Photos courtesy of Oklahoma Cooperative Extension include:
Anthracnose
Aphid (photo #2)
Spider Mite Damage
Snail
Slug
Lacebug
Fungus Gnat
Leafhopper
Leaf Miner Damage
Whitefly

Apple Scab photo courtesy of Kansas Cooperative Extension

Crabgrass photo courtesy of Plant and Soil Sciences Department at Oklahoma State University

Crown Gall photo courtesy of Dr. Mike Smith, Horticulture and Landscape Architecture Department at Oklahoma State University

Fireblight photo courtesy of Department of Entomology and Plant Pathology at Oklahoma State University

Purslane photo courtesy of University of Illinois and the Weeds Science Society of America