Seed coat fragments have been a long-term issue for cotton. Fragment outbreaks occur sporadically every three to five years in some region of the United States. Last year, the region included Alabama, Georgia and Florida, with the biggest outbreak of seed fragment calls in the past 20 years. And it was no coincidence this is also one of the worst years for tropical storms.
Seed coat fragments are formed when a part of the cottonseed wall breaks off and often attaches to fibers. This makes it particularly difficult for the gin and textile mills to remove as all their equipment is designed to keep fibers in the process.
Seed coat fragments have been studied at length. Since 2003, Cotton Incorporated has sponsored a consistent research program on fragment reduction with the U.S. Department of Agriculture-Agricultural Research Service gin labs, Texas Tech University and North Carolina State University. We have learned a lot over that period. Before sharing, I want to emphasize there is strong evidence that what we saw in 2020 is highly weather related.
Conditions Conducive To Seed Coat Fragments
When open bolls get wet, three things can happen that will lead to seed coat fragments:
• Seed sprout — If the seed sprouts in the boll, there will definitely be seed coats found in the cotton when it is ginned.
• Wet seed at the gin — Cotton lint dries much faster than the seed. This can lead to cotton being harvested when it appears to be dry, but the seed is still wet. Wet seed will be pulled through the ribs of the gin stand and forms seed coats
• Wetting and drying of seed in the field — When the seed takes up moisture during high humidity, it will expand and then shrink as it dries. A few cycles of wetting and drying, and the seed coat becomes weak and can easily break during the harvest and ginning process. All three of these likely contributed to seed coat fragments last year.
Some Theories Debunked
I have heard a few theories about what caused seed coat fragment problems beyond weather, and I can dismiss a few. One is that the Macon, Georgia, classing office made too many seed coat fragment calls. The USDA-AMS classing system has a very robust set of checks and balances. They were aware early in the season an anomaly was occurring and were careful to make sure they were properly defining seed coat fragments.
As some evidence, I can personally confirm that Cotton Incorporated’s fiber processing lab purchased 4 bales from Georgia that had seed coat fragment calls, and they were indeed full of seed coat fragments. On the plus side, those bales were purchased so our textile experts could process them and provide assistance to mills on how to handle 2020’s seed coat fragments.
They can be a real challenge for mills if not handled correctly. In addition to potentially ending up in fabric, the oil in the seed coat fragments in a worst-case scenario can coat the equipment and require the mill to shut down for cleaning.
Variety By Environment Interaction
In past years when seed coat fragments were a problem, there was often a strong variety by environment interaction. (For example, a particular variety has seed coat fragments one year when other varieties do not. Then in another year, that same variety does not have them).
There is not conclusive evidence variety was a factor last year; however, the fact that there were not problems in South Carolina and North Carolina where some of the same varieties are grown reinforces the hypothesis that weather was the dominant factor.
Finally, keep in mind the first boll on a plant opens at the bottom when it is hidden from sight and will occur anywhere from 50 to 70 days before the crop is harvested. Those bottom bolls are the ones most likely to stay wet.
Cotton Incorporated-funded research is making progress in addressing seed coat fragments by improving the lint cleaner at the gin and developing tools that could help breeder screen for genotypes that are prone to seed coat fragments in the future. We have found that seed size is not a good predictor of seed coat fragments but how strongly the fiber is attached to the seed (attachment force) and seed coat strength are.
Why is this problem still not solved? Part of it is the infrequent nature of seed coat fragments and the interaction between variety and environment. We will continue to work on this issue with the hope the next time they occur, we can further reduce the problems they cause and possibly reduce the frequency of such events.
Ed Barnes, Cotton Incorporated Agricultural and Environmental Research Division, contributed this article.
California Association Announces Election Results
The California Cotton Ginners and Growers Association has released the election results for the 2021-2024 term. The only nominations received were for the incumbents.
These ginners have been reelected to the board, and two vacancies remain unfilled.
• Tom Gaffney, J.G. Boswell Co.
• Greg Gillard, Olam Cotton.
• Tom Pires, West Island Cotton Growers.
The following growers were reelected:
• Jim Razor, J.G. Boswell Co, Kings County.
• Phil Hansen, Hansen Ranches.
• Geoff Toledo, Hanford.
• Southern California will again be represented by Tim Cox, Palo Verde Valley.
All board member positions are three-year terms, while officers serve in those positions for two years.
The California Cotton Ginners and Growers Association provided this information.