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 disease that is fairly common in Mexico and the southwestern United States resulting in sudden wilt and death of affected plants, usually during the warmer months. It is caused by a soil-borne fungus named Phymatotrichopsis omnivora that attacks the roots of susceptible plants. It was first discovered in 1888 by Pammel and later 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. Host and symptoms Phymatotrichopsis omnivora is a necrotic fungal pathogen that has a very broad host range, attacking almost 2000 dicotyledonous species. It inhabits alkaline, calcareous soils in southwestern United States. It particularly targets dicots as most monocots are immune. Economically important plant hosts affected by the pathogen include: peanuts, cotton, alfalfa, apple, pecans, and ornamental trees. First symptoms of disease is often chlorosis of the leaves then followed by browning and wilting. Two weeks of the first symptoms appear, 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 show extensive discoloration. Beneath the soil surface, other observable signs are present. Distinctive cruciform branched hyphae develop on infected root tissue which are observable with compound microscope (Figure 1). In addition, taproots of the infect plant are covered in mycelial strands. Another macroscopic sign are tan and white spore mats developed on the soil surface near the infected plants during favorable high moisture environmental conditions. Despite the name, these spore mats are not known to aid in dispersal. Although presence of the conidial phase on the spore mats is known, the function of the conidia remains unknown since conidial germination is rarely observed Environment The highest concentrations of Texas root rot disease are found in the southwestern United States and northern Mexico, with cases also reported in India and Pakistan. Texas root rot is caused by a pathogen that prefers alkaline and calcareous soils (pH between 7-8.5), affording the potential for control via soil amendment. Scientific research has discovered that both high precipitation and high temperatures (below 93 degrees Fahrenheit) are further environmental enhancers for Texas root rot by increasing its virulence. The pathogen earned