The genus Diaporthe consists of several species that cause diseases in various plant species. This genus comprises 13 species complexes based on multi-loci phylogenetic analyses with 832 accepted or presumed species. Plant pathogenic Diaporthe species are widely distributed where their host plants thrive well. For instance, the blight pathogen D. vexans is commonly found in eggplant-growing regions. Rain splashes and wind easily disperse spores of Diaporthe species. Diaporthe infects various agronomic and horticultural crops, leading to various diseases, including dieback, damping off, root and fruit rot, stem canker, leaf lesions, necrotic lesions, and wilting. Among the most important species with economic importance are D. vexans, D. helianthi, D. phaseolorum, and D. citri. Diseases caused by Diaporthe species may be addressed by a combination of strategies (integrated disease management) that reduces the pathogen inoculum, kills the pathogen, or increases the plant’s resistance to the disease. Control strategies include pruning dead branches in the case of D. citri on citrus, use of potential biological control agents, planting of less susceptible varieties, and using synthetic pesticides that have been shown to provide reasonable disease control. With its biology, importance in crop production, host range, and lack of complete control, disease-causing Diaporthe species are significant impediments to achieving our food security goal.