Relative susceptibility of oaks to seven species of Phytophthora isolated from oak forest soils

Abstract

Isolates of Phytophthora cambivora, P. cinnamomi, P. citricola, P. europaea, P. quercetorum and two unidentified species were tested for their pathogenicity to eastern US oak species by root and stem inoculations. Experiments were conducted during two different periods and included 1-, 2-and 20-year-old oaks grown under greenhouse and field conditions. Species of Phytophthora were pathogenic in varying degrees to the oak species tested. All species were pathogenic to fine and taproots of at least one oak species. The fine root damage caused by the species of Phytophthora ranged from 9 to 55% when compared to the controls. Roots were more susceptible during the fall inoculation period than the summer. With exception of Phytophthora sp1 and P. quercina-like, all species of Phytophthora were pathogenic to oak stems with P. cinnamomi and P. citricola being the most aggressive. Quercus montana and Q. rubra were the most susceptible oak species to stem inoculation. Lesion sizes were considerably larger when 20-year-old trees were inoculated. Generally, no significant differences in lesion sizes were detected in greenhouse tests when the summer and fall inoculation periods were compared. However, on 2-year-old field-grown seedlings, lesion sizes were considerably smaller or not significantly different from controls during the fall inoculation period, suggesting lower, late season temperatures may restrict lesion development.

Investigation of the fungi associated with dieback of prickly acacia (Vachellia nilotica subsp. indica) in Northern Australia

“…However, the trial site at Richmond was severely water stressed resulting from lower amount of rainfall compared to the Rockhampton site (Appendix 3) which possibly may have influenced the development of larger internal lesions observed at Richmond as found in previous stress-fungus interaction studies . In addition, the plants at Richmond being older were possibly more susceptible to the introduced or native fungi causing larger internal lesions as reported in previous plant-fungi interaction studies (Balci et al 2008;.…”

Comparing the influences of ecological and evolutionary factors on the successful invasion of a fungal forest pathogen

“…It should be noted that there are numerous examples of plant pathogens for which pathogenicity is successfully tested on seedlings, independently of whether the pathogen generally affects the roots, the stem or the branches of its hosts in the field (Green and MacAskill 2007;Balci et al 2008;Thoungchaleun et al 2008). Previous work on H. annosum itself confirms the validity of using seedlings to test pathogenicity levels of fungal genotypes for this pathosystem (Worrall et al 1983;Olson and Stenlid 2001;Werner and Łakomy 2002a, b;Garbelotto et al 2007).…”

Involvement of Phytophthora species in white oak (Quercus alba) decline in southern Ohio

“…Similarly, J önsson‐ B elyazio and R osengren (2006) demonstrated root reduction due to P. quercina on Q. robur trees despite determination that crown symptoms were inconclusive. Furthermore, symptom expression on oak seedlings in artificial soil infestation experiments occurred only when over half of the roots were killed (B alci et al. 2008a), thus the effect of Phytophthora spp.…”