This cool, wet spring has seen an increase in foliar bacterial plant disease incidence in the plant pest lab. See images below for common leaf spot and blight symptoms.
Symptoms of bacterial leaf spot and blight on Magnolia grandiflora. 
Symptoms of bacterial leaf spot and blight on Helleborus species.
These foliar symptoms can appear similar to abiotic stress from heat or water stress resulting in leaf scorch, and fungal pathogens can also cause leaf scorch and spots. When evaluating these samples in the lab, we have to use high magnification microscopes to rule out bacteria as a cause of leaf spots and blights. Please see the video below for bacterial streaming detected from infected leaves of Magnolia grandiflora. Control measures are different for bacteria than fungi. It is important to identify the pathogen causing disease so management recommendations are effective. If your plants are experiencing leaf blight or leaf spots, please contact your local county Extension agent for assistance with disease identification and assistance with sample submission the Soil, Plant and Pest Center plant pest lab.
Post by Dr. Eleanor Lopez, plant pathogen and insect diagnostician.