Phytophthora Root and Collar Rot of Paulownia, a New Disease for Europe

Abstract

Paulownia species are fast growing trees native to China, which are being grown in managed plantings in several European countries for the production of wood and biomasses. In 2018, wilting, stunting, leaf yellowing, and collapse, as a consequence of root and crown rot, were observed in around 40% of trees of a 2-year-old planting of Paulownia elongata × P. fortunei in Calabria (Southern Italy). Two species of Phytophthora were consistently recovered from roots, basal stem bark, and rhizosphere soil of symptomatic trees and were identified as Ph. nicotianae and Ph. palmivora on the basis of both morphological characteristics and phylogenetic analysis of rDNA ITS sequences. Koch’s postulates were fulfilled by reproducing the symptoms on potted paulownia saplings transplanted into infested soil or stem-inoculated by wounding. Both Phytophthora species were pathogenic and caused root rot and stem cankers. Even though P. palmivora was the only species recovered from roots of naturally infected plants, in pathogenicity tests through infested soil P. nicotianae was more virulent. This is the first report of Phytophthora root and crown rot of a Paulownia species in Europe. Strategies to prevent this emerging disease include the use of healthy nursery plants, choice of well-drained soils for new plantations, and proper irrigation management.

DNA Metabarcoding and Isolation by Baiting Complement Each Other in Revealing Phytophthora Diversity in Anthropized and Natural Ecosystems

“…Isolations of Phytophthora specimens from rhizosphere soil samples were carried out in accordance with Jung et al and Aloi et al [8,77]. Within 24 h of the collection, an aliquot of ca.…”

The New Report of Root Rot on Fatsia japonica Caused by Phytophthora nicotianae in China

“…For instance, P. nicotianae was reported to cause asparagus spear and root rot in China [69], cherry stem rot and leaf necrosis in China [70], strawberry crown and leather rot in Florida [71], foot rot of citrus in Texas [72], Dianthus chinensis root rot and foliage blight in China [73], brown rot of citrus fruits in California [74], bud rot disease of Washingtonia palms in Saudi Arabia [75], Catharanthus roseus leaf blight in Bangladesh [76] and Phytophthora blight disease on konjac in Yunan [51]. Recently, it has been reported to cause root and crown rot of paulownia and sago palms in Italy [77,78]. These last reports further expand the list of known hosts of P. nicotianae.…”

Risks, benefits, and knowledge gaps of non-native tree species in Europe

“…However, non-native poplars are a threat to the native Populus nigra (Michalak et al, 2015). Concerns have also been raised regarding the invasive tendencies of Paulownia tomentosa, especially under climate changes (Essl, 2007) in addition to the species being recently pinpointed as a vector of pathogens as Phytophthora species (Aloi et al, 2021).…”