PONTOTOC, Miss. -- Mississippi’s nationally significant sweet potato harvest is shaping up to be below average because of flooding both early and late in the growing season.

The U.S. Department of Agriculture estimates the sweet potato crop to be 37% harvested as of Oct. 10. USDA estimates 38% is in fair condition and 48% in good condition.

Lorin Harvey, sweet potato specialist with the Mississippi State University Extension Service at the Pontotoc-Flatwoods Branch Experiment Station in Pontotoc, said late-September rains did not delay harvest much.

“Two circumstances are not ideal for sweet potato production, and that is early flood conditions that reduce your overall yield and late flood conditions that increase storage issues,” Harvey said. “We had both of these flooding scenarios during the 2021 growing season.”

The Mississippi sweet potato industry is centered around Calhoun City in Calhoun and Chickasaw counties. After a majority of the Mississippi sweet potato crop was planted in late May to early June, the area received 9 inches of rain in a 72-hour period. Accumulation was even higher in places.

“The month of June was the wettest Calhoun County has had in the last 20 years, with 16.8 inches,” Harvey said. “July had 10.65 inches of rain, and August had 8.5 inches more. Normal rainfall is 4 to 6 inches a month in that area, so that put us 5 to 6 inches above average for each of those months.”

That much rainfall early in the growing season stunts sweet potato growth, as plants cannot breathe in saturated soil.

Rainfall at the end of the growing season causes storage problems, such as rot issues.

“Warm, wet soils increase bacteria and fungus growth in the soils,” Harvey said. “These potatoes have the potential to be exposed to more of these soil issues this year, which can cause long-term storage problems.”

In ideal conditions, a good-quality sweet potato can store for 13 months.

“If the market is fetching a higher price right now, people will push to wash and sell fresh potatoes,” Harvey said. “If the market is saturated, people will do their best to store them.”

While the beginning and end of the 2021 growing season have been difficult, it was business as usual through the summer. Neither disease nor insects presented any significant, abnormal challenges to growers.

“The vines looked really healthy this year, but the vines don’t accurately portray the situation in the soil,” Harvey said. “You’re not growing vines; you’re growing storage roots.”

Sweet potatoes are labor-intensive crops to grow, and the Mississippi industry relies on migrant labor for planting and harvest. Harvey said COVID issues slowed the labor pool reaching the job sites, but Mississippi growers were able to get the help they needed to harvest the crop in a timely manner.

Mississippi had 28,000 acres of commercially grown sweet potatoes this year, down just slightly from the 30,000 grown in 2020. Mississippi ranks second nationally behind North Carolina in sweet potato acreage. It ranks third in yield behind California and North Carolina.

“The decrease represents normal acreage fluctuation,” Harvey said. “Early-season flooding damaged some acres, and not all of them were replanted.”

Alba Collart, MSU Extension agricultural economist, said 2021 prices for the prime Mississippi sweet potatoes are more comparable to 2019 prices than to 2020 prices.

“A 40-pound carton of U.S. No. 1 sweet potatoes is bringing $23.44, compared to $26.16 in 2020 and $24.92 in 2019,” Collart said. “U.S. No. 2 sweet potatoes are bringing $17.78 per 40-pound carton this year, which is very close to the price paid for these potatoes the last two years.”

She said U.S. annual sweet potato consumption continues the upward trend from when it was first tracked beginning in 1984.

“Annual average per capita availability, which is a proxy for consumption, increased from 4.2 pounds in 2000 to 7.9 pounds in 2019, which is the most recent estimate,” Collart said. “This year, we can expect demand for sweet potatoes to increase as we approach the holiday season.”