Phytophthora disease of Quercus ilex in south‐western Spain

Abstract

Oak decline that was affecting three holm oak sites in the province of Huelva (south-western Spain) was studied during 1998±1999. The syndromes of dieback and sudden death have been observed and, in both cases, foliar symptoms were associated with root rot. Characterization of the fungal isolates from necrotic roots led us to identify Phytophthora cinnamomi A2 as consistently associated with the disease. The optimum growth temperatures of these isolates were very high (30°C). Inoculation tests under controlled conditions demonstrated the pathogenicity of the isolates on holm and cork oak seedlings. None of the other biotic factors of Mediterranean oak decline that have been previously described were found in the present study and so, in this case, the forest decline model does not seem to be necessary in order to explain the disease observed. The defoliation and mortality of the oaks was primarily caused by P. cinnamomi, although some abiotic factors such as alternating periods of drought and wet weather in the region may play an important role.

Susceptibility of common alder (Alnus glutinosa) seeds and seedlings to Phytophthora alni and other Phytophthora species

“…Similar results were obtained from a previous laboratory test by Santini et al (2003) where an isolate of P. cinnamomi caused mortality of A. glutinosa seedlings after its inoculation using two different methods. In general, P. cinnamomi has been described as a soilborne pathogen and it has been reported causing root rot in Quercus suber and Q. ilex under Mediterranean conditions and stem canker of Q. rubra in France (Brasier et al, 1993;Marcais et al, 1993;Linde et al, 1999;Sanchez et al, 2002). Hardy and Sivasithamparam (1988) recorded the involvement of P. cinnamomi and several other Phytophthora species with root rot of container grown seedlings from 14 nurseries in Western Australia.…”

“…Among those, Phytophthora nicotianae Breda de Haan (= Phytophthora parasitica Dastur) which is a soilborne pathogen, has been recorded causing dieback in Eucalyptus species in South Africa where Eucalyptus species are planted commercially (Maseko et al, 2001); and damaging several woody ornamental plants in nurseries (Schwingle et al, 2007;Donahoo and Lamour, 2008); but it has been also detected in another 298 plant species (Erwin and Ribeiro, 1996). Phytophthora cinnamomi Rands, which is an invasive soil-borne roots pathogen, has been stated as one of the causal agents of the decline of holm oak (Quercus ilex L.) and cork oak (Q. suber L.) in Southwestern Iberian Peninsula (Brasier et al, 1993;Sanchez et al, 2002). And P. citrophthora (R.E.…”

The role of climate change in the widespread mortality of holm oak in open woodlands of Southwestern Spain

“…The activity of pathogenic fungi, which have been recognized as agents of oak decline in SW Spain, is enhanced by climatic instability and stressed hosts (Sánchez et al, 2002). The effect of climate change on tree mortality is also mediated by site characteristics, including edaphic conditions, microclimate, stand structure and composition (Ruiz-Benito et al, 2013;.…”

Phytosanitary problems detected in black truffle cultivation. A review

“…An extremely serious problem found in the evergreen oak savannas (dehesas) from Andalucía and Extremadura (Spain) (Sánchez et al, 2002) but still not detected in truffle plantations in Aragón is the Oomycete Phytophthora cinnamomi De Bary. It occurs when the plant has suffered water stress in the presence of this organism.…”