Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. Previously (Geiser et al. 2013; Phytopathology 103:400-408. 2013), the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani Species Complex (FSSC). Subsequently, this concept was challenged by one research group (Lombard et al. 2015 Studies in Mycology 80: 189-245) who proposed dividing Fusarium into seven genera, including the FSSC as the genus Neocosmospora, with subsequent justification based on claims that the Geiser et al. (2013) concept of Fusarium is polyphyletic (Sandoval-Denis et al. 2018; Persoonia 41:109-129). Here we test this claim, and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species recently described as Neocosmospora were recombined in Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural and practical taxonomic option available.

Downy mildew (Plasmopara viticola) is one of the most important diseases in grape-growing areas worldwide, including Brazil. To examine pathogen population biology and structure, P. viticola was sampled during the 2015/16 growing season from 516 lesions on nine grape cultivars in 11 locations in subtropical areas of São Paulo State, Brazil. For identification of cryptic species, a subsample of 130 isolates was subjected to cleaved amplified polymorphic sequence (CAPS) analysis, and for 91 of these isolates the ITS1 region was sequenced. These analyses suggest that the population of P. viticola in São Paulo State consists of a single cryptic species, P. viticola clade aestivalis. Seven microsatellite markers were used to determine the genetic structure of all 516 P. viticola isolates, identifying 23 alleles and 55 multilocus genotypes (MLGs). Among these MLGs, 34.5% were clonal and represented 93% of the isolates sampled. Four dominant genotypes were present in at least five different locations, corresponding to 65.7% of the isolates sampled. Genotypic diversity (Ĝ = 0.21-0.89) and clonal fraction (0.58-0.96) varied among locations (populations). Most populations showed significant deviation from Hardy-Weinberg expectations; in addition, excess of heterozygosity was verified for many loci. However, principal coordinate analysis revealed no clusters among locations and no significant isolation by distance was found, suggesting high levels of migration. The results indicate that downy mildew epidemics result from multiple clonal infections caused by a few genotypes of P. viticola, and reproduction of P. viticola in São Paulo State is predominantly asexual.

Since the 2000s, production of pitahaya (Hylocereus spp.) has increased significantly in South Florida. However, very limited information is available on the main diseases affecting this crop, particularly in regard to disease epidemiology and economic impact on the commodity. In this study, we surveyed five local pitahaya orchards and documented the most prevalent diseases and their causal agents. Three genera of fungal pathogens (Neoscytalidium, Alternaria, and Colletotrichum) were the major groups associated with symptoms on pitahaya cladodes (stems) during the early growing season. Among these, N. dimidiatum was identified as the most prevalent pathogen, with an overall isolation frequency of 29.8% (range, 13.9 to 47.2%). Hence, the temporal progress of N. dimidiatum stem canker infection was monitored and the relationship between stem canker intensity (incidence and severity) and fruit canker incidence was investigated. A significant positive correlation was found between fruit canker incidence and the standardized area under the disease incidence or severity curve on cladodes, suggesting that high stem canker intensity in the early season may contribute to high fruit canker incidence and thereby impact the aesthetic and market value of fruits. In vitro assays showed that both conidial germination and mycelial growth of N. dimidiatum are positively correlated with increasing temperature, with a maximum growth area at 32°C. This finding suggests a higher risk of infection, under an environment with high temperatures, which is common in South Florida. Data obtained in this study represent baseline knowledge for the future development of integrative management programs for controlling major diseases of pitahaya in South Florida.

Fusarium wilt of Luffa, caused by Fusarium oxysporum f. sp. luffae (Folu), causes great losses in Luffa plants worldwide. In this study, 45 accessions of Luffa germplasm were used to determine their resistance to Folu isolates (FOLUST, FOLUSC, Fomh16, and Fol114) in two independent trials. In the first trial, only FOLUST was used to preliminarily identify resistant accessions. Nine accessions of L. acutangular and five of L. aegyptiaca were resistant to the FOLUST isolate. In the second trial, the other three isolates were then used to reevaluate the 14 resistant accessions. The results indicated that the 14 accessions were resistant to FOLUSC but exhibited variable resistance to the Fomh16 and Fol114 isolates. Eight accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fol114. Seven accessions of L. acutangula and one accession of L. aegyptiaca were resistant to Fomh16. Despite the lack of any symptoms, the Folu isolates were recovered from the hypocotyls of all resistant accessions at 28 days post inoculation, except for isolates FOLUSC and FOLUST on one accession (LA140). A high percentage (87.5%) of accessions collected from Bangladesh were identified as resistant, highlighting the effect of local adaptation on resistance. These results provide potentially valuable genetic resources for breeding programs to develop new varieties or rootstocks that could be beneficial for controlling soil-borne diseases in different cucurbit crops and further investigating the mechanisms of resistance to Folu in Luffa plants.

Dragon fruit, also known as pitahaya, pitaya, and strawberry pear, is a group of vine-like, climbing cacti. In south Florida, production of dragon fruit has been steadily increasing since the 2000s, and growers in Florida consider dragon fruit as a potential alternative fruit crop to avocado and citrus, two economically important fruit crops largely impacted by laurel wilt and huanglongbing, respectively. This new 4-page article focuses on the symptomology and epidemiology of stem and fruit canker, a prevailing disease on dragon fruit. Suggested management strategies for the disease are also discussed based on recent studies conducted in south Florida. Written by Cheng-Fang Hong, Shouan Zhang, Romina Gazis, Jonathan H. Crane, and Jeff Wasielewski, and published by the UF/IFAS Plant Pathology Department.https://edis.ifas.ufl.edu/pp355