VIEW ARTICLE

Disease Detection and Losses

Yield Loss in Two Spring Oat Cultivars due to Puccinia coronata f. sp. avenae in the Presence or Absence of Barley Yellow Dwarf Virus. S. M. Bissonnette, Former graduate research assistant, Department of Plant Pathology, University of Illinois, Urbana 61081, Current address: Champaign Extension Center, University of Illinois, 1401 D Regency Drive East, Savoy 61874; C. J. D’Arcy, and W. L. Pedersen. professor, and associate professor, respectively, Department of Plant Pathology, University of Illinois, Urbana 61081. Phytopathology 84:363-371. Accepted for publication 21 December 1993. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-363.

Individual studies were done to estimate yield loss due to Puccinia coronata f. sp. avenae (crown rust) in the presence or absence of barley yellow dwarf virus (BYDV-PAV-IL) for two spring oat cultivars at two locations. Crown rust disease severity was assessed several times and related to yield and yield components. Linear critical point regression models were developed with analysis of covariance. Yield loss for each percent increase in crown rust severity (modified Cobb scale A) was 56.7 kg/ha for cv. Noble and 46.0 kg/ha for cv. Ogle. Test weight decrease for each percent increase in crown rust severity was 1.2 kg/m³ for Noble and 1.1 kg/m³ for Ogle. Ogle exhibited tolerance to yield loss from crown rust. Yield loss, due to each percent increase in crown rust severity in BYDV-infected plots, was 19.2 kg/ha for Noble and 28.7 kg/ha for Ogle. Test weight decrease, for each percent increase in crown rust disease severity, was not different from zero (P ≤ 0.05) for Noble and 0.7 kg/m³ for Ogle. Noble exhibited tolerance to yield loss from crown rust in BYDV-infected plots. The effect of BYDV on yield and reduction in test weight due to crown rust was not additive.