Editor's note: As cotton nears maturity, the National Cotton Council has initiated a series of information pieces to help producers better understand weather effects on fiber quality, especially micronaire and length. The following is the second in the series.)
Post cutout irrigation decision is vital part of harvest preparation.
Scheduling irrigation late in the season is an important practice to help young bolls grow to maturity, especially following periods of hot dry weather such as those experienced in much of the Cotton Belt this year.
In areas of the Cotton Belt where crop development is still proceeding, producers should weigh the benefits of boll filling against the risks of boll rot and potential regrowth-defoliation problems.
A conservative approach is to schedule the last irrigation about seven to 10 days after cutout, which occurs when the number of Nodes above White Flower (NAWF) equals 4 or 5. The higher proportion of the bale containing fiber from mature, young bolls will help keep micronaire out of the discount range.
Boll loading in much of the Cotton Belt, especially the Mid-South, proceeded rapidly this year due to extraordinarily high fruit retention early in the season. Traditional harvest preparation timing measures may result in higher-than-desirable micronaire values with resultant penalties.
Data published in North Carolina and Mississippi indicate that when boll loading is concentrated over a small number of fruiting branches, the defoliation applications can be made as early as when 50 percent of the bolls are open. By terminating the crop early, high micronaire grades can be minimized.
During years of potential high micronaire, once-over harvesting is a strategy to help keep micronaire readings in the desirable range. By harvesting young, mature bolls at the same time as older bolls, bales are less likely to be discounted.