1. Experiences of a West Texas Cotton Farmer with Phymatotrichum Root Rot
Douglas Wilde
Wall, Texas

2. Phymatotrichum Root Rot
Indigenous soil born fungus
Occurs in the Southwestern US and Mexico
The fungus invades the cortical tissues of roots and damages the conducting system, induces severe water stress, and causes premature plant death by desiccation.

3. Symptoms
Bronzing and Wilting

4. Symptoms
Plants die suddenly
Leaves remain firmly attached to plant

5. Symptoms
Hyphal webs on infected roots

6. Root Damage

8. Susceptible Plants
Trees
Pecan
Apple
Peach
Fig

9. Susceptible Plants
Cotton
Alfalfa
Peanuts
Vegetable
Peppers
Carrots

10. Susceptible Plants
Shrubs
Pomegranate
Grapes
Roses

11. Immune Plants Monocots are immune Palms, Yuccas, Agave Corn
Grain Sorghum
Wheat
Sesame
Grasses

12. Tolerant Plants Tolerant Dicots Mesquite, Strawberry,
Prickly-pear cactus

13. Immune Soils
Soils that have over 400 ppm of Na, (sodium) in the profile (3 ft.) – have almost no cotton root rot.
Acidic soils

14. Favorable Disease Conditions
High soil moisture
High soil temperature
Trapped CO2
Plant stress

15. Problems
Harvest
Yield
Grade
Planting

16. Harvest Problems Decreased harvest speed Increased harvest fires
Increased wear on parts

21. Yield Decrease Up to 60% decrease in yield
Up to 90% disease infestation in fields

23. Non-Diseased Area
Diseased Area

24. Decreased Grade Decreased Micronare Decreased Staple Length
Increased Leaf
Increased Bark Grade
Gr St Lf Mic Rmrks Strn Uni Loan Rate
Diseased Areas
Light Bark
Light Bark
Non-Diseased Areas

25. Disease Management Increase Organic Matter Rotation Deep Plowing
Hot Bed
Manure
Rotation
Deep Plowing
Avoid Infested Locations
Fertilizer Application
Decrease pH of soil

26. Disease Management Reduced plant stress Plant early and a fast variety
Plant late and a fast variety

27. Current Research Projects
Soil fungicide treatment
Stem Drench
Drip injection
Biological management
Genetic resistance
Determining when fungus attacks plant

28. Conclusion No practical control for Cotton Root Rot
Emphasis on genetic resistance
Increase organic matter (microbes)

29. Thanks
Rick Minzenmayer
Dr. Tom Isakeit
Arnold Matthiesen