The American Soybean Association (ASA), a trade group that represents 26,000 U.S. soybean farmers, has called for greater measures to safeguard 72 million acres of domestic soybean production from Asian rust disease. ASA and the Animal and Plant Health Inspection Service (APHIS) of the United States Department of Agriculture (USDA) have had a series of ongoing meetings about the rapidly increasing prevalence of rust in South America.

Early this month, ASA leaders again met with APHIS Administrator Bob Acord and other APHIS officials to discuss appropriate safeguards necessary to prevent the introduction of rust spores into the United States. Accompanying the ASA leaders was Dr. Michael McNeill, a researcher who has worked on soybean rust for the past 30 years.

"Due to low ending stocks of domestically produced soybeans, I’m particularly concerned that some companies may seek to import whole soybeans from South America where soybean rust has progressed significantly in the last two growing seasons," said ASA First Vice President Ron Heck, a producer from Perry, Iowa. "ASA has urged APHIS to implement a rigorous inspection and quarantine process to safeguard U.S. soybean production. If determined necessary by pest risk analysis, APHIS should implement a prohibition on whole soybean imports, and adequate inspection and processing procedures for soybean meal."

Soybean rust attacks the foliage of a soybean plant causing the leaves to drop early, which inhibits pod setting and reduces yield. The amount of damage depends on how early in the growth of the soybean plant the infection occurs. An infection in mid-September would probably cause minimal losses compared to an introduction in mid-July, when it could be devastating.

"It is possible for soybean rust to be introduced into the U.S. through shipments of whole soybeans from South America," Dr. McNeill said. "I recently returned from Brazil where I found evidence of rust in growing areas southwest of Sao Paulo, in central and central west areas, and in a small area north of the Amazon River."

There is the potential for a natural introduction of soybean rust into the United States that would likely result from spores being carried on wind currents or storms from West Africa or northern South America and the Caribbean. However, ASA is also concerned about the immediate risk of human assisted movement of soybean rust that could occur as a result of imported plant materials infected with the disease. Imported whole soybeans are allowed to contain up to 2 percent foreign material that mostly consists of pieces of plant stems, pods and leaves capable of transmitting the rust spores.

In a Phytosanitary Alert issued in February by the North American Plant Protection Organization (NAPPO), it was estimated that soybean rust could adversely affect all soybean varieties in the United States at an estimated cost of $7.2 billion, which represents about half the value of the U.S. soybean crop.

"During the course of our discussion, APHIS officials indicated they would examine requiring any shipments of whole soybeans to the U.S. to be quarantined for a sufficient period to prevent transmission of rust disease," Heck said. "APHIS has the authority under the Plant Protection Act to control the importation of commodities that may serve as a pathway for the introduction of foreign plant diseases. ASA supports a rigorous inspection and quarantine process to safeguard domestic soybean production from infection."

Although rust resistant soybean varieties would be the most economically viable solution, there is little resistance in the commercial varieties currently grown in the United States. In a December 2002 statement, the International Association for the Plant Protection Sciences (IAPPS) said that the availability of rust resistant soybean varieties in the United States is probably five to seven years away.

"ASA has met with USDA researchers and officials to urge that research efforts be accelerated," Heck said. "In the meantime, we must do everything possible to minimize the risk and delay the potential introduction of soybean rust in the U.S. to give plant breeders the time they need to develop rust resistant varieties."

Costly fungicide treatments currently represent the only option for containing soybean rust. ASA and APHIS discussed the fungicide products that are currently approved for treating soybean rust, and the high cost of controlling the fungus once it is established. According to USDA, eradication would not be technically possible because the disease has many uncultivated host plants that grow in the United States. Green bean, kidney bean, lima bean and cowpea producers would also experience losses.

"APHIS appeared to be prepared to consider destroying any small infestations that may occur as a preferable means of ensuring the disease is not able to spread during treatment," Heck said. "We asked APHIS to review their monitoring and protection measures, and they acknowledged that ASA and Dr. McNeill had provided information requiring a possible tightening of restrictions."

Dr. McNeill also indicated that he and other researchers have been working to detect the canopy reflectance signature of soybean rust by satellite as a better means to rapidly identify and prevent its spread. APHIS officials expressed interest in this work, and agreed to continue to share information with ASA and Dr. McNeill on rust detection and treatment methods in the future.

"ASA established with APHIS an ongoing process for sharing information and discussing further actions," Heck said. "I want to compliment APHIS on their past vigilance and their continuing efforts to work with ASA. Working together I hope we can prevent rust from becoming a serious problem in the U.S."