Symptom Identification of Pecan Phymatotrichopsis Root Rot (PRR)
- Commonly known as cotton root rot or Texas root rot.root rot.
- PRR is caused by the soilborne fungus Phymatotrichopsis omnivora.
- PRR is geographically limited to the southwest and parts of the south central US and northern Mexico.
- The fungus persists as sclerotia (1 to 5 mm in diameter) and mycelial strands (rhizomorph) for decades in the soil, in particular calcareous clay soils (pH range of 7 to 8.5).
- The fungus forms spore mats (white to tan in color and 2 to 16 inches in diameter) on the soil surface during warm, rainy weather. The spores are sterile.
- Spread directly to adjacent plants by fungal strands that grow through the soil. Affected areas often appear as circular patterns of dead trees.
- All pecan varieties are susceptible. PRR affects over 2,000 species of dicots (broadleaf plants), but does not affect monocots (grasses).
Publication Date:
April 2020
AZ1814-2020
Pages:
4