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Cotton > Year-Round
IPM Program >
First Open Boll to Preharvest > Stem Sampling for Verticillium Wilt
Cotton
Stem Sampling for Verticillium Wilt
If you have evidence of a Verticillium problem in your field or if you want to plant a new variety next season
with unknown Verticillium tolerance, conduct a stem sampling (percent vascular discoloration) test. Stem sampling
can take place any time from crop maturity through harvest.
How to do a stem sample (percent vascular discoloration) test:
- Cut and examine 25 plant stems from various parts of
a field that has a history of Verticillium. Look for discoloration.
- If 20% or more of the stems are discolored, take action to address your situation. For instance, rotate the field
out of cotton, solarize the soil, or plant Verticillium-tolerant varieties.
- When 80% or more of the cotton stems are discolored, expect major losses in lint production in subsequent cotton
crops planted in that particular field.
Percentage of plants
with
vascular discoloration |
Verticillium wilt level |
| 10 |
Low |
| 50 |
High |
If the percentage of discolored stems is high, or if you would like to determine the length of time for rotation out
of cotton, consider sampling the Verticillium inoculum (microsclerotia) levels using soil
sampling.
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