ESTIMATING THE ECONOMIC-IMPACT OF BREEDING NONSPECIFIC RESISTANCE TO LEAF RUST IN MODERN BREAD WHEATS

Breeding for resistance to rust diseases in wheat is an example of pro ductivity maintenance research. Productivity maintenance research is n ecessary to avoid contractions in the wheat supply curve that result f rom changes in the biological or physical environment. In this study, the benefits of incorporating nonspecific resistance to leaf rust caus ed by Puccinia recondita into modern bread wheats (Triticum aestivum) have been estimated using data on resistance genes identified in culti vars, trial data, and area sown to cultivar in the Yaqui Valley, Sonor a State, Mexico. In the most pessimistic scenario, the gross benefits generated in the Yaqui Valley from 1970 to 1990 were 17 million U.S. d ollars (in 1994 real terms). Even when costs were overstated and benef its were understated, the internal rate of return on capital invested was 13%, well within the range recommended for use in project evaluati ons by the World Bank. Substantial economic benefits likely are associ ated with deployment of nonspecific resistance in many wheat-producing areas of developing countries where farmers change cultivars slowly b ecause of delays in cultivar release, incomplete seed markets, and eco nomic factors related to adoption or where disease pressure is heavy a nd the costs of treating disease outbreaks is high.