J. Phytopathology 126, 183—]89 (1989) © 1989 Paul Parey Scientific Publishers, Berlin and Hamburg ISSN 0931-1785 Influence of Temperature, Wetness Duration, and Leaf Type on the Quantification of Monocyclic Parameters of Bean Rust B. M. J. MENDES and A. BERGAMIN FILHO Authors' addresses: Dr. B. M, j . MENDES, Centro de Energia Nuclear na Agricuttura, Piracicaba — 13400 (Brazil). Dr. A. BERGAMIN FILHO, Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba— 13400 (Brazil). With 3 figures Received June 10, 1988; accepted November !, 1988 Abstract Monocyclic parameters of bean rust {Uromycesphaseoli var. typica) were quantified in growth chambers, on two bean cultivars for three temperatures {17, 21, and 25 °C), two types of ieaves {unifoliolate and trifoiiolate leaves), and nine leaf wetness periods (0, 4, 7, 10, 13, 16, 19, 22, and 25 hrs). The expression of disease was greatly influenced by post-inoculation temperatures. The incubation and latent periods were shortest at 21 "C for both cultivars and leaf types. For both cultivars, trifoiiolate leaves were more susceptible than unifoliolate leaves. A wetness period of at least four hours was required for disease to occur. The maximum disease efficiency for both cultivars occurred with 22 hrs of leaf wetness at 17 °C. The disease efficiencies for temperatures of 17—29 °C and leaf wetness periods of 0—25 hrs were adequately described by a response-surface model. Because of the great influence of temperature and leaf wetness on infection, bean rust is unlikely to occur at high temperatures (> 25°C) and short leaf wetness periods {< 7 hrs). Zusammenfassung Einflu^ von Temperatur, Dauer der Nasse und des Blattyps auf die Quantifikation der monozyklischen Parameter beim Bohnenrost In Klimakammem wurden die monozyklischen Parameter des Bohnenrostes (Uromyces phaseoli var. typica) an zwei Bohnensorten, bei drei Temperaturen (17, 21 und 25 °C), mit zwei Blattypen (einblattrige und dreiblattrige Blatter) und bei neun verschiedenen Perioden der Blattnasse (0, 4, 7, 10, 13, 16, 19, 22 bzw. 25 Std.) quantifiziert. Die Entwicklung der Krankheit wurde sehr stark durch die Temperatur nach dem Inokuiieren beeinflufit. Die Inkubations- und Latenzperioden U.S. Copyright a « r . n « Center Cod^ S.,,emen<: 0 9 3 M 785/89/2602-01 83$02.50/0