Rice growers in Louisiana face a persistent challenge, managing diseases that threaten crop health and yield. LSU AgCenter rice plant pathologist Felipe Dalla Lana is leading research to better understand these threats and develop more effective, tailored management strategies.

Sheath blight: A chronic concern

One focus of Dalla Lana’s integrated disease management research is sheath blight, a disease that, while not always the most damaging, is consistently present in Louisiana rice fields.

“Sheath blight is more of a chronic disease in Louisiana. What that means is it’s not necessarily the disease that will cause the most problems, but it’s always there and sometimes very severe,” Dalla Lana said.

Crop rotation plays a key role in mitigating its severity. Rotating rice with crawfish, rather than soybean, has shown promise in reducing the disease’s impact.

“Thanks to some management choices that growers are doing, the damage by sheath blight reduces quite a lot,” he said.

Fungicide trials and tailored recommendations

Dalla Lana conducts extensive fungicide trials to evaluate performance under consistent conditions.

“We take all the fungicides — the active ingredients that are labeled for rice — and we put them together at the same trial, same variety,” he said. “Everything is the same, sprayed at the same time. So, we have what we call a fair comparison between them.”

His research also explores how planting time and variety susceptibility affect disease management decisions.

“Our hypothesis is that those scenarios might have different optimal management, and that’s what we want to put numbers on so they can look at the research and come to what’s best for them to use in their fields and their situation,” he said.

With fungicide resistance emerging in some fields, Dalla Lana is testing combinations of products to improve efficacy and reduce costs.

Timing of applications is another critical factor.

“Growers have a limited number of fungicide applications that is economically viable,” he said. “If they start early, they might need additional applications which is not always economically viable. If they start late, it might build so much disease that the control will not be efficient.”

Cercospora: An emerging threat

Cercospora has gained attention as a more prominent disease in recent years. Dalla Lana said it has become a much more important disease recently.

Past management strategies focused on leaf symptoms, but new findings show that resistance genes may not protect other parts of the plant.

“We identified genes that confer resistance to the symptom on the leaf, but that gene does not confer resistance to the sheath or the panicle,” he said.

To address this, Dalla Lana is testing fungicide timing and newer products.

“We tested three fungicides propiconazole, prothioconazole and mefentrifluconazole — all from the same mode of action, but each with different chemistry — to see if there’s anything that can improve control,” he said.

Phenotyping for breeding: Building better varieties

In addition to disease management, Dalla Lana supports the breeding program by evaluating disease resistance in potential new rice varieties.

“The idea on this project is how can we improve our disease phenotyping protocols? Can we find ways to make it faster, make it more accurate, and bring more information so the breeding program can make improvements on the disease resistance?”

His team uses remote sensing, statistical modeling and controlled environment trials to assess disease progression and resistance.

For kernel smut, a disease often hidden inside the grain, Dalla Lana is developing new detection methods using potassium hydroxide to enhance the symptoms in the kernels and improve the ability to distinguish what is healthy and unhealthy.

He’s also collaborating with entomology researchers to apply machine learning and computer vision to automate disease detection.

“If we’re successful, we’ll be able to improve our capacity to acquire quality data.”

Looking ahead

Dalla Lana’s work is grounded in the concept of the disease triangle: the interaction between a susceptible host, a conducive environment and a virulent pathogen.

“All these three factors are not black and white most of the times. They have some variations. So, if you take a lot of these studies that we do, they work with one or multiple components of this disease triangle,” he said