Two Florida populations of foliar nematodes were collected from strawberries originating from Cashiers, North Carolina (USA) located west from Willard, the type locality of Aphelenchoides besseyi. Both nematodes were cultured on Monilinia fructicola and identified using morphological characteristics and molecular assays as Aphelenchoides besseyi and Aphelenchoides pseudogoodeyi sp. n., a herein described new species related to Aphelenchoides goodeyi belonging to the Group of Aphelenchoides exhibiting stellate tails. The morphological and biological characters of Florida A. besseyi fit those of the original description of this species. A. pseudogoodeyi sp. n., which was initially misidentified as Aphelenchoides fujianensis, differed from the type population of the latter species from China because it was without males, and females lacked a functional spermatheca, whereas type A. fujianensis is an amphimictic species. Phylogenetic analyses using near full-length 18S ribosomal RNA (rRNA), the D2-D3 expansion fragments of 28S rRNA, and partial COI gene sequences indicated that A. besseyi is a species complex. A. pseudogoodeyi sp. n. grouped in different clades from those of the type A. fujianensis, instead merging with populations identified of ‘A. fujianensis’ from Brazil and other countries, suggesting that the latter are conspecific and incorrectly identified. The Florida A. besseyi infected strawberry and gerbera daisy, but not soybean and alfalfa. A. pseudogoodeyi sp. n. is mainly mycetophagous. Localized inoculation of 300 specimens applied with filter paper adhering to the blade of the soybean leaves resulted in nematode penetration into the mesophyll with subsequent development of lesions limited to the inoculated area of the blade.

Anthracnose fruit rot and leaf blight caused by Colletotrichum species are important diseases of pomegranate in the southeastern United States. In this study, 26 isolates from pomegranate were identified based on pathological and molecular characterization. Isolates were identified to species based on multilocus sequence analysis with the internal transcribed spacer region, glyceraldehyde-3-phosphate dehydrogenase, β-tubulin, and chitin synthase genomic genes. Pomegranate isolates grouped within the C. acutatum and C. gloeosporioides species complexes, with more than 73% belonging to the latter group. Three species were identified within the C. acutatum species complex (C. nymphaeae [n = 5], C. fioriniae [n = 1], and C. simmondsii [n = 1]), and three other species were identified within the C. gloeosporioides species complex (C. theobromicola [n = 11], C. siamense [n = 6], and C. gloeosporioides [n = 2]). Inoculations of pomegranate fruit showed that isolates from the C. acutatum species complex were more aggressive than isolates from the C. gloeosporioides species complex. Interestingly, opposite results were observed when leaves of rooted pomegranate cuttings were inoculated. In addition, Colletotrichum isolates from pomegranate, strawberry, blueberry, mango, and citrus were cross-pathogenic when inoculated to fruit. This is the first study identifying six different species of Colletotrichum causing pomegranate leaf blight and fruit anthracnose in the southeastern United States and the potential cross-pathogenic capability of pomegranate isolates to other commercially important crops.

Anthracnose caused by Colletotrichum sublineola is an important disease of cultivated sorghum (Sorghum bicolor) worldwide. Anthracnose is also common on the ubiquitous wild sorghum relative Johnsongrass (S. halepense). Analysis of repetitive molecular fingerprinting markers revealed that isolates of C. sublineola from both hosts in the southeastern United States were genotypically diverse, with relatively few haplotypes found in more than one location. With few exceptions, isolates recovered from S. bicolor belonged to a population that was genetically distinct from the population recovered from S. halepense. Twenty-three isolates from cultivated sorghum were all pathogenic to at least one of 13 heritage inbred lines of S. bicolor. In all, 4 of 10 isolates from S. halepense were also pathogenic to one or more of the lines, while the rest caused no disease in greenhouse assays. The four pathogenic isolates from S. halepense were less aggressive, on average, than isolates from S. bicolor, although the ranges overlapped. Pathogenicity tests involving 15 representative pathogenic isolates from S. bicolor and S. halepense on eight heritage inbred lines of S. bicolor identified 12 races. The combined results of this study demonstrated that C. sublineola comprises two separate host-associated subpopulations in the field, even though some isolates from S. halepense were able to cause disease on S. bicolor under ideal greenhouse conditions. Nonetheless, the apparent existence of infrequent cross-infection events in the field, indicated by molecular fingerprinting, suggests that Johnsongrass has the potential to serve as a refuge and an incubator for genetic diversity in C. sublineola, which can complicate efforts to develop and deploy resistant sweet sorghum varieties in the region.

