Feb 16, 2026
How to Adequately Control Asian Soybean Rust
Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.
The best way to control Asian soybean rust is with adequate plant spacing, early planting, adoption of cultivars with genetic resistance, sequential applications of fungicides with different modes of action, a soybean-free period, and monitoring of neighboring areas. Asian rust develops with greater intensity at mild temperatures between 20°C and 25°C (68°F to 77°F) with prolonged periods of leaf wetness, ranging from eight to ten hours.
The disease can impact soybeans from the plant's early development, but it is during reproduction that the plant has lower reaction capability, which usually results in greater losses. After establishment in the plant, control becomes extremely difficult, reinforcing the importance of preventative and anticipated action.
Asian rust survives in host plants, with soybeans themselves being the main one. A soybean-free period when no live soybean plants are permitted is critical for controlling the disease from one season to the next. Lack of adequate control can result in total losses.
Agricultural research has contributed to the advancement in the control of Asian rust with the development of new active chemicals, more efficient mixtures, and cultivars with genetic resistance, but there is a risk of the disease developing resistance to the fungicide if the same one is used constantly. The rotation of fungicides is essential for adequate long-term control. Currently, the disease no longer causes the same fear as in the past due to greater technical knowledge of the Brazilian producers.