Screening of Corymbia and Eucalyptus species for resistance to Calonectria pteridis leaf blight

Calonectria leaf blight (CLB), caused by Calonectria pteridis, is a major foliar disease of eucalypt plantations in warm and high rainfall regions in Brazil. The use of resistant genotypes is the best method for disease control in the field, so identification of sources of resistance is strategic for the long-term genetic breeding programmes of eucalypt. In this study, resistance of 13 species of Eucalyptus and 3 species of Corymbia to CLB was evaluated by spray inoculation of a spore suspension (1x10(4)conidiaml(-1)) of the pathogen, under controlled conditions. Eucalyptus brassiana, E.saligna, E.scias and E.agglomerata were the most resistant, while E.robusta, E.urophylla, E.camaldulensis, E.longirostrata and C.toreliana were moderately resistant and E.cloeziana, E.pellita, E.tereticornis, E.pilularis, C.maculata, E.grandis, E.dunnii and C.citriodora were the most susceptible. The broad inter and intraspecific variability of the species tested demonstrates the potential forintrogression of resistance genes into valuable genotypes as a strategy for the breeding programmes and commercial plantation of eucalypt.