# Brown Rot Caused by _Gnomoniopsis smithogilvyi_ (syn.
## 2 _Gnomoniopsis smithlogilvyi_--Biology, Epidemiology, Symptomatology, and Identification
Furthermore, [PERSON] et al. [41] reported that higher temperatures will allow the introduction and settlement of pests. Moreover, market globalization and transport, also linked with rising temperatures, had created favourable conditions for those pests. Therefore, in managing these pests, sustainability must always be considered. Secondary infection, related to the asexual phase of the fungus (conidia), is not yet sufficiently studied. However, it is thought to be related to the attacks of the wasp _D. kurophilus_, known as the chestnut gall wasp, and responsible for forming galls in the branches and leaves of chestnut trees [42; 43]. Indeed, there are several reports of the presence of _G. smithogilvyi_ conidia in these galls, which can be an inoculum source and thus promote fungus dispersion [42; 43]. Although the role of this wasp on the _G. smithogilvyi_ epidemiology is not yet documented, it was suggested that the stress induced on chestnut by _D. kurophilus_attacks could lead to the transition of the endophyte _G. smithogilvyi_, naturally present in chestnut tissues, from a latent mode to an active virulent pathogen [44]. Likewise, [PERSON] et al. [45] reported that the endophytic lifestyle of _G. smithogilvyi_ may play a fundamental role in its epidemiology, allowing the asymptomatic colonization of the host tissues by the fungus. The detection and accurate identification of _G. smithogilvyi_ are critical steps for its understanding and control. Table 1 shows the methods most used in the detection of _G. smithogilvyi_. Most of these methods require the isolation of the fungus from previously surface-disinfected asymptomatic or symptomatic fruits in culture media, such as MEA (malt extract agar), MYA (malt yeast agar), or PDA (potato dextrose agar) media [22]. Furthermore, the fungus isolation can also be carried out from _D. kuriphilus_ galls, _G. smithogilvyi_ fruiting bodies on galls, chestnut branch tissues, chestnut gems and flowers, and chestnut burrs. The fungal isolates obtained are then identified mainly through molecular techniques. The identification based on the morphological features of the fungus may not be conclusive due to the similarities in the vegetative and reproductive structures between _G. smithogilvyi_ and other closely related species colonizing the same plant tissues. Nevertheless, some authors [34] reported the morphological-based identification by analyzing and measuring conidia, fruitbodies, and mycelium. Figure 1: Process of infection of the fungus _Gnomoniopsis smithogilvyi_. Source: Adapted from [PERSON] and [PERSON] [37]. The molecular identification of _G. smithogilvyi_ is mostly based on the sequencing of a segment of the encoding ribosomal RNA genes, which includes the entire internal transcribed spacer region (ITS) (ITS1-5.8S-ITS2), or the 28S gene of the large ribosomal subunit (LSU) (Table 1). The sequencing of various protein-coding genes has been used together with the ITS region. Among protein-coding markers, the second largest (RPB2) subunits of RNA polymerase, translation elongation factor 1-alpha (EF1-\(\alpha\)), calmodulin, and beta-tubulin have been used to identify _G. smithogilvyi_ reliably (Table 1). The technique of real-time PCR (qPCR) also proved to be effective in detecting and quantifying _G.