Método de seleção e identificação de fontes de resistência à murcha do eucalipto causada por Ceratocystis fimbriata

Abstract

The objective of this work was to develop a screening method and to identify resistance source to eucalyptus wilt caused by Ceratocystis fimbriata. The inoculation of 5 ml of pathogen inoculum (2.5 × 104 spores/ml) on the wound root crown of seedlings at 60 days of age was the most efficient method to reproduce the disease symptoms. For this method, disease severity and plant mortality in function of time after inoculation were assessed. A 30-day period after inoculation was sufficient to reproduce disease symptoms. The developed inoculation protocol showed high performance (400 plants/h), and less space consume, when compared with other methods, mainly because it enables the inoculation of young eucalyptus seedlings (60-90 days of age). In the second phase of this work, it was evaluated the eucalyptus inter-specific resistance to C. fimbriata by using the species: Eucalyptus camaldulensis, E. dunnii, E. grandis, E. pellita, E. saligna, E. tereticornis and E. urophylla. There was resistance segregation for all species and according to the origin place of the population. For E. urophylla, for example, occurred the greatest variations among the number of resistant individuals and susceptible to diseases. Those variations can be linked to seed precedence and to genetic improvement program characteristics.