Plant experts are warning Indiana homeowners to watch for signs of a disease called fire blight that can kill pear trees. Purdue University's College of Agriculture says the disease gets its name from the dark brown or black color it gives the tree leaves, making them looked scorched. Purdue Plant and Pest Diagnostic Laboratory director Tom Creswell tells the Journal & Courier that freeze damage from this year's harsh winter is a factor in the increased occurrence of the blight. The disease is passed from tree to tree by water in cracks to the bark. Creswell suggests pruning the affected parts of the tree 12 to 18 inches beyond the diseased part and into green, healthy-looking tissue.