Key Features
- Large, irregular leaf spots
- Browned or blackened leaves
- Branch death, leaves attached
Symptoms
Leaf blotch and leaf blight are general terms used to describe foliar symptoms of disease or injury. They can be caused by a variety of fungi and bacteria. Blotch refers to large areas of dead leaf tissue, varying in size, shape and other characteristics. Blotches are distinguished from leaf spots by their irregular, fading edges. Guignardia blight of horse-chestnut and Virginia creeper are examples of blotches. Leaf blight refers to a branch with multiple leaves wilted, dead, or dropped prematurely, from any point along the branch to the tip. Blights can be caused by disease, insects, or environmental, chemical or mechanical injury. Blights often begin as leaf spots, but continue to kill the leaf and work their way down the petiole and into branches. Fire blight, Kabatina blight and Rhizoctonia blight are all examples of blight.
Biology
The life cycle of blotches and blights depends on the cause (specific disease or pest), host, and environment. Always correctly diagnose the problem before attempting controls. Most control measures are very specific to specific situations; a treatment that may reduce one disease can make another more severe. If unable to identify the cause of the disease, samples can be sent to a plant and pest disease diagnostic lab for analysis.
Management Recommendations
Many different types of pathogens cause blight, making a correct diagnosis essential to properly manage "blight". Fungicides labeled for control of Phytophthora blight will not work on Botrytis blight or bacterial blight. Be sure your diagnosis is correct, and implement cultural practices before any chemical control is applied. Some basic cultural practices that work for all "blights" include removal of dead and dying plants, good spacing of plants, and making sure plants are properly sited (for example, growing high light plants in full sun).
Effective Pesticides
Pesticides are neither available nor recommended for managing this disease.
Resources
- Not satisfied with ID? Contact the Purdue Plant and Pest Diagnostic Lab
- Sign Up for the Purdue Landscape Report