Target spot of tomato caused by Corynespora cassiicola is one of the most economically destructive diseases of tomato in Florida. A collection of 123 isolates from eight counties in Florida were evaluated for sensitivity to azoxystrobin and fenamidone based on mycelial growth inhibition (MGI), spore germination (SG), detached leaflet assays (DLAs), and sequence-based analysis of the cytochrome b gene (cytb). Cleavage of cytb by restriction enzyme (Fnu4HI) revealed the presence of a mutation conferring a glycine (G) to alanine (A) mutation at amino acid position 143 (G143A) in approximately 90% of the population, correlating with quinone outside inhibitor (QoI) resistance based on MGI (<40% at 5 μg/ml), SG (<50% at 1 and 10 μg/ml), and DLA (<10% severity reduction). The mutation conferring a phenylalanine (F) to leucine (L) substitution at position 129 (F129L) was confirmed in moderately resistant isolates (#9, #19, and #74) based on MGI (40 to 50% at 5 μg/ml), SG (50% at 10 μg/ml), and DLA (>10% and 50% at 5 μg/ml), SG (>50% at 1 μg/ml and 10 μg/ml), and DLA (>50% severity reduction) correlated to non-mutation-containing isolates or those with a silent mutation. This study indicates that QoI resistance among C. cassiicola isolates from tomato is widespread in Florida and validates rapid screening methods using MGI or molecular assays to identify resistant isolates in future studies.

Pomegranate (Punica granatum L.) has emerged as an alternative fruit crop for growers dealing with devastating threats to citrus and avocado in the southeastern United States. However, foliar and fruit diseases are major constraints to commercial pomegranate production. Replicated field trials were performed in 2015 at three separate sites in Florida (Dover, Plant City, and Parrish) to evaluate Merivon (pyraclostrobin and fluxapyroxad), Luna Experience (fluopyram + tebuconazole), and a rotational program consisting of these two fungicides as well as Penncozeb 75DF (mancozeb) for the management of leaf spot and fruit rot of pomegranate. The fungicide programs were evaluated on the varieties Vietnam in Dover, FL; Angel Red in Plant City, FL; as well as Christina, Azadi, Vikusnyi, Alsirinnar, Sakerdze, and Wonderful in Parrish, FL. Mean leaf spot severity varied across sites at the end of each trial in August, with values ranging from 4.5 to 62.5% in Plant City, 7.5 to 45.8% in Dover, and 4.5 to 54.2% in Parrish. Based on area under the disease progress curve, all treatments that included at least one at bloom application significantly reduced disease levels compared with postbloom treatments and the nontreated control across all trial sites. Based on fruit rot incidence, Luna Experience and Merivon, when applied twice at bloom in the beginning of the season, reduced disease by 66.6 and 88.4%, respectively, in comparison with the nontreated control in Plant City. A rotational program further reduced disease by at least 97% at the end of the season in Parrish. The proper timing of fungicide application and rotation with different modes of action provided a feasible disease management option for pomegranate growers in the Southeast United States.

Pathobiomes, the complex microbial communities associated with plant diseases, play a crucial role in shaping host–pathogen interactions. In crops such as maize, understanding these microbial dynamics is essential for managing diseases such as tar spot, caused by the fungus Phyllachora maydis. Thus, the objectives of this study were to investigate the mycobiome composition associated with tar spot disease in corn and to evaluate the genetic diversity of P. maydis in Florida. Amplicon sequencing of the internal transcribed spacer (ITS) region revealed 1,267 unique amplicon sequence variants (ASVs) across asymptomatic and symptomatic (tar spot stroma) maize tissues, with Ascomycota dominating both tissue types. Although the overall fungal diversity was similar between symptomatic and asymptomatic tissues, P. maydis was significantly more abundant in symptomatic samples. Key taxa, such as Fusarium and Epicoccum, were enriched in tar spot lesions, contributing to a distinct fungal community structure. Co-occurrence network analysis further demonstrated a more complex fungal interaction network in tar spot-affected tissues, suggesting the importance of Fusarium, Curvularia, and Phaeosphaeria, among others, in shaping these interactions. Low genetic diversity within the P. maydis population in Florida was confirmed based on nucleotide diversity and phylogenetic analysis of 16 ASVs and 88 individual isolates collected from single tar spots across different fields during 2022 and 2023, showing minimal nucleotide variations across the ITS, large subunit, and small subunit regions. These findings enhance our understanding of the fungal community dynamics and P. maydis population structure in tar spot disease. By framing these dynamics within a pathobiome perspective, this study offers insights that could inform future microbiome-based management strategies. [ ] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .