Ulisses Antuniassi, a professor from Sao Paulo State University in Brazil, answers common questions on Asian soybean rust:

Q. Which has proved to be better in your area, aerial or ground application of fungicides?

A. “Despite being systemic, all the fungicides for Asian soybean rust require good horizontal and vertical distribution. We've run some trials in the past two years and we've found that both aerial and ground applications provide good control.”

Q. What tips would you give American farmers to help them better penetrate the soybean canopy with their fungicide applications?

A. “It's important to understand how most of the systemic fungicides for rust move on the plants.

• “First, there is no movement from one leaf to another. That's why it's important to have good droplet penetration on the canopy. Good fungicide deposits on the top of the plant do not control the rust on the lower parts of the plant because the fungicide does not go down.

• “Second, most fungicides have good movement across the leaf surfaces. That means good coverage on the upper surface of the leaf will control the rust on the opposite surface.

• “Third, there are differences among fungicides concerning movements inside each leaf. Farmers should always try to choose a fungicide that is able to offer more movement on the leaves.

“Since rust moves from the bottom to the top of the plant, the most successful treatments in Brazil have been those that offer some deposits and coverage on the bottom part of the canopy.”