Study compares corn yield loss with incremental defoliation

Johnny Morgan, Gould, Frances I., Blanchard, Tobie M.  |  11/9/2017 5:02:50 PM

LSU AgCenter plant pathologist Clayton Hollier is evaluating the damage suffered by corn plants due to wind, hail, insects and disease to determine the effects of incremental defoliation of the crop.

“What we are doing with this project is mimicking pest and environmental damage with incremental defoliation by taking out different levels of leaves at different points in the growing stages,” Hollier said.

In the study, the results have shown that yields are affected when defoliation has occurred, he said.

The goal of the research project is to determine how and when to treat for disease in the corn plant that would occur under normal field conditions.

The process shows how defoliation of the plant from nature can allow the development of diseases to attack the plant.

“One of the causes of defoliation, especially in corn up north, is usually hail damage. And here we have occasional wind damage that tends to shred the leaves followed by disease,” Hollier said.

The treatments for the study are to take out the lower leaves or the leaf just under the corn ear. Other treatments take out leaves that are higher levels depending on the growth stage.

The two plots where the study was conducted were in Baton Rouge and Alexandria. This is the second year of the study, and Hollier hopes to continue in order to have at least three years of data.

“This not an expensive study, but it is time-consuming because the leaves have to be hand clipped and the corn has to be hand harvested in order to have standard results,” he said.

The idea for the study began several years ago when a graduate student looked at the effects of defoliation in wheat, Hollier said.

Once the study is completed, Hollier hopes to have data to show the best time to treat for insects or diseases.

“We want to know when the best possible time to spray occurs,” he said. “By checking at different corn growth stages, we are able to tell when the most optimal time for spraying is in order to decrease the amount of losses.”

The results of the study are not so much about the loss of leaves, but more about the percent of loss from the entire plant.

“We are more interested in studying the reproductive stages of the plant, rather than just looking at the vegetative stages of growth,” he said.

The study will help growers know when they should be spraying in order to minimize yield loss, Hollier said.

Johnny Morgan

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