Pear trees are fairly hardy specimens, whether planted in the home garden or in a commercial orchard. However, one of the more serious diseases that can affect them is called fire blight and results in the leaves turning brown. The disease is caused by a fungus that will kill the pear if left untreated. With the proper treatment, the fungus can be controlled, and the pear tree will begin to thrive again.
Wait until late winter, and locate a branch that has brown leaves or reddish brown spots on the bark. Prune the limb off about 7.5 cm (3 inches) past the diseased sections using a pruning saw.
Fill a bucket with a diluted mixture of 1 part bleach to 10 parts of water. Dip the pruning saw into the solution for two seconds after making each cut to kill the fungus. Doing this disinfects the saw and prevents spreading the disease to healthy parts of the pear tree.
Continue pruning off any remaining diseased branches in the same manner and disinfecting the saw in between each cut.
Place all diseased limbs into a rubbish bag for disposal. Rake up all leaves under the pear tree, and dispose of them as well, since they may also be diseased.
Wait until spring, and examine the pear tree weekly for signs of new brown leaves. If brown leaves develop, reprune the pear tree, cutting off each diseased limb 30 cm (12 inches) below the diseased area.
If a limb is too large to cut off, use a knife to cut into it and scrape out the diseased sections. Apply a thin layer of tree wound sealer over the area.