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Sept. 6, 2019 - Managing late season cotton prior to maturity

Update on East Georgia cotton conditions and thoughts on irrigation termination timing and late season finishing growth regulators.

For what felt like months, we had our eyes on Hurricane Dorian as it battered the Northern Bahamas trying to make up its mind on which direction to head. While our thoughts and prayers are with the Bahamians and other families impacted by this storm, it thankfully provided ideal rainfall based on crop stage and condition for the cotton growing areas in Georgia. The previous 7-day precipitation map below shows rainfall ranged from .25” in southwest Georgia, up to 2” in areas around I-16. Many areas that have been overly dry received sufficient rainfall. 


USDA conditions place almost 70% of acres in the good-to-excellent range with adequate soil moisture in most of the state. USDA Crop Progress and Condition Report places 100% of acres at setting bolls for the first time, up 3% from this time last year. Acres with open bolls were reported at 42%, up 18% from this point in 2018. Traveling across Central and East Georgia, I believe the rainfall map fairly accurately depicts cotton maturity across the state, supplying amounts of water required for current stages of development.

As we start to see more first position cracked bolls, irrigation termination timing has become more of a question. Based on University of Georgia recommendations, once reaching 10% cracked bolls, or 1-2 open bolls, we should terminate irrigation if soil moisture is adequate. I support this recommendation; however, I encourage growers to check soil moisture down to the 12” or deeper range. With droughty conditions early, many of our root zones mined deeper through the profile following the depleting moisture. To ensure adequate moisture for boll filling, we want moisture down in the 12” range. If required during boll fill, secondary roots can be developed in shallow depths to mine for sub-surface moisture provided by late summer, isolated showers. Checking for soil moisture in deeper depths may help save a few dollars on a final watering.

A final, popular topic is a finishing shot of plant growth regulator. Most university data suggests there is not an economic benefit from applying a final application of a plant growth regulator to “finish” the crop. In most scenarios I support this recommendation. In areas with later-planted, full season varieties in which fruit set did not start until 8-10th position, however, a final application of plant growth regulator may be beneficial to try to halt the indeterminate growth, such as with PHY 580 W3FE pictured below.

With adequate moisture, nutrients, and solar radiation, the plant will continue to push to generate additional positions while aggressively loading up the plant with bolls and squares. With average, last effective bloom dates occurring within the next week, we want to begin diverting all resources to currently set fruit. Also, dependent on the variety, we can have some control on micronaire and fiber premiums with a final plant growth regulator. The next 7-day forecast looks prime for pushing the 2019 crop to the finish, with warm temperatures and dry sunny weather.


For more information about cotton production practices in your area, contact your state Extension cotton specialist. As always, your PhytoGen cotton development specialist also is available to discuss agronomic options.

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