The sweet potatoes were a bit undersized. That kept us from harvesting for a couple of weeks. The temperatures did level out towards the end of September and early October, the crop responded well, and then we were harvesting full speed ahead.”
Overall, the 2010 growing season was solid for Louisiana sweet potatoes. The majority of the crop was planted in a timely manner under good conditions.
“We did have some hot, dry weather in June that caused some skippy stands,” says Tara Smith, LSU AgCenter sweet potato specialist who is based at theSweet Potato Research Station in Chase, La. “But for the most part we were able to stay on track with our irrigation capabilities.”
The heat and dry conditions caused the crop to be delayed for harvest. “The sweet potatoes were a bit undersized. That kept us from harvesting for a couple of weeks. The temperatures did level out towards the end of September and early October, the crop responded well, and then we were harvesting full speed ahead.”
This year, Louisiana has “a good, average crop. It has good quality. Yields are between 350 and 400 bushels per acre on most farms. Some have realized yields higher than that.”
Sweet potatoes don’t deal with a lot of in-field diseases, says Smith. “Viruses are a concern with a vegetatively-propagated crop. We address that through our foundation seed program. Growers incorporate virus-tested foundation seed material into their own on-farm seed programs.”
Through ongoing research, “we’re making more of a conscious effort to look at managing vectors – aphids and whiteflies -- more appropriately in the crop.”
As for insect pressure, 2010 was a “relatively mild” year. The biggest concern that emerged was late-season damage from the sugarcane beetle, a sporadic insect pest.
“Sugarcane beetle damage between years – and even between fields in a given year – is highly variable. One field can be devastated by that insect while a neighboring field isn’t hurt.
“We’re studying different methods to develop a management strategy for the sugarcane beetle. So far, there is no silver bullet in hand to give producers. We’re looking at both chemical options and also cultural practices.”
When it comes to heat and water requirements “sweet potatoes are kind of alone. It’s hard to compare them to another agronomic crop. They need good soil moisture and conditions to get established. The first 30 days after planting are critical for root initiation to occur properly.”
Any stress during that first 30 days – whether inadequate moisture or some other environmental or biological variable that may be awry – can negatively affect root initiation. After the crop is established, though, sweet potatoes (a semi-tropical to tropical crop) do well in hot, humid conditions.
“They do need a little moisture, right along. Ideally, the crop would get an inch of rain per week. We all love to get a rain on Friday afternoons. This year, we got a bit of rain late in the growing season. That helped size the crop up.”
However, too much rain close to harvest can be detrimental. “That’s what has happened the last two years. This year, we were watching the horizon, hoping the rains would hold off – thankfully, they did.”
Currently, the U.S. sweet potato industry is in the midst of a three-year USDA specialty crop research initiative project that will run through the fall of 2012. The LSU AgCenter is the lead institution on the project which is being conducted in conjunction with Mississippi State University, North Carolina State University and the University of California-Davis.
The effort is a multi-disciplinary, multi-state project focused on several aspects of the crop. Those include improving production efficiency, addressing quality and food safety.
“One of the things we’re most excited about is that the project is very cohesive and includes the industry, our stakeholders, to a large extent,” says Smith. “We worked with them in the year prior to submitting this project through an advisory-type process. We solicited information from the stakeholders on their most pressing concerns with production and management of sweet potatoes.
“This was the first year where we had field trials out in all participating states. It has a large Extension component. We’re doing a lot of the research and model validation work with producers. It’s interesting because there’s tremendous variability in sweet potato crops (around the country) from the bedding process through harvest.”
Smith is also continuing to study fertilizer regimes in sweet potatoes.
“We’re looking at different source of potassium. Do we see any yield response with sulfate of potash (SOP) versus muriate of potash (KCl)? We want to know.
“We’re also checking some combinations of those two products along with KMAG (potassium formulated with magnesium).”
What about varieties?
“Evangeline is the newest commercial release. It was released in 2007 and is catching on across the Southeast. Producers were pleased with what they saw with Evangeline this year.”
Smith estimates Louisiana sweet potato acreage is “90 percent Beauregard and 10 percent Evangeline. I think the slowness of producers to adopt Evangeline is due to the negative seasons we had in 2008 and 2009. It’s taken a while for producers to build up a seed supply and move forward with Evangeline on a larger scale. But we’ll see more and more of that variety in the coming years.”
Heading into the holiday season, Smith says there is enough cured, high-quality sweet potatoes to meet demand. “With the new processing facilities and growing customer demand – fries, baby food, juice -- there’s a sweet potato market year-round. But around 35 percent of the crop is moved” during the holidays.