What is in this article?:
- 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.
As is the case in many years, the 2013 Georgia cotton crop is widely variable in terms of growth stage depending upon planting date.
Most of the early planted fields (late April to early May) are within the first couple of weeks of bloom, with several slightly later planted fields at various stages of squaring, and late planted cotton (early to mid-June) ranging from seedling to 4-5 true leaves.
Most of the double-cropped cotton was planted noticeably later than normal this year. Soil moisture has recently been adequate to excessive in most of Georgia’s cotton belt due to frequent and hefty rains. Effects have been variable with regard to growth and development. Many fields have been waterlogged which has noticeably slowed growth of younger cotton, while other fields of older cotton (near bloom or within the first couple of weeks of bloom) are currently showing signs of vigorous growth.
Due to wide variability in crop growth, we strongly recommend that growers make growth management decisions on a case-by-case and field-by-field basis, as opposed to a one-size-fits-all approach. When making plant growth regulator decisions, it is important to recognize the actual effects that mepiquat-containing PGRs have on the plant and how this may or may not benefit the grower.
Mepiquat-containing PGRs reduce the production of plant hormones called gibberellins or gibberellic acid. Gibberellins are natural plant hormones that are involved in cell expansion. When mepiquat is applied, the internodes near the terminal of the main stalk or on lateral branches (regions where elongation occurs) may not elongate to the degree that non-treated plants would.
This usually results in shorter plants, with more compact nodes. Most mepiquat-containing PGRs, with the exception of Stance, generally have similar effects on plant growth. When applied at similar rates (except for Stance), similar results should be expected. Stance contains a higher concentration of mepiquat than other mepiquat products, and also includes cyclanilide. This product is used at much lower rates than standard mepiquat products.