Iris Weed Control Study Being Conducted

Jr. Fletcher, Strahan, Ronald E., Morgan, Johnny W.  |  4/19/2005 10:29:22 PM

News Release Distributed 08/31/04

Two faculty members from the LSU AgCenter recently began a two-year weed control study in Chacahoula that could benefit iris growers statewide.

Bobby Fletcher, the LSU AgCenter’s area horticulture agent in Terrebonne and Lafourche parishes, and Dr. Ron Strahan, an AgCenter assistant professor of agronomy, are working with a Louisiana iris grower in Terrebonne Parish to control weeds in her operation.

Fletcher said that test plots are being set up on the grower’s property to see which herbicides can be used for facilitating iris production.

"The weeds were burned down recently with glyphosate, and several herbicide programs will be observed to determine which treatment works best," Fletcher said.

Russella Ramp Ostheimer, an iris grower since 1961 and in the business of producing iris for sale since 1983, says this research will be helpful to her operation.

"It’s really hard to control weeds in Louisiana iris during the summertime," she said, adding, "These research plots will show me how to grow irises better and will also make it easier to take care of them."

Ostheimer, who is a member of the American, Louisiana, Acadiana and New Orleans iris societies, said she almost shut the business down two years ago.

When my husband died suddenly, I was ready to mow the whole thing down, but a fellow grower told me not to make a rush decision and offered to help with the operation," she said, adding, "I have decreased in size from 5 acres to 3 acres, but I’m staying."

Weeds seem to be the biggest enemy of iris growers, Strahan said.

"The key to iris weed control is to have a good pre-emergence herbicide, since post-emergence weed control options are limited," he explained.

Strahan, whose job is to conduct weed control research and extension programs in turfgrass and ornamentals for the LSU AgCenter, said this is the only weed control study in the state concentrating on field production of Louisiana iris, and its purpose is to increase yields and reduce weed competition.

He explained that this research began by "burning down" – killing – the weeds in the designated area with 2 quarts of glyphosate per acre.

"In a couple of weeks we’ll come back in and till this area and allow it to settle," Strahan explained. "Then we’ll probably burn it down again with another glyphosate application. Then we’ll plant the iris rhizomes."

Strahan said the irises could be planted before "burn down," but it’s a lot easier to till the soil if the existing vegetation is dead and decaying. "You just till the dead vegetation into the soil, and it becomes organic matter," he said.

During the two-year study, the goal is to produce irises that are as weed-free as possible.

"We’ll look at 10 different programs because there’s no magic bullet approach," Strahan said, adding, "The iris growers will teach us a lot about field iris production, and we hope to teach them about weed control."

Ostheimer explained that September, October and November are the best months to market irises. She says she has shipped Louisiana irises as far away as Canada and South Africa.

Fletcher said this research plot will be showcased to a national audience as part of a tour when the Society for Louisiana Iris holds its national meeting in Lafayette in April 2006.

For additional information on a variety of topics, including commercial agricultural production and caring for home lawns and gardens, contact your parish’s LSU AgCenter office or visit the AgCenter Web site at


Contacts: Bobby Fletcher at (985) 446-1316 or
Ron Strahan at (225) 578-2392 or
Writer: Johnny Morgan at (504) 838-1170 or

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