Insect, disease control critical to successful pecan production

Mary Ann Van Osdell, Sanderlin, Randy S.

News Release Distributed 06/17/11

SHREVEPORT, La. – Ninety pecan growers from seven states gathered at the LSU AgCenter’s Pecan Research and Extension Station field day on June 16 to hear about the latest information on how to have successful production.

Control of insects is essential, said Mike Hall, LSU AgCenter entomologist. Common problems in controlling pecan insect pests are mistiming of insecticide application, selecting the wrong insecticide, using the wrong rate, and poorly maintained and incorrectly calibrated spray equipment.

With the costs associated with making insecticide applications, it is imperative that spray equipment be well-maintained and calibrated to deliver the correct amount of insecticide to the target, Hall said.

He said a new LSU AgCenter online publication entitled “Sprayer Calibration for Pecan Orchards” provides growers with information on how to calibrate any type of air-blast sprayer being used for the application of insecticides and fungicides.

Hall suggested cleaning nozzle tips because they become plugged with impurities present in water. The pH of sprayer water can have detrimental effects on insecticides, Hall said, adding that the range should be 5.5 to 6.5.

“Please don’t always use the same insecticide because it’s cheaper,” he said. “Rotate insecticides to avoid development of resistance.”

Randy Sanderlin, LSU AgCenter Pecan Station research coordinator, said scab disease was generally not a problem at any point during the 2010 growing season because of the continuing drought across most of the state and the high temperatures. It is difficult to recommend routine fungicide applications under such conditions, Sanderlin said.

Nevertheless, he said, pecan orchard managers should pay close attention to the rain forecast and be ready to quickly apply fungicide should conditions change during the next six to eight weeks of summer. Applications are good for a couple of weeks and after that period, the nuts are vulnerable to infection during a rainfall.

Sanderlin encouraged producers to rotate chemical activity groups at each fungicide application to try to reduce the chances of a scab pathogen strain resistant to one or more of the fungicide groups. He asked growers to report their data back to the pecan station.

Sanderlin introduced a new orchard planted in March and grafted in May. “I hope in 20 years we’re thinning these trees,” he said, adding that the station is operating as if I-69 is not going to cut through it as has been proposed in some alignments of the project.

The new trees are next to 80-year-old trees, which have been in existence since the facility was established in 1930.

John Russin, interim vice chancellor, said the LSU AgCenter does not know where I-69 is going to land and has another meeting with the Department of Transportation and Development in a few weeks. He said the Pecan Station was critical to pecan production in this part of the United States.

LSU AgCenter research horticulturist Charlie Graham shared information on his evaluation and comparison of phosphorus acid biofungicides and fertilizer on control of pecan scab. The objectives of the research are to compare the efficacy of foliar applications of Fosphite, Rampart, Phostrol and Nutri-phite on pecan scab to a commonly used conventional fungicide and to determine if soil applications of those four products provide any protection against pecan scab infection.

Two pecan orchards will be used in the tests, one in Red River Parish and the other in Pointe Coupee Parish. “I want to thank all the growers for off-station tests, letting us use their orchards and trees without any compensation,” Graham said.

Graham said a wide range of phosphorus-containing compounds were tested in the 1930s as plant fertilizers, at which time it was determined that phosphite was a poor source of nutritional phosphorus. In the 1970s, interest was renewed in phosphites when it was determined they were effective against such plant diseases as phytophthora and pythium.

Now, there are more than two dozen products, with just over half being registered as a fungicide and the rest as fertilizers or growth aids.

Hilary Langlois, a grower in Pointe Coupee Parish, spoke about Louisiana native pecan selections. “I think people should plant more natives. You can get seedlings from the state for 40 cents apiece, and they do fairly well. It’s a cheap way to establish an orchard.”

The latest information about pecan production is on the LSU AgCenter’s website at Then search for the Pecan Research Station. The site also includes issues of the “In a Nutshell” newsletter produced by the specialists at the station.

Mary Ann Van Osdell
6/18/2011 12:56:08 AM
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