Asian soybean rust has already been found in 1,175 locations in Brazil this growing season. As of late March, about 50 percent of Brazilian soybean fields were still vulnerable to an Asian rust outbreak, says Embrapa, the National Agricultural Research Company.
Soybeans still vulnerable are in blooming and pod-filling stages. Outbreaks in late stages normally have accounted for more than half of the heavy losses taken by Brazilian farmers in recent years.
Most Asian rust has been found in commercial fields, rather than in sentinel plots. Still, farmers say the plots are playing an important role this season, helping them set their spraying schedules for when the disease hits.
The most affected states in the country are Mato Grosso do Sul, with 254 reported cases, followed by Rio Grande do Sul (250 reports) and Paraná (224 reports). Although little rust has been found in Mato Grosso, the leading state in soybean production, farmers are extremely concerned about the severity of the disease that has been found.
To Embrapa officials, the custom of growing soybeans in the mid-season could be a problem for soybean producers in Mato Grosso. “The fact that all year round there is plenty of leaf cover for the fungus to spread is one of the major causes of the quick spreading of the disease,” says an agronomist from Embrapa.
The solution? “Avoid infestation and act preventively. And remember, it's not a good idea not to grow soybeans in the mid-season,” he says.
All rust-infected crops have been treated with fungicides. According to specialists, the high number of affected crops doesn't mean a major outbreak is occurring, or that the disease is out of control, although in January and February alone, more than 700 infected spots had been found in Brazilian soybean fields.
Where rust has been found in Mato Grosso state, farmers are spraying fungicides three, sometimes four, times to contain outbreaks. The average is two preventive sprayings per season. The fact that they're spraying a third or fourth time shows that they're needing to act curatively to avoid higher losses.
According to the Brazilian Soybean Growers Association, each additional fungicide spraying comes at a cost of $10 per acre. Brazil also must deal with cheaper smuggled fungicides or knockoffs which just don't deliver the expected protection to the crop. Brazilian farmers are also facing a financial crunch.
March was the beginning of the rainy season in Brazil. Rain could prevent spraying for days. In normal years, a delay of just five days in spraying could mean a yield loss of 40 percent. With the faster-spreading disease as seen in Mato Grosso, estimates are even higher.
“Spraying in the right time means saving money,” says an agricultural market analyst in Brazil. “The question of rust prevention is not technical nor chemical, but operational.” He adds that the presence of sentinel plots and alerting farmers of the danger of an outbreak has proven one of the most efficient weapons against the disease, but only if it is used along with a good operational plan.
Last season, Brazil lost around $1.12 billion due to Asian rust, and spent over $800,000 in control costs. This was the lowest figure for loss plus control costs in three years. But much of this could be attributed to a drought which affected much of the country in 2005.
Jose Sergio Osse is a Brazilian agricultural journalist and owns a public relations firm in Sao Paulo. He has worked as a press advisor for Syngenta, Brazil, and as an agricultural reporter for the country's major newspaper.