Puccinia psidii on Eucalyptus globulus in Uruguay

Puccinia psidii is native to South and Central America and the Caribbean, where it causes a serious leaf and shoot disease of a wide range of Myrtaceae (Coutinho et al., 1998). These include the native Psidium guajava (guava) and introduced Eucalyptus species (Ferreira, 1983). In 2002 a rust fungus was observed causing severe damage to one-year old trees during a routine disease survey of E. globulus in Uruguay. The disease occurred only in one plantation in the Levalleja area and damage was uniform throughout the stand. The rust produced egg-yolk yellow pustules on the leaves and resulted in shoot tip die-back. The characteristic pustules and morphological examination of uredinia and urediniaspores showed that the fungus was indistinguishable from Puccinia psidii.

Puccinia psidii has previously been reported in Uruguay on native Myrtaceae (Koch de Brotos et al., 1981) and in recent years has been observed by the senior author on Psidium guajava and E. grandis. The rust has been reported on other Eucalyptus species in South and Central America, including E. grandis and E. urophylla but this is the first report of Puccinia psidii occurring on the economically important E. globulus. This species is being widely planted in South America and the diseases poses a particular threat to Chile and a potential risk to countries such as Portugal, which has extensive plantings of E. globulus. This fact, together with the wide host range of the fungus makes it a pathogen of considerable global importance (Coutinho et al., 1998). Countries such as South Africa and Australia, which have a number of native species of Myrtaceae are particularly at risk.