Soybean rust is a disease that affects soybeans and other legumes. It is caused by two types of fungi, Phakopsora pachyrhizi, commonly known as Asian soybean rust, and Phakopsora meibomiae, commonly known as New World soybean rust. P. meibomiae is the weaker pathogen of the two and generally does not cause widespread problems. The disease has been reported across Asia, Australia, Africa, South America and the United States.

Importance

Soybean is one of the most important commercial crops around the world. Asian soybean rust is the major disease that affects soybeans. It causes lesions on the leaves of soybean plants and eventually kills the plants. The disease has caused serious yield loss of soybeans. In 2002, USDA reported 10-60% yield losses in South America and Africa.

Host and symptoms

Soybean rust is caused by two types of fungi, Phakopsora pachyrhizi and Phakopsora meibomiae. leguminous forage crops such as trefoil and sweet clover and weeds such as kudzu.

Disease cycle

Soybean rust is spread by windblown spores and has caused significant crop losses in many soybean-growing regions of the world.

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.

Further reading

  • Using Foliar Fungicides to Manage Soybean Rust
  • , National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Soybean Rust.