Phoenix dactylifera L. is an economically and aesthetically important tree in the southwestern US. Approximately 4900 ha of dates are commercially grown for its edible fruit in the US, including about 1600 ha in the Yuma area and the Hyder Valley of Arizona (USDA, 2023). In October 2022, a severe rot was observed on three date palms in the Phoenix Metropolitan area. Early symptoms were brown spots that turned to a black scorch appearance extending along the leaf base and rachis, leading to the lower fronds\' wilting, drying, and folding. As the disease progressed upwards, the terminal bud became necrotic and eventually collapsed. Isolation from the necrotic leaf lesions on a potato dextrose agar (PDA) consistently yielded a fast-growing fungus that was initially white with abundant fluffy aerial mycelium, which gradually turned dark olivaceous after growing at 22-25oC under 12 h light for a week. Pycnidial conidiomata formed on pine needles in a water agar were black and globose. Conidiogenous cells were hyaline and cylindrical. The conidia exhibited a thick-walled, ovoid to ellipsoid morphology, initially appearing hyaline and aseptate and transitioned to 1-septate with a dark brown, striated appearance, measuring 19.6 to 23.0 μm x 10.3 to 12.2 µm (n = 20). For molecular identification, genomic DNA was extracted from the mycelia of two isolates. Partial DNA sequences of the internal transcribed spacer (ITS) region of rDNA and β-tubulin (TUB) gene were amplified and sequenced using primers ITS5/ITS4 (White et al. 1990) and Bt2a/Bt2b (Glass and Donaldson 1995). The resulting sequences of ITS (PP346666) and TUB (PP372690) were deposited in the GenBank. A BLASTn search of ITS and TUB sequences revealed a 99 to 100% similarity with the sequences (JX456475, KF766198, and OK338070) of Neodeightonia phoenicum strains causing palm rot in Greece (Ligoxigakis et al. 2013), leaf spot on pygmy date palm in China (Zhang and Song 2022), and an ex-type CBS 122528 culture. Based on these morphological and molecular data, the fungus was identified as N. phoenicum. A pathogenicity test was conducted twice in a greenhouse (daily temperatures:18 ~ 30 oC, relative humidity: 45% ~ 95%) on 4 healthy 1-year-old date palm plants. The petioles of 3 older leaves per plant were wounded by pricking the epidermis of the leaf with a needle (ca 20 pricks per petiole) and inoculated with agar discs from a 4-day-old PDA culture of the fungus. The control consisted of 4 mock-inoculated plants by placing plain PDA on the wounds of leaf petioles. Five weeks after inoculation, all the inoculated leaves showed symptoms of black scorch, petiole rot, and leaf necrosis, which were the same as those symptoms observed on the original diseased trees, while the controls did not show any symptoms. The fungus was re-isolated and confirmed as N. phoenicum by morphology. N. phoenicum has been reported to cause leaf spot, shoots blights, stalk and root rots as well as black scorch on different palm species all over the world. However, to our knowledge, this is the first report of N. phoenicum causing black scorch and rot disease in Arizona. The possible spread of N. phoenicum could have a significant economic impact and requires immediate attention through suitable disease management initiatives.

Botryosphaeriaceae are fungi involved in the decay of various woody species, including the grapevine, leading to significant production losses. This fungal family is largely ubiquitous, and seven species of Botryosphaeriaceae have been identified in French vineyards, with variable levels of aggressiveness, both in vitro and in planta. Mycoviruses can impact the life traits of their fungal hosts, including aggressiveness, and are one of the factors influencing fungal pathogenicity. In this study, the RNA mycovirome of fifteen Botryosphaeriaceae isolates was characterized through the high-throughput sequencing of double-stranded RNA preparations from the respective samples. Eight mycoviruses were detected, including three potential novel species in the Narnaviridae family, as well as in the proposed Mycobunyaviridae and Fusagraviridae families. A large collection of Botryosphaeriaceae isolates was screened using RT-PCR assays specific for 20 Botryosphaeriaceae-infecting mycoviruses. Among the mycoviruses detected, some appeared to be specialists within a single host species, while others infected isolates belonging to multiple Botryosphaeriaceae species. This screening allowed us to conclude that one-third of the Botryosphaeriaceae isolates were infected by at least one mycovirus, and a significant proportion of isolates (43.5%) were found to be coinfected by several viruses, with very complex RNA mycoviromes for some N. parvum isolates.

