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January 28, 2021

Excessive Rain Increases Disease and Pest Pressures on Parana Soy

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

Soybean producers in the state of Parana in southern Brazil had a difficult time planting their 2020/21 soybeans due to dry conditions in September and October. The soybeans ended being planted at least 30 days later than normal and some of the soybeans had to be replanted due to poor plant populations.

The summer rainfall started to improve during the second half of December and into January. Since early January, the rainfall has been excessive in some parts of Parana and the forecast is calling for more rain over the next two weeks. As a result, some of the crops in western Parana are being negatively impacted by the constant wet weather.

In the municipality of Pato Branco, which is located in southwestern Parana, the president of the Rural Syndicate of Pato Branco/PR indicated that disease and pest pressures are building on soybeans, but the wet weather has kept farmers from applying control measures.

For soybeans, the biggest potential problems are soybean rust and white mold. Fungicides must be applied at regular intervals to control soybean rust, which is the most destructive disease for soybeans. White mold is another late-season disease which can proliferate in the wet conditions. Farmers are concerned that if the wet weather continues, the quality and the yields of the soybeans will be negatively impacted.

That has already happened for the dry beans in the municipality. About half of the dry beans in the municipality have been harvested, but the quality of the second half of the harvest has already deteriorated to the point where the beans will only be suitable for animal rations instead of human consumption.

The soybean harvest was already going to start later than normal and now the wet weather is going to delay the start even more. All across Brazil, the early soybean harvest is starting later than in previous years. As of late last week, AgRural reported that 0.7% of Brazil 2020/21 soybeans had been harvested compared to 4.2% last year.

Additionally, Brazilian truck drivers are threatening a nationwide strike starting Monday, February 1st which could also delay some of the early soybean harvest. Most Brazilian farmers do not have adequate on-farm storage for their soybeans, so they must rely on hired trucks to transport the soybeans from the field to the local grain elevator or co-op. If trucks are not available, they cannot harvest their soybeans.