Texas A&M AgriLife Research Culminates in New Label for Cotton Root Rot Control in Alfalfa

Jul 07, 2020

By Kay Ledbetter

AgriLife Extension helps add alfalfa to list of crops treated by Topguard Terra

This year, when alfalfa growers start seeing the menacing cotton root rot showing up in their fields, they can rest assured that almost 120 years after it was first characterized, Texas A&M AgriLife researchers have helped find a control for the fungus.

This alfalfa field shows the significant difference between the untreated left side and treated right side.

The cotton root rot fungus, Phymatrotrichopsis omnivora, attacks multiple plant species in the alkaline soils of the southwestern U.S., including cotton, grape and alfalfa. This disease, also called Texas root rot, TRR, rots the tap roots, causing plants to wilt and eventually die, leaving dry, brown leaves stuck to the stems.

David Drake, Ph.D., Texas A&M AgriLife Extension Service integrated pest management agent, Commerce, has conducted trials on alfalfa with the fungicide Topguard Terra, with the active ingredient flutriafol, since 2011.

Although not large in acreage compared to row crops, Drake said alfalfa is grown throughout Texas and is especially important to the dairy and livestock industry. In 2019, the value of alfalfa in Texas was estimated at $100 million.

Topguard Terra was given a section 24 label by the Texas Department of Agriculture to control root rot in cotton in 2012 and has been used successfully since, Drake said. A 24C local-needs registration was also granted for use on grapes in 2015.

Now, finally, in 2020, a supplemental label has been granted for the use of Topguard Terra on alfalfa in eight states.

AgriLife Extension finds the needed ingredient

The active ingredient in Topguard Terra, flutriafol, was the first and only active ingredient found to provide satisfactory control of cotton root rot in field trials of cotton or any other crop.

Credit for finding the product goes to Tom Isakeit, Ph.D., AgriLife Extension plant pathologist, College Station, and Rick Minzenmayer, AgriLife Extension integrated pest management specialist, Ballinger, who conducted a product screening program in San Angelo for many years.

TRR in alfalfa results in low hay production and bare areas where weeds can grow and contaminate hay, Drake said.

“What makes it more devastating is that farmers invest hundreds of dollars in alfalfa seed expecting the field to last five or more years and TRR can wipe out large areas of a field in a single year,” he said.

Alfalfa hay samples from treated and untreated areas

Application information

In alfalfa, Topguard Terra is soil or stubble applied to protect plant roots. Drake’s research has shown good results with spring broadcast applications and between cutting applications as late as July.

A 2-year-old alfalfa stand infected with Texas root rot. Producers typically get five years from a stand.

“Earlier is better, as is the case with many soil-applied crop protection products that take irrigation or precipitation to be moved into the soil,” he said.

Drake said Topguard Terra should be applied to fields with a history of TRR in alfalfa, cotton or other crops. This disease tends to appear in the same areas year after year. Preventive treatments in areas known to have root rot will protect alfalfa stands. Annual treatments of already-diseased alfalfa fields will result in healthier plants and reduced spread of the disease.

Early research on alfalfa showed some protection with annual applications of 4 or 8 fluid ounces of Topguard Terra with the higher rates giving more consistent results, he said. Higher rates should be used in areas with active root rot or historically severe root rot and on heavier soils.

The label has expanded applications that allow two treatments per year not to exceed 12 fluid ounces per application and 19.5 fluid ounces per growing season. More research is currently being done on split applications, Drake said. He stressed producers need to read and follow all label guidelines.

“Some producers with the use of aerial mapping and site-specific application will be able to reduce costs by applying the fungicide only to portions of the field that are affected by the disease,” he said. “This technology is being used for TRR in cotton.”

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Video: Why Rob Saik is Trying to Build the World’s Most Connected Agriculture Network

In a recent interview at the SeedLink Conference in Brandon, Man., Rob Saik, author, speaker, and CEO of AGvisorPRO, took a trip down memory lane, reminiscing about the beginnings of his career and what the future holds.

Graduating from the University of Alberta in 1983, Saik embarked on a journey that started in Brandon, Man. “I got a job with Elanko, got a U-Haul truck, threw everything I had into it, drove to the Victoria Inn, and lived there for three months while they tried to find an apartment for me to move into. So I started my career in Brandon,” Saik shared.

Fast forward to the present, Saik has evolved into an accomplished author and speaker, traversing the globe to engage in high-level discussions about the future of agriculture and the critical role it plays in feeding the world. Yet, despite his global presence, he finds himself back in Brandon, addressing a group of seed growers. But why? Saik emphasizes the fundamental importance of seeds, stating, “It all begins with a seed, doesn’t it?”

Reflecting on his own experiences as a farmer, Saik expresses his excitement when a planted seed germinates and evolves into a thriving crop. He underscores the significance of technology and breeding in seed development, recognizing the crucial role they play in ensuring farmers can propagate seeds, grow profitable crops, and contribute to global food security.

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As Saik works on his upcoming book, tentatively titled prAGmatic, he sheds light on its central theme. “The thesis would be that I want to write a book that takes what the consumer wants, challenges what the consumer believes, and positions that against what the farmers can actually do pragmatically,” he explains. The book aims to bridge the gap between consumer expectations and the realistic capabilities of farmers, promoting sustainable intensification as the necessary path to feed the planet.

Looking ahead to 2024, Saik emphasizes the need for enhanced connectivity within the seed industry. He discusses his platform, AgvisorPro, which is designed to facilitate connections between farmers, experts, and companies in a way that transcends conventional social media platforms. Saik envisions a credible, connected agricultural network that goes beyond the noise of platforms like LinkedIn or Twitter.

In a passionate vision for the future, Saik imagines a tool for teachers that allows them to pose questions from students, answered by verified farmers and ranchers. This, he believes, would provide an authentic and valuable educational resource, connecting classrooms with individuals who truly understand the intricacies of agriculture.