Mato Grosso, Brazil's biggest grains state, has clamped down on the practice of planting soybeans as a second crop in an effort to control disease, especially Asian rust.
Under new rules published in the state's official register Thursday, farmers will only be allowed to plant soybeans between Sep. 16 and Dec. 31 and all beans must be harvested by May 5.
The ban on planting a second crop of soybeans, known locally as a 'safrinha,' immediately after a summer crop also remains in place.
The measure will not affect Mato Grosso's productive capacity. Second-crop planted area is only 250,000 acres in the state, or around 1% of total planted area in Brazil's No. 1 producing state. Meanwhile, yields are often poor because of the typically dry weather after April and increased disease and pest pressure. The practice typically becomes more popular in years when prices for corn are low.
Crop researchers have long been campaigning to ban the second crop because of the threat it represents to the summer crop.
Safrinha soy allows Asian rust fungus to remain present in the state's fields long after the main harvest is over. That, in turn, means spore populations are much larger when the next crop starts in September.
Asian rust is one of the biggest threats to Brazilian soybean crops. Since it first appeared a decade ago, farmers have learned to control it by spraying preemptively and often. But the pressure from this, and other diseases and pests, is growing, forcing farmers to spray more and, in turn, causing resistance to develop quicker.
Researchers say the only way to ease the pressure is through better agronomic practices and banning the second-crop soy is a step toward that. However, the Mato Grosso Soybean and Corn Growers Association (Aprosoja-MT) has traditionally defended the right of farmers to employ the practice.
Mato Grosso's neighboring state, Goias, has also restricted second-crop soybean planting and Parana, Brazil's No. 2 soybean state in the south, is considering it.
Earlier this week, the Parana state legislative held an audience to discuss various measures including a total ban on second-crop soybeans from the 2016-17 season.
Parana planted around 275,000 acres of second-crop soybeans, possibly making it Brazil's biggest producer.
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