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Strong Cotton Requires Solid PGR Management

By Jay Mahaffey, Bayer Science Fellow and Manager of the Bayer Scott Learning Center in Mississippi

Managing Deltapine® brand cotton varieties for their optimal performance requires correct and timely plant growth regulator (PGR) applications.

The tools available for cotton production have changed greatly over the past five years, with the introduction of new insect-protection traits, improved varietal genetics and alternate crop management systems. As new traits are introduced, each cotton variety containing those new traits must also be evaluated for a range of responses to planting population, PGR use and environmental adaptation. Each of these factors can potentially impact the productivity of a cotton field or even a particular variety.

PGR response must be identified and characterized very early in the introductory process for new cotton varieties and traits. The Bayer Scott Learning Center in Mississippi focuses on this by measuring the relative response of varieties in height reduction through experimentation. Each variety is different in its response. This information can then be used to place varieties into various adapted systems and make adjustments to agronomic practices for optimal production.

Promo Tools of undefined

Deltapine® brand Bollgard® 3 ThryvOn Cotton with XtendFlex® Technology varieties are in many growers’ planting plans for 2024 for its performance against early-season thrips. But with that control comes a healthier-growing plant that reaches pinhead square rapidly, resulting in the possible need for earlier plant-growth management. There are basic considerations for variety placement and PGR strategy, however, that should be applied, regardless of the trait package being planted.

Field History

Has the field been a growth control problem in the past? If so, several potential adjustments can be made, including:

  • Shifting to less growthy, more determinate varieties.

  • Altering seeding rate

Many growthy fields can see better results from reduced seeding rate. Many growers are effectively doing this today in response to technology costs, but the agronomic results are indisputable. As plants care forced to compete more with each other, PGR response is reduced. When farming historically very growthy fields, reductions in seeding rate can make a real difference in results. On less productive fields, seeding can be maintained or increased.

Promo Tools of Field History

Timing and Rate

Two primary considerations in PGR management are timing and rate. PGRs are active at dry weight concentrations. Therefore, as plants become larger, more active ingredient is required to exceed the active dose. The effects of growth regulator application on a cotton plant are long lasting. Even with lower rates or fewer applications early in the plant’s life cycle, it is easier to get back above the threshold of activity as mid-late season applications are made.

Stance® Plant Growth Regulator is a recommended product to start PGR programs with, featuring convenience and simplicity and fits most management programs.

Promo Tools of Timing and Rate

Most cotton fields should receive some amount of PGR as soon as the label allows. This often allows for better control of plant growth to be maintained into the late season. Very little PGR response is observed from applications prior to recommended timings. Using correct rate of PGR matters, particularly as it interacts with plant size. PGR rates should generally be reduced in dry, less growthy conditions and rates increased in high-growth environments or in fields with productive soils, all while considering varietal background and PGR response, surviving plant population in the field, and expected weather conditions and/or rainfall.

As new varieties are introduced, particularly ones that have technology potentially interacting with fruit accumulation, such as Deltapine® brand Bollgard® 3 ThryvOn™ Cotton With XtendFlex® Technology varieties, a new set of considerations may emerge.

Varietal Response

We know that response to PGR application can be unique for each cotton variety. As chronic thrips feeding is reduced in fields planted to Deltapine® brand Bollgard® 3 ThryvOn Cotton With XtendFlex® Technology varieties, potential growth pattern changes may be observed. A lack of thrips feeding on young cotton plants may have two primary influences: accelerated early season growth and increased early fruit retention. These factors could counteract each other, but that will likely occur into the bloom/boll development stage of growth.

Promo Tools of Varietal Response

The net effect is that PGR applications become more critical as field conditions and scouting dictate. Scouting plant growth for node elongation is a good indicator of when a field may need a PGR application, especially when taking into consideration the weather forecast for the next week to 10 days.

With appropriate and timely PGR management the latest genetic and technology cotton varieties can be farmed to perform optimally.