Neofusicoccum parvum, is a fungal pathogen and one of the etiological agents of dieback disease in grapevines. The fungus causes deterioration of vines due to vascular colonization and/or production of toxins. We report herein the inhibitory effects of Trichoderma spp. isolates and the antifungal effects of cell-free supernatants (CFS) from Xenorhabdus and Photorhabdus bacteria against N. parvum in agar plates. We also evaluated the effects of the most effective fungi and bacteria against the pathogen in pruning wounds of vine shoots. All isolates of Trichoderma exhibited antifungal activity ranging between 82 and 97.5% at 14 days of post-treatment. All Xenorhabdus and Photorhabdus CFS at 10 and 33% concentrations inhibited mycelial growth with X. szentirmaii PAM 11 and PAM 25 causing the highest inhibition (>74%). In the shoot experiments, T. asperellum IB 01/13 and T. asperellum Quality®, X. szentirmaii PAM 11 (undiluted growth culture and CFS) suppressed the fungus by ≥ 93%. Our study highlights the potential of Trichoderma and X. szentirmaii PAM 11 for use as biofungicides in the management of N. parvum in grapevines. Further studies should be conducted to develop formulations of Trichoderma and Xenorhabdus that enhance stability in shelf-life and increase the efficacy of N. parvum control in grapevines under field conditions.

Botryosphaeria spp. are important phytopathogenic fungi that infect a wide range of woody plants, resulting in big losses worldwide each year. However, their pathogenetic mechanisms and the related virulence factors are rarely addressed. In this study, seven lignin peroxidase (LiP) paralogs were detected in Botryosphaeria kuwatsukai, named BkLiP1 to BkLiP7, respectively, while only BkLiP1 was identified as responsible for the vegetative growth and virulence of B. kuwatsukai as assessed in combination with knock-out, complementation, and overexpression approaches. Moreover, BkLiP1, with the aid of a signal peptide (SP), is translocated onto the cell wall of B. kuwatsukai and secreted into the apoplast space of plant cells as expressed in the leaves of Nicotiana benthamiana, which can behave as a microbe-associated molecular pattern (MAMP) to trigger the defense response of plants, including cell death, reactive oxygen species (ROS) burst, callose deposition, and immunity-related genes up-regulated. It supports the conclusion that BkLiP1 plays an important role in the virulence and vegetative growth of B. kuwatsukai and alternatively behaves as an MAMP to induce plant cell death used for the fungal version, which contributes to a better understanding of the pathogenetic mechanism of Botryosphaeria fungi.

Stem blight is a major disease of blueberry caused by Botryosphaeriaceae fungi. Chemical and cultural management options are limited, putting emphasis on breeding efforts to identify sources of resistance. The efficacy and durability of host resistance could be impacted by the species composition of the pathogen population in a region and by the isolates employed in the screenings used to identify the resistance. Samples (365) were collected from southern highbush (SHB) and rabbiteye blueberry (REB) cultivars from 28 sites in the southeastern US (AL, FL, GA, NC, and SC). Colony morphology identified 86% of the isolates as Botryosphaeriaceae. Conidia morphology and Maximum Likelihood analysis of the Internal Transcribed Spacer rDNA regions (ITS), translation elongation factor one alpha (tef1-α), and β-tubulin were used to identify isolates at genera or species level. A PCR-restriction fragment length polymorphism (PCR-RFLP) test was used to identify isolates to genus. Neofusicoccum and Lasiodiplodia were the predominant genera. N. kwambonambiense, N. ribis, L. theobromae and L. pseudotheobromae were the most common species isolated. Phylogenies conducted with a limited number of isolates indicated non-clonal and potentially diverse populations occur on blueberry that warrant additional study. Botryosphaeria corticis, B. dothidea, and Diplodia seriata were isolated infrequently.

