Mississippi State -- Even as the remnants of Hurricane Isaac were leaving Mississippi on Friday, Mississippi State University Extension agents were assessing its impact on crops that were so close to harvest.

Lodging, or laying down, can be a significant harvest challenge in wind-blown fields, especially corn.

Extension corn specialist Erick Larson is cautiously optimistic that most of the corn crop escaped with minimal damage.

“Mississippi Agricultural Statistics estimated 72 percent or more of our corn crop was harvested prior to Isaac's arrival,” Larson said. “Most of our unharvested corn is in north and northeast Mississippi, where rainfall and winds were not excessive.”

Larson said grain sorghum may be much more vulnerable to damage.

“Mature sorghum is prone to kernel sprouting if rain and high humidity persist for several days or weeks,” he said. “Sprouting makes the grain unmarketable.”

Darrin Dodds, Extension cotton specialist, said much of the state's cotton crop was at a critical stage when the storm came through the state. As of Aug. 26, about 55 percent of the crop had open bolls, and some of the crop had been defoliated.

“Defoliated cotton has no leaves that can protect open bolls from weather-related damage,” he said. “That cotton is subject to the lint stringing out of the bolls, which can result in yield losses, fiber quality degradation, and seeds sprouting in the boll, among other issues.”

Dodds said cotton that has not been defoliated but has open bolls is at risk for increased hardlock and bollrot from heavy rainfall. Bolls that are cracking and receive excessive moisture can rot or never properly open. Much like the other crops, high winds can cause cotton to lodge, making it more difficult to defoliate and harvest.

Nathan Buehring, Extension rice specialist, said lodging will be the main challenge caused by Isaac in rice fields. The week before the storm, Mississippi had more than 30 percent of the rice harvested. Growers worked around the clock before rains started to harvest as much as possible.

“We won't lose a lot of yield from the storm, but fields with lodging will take about three times as long to harvest,” he said. “The muddy conditions at harvest will also increase land preparation costs for next year.”

Extension soybean specialist Trent Irby said portions of the later-planted crop still needed rain to finish maturing.

“However, no one wants to see excessive rains, which can influence yields in different ways this time of year,” he said. “Excessive rain can cause seed quality issues on soybeans that are ready, or nearly ready, for harvest. If pods were already compromised, the extra moisture may cause seed rot or sprouting inside the pods.”

Irby said heavy rainfall also can cause plants to die, particularly in low-lying areas where water may stand for an extended period of time.

“Strong winds that come along with tropical storms also may impact yield potential due to lodging that can occur,” Irby said. “If severe lodging occurs, there may be a decrease in harvest efficiency. In addition, moisture from the rains can be trapped under the canopy, allowing for a prime environment for disease development, which may cause issues as well.”

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