Rust incidence is frequent among nursery seedlings and young plants in the field; this disease is caused by Puccinia psidii and is one of the most severe affecting Eucalyptus tree. The present study aimed to quantify the partial resistance to eucalypt rust for the species E. propinqua, E. citriodora, E. grandis, E. urophylla, E. microcorys, E. urograndis (E. grandis x E. urophylla), E. robusta, E. saligna, E. dunni and E. phaeotricha. The experiment was conducted in a greenhouse of the Department of Entomology and Plant Pathology of UFRRJ. A total of 100 eucalypt seedlings aged 3 months were obtained from seeds. Experimental design was completely randomized, with 10 treatments and 10 replicates, i.e., 1 plant per replicate. Inoculation was performed by atomizing the leaves with a suspension of urediniospores at the concentration of 2x 10(4) spores/mL, obtained from fresh pustules. Then, seedlings were incubated in a wet,dark chamber for 48 hours. The evaluated parameters of resistance were: mean number of pustules per leaflet, severity, mean latent period and AUDPC. The obtained data were transformed into <img border=0 width=32 height=32 src="../../../../../../img/revistas/sp/v40n1/car01.jpg" align=absmiddle>and arcsen <img border=0 width=32 height=32 src="../../../../../../img/revistas/sp/v40n1/car02.jpg" align=absmiddle>, and subjected to analysis of variance and comparison of means according to Scott-Knott test at 5% probability, using the software SAEG. Significant differences were found among eucalypt species for the studied parameters. E. urograndis (E. grandis x E. urophylla) had a smaller mean number of pustules per leaflet, lower severity, greater mean latent period and lower values of area under the disease progress curve, showing thus greater partial resistance to rust.
partial resistance; pustule; severity; Myrtaceae
