Phymatotrichopsis Root Rot of Cotton
Published: 08/25/2023
Phymatotrichopsis root rot is a disease affecting cotton and other crops in Texas and Arizona, causing significant annual economic losses. It is caused by a fungus called Phymatotrichopsis omnivora, which lives in the soil infecting over 1,800 different types of plants. The disease appears in late spring or early summer when soil temperatures reach 82°F (28°C). Infected plants start wilting and eventually die within a few days. Roots become rotted and can easily be pulled from the soil. The disease often manifests as circular spots within fields that enlarge after rainfall or irrigation. The fungus is most active in alkaline soils.
Managing Phymatotrichopsis root rot has been challenging, but the fungicide flutriafol (most commonly sold as Topguard(R)) applied as a “t-band” has been beneficial. Crop rotation with resistant plants like corn or sorghum and deep tillage in the summer and early fall when the soil is dry may be helpful.
Written and reviewed by Travis Faske, University of Arkansas; Tom Allen, Mississippi State University; and Trey Price, Louisiana State University.
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