LAUSR

Commercial production of adzuki bean [Vigna angularis (Willd.) Ohwi & Ohashi] began in the early 1900s on the northern island of Hokkaido, Japan. The cultivation area, comprising more than 60,000 ha in 1960, has been maintained at about 20,000 ha even in recent years, indicating that adzuki bean has been one of the most important upland crops in Hokkaido. Diseases caused by soilborne pathogens, as well as other microbial pathogens and insect pests, have been factors that limit the production of adzuki bean. The most important diseases are brown stem rot, Phytophthora stem rot, and Fusarium wilt caused by Cadophora gregata (formerly Cephalosporium gregatum or Phialophora gregata), Phytophthora vignae, and Fusarium oxysporum, respectively. Crop rotation as a cultural control method can effectively prevent these diseases, but may not dramatically reduce these diseases on adzuki bean because of its short intervals of cultivation. Therefore, growers in Hokkaido have been hoping for the development of varieties that are resistant to these diseases. Extensive research to develop such resistant varieties has been carried out for more than 40 years. Successful breeding of disease-resistant varieties generally requires knowledge not only of the sources of heritable resistance, but also of the biology and genetics of pathogens. In this review, I present the current understanding of the ecology and pathogenic specialization of the three pathogens and advances in breeding for resistance in adzuki bean. Brown stem rot