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:
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.