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Louisiana harvesting sweet potatoes

BATON ROUGE, La. -- Louisiana's sweet potatoes are ready for the shed. "We're in the thick of harvest, right now — full-speed ahead," says Mike Cannon. "We've got folks sweating and boxes being filled."

Yields seem to be good as is quality, says the director of the Sweet Potato Research Station in Chase (the only sweet potato-dedicated facility in the world). But it is a tad late.

"For some reason, the crop is sizing up slowly — perhaps because we've got such a good set of roots. We've got a great set and good numbers of potatoes under the hill, but getting some growth on the potatoes is taking a bit longer."

That means harvest was pushed back a little. Producers, says Cannon, are anxious to get out, get dug and get the crop into the shed. No one wants to deal with a fall like last year's when rains arrived and never left.

Last year's disaster

"We probably left as much as 40 percent of the crop in the field last fall. It was just too wet, and a huge percentage rotted in the ground. There's not much to do in such a situation.

"Some producers tried to harvest those sweet potatoes, and there was a lot of breakdown in storage. Once a sweet potato goes through saturated soil and the breakdown process begins, you can't turn the degradation around. When you catch the process at the beginning stage, many of the potatoes are put in the shed because they look fine. But the breakdown has already begun, and that becomes obvious fairly quickly.

"So, between the sweet potatoes left in the field and those that rotted in the shed, we had a rough go of it last year. And it was a shame, because we had a good crop in the field."

This season's conditions

Louisiana's sweet potato acreage is located in the south-central and northeast parts of the state. This growing season, both areas faced different weather conditions.

South-central sweet potatoes started out in drought. There was a two-month period — May through early June — with scant rainfall. That slowed down transplanting.

"Then, in some places, the rains began to fall in abundance. Some fields got 20 inches of rain over a few weeks," says Cannon.

In north Louisiana, rains have fallen fairly uniformly the entire season. Some areas have been "awfully" wet, but in general, most rains have been timely and beneficial. As a result, producers had to irrigate some but not nearly as much as normal.


What about insect pressure?

"We had some armyworms and beet armyworms flare up in August and early September. Those were brought under control."

While armyworms have been controlled, a new problem with an old pest is showing up. In sweet potato-growing areas across the state, adult sugarcane beetles are causing damage to the crop.

"It's kind of strange because the grub stage is what we're normally concerned about," says Cannon. "This time around, though, the adults are burrowing into the ground and feeding on the potatoes. The damage looks like that caused by grubs, but it's actually the adult sugarcane beetles.

"There's really no control measure for it. It isn't feeding on the foliage and seems to be digging straight to the roots. None of our preplant materials used to control grubs seem to be strong enough — or residually strong enough — to control the adult stage. We're at a loss to know how to control it."

This problem is scattered across the state and varies in intensity. Researchers and producers haven't found a common denominator as to why some fields have them and others don't. Cannon says it does seem that weedy fields have more of a problem than clean fields. But that explanation only goes so far.

"There are still plenty of clean fields showing damage. So we're stumped right now."

Weed control

Researchers are also looking at new weed controls — the second most important problem, after insect pests, in sweet potato production.

"The weeds especially problematic are broadleaves and sedges. So, first, we're looking at Valor (a Valent product). It's doing a really good job of controlling pigweed, smell melons, copperleaf, teaweed and others.

"We're also looking at Sandea (made by Gowan). It has good activity on sedges — yellow nutsedge, rice flatsedge — that we have such tremendous problems with.

This year, a crisis exemption for Valor was declared.

"We're not sure whether Gowan will pursue a label for Sandea, but it looks really good on sedges and has activity on small pigweed."

Louisiana sweet potato growers need new weed-control options, says Cannon.

"The only pre-emerge we have is Command, which doesn't do a great job controlling sedges or pigweed. If we can get the labels for Valor and Sandea, they'd immediately be important tools."

The price swings up

Certainly welcome news to producers, the price of sweet potatoes is going up. It appears this is in response to a predicted short crop nationwide.

"That's always encouraging. If we can get a good price with a good yield, it will really help some of the producers in financial straits to pay off some debt and keep farming.

"Right now, the price for (top grade) sweet potatoes is $15 per 40-pound box. Last year, the price was around $10 or $11. I'm telling you, this price jump couldn't have come at a better time following the devastating harvest last fall."


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