CHASE, La. — Scientists at LSU AgCenter’s Sweet Potato Research Station in Chase, La., are studying the effects of herbicides and soil compaction as they relate to producing high-quality sweet potatoes.

LSU AgCenter researchers Steve Kelly and Arthur Villordon believe their work will help Louisiana producers grow more-profitable crops.

Kelly’s research, funded in part by Louisiana sweet potato growers, focuses on two herbicides, Sandea and Valor, which were recently approved by the Environmental Protection Agency and the Louisiana Department of Agriculture and Forestry for use with sweet potatoes.

This is the first year Sandea is being used in sweet potatoes and the second year for Valor. Sandea previously was labeled for use in other vegetables, and Valor was previously used in cotton and soybeans.

“The research plots we’re working with show pigweed can cause as much as a 60 percent loss in yield,” Kelly said of the sweet potato studies. “We’re finding Valor controls pigweeds, ground cherry, copperleaf and smellmelon in sweet potatoes. Sandea is used to control sedges.”

Pigweeds and sedges are the primary weeds found in Louisiana sweet potatoes, Kelly said. The cost of using Valor is $8 to $9 per acre. Sandea costs about $32 per acre.

In addition to those studies, Villordon is conducting research to characterize the influence of soil compaction on the shape of sweet potatoes.

“Sweet potatoes are a unique crop in that the grower is dealing with an underground produce that cannot be seen until it is dug up,” Villordon said. “The quality — for example, the size and shape — of the sweet potato is a very important economic factor. It can determine how much money the producer can get from his crop.”

Villordon’s study is investigating the effect of land preparation operations on sweet potato storage quality.

“Typically, compaction within a field can produce sweet potatoes that vary considerably in length and shape,” he said. “Understanding the role of soil compaction in sweet potato shape can lead to adjustments in tillage operations by the grower.

“For instance, subsoiling operations can be reduced or minimized where less-compacted soil is present. This reduces unnecessary field operations by the grower.”

U.S. No. 1 is the grade producers are aiming for. These potatoes generally are 3 inches to 9 inches in length and elliptical in shape.

“These are the premium sweet potatoes that are sold as fresh produce in stores,” Villordon explained. “The grower typically is paid a wholesale price of about $14 to $15 per bushel for this grade.”

The sweet potato industry plays an important role in the state’s economy. According to the Louisiana Summary of Agriculture and Natural Resources, published by the LSU AgCenter, the sweet potato industry contributed more than $87.6 million to the state’s economy in 2003.