Phymatotrichum omnivorum

Phymatotrichum omnivorum, commonly known as Cotton Root Rot, is a plant pathogen that is native to North America. It is a soil-borne fungus that affects a wide range of plant species, including many important agricultural crops.

Taxonomy

The fungus was first described in 1888 by Charles Horton Peck, an American mycologist. It was initially classified in the genus Phymatotrichum, but has since been reclassified to the genus Armillaria. Despite this, the common name "Phymatotrichum root rot" is still widely used.

Distribution and Habitat

Phymatotrichum omnivorum is found primarily in the southern United States, particularly in Texas, Oklahoma, and New Mexico. It prefers alkaline soils and is most common in areas with a high clay content.

Host Range and Symptoms

Phymatotrichum omnivorum has a broad host range, affecting over 2,000 species of plants. This includes many economically important crops such as cotton, alfalfa, fruit trees, and ornamental plants. Symptoms of infection include wilting, yellowing of leaves, and root rot. In severe cases, the fungus can cause the death of the plant.

Disease Cycle

The fungus survives in the soil as sclerotia, which are resistant structures that can remain dormant for many years. When conditions are favorable, the sclerotia germinate and infect the roots of host plants. The fungus then spreads through the plant's vascular system, causing wilting and death.

Management

Management of Phymatotrichum omnivorum is challenging due to its wide host range and ability to survive in the soil for long periods. Strategies include crop rotation, use of resistant varieties, and soil amendments to reduce soil pH.

See Also

• Plant Pathology
• Soil-borne Diseases
• Fungal Plant Pathogens