Our Callery Pear tree leaves are turning brown - Ask Extension
Our tree has brown spots on the leaves on the bottom and interior of the tree. It is a Callery Pear Tree. The leaves started to become orange about...
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Our Callery Pear tree leaves are turning brown #805709
Asked August 10, 2022, 9:54 PM EDT
Our tree has brown spots on the leaves on the bottom and interior of the tree. It is a Callery Pear Tree. The leaves started to become orange about two weeks ago and now they are brown, but the top and exterior leaves are still green.
Denver County Colorado
Expert Response
I can't see enough of your tree to say definitely what the problem is but there are several possibilities.
The first is a bacterial disease called fireblight, common in pears and apples along the Front Range. The symptoms include the ends of some branches in the canopy blackening and "crooking over" into a curve with the discolored and dead leaves remaining attached. As the disease travels down the stem, you can see discoloration which distinguishes infected tissue from uninfected tissue. In your photo, the stem leading to those necrotic leaves looks black and bent but it may just be a shadow; I can't tell. Here is a link to a fact sheet about fireblight which you can read and use to compare with your tree:
https://extension.colostate.edu/topic-areas/yard-garden/fire-blight-2-907/
The other possibility is that the tree is suffering from heat and water stress because of how hot and dry it is and that is why some of the leaves are starting to redden. If that is the case, the leaves would browning on the outer edges starting from the top of the tree and progressing downward and the tips of the branches and progressing inward. If that sounds like what you are observing, I recommend using a screwdriver or something similar to probe the soil under the tree canopy particularly at the dripline to assess the moisture situation. If the tool slides in easily, you can assume the tree has enough water; if the tool is hard to push in, you may need more water or more frequent watering.
The first is a bacterial disease called fireblight, common in pears and apples along the Front Range. The symptoms include the ends of some branches in the canopy blackening and "crooking over" into a curve with the discolored and dead leaves remaining attached. As the disease travels down the stem, you can see discoloration which distinguishes infected tissue from uninfected tissue. In your photo, the stem leading to those necrotic leaves looks black and bent but it may just be a shadow; I can't tell. Here is a link to a fact sheet about fireblight which you can read and use to compare with your tree:
https://extension.colostate.edu/topic-areas/yard-garden/fire-blight-2-907/
The other possibility is that the tree is suffering from heat and water stress because of how hot and dry it is and that is why some of the leaves are starting to redden. If that is the case, the leaves would browning on the outer edges starting from the top of the tree and progressing downward and the tips of the branches and progressing inward. If that sounds like what you are observing, I recommend using a screwdriver or something similar to probe the soil under the tree canopy particularly at the dripline to assess the moisture situation. If the tool slides in easily, you can assume the tree has enough water; if the tool is hard to push in, you may need more water or more frequent watering.
