U.S. Soybean Producer Perceptions and Management of Soybean Rust in the United States under the USDA Pest Information Platform for Extension and Education

Article excerpt

Recent survey data are examined to improve current understanding of the factors that help to determine the value of information reported on a website that serves as the centerpiece of the USDA's "Soybean Rust Integrated Pest Management-Pest Information Platform for Extension and Education." Respondents' initial beliefs about their chances of experiencing a rust outbreak are shown to affect the likelihood that soybean producers will visit the website and change their management of fungicide use as a result.

Key Words: Asian soybean rust, probability beliefs, PIPE website, ARMS data, USDA Rural Development Broadband Program

(ProQuest: ... denotes formulae omitted.)

Asian soybean rust is a plant disease caused by an airborne, fungal pathogen, Phakopsora pachyrhizi. Yield losses, due to reduced numbers of pods, beans per pod and bean weights, and fungicide cost increases, have been attributed to rust outbreaks everywhere soybeans are grown; however, P. pachyrhizi was only very recently reported in the Americas. Rust was first reported in Brazil and Paraguay in 2001, where it became widespread in areas where soybeans are produced, because climatic conditions and the availability of suitable hosts promote proliferation of the fungus year-round. It was first reported in the United States in November 2004 (USDA 2006). Although the pathogen can overwinter in southeastern coastal areas on uncultivated plants, such as kudzu, it cannot survive the winter where the majority of soybeans are produced (Pivonia and Yang 2004). As a result, rust outbreaks have not been as widespread in the United States as in South America. Analysis of climatic data, however, suggests that it is possible for rust to occur everywhere U.S. soybeans are produced. Based on assumptions regarding regional impacts on yields and fungicide application costs associated with a fully established population of P. pachyrhizi, simulation results indicate that between 14 and 55 percent of planted acres might receive fungicides at an annual cost between $262 and $1,736 million (2006 US$), and that aggregate returns to soybean production might decline between 3 and 21 percent (Livingston et al. 2004, Johansson et al. 2006).

P. pachyrhizi can survive the winter in northern Mexico, the northern Caribbean islands, and along the coastlines of Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas. However, over 96 percent of U.S. soybeans are produced in other states (USDA 2008). The likelihood and severity of a rust outbreak occurring on a specific farm in areas where the majority of soybeans are produced is therefore very difficult to gauge at the beginning of any growing season, because it depends on the status of the pathogen in the south, the distance between the farm and southern source areas, how those areas expand northward during the growing season, the number of spores blown onto the farm when soybeans are present, contemporaneous weather conditions, and whether and how fungicides are applied.1 Fungicides must be used between developmental stages R1 (beginning-bloom) and R6 (full-seed) to reduce yield loss efficiently in the event that spores arrive on the farm when conditions suit development of an outbreak. Preventative fungicides, which reduce the likelihood of an outbreak, must be applied shortly before spores arrive, and curative fungicides, which reduce the effects of an outbreak, must be applied shortly after arrival.

Because resistant plant varieties are not available, soybean producers must choose between three management options, which are to apply no fungicide whether or not rust occurs, to monitor their fields and apply a curative fungicide if an outbreak is observed, or to apply a preventative fungicide before spores arrive (Dorrance, Draper, and Hershman 2007). To improve the ability of producers to determine whether, when, and what type of a fungicide application might be needed, the U.S. Department of Agriculture (USDA) facilitated the development of the "Soybean Rust Integrated Pest Management-Pest Information Platform for Extension and Education" (PIPE), which is a coordinated surveillance, reporting, forecasting, and research program with land-grant universities, state departments of agriculture, and industry (U. …