten the locust so that's why the Adonis and sevin was used. The pear tree and shrub got worse after using the sevin, the shrub now has some yellow leaves. These plants have all been planted about 4 years ago.

Adams County Colorado

Expert Response

There may be more than one thing going on here.

The cupping of the plant's leaves is consistent with damage caused by an herbicide. 2,4-D for example, which is the active ingredient in many products labeled to control weeds lawns including many weed-n-feed fertilizers, can cause symptoms like you are seeing.   If applied when temperatures are warmer than ~85-90 degrees Fahrenheit 2,4-D can volatilize (turn into a gas) and drift into non target plants. We see this sort of injury pretty commonly in during the warmer portions of the growing season.   A single exposure will not kill the tree but it would be best to avoid future exposures.  Once volatilized 2,4-D can drift long distances so the damage may not be from any product you applied.   

The spotting you are seeing is probably  unrelated. I cant say with certainty from the pictures but it could be caused by either by the residue from the insecticide which was applied (the timing seem to fit with this) or potentially by mites. The symptoms don't seem quite right for mite damage from what I can see but you can find more information here:http://webdoc.agsci.colostate.edu/aes/wcrc/techbulletins/leaf%20blister%20mites-rev%203-11).pdf 

Also,  it very unlikely that the same pests which may have affected the honey locust are affecting your pear. Most pest issues only affect related groups of plants.   So the good news is you rarely have to worry about issues jumping from one unrelated plant to another.  


I hope this helps, please let me know if you have further questions.

An Ask Extension Expert Replied June 15, 2018, 1:36 PM EDT

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