Soybean cultivars: the key to more effective disease control

Disease control in soybeans has evolved, but challenges remain. Since the emergence of Asian soybean rust in the early 2000s, farmers have faced increasing fungicide resistance. At first, new fungicides seemed to solve the problem, but by 2007, resistance issues began appearing due to excessive curative applications.

This led to the introduction of protective fungicides, initially as tank mixes and later pre-formulated with systemic products. Additionally, bioproducts, defense activators, and plant growth enhancers have been incorporated into disease management programs. However, despite more frequent applications, diseases continue to threaten soybean yields.

What are we overlooking in disease management?

According to Ricardo Balardin, agronomist, PhD, and CRO at DigiFarmz, the mistake lies in focusing solely on fungicides while ignoring other critical factors. "Diseases result from the interaction between the pathogen, environment, and host. For years, chemical control dominated, and we neglected the role of soybean genetics," he explains.

Since 2007, research has shown that soybean cultivars significantly impact fungicide effectiveness. Factors such as absorption rate, metabolism, mobility, and pathogen sensitivity influence disease control outcomes.

Yet, fungicide selection is still largely based on pathogens, with little consideration for varietal genetics. This issue isn’t unique to Brazil. "In the U.S. Midwest, fungicide spraying on soybeans was uncommon until 2017/18, when farmers realized profitability depended on the right combination of fungicides and application timing," Balardin notes. Regional trials also indicate that cultivars influence fungicide performance.

Cultivars as a central piece in disease control

Choosing the right cultivar can be a game-changer for chemical control programs. However, there’s a concerning trend of reduced investment in disease management, which could further weaken control strategies.

"The future of soybean disease control remains uncertain," Balardin warns. "Without a science-based, integrated approach, the risk of yield losses increases."

The solution? A management strategy that goes beyond fungicides, taking cultivar genetics, environmental conditions, and optimal application timing into account. Only then can farmers maximize disease control and ensure long-term soybean productivity.

Fabiana Duarte
Communication advisory
BR-US-LATAM
fabiana.duarte@digifarmz.com
+55 54 99675-0956