Corteva Agriscience has agreed to buy the crop biologicals company Stoller Group for $1.2 billion. Stoller makes microbial and other products that can improve a plant’s ability to absorb nutrients or tolerate stressful conditions. Stoller expects to achieve $400 million in sales next year. In September, Corteva announced plans to acquire Symborg, which makes biostimulants and biofertilizers to increase nutrient uptake and crop yields. Corteva says it has been building its biologicals portfolio over the past few years.