Family Botryosphaeriaceae and the genus Diaporthe (family Diaporthaceae) represent diverse groups of plant pathogens, which include causal agents of leaf spot, shoot blight, branch and stem cankers, dieback, and pre- and postharvest apple fruit decay. Apple fruit with symptoms of light to dark brown decay were collected during and after harvest from 2016 to 2018. Thirty selected isolates, on which pathogenicity was confirmed, were identified and characterized based on multilocus phylogeny and morphology. Five species from the family Botryosphaeriaceae and two from the genus Diaporthe (fam. Diaporthaceae) were discovered. The most commonly isolated was Diplodia seriata followed by Botryosphaeria dothidea. In this work, Diaporthe rudis is described as a new postharvest pathogen of apple fruit. Diplodia bulgarica, Diplodia sapinea, Neofusicoccum yunnanense, and Diaporthe eres are initially described as postharvest apple and D. sapinea as postharvest quince and medlar fruit pathogens in Serbia. Because species of the family Botryosphaeriaceae and the genus Diaporthe are known to cause other diseases on their hosts, have an endophytic nature, and have a wide host range, findings from this study imply that they may become a new challenge for successful fruit production.

The Botryosphaeriaceae accommodates many important pathogens of woody plants, including Eucalyptus. Recently, Botryosphaeriaceae were isolated from diseased plant parts from surveys of Eucalyptus plantations in the YunNan Province, China. The aims of this study were to identify these Botryosphaeriaceae isolates and to evaluate their pathogenicity to Eucalyptus. A total of 166 isolates of Botryosphaeriaceae were obtained from six regions in the YunNan Province, of which 76 were from Eucalyptus urophylla × E. grandis hybrids, 49 from E. globulus trees, and 41 isolates were from other unknown Eucalyptus species or hybrids. Isolates were identified by comparing DNA sequences of the internal transcribed spacer ribosomal RNA locus (ITS), partial translation elongation factor 1-alpha (tef1), β-tubulin 2 (tub2) and DNA-directed RNA polymerase II subunit (rpb2) genes, and combined with their morphological characteristics. Eleven species were identified, including Botryosphaeria fusispora, B. wangensis, Lasiodiplodia pseudotheobromae, Neofusicoccum kwambonambiense, N. parvum, and six novel species described as B. puerensis, N. dianense, N. magniconidium, N. ningerense, N. parviconidium and N. yunnanense. The dominant species across the regions were N. yunnanense, N. parvum and B. wangensis, representing 31.3, 25.3 and 19.9% of the total isolates, respectively. Species diversity and composition changed across the different climatic zones, despite their relatively close geographic proximity and the fact that some of the species have a global distribution. All the Botryosphaeriaceae species were pathogenic to one-year-old plants of an E. urophylla × E. grandis clone and E. globulus seed-derived plants, but showed significant inter- and intra-species variation in aggressiveness amongst isolates. The study provides a foundation for monitoring and management of Botryosphaeriaceae through selection and breeding of Eucalyptus in the YunNan Province of southwestern China.

