Phymatotrichopsis omnivora
| Texas root rot | |
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| Scientific classification | |
| Kingdom: | Fungi |
| Division: | Ascomycota |
| Class: | Pezizomycetes |
| Order: | Pezizales |
| Family: | Rhizinaceae |
| Genus: | Phymatotrichopsis |
| Species: | P. omnivora |
| Binomial name | |
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Phymatotrichopsis omnivora (Duggar) Hennebert, (1973) |
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| Synonyms | |
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Grandiniella omnivora (Shear) Burds., (1977) |
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Grandiniella omnivora (Shear) Burds., (1977)
Hydnum omnivorum Shear, (1925)
Ozonium auricomum Link [as 'auriconum'], (1809)
Ozonium omnivorum Shear, (1907)
Phanerochaete omnivora (Shear) Burds. & Nakasone [as 'omnivorum'], (1978)
Phymatotrichum omnivorum Duggar, (1916)
Texas root rot (also known as Phymatotrichopsis root rot, Phymatotrichum root rot, cotton root rot, or, in the older literature, Ozonium root rot) is a pathogen fairly common in Mexico and the southwestern United States that causes sudden wilt and death of affected plants, usually during the warmer months. It is a soil-borne fungus of the species Phymatotrichopsis omnivora that attacks the roots of susceptible plants. It was first discovered in 1888, and was named by Duggar in 1916.
A monograph of this disease, which includes a historical review, was written by R.B. Streets and H.E. Bloss in 1973.
Phymatotrichopsis omnivora is a necrotic fungal pathogen that has a very broad host range, attacking almost 2000 dicotyledonus species. It is known to inhabit in the alkaline, calcareous soils in Southwest United States. It particularly targets dicots as most monocots are immune. Economically important plant host affected by the species include: peanuts, cotton, alfalfa, apple, pecans, and ornamental trees.
First symptoms of disease is often chlorosis on the leaves. This is then followed by browning and wilting of the leaves. Eventually after two weeks of the first symptoms the plant dies. In the field, infected cotton plants exhibit wilting in the mid to late summer form large circular patches and later die. Upon closer examination, the host plant's vascular system will show extensive discoloration. Underneath the soil, more observable signs are present. Distinctive cuniform branched hyphae are found on infected root tissue which are observable with compound microscope (Figure 1). In addition, taproots of the infect plant will be covered in myclieal strands.
Another macro sign is during favorable high moisture environmental conditions where spore mats appear. Despite the name, the purpose of these spore mats are not known to aid in dispersal. Although presence of the condial phase on the spore mats is known the function of the produced condia remains unknown since condia germination is rarely observed The spore mats are tan and white, found on the soil surface near the infected plant.
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Wikipedia