Brazilian crop protection company Si company is set to launch the country's first pre-formulated herbicide combining clomazone and flumioxazin, introducing a new pre-plant burndown option for soybean growers facing increasing pressure from glyphosate-resistant and glyphosate-tolerant weeds.

The product, scheduled for official launch during the Brazilian Weed Science Congress in Foz do Iguaçu on August 3-6, has demonstrated strong performance in independent field evaluations conducted by CentroAGRO, a research and development company specializing in Cerrado production systems.

According to Dr. Fellipe Goulart Machado, founder of CentroAGRO and a weed science specialist, the new formulation represents an important addition to integrated weed management programs.

"This mixture will strengthen weed management systems, particularly difficult-to-control species," Machado said in an interview.

CentroAGRO was among the first independent research organizations to evaluate the new herbicide under Brazilian field conditions. According to Machado, trials showed a minimum efficacy of 80% against several problematic weed species, including goosegrass (Eleusine indica), Benghal dayflower (Commelina benghalensis), sourgrass (Digitaria insularis), and ivyleaf morning glory (Ipomoea hederacea).

The research also demonstrated substantially improved control of certain broadleaf weeds, compared with single-active pre-emergence herbicides.

"For species such as hairy beggarticks (Bidens pilosa), we observed an average control increase of around 60% compared with products containing only one active ingredient," Machado said.

Residual activity supports early-season weed control

Beyond its pre-emergence efficacy, the herbicide also delivered extended residual activity, an increasingly important characteristic as Brazilian growers seek to reduce early-season weed competition in soybean production.

"In some cases, weed control remained close to 80% even 27 days after application, indicating prolonged residual activity that facilitates subsequent post-emergence management in soybeans," Machado noted.

The extended residual control could prove particularly valuable against goosegrass, one of Brazil's fastest-growing herbicide-resistant weed problems.

According to Machado, uncontrolled infestations of goosegrass can become so severe that harvesting operations are compromised.

"We have seen situations in the Rio Verde region where growers decided not to harvest field borders because weed infestations made harvesting impossible. The soybean field was essentially overtaken by goosegrass," Machado said.

He added that while the new herbicide provides broad-spectrum control, its effectiveness against goosegrass is expected to be one of its main commercial advantages. The mixture also demonstrated activity against other troublesome weeds, including glyphosate-resistant populations of hairy beggarticks that have become increasingly common in southern Brazil.

Additional contribution during burndown

CentroAGRO's evaluations also found that the formulation contributes to burndown programs before planting.

"In addition to its pre-emergence activity, the ready-mix also produced favorable results during burndown operations," Machado said. "Once commercialized, it will become an important component of integrated weed management, especially where growers are dealing with glyphosate-resistant and glyphosate-tolerant weeds."

Integrated modes of action

According to Si company, the product combines two complementary herbicide active ingredients that work synergistically to suppress both grass and broadleaf weeds during the critical early stages of soybean establishment.

"This herbicide combines two active ingredients that work in synergy to prevent early weed competition and provide a high level of efficacy against difficult-to-control grass and broadleaf weeds," said Eric Ono.

The launch comes as Brazilian soybean producers increasingly diversify herbicide programs to address the spread of resistant weed populations and preserve the effectiveness of existing herbicide technologies. By combining two established modes of action into a single pre-mix formulation, Si aims to provide growers with a new resistance-management tool, while simplifying application logistics during the narrow planting window.