Asian Soybean Rust - Management and Control

Management and Control

Disease control options for ASR are limited. Rust descends in clouds of spores across the countryside. Cultural practices such as row spacing and crop rotations have little effect. Resistant cultivars do not exist. When weather and disease infection conditions are favorable, the occurrence of ASR can be widespread. Thus, remedial control measures—using fungicides as protective sprays—are the only effective disease control method.

Synthetic fungicides are the primary disease control option for protection against Asian soybean rust. The cost of spraying is estimated to be about $15 to $20 per acre; however, two or three sprays may be needed over the course of the growing season. These are significant additional production costs for soybean growers.

Fungicide screening trials to determine disease control efficacy have been field conducted in South America and South Africa. These reports are available on the Web through USDA's Integrated Pest Management Information Centers. These research trials form the basis for fungicidal recommendations in the U.S.

In some regions, the selection of winter cover crops and forage legumes may be effected, since they can serve as host plants. Resistant soybean varieties are not yet available. However, resistance genes have been identified and host resistance is expected to be an effective, long-term solution for soybean rust. Until resistant commercial varieties are in place, the management of rust depends on judicious use of fungicides.

When untreated, soybean rust, causes yield losses due to premature defoliation, fewer seeds per pod and decreased number of filled pods per plant.