Rice pathologist works on several fronts to control ‘disease triangle’

Felipe Dalla Lana sees plant disease issues as a triangle. The rice plant pathologist said on one side you have how resistant the plant is to the disease. Another side is environmental conditions and how that affects disease potential. On the third side is pathogen population.

The better the plant pathologist can manage one or two sides of the triangle, the less likely that diseases will occur. Dalla Lana’s research focuses on identifying what area is of most concern for the growers in Louisiana and working on management strategies aligned with the growers’ needs.

The researcher conducts fungicide trials on multiple varieties with different timing of fungicide application.

“What we want to do in the management is maintain the profitability for the growers while we maintain the quality of the products for our consumers and have as minimal environmental impact as possible,” Dalla Lana said.

Another aspect of his research is supporting the rice breeding program. He is classifying the varieties in terms of how they react to different diseases.

“We work with varieties that are already available to the growers, and we work with varieties that are in the pipeline that will be released and available to the growers maybe five years from now,” he said.

Dalla Lana said sheath blight is currently the disease he is most focused on. He said they don’t have varieties that offer good resistance to the disease.

Blast is another concern, and while growers have varieties that are resistant to blast, the pathogen that causes this disease has potential to mutate and break the resistance.

“This happened in the past and probably will happen in the future, so it's important for us to keep monitoring all the fields and have a kind of surveillance to anticipate when this resistance will break.”

This surveillance includes collecting plant samples from multiple fields in different locations and testing the varieties in the lab for resistance. Dalla Lana also works with a blast nursery at the H. Rouse Caffey Rice Research Station where he develops conditions that promote disease as much as possible.

“We will have in the field a variety that we expect to be resistant to blast, and we keep track of that variety. If eventually we see blast in that variety, that means is something is changing in the pathogen population,” he said.

The second tier of diseases concerning Dalla Lana and rice growers are Cercospora, bacterial panicle blight and kernel smut.

Dalla Lana said kernel smut is increasing in importance in recent years and is difficult to control.

“For many other diseases, you can go and scout the field and see how much disease you have, and if you reach a certain threshold, you are justified to use a fungicide or not,” he said. “For kernel smut, we don't have those thresholds because we only see the disease by the time of harvest and that's too late to do anything.”

The recent rice season didn’t yield much in terms of data for Dalla Lana. Hot, dry conditions kept diseases from developing. While it was great news for growers, he was not able to conduct typical research.

The next step for Dalla Lana is to incorporate the use of remote sensing more into his research — using drones to detect diseases in the fields as early as possible. This technology can view a field more quickly and efficiently than a farmer walking the field looking for incidences of disease can.

“Sheath blight is a disease that has a very strong spatial aggregation in the field, so you might have parts of field that look completely healthy and other parts that have a lot of disease,” he said.

The sensors on drones can even detect diseases before our eyes can, Dalla Lana said.

A man holds a rice plant while standing in a field.

LSU AgCenter rice pathologist Felipe Dalla Lana inspects rice for signs of disease.

Closeup of blades of grass.

Symptoms of sheath blight visible on rice plants.

Closeup of rice plants.

Symptoms of Cercospora or narrow brown leaf spot. Photos provided by Felipe Dalla Lana

11/21/2023 9:18:48 PM
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