Potential Interactions between Invasive Fusarium circinatum and Other Pine Pathogens in Europe

Abstract

Pines are major components of native forests and plantations in Europe, where they have both economic significance and an important ecological role. Diseases of pines are mainly caused by fungal and oomycete pathogens, and can significantly reduce the survival, vigor, and yield of both individual trees and entire stands or plantations. Pine pitch canker (PPC), caused by Fusarium circinatum (Nirenberg and O’Donnell), is among the most devastating pine diseases in the world, and is an example of an emergent invasive disease in Europe. The effects of microbial interactions on plant health, as well as the possible roles plant microbiomes may have in disease expression, have been the focus of several recent studies. Here, we describe the possible effects of co-infection with pathogenic fungi and oomycetes with F. circinatum on the health of pine seedlings and mature plants, in an attempt to expand our understanding of the role that biotic interactions may play in the future of PPC disease in European nurseries and forests. The available information on pine pathogens that are able to co-occur with F. circinatum in Europe is here reviewed and interpreted to theoretically predict the effects of such co-occurrences on pine survival, growth, and yield. Beside the awareness that F. circinatum may co-occurr on pines with other pathogens, an additional outcome from this review is an updating of the literature, including the so-called grey literature, to document the geographical distribution of the relevant pathogens and to facilitate differential diagnoses, particularly in nurseries, where some of them may cause symptoms similar to those induced by F. circinatum. An early and accurate diagnosis of F. circinatum, a pathogen that has been recently introduced and that is currently regulated in Europe, is essential to prevent its introduction and spread in plantings and forests.

Pestalotiopsis pini sp. nov., an Emerging Pathogen on Stone Pine (Pinus pinea L.)

“…In fact, D. sapinea, S. polyspora and other fungi were also present in some of the sampled symptomatic material (data not shown). Diverse authors also report more than one species involved in dieback and blight diseases, including pestalotioid species and other fungi [8,[45][46][47] and observed that some abiotic factors also have a major role in disease development, namely water stress and air temperature [41,42,47]. In this case, a synergic effect among Pe.…”

Bot Gummosis of Lemon (Citrus × limon) Caused by Neofusicoccum parvum

“…Neofusicoccum parvum is a generalist, cosmopolitan pathogen, occurring in various environments with a temperate, Mediterranean, or subtropical climate. The host range of this species encompasses at least 90 botanical entities, especially woody angiosperms, including conifers and many horticultural plants [ 4 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 ]. In association with other fungal pathogens, including other Botryosphaeriaceae species, N. parvum is involved in the trunk disease complex of grapevine, also known as Botryosphaeria dieback, and is regarded as one of the most aggressive causal agent of this disease, which is responsible for severe economic losses in vineyards worldwide [ 45 , 46 ].…”

Global Geographic Distribution and Host Range of Fusarium circinatum, the Causal Agent of Pine Pitch Canker

“…In nine countries, only visual inspection of symptoms in the field or morphological diagnosis of cultures in the laboratory was used to confirm pathogen absence or presence. However, visual inspection alone may not be sufficiently reliable for F. circinatum detection and identification because the fungus may behave as an endophyte or latent pathogen with no visible external symptoms or it can be mistaken for other pathogens that cause similar symptoms [7,47,48]. It is preferable, therefore, to combine visual surveys with molecular detection methods for reliable and more precise identification [46,49,50].…”