A valuable feature of the petiole testing program is that since samples are taken weekly, trends can be monitored and deficiencies or excesses can be detected up to two weeks in advance. Most importantly, petiole testing allows in-season correction of problems. Consistent soil moisture increases the reliability of petiole results. Therefore, in general, petiole testing works better under irrigated conditions. However, unless there is very erratic soil moisture, petiole testing works well enough to be a valuable tool under non-irrigated conditions.
Representative samples are even more critical for petiole testing than with soil testing.
Growers or their scouts are urged to closely follow sampling instructions and to provide exact information requested for each sample. Apart from good sampling techniques, petiole test results will be unreliable and confusing. Foliar N and K Foliar N applications can be made as part of an overall N management strategy or as determined by petiole testing. Urea is the most reliable, economical, and proven foliar N material. A good soil-applied K program with proper rates and split applications should provide sufficient K for Georgia cotton in most cases.