- Below-ground seedling health a factor in cotton replanting decision.
- Use burn-down herbicide on old stand before replanting.
Appearances can be deceiving when evaluating a drowned cotton field for replanting.
“When evaluating your current stand, make sure to check the health of the plant both above ground and below ground,” said Tom Barber, Extension cotton agronomist and associate professor for the University of Arkansas Division of Agriculture, on Thursday. “The plants can look pretty ragged and still survive as long as the root system is healthy.”
Seedling cotton is very sensitive to excessive rainfall or flooding.
“Heavy rainfall in the spring cools the soil, reduces soil oxygen content, and increases the pressure from seedling diseases,” Barber said. “Waterlogged conditions for 24 to 36 hours will cut off the oxygen supply to the young root system. After 36 hours of waterlogged conditions young roots may die, leading to the death of the seedling.”
However, he reminded growers that in a flooded field, “it will take some time for the current stands to recover. Seedlings may look yellow and off color, but as the soil dries oxygen will return to the roots and plants should begin to green back up.”
Most cotton is grown on soils that are well drained and prevent saturation of water.
“However, given the sequence of events the last few days and weeks, most producers will have some replanting to do once fields begin to dry.”
Barber said growers should ask these questions before making a replant decision:
- What is the calendar date?
- What is the population of plants that will survive?
- What is the health of those plants, especially their roots?
- Is seedling disease present?
- What is the population uniformity, are there large skips and frequent skips?
- What is the productive capability of the soil, and is the field irrigated?
- How much yield potential will be lost by replanting?
“Variety selection is also important when replanting. It’s not a good idea to plant a full season variety if the replanting date is past May 15. An early maturing variety will do better when the season is shortened because of a late planting date.”
If plant distribution is fairly uniform in fields on productive soils, good yields can be made with low plant populations, perhaps in the low 20,000 plants per acre range, or as low as 1.5 plants per row-foot with no or few skips.
“If the stands are broken with numerous skips, replanting is in order at populations below 30,000 plants per acre, depending on the size and frequency of skips.
“Data from the Mid-South and Southeast suggests that if you have 10 to 13 skips that are 3 feet or longer in 80 feet of row, then a re-plant will be justified. In some cases a grower may try to spot plant, but this type of planting isn’t recommended because late season management will be difficult.”
Growers who replant must continue to use insecticides and fungicides, especially if the first stand died from seedling disease.
Growers should also “use a burn-down herbicide to kill the old stand of cotton and any weeds that may have emerged on the row” to minimize weed issues in the replanted crop.
“Always remember, ‘If you have enough cotton left to make the decision difficult, you probably have enough to keep’,” Barber said.