What is in this article?:
- Make cotton PGR decisions on field-by-field basis this year
- Some PGR misconceptions
- Growing season, weather affect PGR decisions
- It is important to know what mepiquat-containing PGRs do to plants and how this may or may not benefit the grower.
- Georgia cotton growers need to consider growing season and weather as it relates to cotton maturity and fruit retention.
- Some of the earlier maturing varieties with less growth capacity may not need a pre-bloom PGR application in order to prevent excessive growth.
DUE TO variable weather patterns, Georgia's cotton crop this year is widely variable in growth. Growers need to make PGR decisions based on what is happening in the field not by old habits.
Growing season, weather affect PGR decisions
One other thing to consider in Georgia is the length of the growing season and weather as it relates to cotton maturity and fruit retention:
Most importantly, one should consider that our relatively high temperatures and high humidity create a situation where fruit retention can be an issue to consider, such that fruit retention on lower nodes may explain why the crop is difficult to control with PGRs.
It is also important to remember that conditions which occur during boll opening (especially in early planted fields) may impact the ability to harvest those bolls on lower positions, whereas boll rot can greatly impact the harvestability of fruit particularly those deeper in the canopy. These factors should be considered when attempting to decide the optimum plant height required to maximize yields.
Another somewhat unique factor with Georgia’s environment is the length of the growing season. Our conditions often allow for cotton to be produced much later in the season than cotton grown in neighboring states (especially those north of us) and consideration should be made when comparing PGR ideas and recommendations from those regions.
This is not intended to make Georgia growers weary of PGR recommendations from other states, but it can potentially explain differences in PGR philosophies in Georgia compared to other states.
We now are dealing with some newer varieties that tend to be earlier maturing than DP 555 BR with generally less growth capacity than that of DP 555 BR. The range of maturity and growth capacity is very wide among these newer varieties, with some varieties showing somewhat similar characteristics to that of DP 555 BR. It is important to familiarize yourself with these characteristics of the varieties you choose to plant.
When DP 555 BR was still widely planted, most growers began their PGR applications at the 8- to 10-leaf stage, which was generally followed by applications at or near first bloom and again 2 to 3 weeks later. This program was a more preventative-type prophylactic program that generally worked well for DP 555 BR, especially in irrigated fields, as this variety could consistently result in (and was likely to result in) excessive growth and extremely tall plants.
Most (but not all) of the newer varieties tend to develop a larger boll load slightly quicker than DP 555 BR, which can restrain terminal growth to some degree, therefore growers can be more reactive than proactive/preventative with PGR management in some situations, especially with the earlier maturing varieties.
Some of the earlier maturing varieties with less growth capacity may not need a pre-bloom PGR application in order to prevent excessive growth, and delaying these decisions until first bloom may allow for better growth management decisions.
Keep in mind that some of the earlier maturing varieties may exhibit vigorous or aggressive growth prior to first-bloom, however the growth rate may rapidly decrease once these varieties enter the bloom period when the rapidly developing boll load begins to retrain terminal growth.
Aggressive, preventative approaches for early maturing varieties may in fact prevent plants from reaching an optimal plant height in some environments thereby risking yield loss associated with inadequate numbers of fruiting sites.
For later maturing varieties with greater growth potential, especially in timely irrigated fields, a more aggressive preventative approach (which may include pre-bloom applications) may be necessary to prevent excessive growth, but a one-size-fits-all approach is no longer suitable.
For specific information on varietal impact on PGR decisions, go to www.ugacotton.com