To control seed and technology costs, some cotton producers are considering lowering their seeding rates. However, as Owen Gwathmey, University of Tennessee (UT) crop physiologist, and UT weed specialist Larry Steckel discovered, it’s not a matter of just turning down your planter. Farmers must have an all encompassing plan.
“It’s important to have enough of a stand to help with weed suppression as well as a minimum stand needed for optimum yield and fiber quality,” Gwathmey says.
Critical Factors To Consider
Before committing to a lower seeding rate, consider the following:
• Is the planter tuned up and calibrated for a particular seed lot?
• Does the seed lot have a good seed germ percentage? Be sure to get the actual cool and warm seed germ from your seed distributor for each seed lot.
• How good is the seedbed for conventional or no-till systems? Will the planter work well in that seedbed?
• How good is the seven-day weather forecast? Avoid 40-degree cool nighttime temperatures.
“If everything goes well, we can use lower seeding rates,” Gwathmey says. “We can go somewhat lower in the 15-inch row configuration than in the 30s. In the 30s, in particular, we found that we can’t go below two seeds per foot of row without having so many skips in the stand that the weeds take advantage of us.
“In our tests, we were looking at a plant population of 21,000 to 22,000 plants per acre from a seeding rate of around 29,000 to 30,000 seeds per acre as being the lowest we could go without losing yield and net returns on our seed and tech fee investment,” he adds.
Weed Control Options
Obviously, weeds need water and heat to germinate and get established. But, as Steckel points out, weed seeds, particularly pigweed, also need light to promote germination. The question is, “How do you compensate for the additional light that is available with lower seeding rates?”
“We didn’t see as many weed problems in the narrow-row configuration as we did with the wider rows, especially where there is a skip row,” Steckel says. “One option to help suppress weeds is to plant a cover crop in the fall – such as a cereal rye – spray it in the spring, then plant into it.”
In addition, make sure the planter is tuned up and as close as it can be to planting a “picket fence” stand, which more quickly provides shade, as opposed to a stand with big gaps.
“Also put down a pre-emergence herbicide, using residuals such as Valor or Reflex early pre-plant,” Steckel says. “Or, farmers can apply Cotoran or Caparol right behind the planter. Even if the cotton stand is thin, it should have enough height to start shading the ground when these herbicides begin to run out of gas.”
As Gwathmey notes, moving to a lower seeding rate is a calculated risk-reward tradeoff. “Farmers must consider production factors they have a handle on and know their tolerance for risk in reducing their seeding rates.”
Contact Carroll Smith at (901) 767-4020 or firstname.lastname@example.org.