Cotton Quality Affected by Late Rainfall

  • Late-season rainfall has caused boll rots, seed sprouting in the bolls, and other issues that may reduce cotton quality.
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  • Timely defoliant and desiccant applications can help growers preserve cotton quality and yield potential.
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  • Growers should delay harvest until sprouted seed has dried naturally or apply a desiccant to encourage seedling drydown.
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  • With the potential for additional rainfall, growers should apply defoliants and harvest cotton as soon as fields are dry enough to support the weight of a harvester.
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Weather Impacts

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Cloudy, overcast skies, frequent and often heavy rainfall, humid conditions, and infrequent sunshine have taken a toll on cotton quality across the south and southeast. A significant portion of the cotton crop is affected by delayed defoliant applications, boll rots, seeds sprouting in the bolls, and some cotton falling out of bolls. University cotton specialists are urging farmers to thoroughly scout fields and to maintain cotton quality by making timely defoliant or desiccant applications and carefully planning harvest timing.​

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Sprouting Seed

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“The prolonged rainy spell has caused a lot of seed to sprout in the bolls,65533;? says Guy Collins, Cotton Extension Associate Professor, North Carolina State University. “Moisture found its way into opened bolls and the seeds began sprouting. Sprouting may have been more severe in fields that had already been defoliated, with less sprouting in fields that were not defoliated and had fewer opened bolls. Farmers should scout their fields to determine which fields or portions of fields have been affected.65533;? (G. Colllins, personal communication, October 7, 2015).

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Sprouted seed can cause several issues, including: higher trash content, seed coat fragments, and lint discoloration. In addition, if fields are harvested before sprouted seeds dry down, this could lead to undesirable moisture in harvested cotton. Sprouted seed may also result in decreased seed quality and significantly less seed available to offset ginning costs. It is important for farmers to monitor modules for increases in temperature from high-moisture cotton that could lead to further reduced quality and ginning difficulties.

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“It is absolutely critical to wait until these germinated seed completely dry out before harvesting these fields,65533;? says Collins. He says warm, sunny, dry weather can quickly dry sprouted seed, reducing moisture content and decreasing harvesting and ginning challenges.

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“If fields have already been defoliated, growers can apply a desiccant (such as paraquat or one of the PPO-inhibitor herbicidal defoliants) A few days before harvest to accelerate the drying process,65533;? says Collins. “A desiccant can dry down the sprouted seedlings quicker; however, the integrity of the sprouted seed has already been lost, which could complicate the ginning process. If warm, dry conditions prevail, waiting a couple of days more before harvesting could provide the same results as applying a desiccant,65533;? he says.

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Collins cautions farmers who may have difficulty harvesting cotton with sprouted seeds to contact their crop insurance agent. “It is important to call your crop insurance agent an document this on the front end, before harvest is complete in these fields,65533;? he says.

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Defoliation and Harvest Timing

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“Cotton is like any other fruit,65533;? says Jared Whitaker, Extension cotton specialist, University of Georgia. “Once it is ripe, poor conditions can cause it to deteriorate rapidly. “The same conditions that have led to seed sprouting in the bolls has caused a significant amount of boll rot in some areas. Fields which have open bolls are susceptible to heavy rainfall and winds which has caused some lint to fall out. Farmers should concentrate now on timely defoliant applications and timely harvest.65533;? (J. Whitaker, personal communication, October 7, 2015).

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“Farmers should take advantage of any opportunity to defoliate as soon as field conditions allow and the crop is ready,65533;? Whitaker says. “We don’t want to lose the more valuable bottom bolls while waiting for a few more top bolls to open. Remember that the potential exists for more rain.65533;? Plentiful moisture late in the season may also stimulate regrowth in the top and possibly from the bottom of plants. Whitaker urges growers to use defoliation products that will kill regrowth and prevent additional regrowth.

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“With good sunshine, we should be fine with our standard defoliation recommendations,65533;? he says. “Using the right products with adequate pressure and water volumes should result in good defoliation and little regrowth.65533;?