Poplar canker, mainly caused by Botryosphaeria species, is a serious disease that has resulted in the reduced productivity and death of poplar worldwide. Different Populus species have varied resistance levels to poplar canker; however, whether phenolic compounds in poplar are involved in this resistance remains uncertain. Here, we determined the concentrations of phenolic compounds and their antifungal activities in canker-resistant P. tomentosa and canker-susceptible P. beijingensis. We identified 29 phenolic compounds with significantly different concentrations between the two species. Salicylic acid (SA), tremuloidin, salicin, and poplin were dominant in P. tomentosa, while benzoic acid (BA) and catechol were dominant in P. beijingensis. These six phenolic compounds were further tested for antifungal activities. SA, BA, and catechol showed significant antifungal activities against Botryosphaeria dothidea, while the other three compounds showed no activity. As BA or catechol can be converted in plants to SA, which is a remote signaling molecule that plays an important role in plant defenses, we presumed that the resistance of P. tomentosa was initiated by SA, while the susceptibility of P. beijingensis resulted from the absence of SA. Further studies are required to confirm this hypothesis. These results provide a foundation for future research on the disease-resistance mechanisms of poplar.

In recent decades, the cultivated area and production of nuts and olives have increased, driven by an increasing consumer interest in healthier food. Diseases of almond, pistachio, olive, and walnut crops caused by species belonging to the Botryosphaeriaceae family have caused concern worldwide. Although considerable progress has been made in elucidating the etiology of these diseases, scientific knowledge of other aspects of these diseases is more limited. In this article, we present an overview of the most important diseases caused by Botryosphaeriaceae fungi affecting almond, pistachio, olive, and walnut crops by focusing on ecology and epidemiology, primarily in California and Spain.

The Botryosphaeriaceae is a species-rich family that includes pathogens of a wide variety of plants, including species of Eucalyptus. Recently, during disease surveys in China, diseased samples associated with species of Botryosphaeriaceae were collected from plantation Eucalyptus and other plants, including Cunninghamina lanceolata, Dimocarpus longan, Melastoma sanguineum and Phoenix hanceana, which were growing adjacent to Eucalyptus. In addition, few samples from Araucaria cunninghamii and Cedrus deodara in two gardens were also included in this study. Disease symptoms observed mainly included stem canker, shoot and twig blight. In this study, 105 isolates of Botryosphaeriaceae were collected from six provinces, of which 81 isolates were from Eucalyptus trees. These isolates were identified based on comparisons of the DNA sequences of the internal transcribed spacer regions and intervening 5.8S nrRNA gene (ITS), and partial translation elongation factor 1-alpha (tef1), β-tubulin (tub), DNA-directed RNA polymerase II subunit (rpb2) and calmodulin (cmdA) genes, the nuclear ribosomal large subunit (LSU) and the nuclear ribosomal small subunit (SSU), and combined with their morphological characteristics. Results showed that these isolates represent 12 species of Botryosphaeriaceae, including Botryosphaeria fusispora, Cophinforma atrovirens, Lasiodiplodia brasiliense, L. pseudotheobromae, L. theobromae and Neofusicoccum parvum, and six previously undescribed species of Botryosphaeria and Neofusicoccum, namely B. pseudoramosa sp. nov., B. qingyuanensis sp. nov., B. wangensis sp. nov., N. hongkongense sp. nov., N. microconidium sp. nov. and N. sinoeucalypti sp. nov. Aside from B. wangensis, C. atrovirens and N. hongkongense, the other nine Botryosphaeriaceae species were isolated from Eucalyptus trees in South China. Botryosphaeria fusispora (26 % of the isolates from Eucalyptus) is the dominant species, followed by L. pseudotheobromae (23 % of the isolates from Eucalyptus). In addition to species found on Eucalyptus trees, we also found B. pseudoramosa on M. sanguineum; B. wangensis on C. deodara; C. atrovirens on D. longan; L. theobromae on C. lanceolata, D. longan and P. hanceana; and N. hongkongense on A. cunninghamii. Pathogenicity tests showed that the 12 species of Botryosphaeriaceae are pathogenic to three Eucalyptus clones and that Lasiodiplodia species are the most aggressive. The results of our study suggest that many more species of the Botryosphaeriaceae remain to be discovered in China. This study also provides confirmation for the wide host range of Botryosphaeriaceae species on different plants.