Cotton producers who planted DP 555 BG/RR learned quickly to take an aggressive approach to control the strong vegetative growth habits of the variety with plant growth regulators. However, a less aggressive approach is needed to control vegetative growth in new cotton varieties in the Deltapine brand Class of 09 and Class of 10, according to Monsanto.
For example, DP 0920 B2RF has shown the most response to mepiquat, meaning lower rates or fewer applications may be needed. DP 1050 B2RF has shown the least response to mepiquat, meaning timely early-season applications at higher rates or more applications may be needed to control vegetative growth (growth similar to DP 555 BG/RR).
More on the use of PGRs on cotton can be found at http://deltapine.com/dp/home.
Mismanagement of mepiquat or other PGRs can have a negative effect on yield, especially when applied too early, when applied to stressed cotton, or when applied to a determinant cotton.
Proper use of PGRs in cotton can help balance vegetative and reproductive growth, in turn controlling plant maturity, improve square and boll retention and controlling plant height to improve harvest efficiency. Determining the optimum PGR use rate and application timing is difficult and can vary depending on many factors, including the soil texture, weather conditions, fertility, etc.
Understanding a cotton variety’s growth habit and response to PGRs is one of the most important factors in developing a growth management strategy.