Despite best efforts by growers, cotton planting conditions this spring were not favorable for even vigorous cotton seed to emerge without difficulty in some locations.
In Georgia, the weather was much like it is each spring with variable (and at times extreme) temperature fluctuations coupled with the one-two punch of drought conditions followed by heavy rainfall. According to University of Georgia Extension cotton agronomist Jared Whitaker, cotton emergence was a hard issue for many farmers across the cotton-growing region of the state.
“Each year is different, but this year had conditions that caused headaches for growers attempting to get adequate stands in dryland and even irrigated fields,” he said.
It was not uncommon for fields to need replanting, at least in spots, due to poor, thin stands, and some cotton was being replanted as late as mid-June, pushing planting a bit too late.
“My suggestion is that growers should be very cautious about planting this late, especially this late planting dryland acres. Yield potential will undoubtedly be lower and potentially too low to warrant planting,” Whitaker said. “If it was before the middle of June, I would feel much more comfortable about planting.”
For irrigated land planted this late “to make even fair yields,” he said, the irrigation will have to be used to eliminate any delay in cotton maturity due to lack of rainfall.
Weather was the major factor going against good cotton stands for several reasons this year, he said.
“The planting window was very dry during most of the period but interrupted with big rainfall events. With dry conditions, cotton is often ‘dusted in’ or planted very shallow in very dry soil. This practice can work very well, but is often not best practice when planting. First, in this case it has to rain to germinate seed, and rainfall patterns following dusting in cotton are critical to getting a stand,” he said.
In Georgia, the rain that germinated those dusted seed came in large doses and caused excessive soil packing. In those cases, the soil got tight and difficult for cotton to come through.
“(And heavy rain) can also actually move seed deeper than originally planted, which can impact emergence. When this happens, you see some issues where plants run out of energy before emergence, and seedling disease is more likely to occur because the unemerged seedlings are stressed trying to reach the soil surface,” Whitaker said.
Seed vigor is related to seed size
Even irrigated cotton had some problems due to dry weather. “To help with emergence, growers often use irrigation in small amounts several times to assist emergence, and this can also create favorable seedling disease conditions as well as create more preemergence herbicide injury,” he said.
Seed vigor becomes an important factor when weather conditions are tough, like they are often during spring planting. Some seed companies take pride and market the vigor of their varieties, but seed vigor can vary even among seed lots, he said.
“One thing that we’ve worked on at UGA with regards to seedling vigor is to quantify what plays a role in determining vigor and how can we compare varieties across and within brands. UGA cotton physiologist Dr. John Snider has led our efforts with success. One thing we have confirmed is that many things play a role in seedling vigor, but relative seed size is by far the greatest predictor of seedling vigor,” he said.
The Georgia research finds larger seed have better vigor and smaller seed can have weaker vigor. “This matters when considering varieties where a variety is fairly consistent with what seed size it has. This is important because most of our successful yielding cotton varieties have very small seed and ultimately somewhat weaker vigor,” Whitaker said. “And even though we grow small-seeded varieties, most of the time we have relatively no issues with emergence. ... But growers have the opportunity to make variety selections based on vigor (seed size) if they feel like conditions could be tough."
If you have questions about cotton emergence this year or want to know more about the cotton seed vigor study in Georgia, contact your local county Extension agent.