Soil Pathogens

Fusarium species cause root rot, wilt and yellows disease on many agronomic crops including onions, tomatoes, strawberries, Cole crops and Cucurbits. Macrophomina phaeseolina is a causal agent of charcoal rot disease. This fungus has a wide host range, more than 500 species. It causes variety of symptoms, including seedling rots, root and stem rots and wilts. Hot weather promotes the disease development. Phoma terrestris is a causal agent of onion pink root disease. It is also wide spread pathogen affecting several other crops such as cereals. Phytophthora genus includes several economically important plant pathogens that cause blights, cankers and rots in various plant species. Production of vegetables, fruit trees and nursery industry are most commonly affected by these diseases. Pythium species such as its relatives, Phytophthora spp., are water-loving organisms, many of which are plant pathogens. Pythium species commonly cause seed rots and damping-off of young seedlings. Mature plants are also affected; Pythium-root rots of established plantings lead to poor growth and yield losses. Pythium diseases commonly affect nursery and greenhouse production. Rhizoctonia solani is a common soil pathogen causing damping off, root and stem rots of variety of plant species. Sclerotinia species, most commonly S. sclerotiorum and S. minor are causal agents of stem and soft rots of many agronomic crops such as celery (pink rot), lettuce (lettuce drop), tomatoes (white mold) and ornamentals (cottony rot). Sclerotium species cause damping-off, stem canker, crown blight, root, crown, bulb and tuber rots on wide variety of plants, including vegetables, legumes, and cereals. Diseases caused by these species are often called Southern blights or wilts. Verticillium dahliae, a causal agent of Verticillium wilt is a true soil-borne pathogen that can survive in soil for up to 15 years as microsclerotia. Another Verticillium species, V. albo-atrum also causes wilts but is differentiated from V. dahliae in that it does not produce sclerotia. Verticillium species attack over 200 plant species including vegetables, flowers, strawberries, fruit trees, field crops and shade and forest trees.