Elisabeth Eirian Jones

The cosmopolitan phytopathogenic fungus Sclerotinia sclerotiorum (Lib.) de Bary infects many dicotyledonous species, including major crops and weeds. Its virulence toward key pasture weeds and the innate immunity of grasses has motivated research in North America and New Zealand into its potential as a microbial bioherbicide for pastures. Independently, discovery in China that S. sclerotiorum adopts a symptomless endophytic lifestyle in grasses protecting them against fungal diseases has stimulated research into its potential as a cereal crop vaccine. Together, these findings raise the prospect of deploying a single fungal strain as a broad‐spectrum biological tool for integrated weed and disease control in pastures and cereals, challenging long‐held assumptions about the ecological roles and applied value of this pathogen. We evaluate S. sclerotiorum as the active ingredient of such a dual‐purpose biocontrol product using four foundational pillars for success—hypervirulence (efficacy), low production cost, formulation suitability and biosafety. Wild‐type strains are sufficiently virulent and competent endophytic mutualists, whereas microsclerotia offer a cost‐effective scalable active ingredient alternative to mycelium. Further innovation is needed to optimize industrial‐scale production and formulation. To meet biosafety requirements, we propose developing a non‐sclerotia‐forming strain retaining hypervirulence and endophytic competence. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Aims: Myrtle rust, caused by the biotrophic fungal pathogen Austropuccinia psidii, is a significant invasive plant disease affecting members of the Myrtaceae worldwide. This research aimed to characterize the diversity and composition of phylloplane fungal communities on symptomatic and asymptomatic leaves of two native myrtaceous host plants in New Zealand, with particular emphasis on their association with myrtle rust infection. Methods and results: Field surveys were conducted on Lophomyrtus bullata and Metrosideros excelsa across urban and native forest environments. Both epiphytic and endophytic fungal communities were characterized using metabarcoding. The findings revealed that host plant identity, rust infection status and geographic location (with associated environmental differences) did not affect alpha diversity (richness and evenness) but did influence beta diversity and fungal community composition. Random Forest analysis identified Puccinia as the strongest indicator taxon associated with symptomatic leaves across all regions, alongside additional site-specific indicator taxa. In contrast, asymptomatic leaves were associated with other fungal genera, including Trichoderma and Sphaerellopsis, both of which have previously been reported as antagonists of rust fungi. Complementary culture-dependent isolation resulted in a living collection of 201 fungal isolates spanning 59 genera, serving as a resource for functional studies. Conclusion: Asymptomatic leaves harboured microbial communities distinct from those of symptomatic leaves, with these differences driven by key distinguishing taxa that may serve as a source of fungal antagonists against myrtle rust.

In September 2024, reddish-brown lesions were observed on shoots of blueberry (Vaccinium corymbosum cv. ‘Emerald’) in a commercial blueberry farm in Anqing, Anhui Province, China. Disease incidence was approximately 60%. Lesions rapidly coalesced, resulting in shoot desiccation, leaf wilting, and severe growth reduction. Symptomatic stems were collected from three randomly selected sites. Tissue segments (5 mm) excised from lesion margins were pooled, surface sterilized, and plated on PDA. After purification by single hyphal tipping, 7 morphologically similar isolates were obtained from 18 cultures. Representative isolate Dpj4 was selected for further characterization. After 7 days incubation at 25°C, colonies on PDA were circular (mean 58 mm, n = 5) with white cottony aerial mycelium and irregular margins; the reverse was light yellow. Black conidial pustules developed on the colony surface after 15 days. Conidia were fusiform, straight to slightly curved, five-celled, and measured 20.99–31.14 × 4.90–8.12 μm (mean 25.2 × 6.4 μm, n = 50). The three median cells were pigmented, with the upper two dark brown and separated by melanized septa and the third pale brown. The apical cell was hyaline and conical, bearing 2–4 filiform appendages, 18.62–46.12 μm long (mean = 31.3 μm, n = 50). The basal cell was hyaline with a central pedicel-like stalk. Based on morphological features consistent with those of Neopestalotiopsis spp. (Maharachchikumbura et al. 2014), the isolate was preliminarily identified as Neopestalotiopsis sp. The isolate showed optimal mycelial growth at 25 °C and pH 7.0, with glucose and peptone as the optimal carbon and nitrogen sources, respectively, under continuous light (24 h). Genomic DNA of isolate Dpj4 was amplified using primers ITS1/ITS4 (ITS), Bt2a/Bt2b (β-tubulin), and EF1-728F/EF1-986R (TEF1-α) (White et al. 1990; Glass and Donaldson 1995; Carbone and Kohn 1999). The resulting sequences (528 bp, 432 bp, and 259 bp, respectively) were deposited in GenBank under accession numbers OQ607755, OQ658114, and OQ658115. BLASTn analysis showed 99.81%, 100%, and 100% identity with Neopestalotiopsis rosae sequences MN341543.1 (ITS), PV033951.1 (β-tubulin), and MN704868.1 (TEF1-α), respectively. Sequences were aligned in Geneious Prime 2022.2.1, and phylogenetic analysis of the concatenated ITS, β-tubulin, and TEF1-α dataset was performed using MrBayes (Huelsenbeck and Ronquist 2001) under the HKY+G substitution model (Hasegawa et al. 1985). The analysis placed isolate Dpj4 within the Neopestalotiopsis rosae clade, clustering with reference strains CBS 101057 and CBS 124745, with strong support. Pseudopestalotiopsis cocos CBS 272.29 was used as the outgroup. Pathogenicity tests were conducted on detached shoots (n = 8) and one-year-old potted plants (n = 4) of blueberry cv. ‘Emerald’. Mycelial plugs (7 mm diameter) from 7-day-old PDA cultures were placed on wounded stems; sterile PDA plugs served as controls. Seven days after inoculation, distinct necrotic lesions developed on shoots inoculated with isolate Dpj4, resembling symptoms observed in the field, whereas control plants remained symptomless. The pathogen was re-isolated from symptomatic tissues and showed morphological characteristics identical to the original isolate, fulfilling Koch’s postulates. To our knowledge, this is the first report of Neopestalotiopsis rosae causing shoot blight on blueberry in China.

Pollinators interact with flowers partly through direct surface contact, yet the bacterial communities associated with their external surfaces (epibionts) remain poorly understood compared with their gut microbiomes. This study characterised the epibiont bacterial communities of four pollinator species associated with northern highbush blueberry ( Vaccinium corymbosum ‘Duke’) in New Zealand: bumble bee ( Bombus terrestris ), honey bee ( Apis mellifera) , drone fly ( Eristalis tenax ), and a New Zealand native bee ( Lasioglossum sordidum ). Using 16 S rRNA gene sequencing, we detected distinct epibiont communities among pollinator species, with significant differences in alpha and beta diversity. Bumble bees consistently exhibited specialised and low‑diversity communities, whereas drone flies showed the highest bacterial diversity. Several pollinator gut‑associated core bacterial genera, including Gilliamella , Lactobacillus , and Snodgrassella , were detected across most species, representing the first reports of Snodgrassella on E. tenax and of Lactobacillus and Gilliamella on L. sordidum . Environmentally acquired taxa dominated the epibiont communities, consistent with pollinator exposure to floral and habitat‑specific bacterial sources. Differential abundance analysis identified species‑specific bacterial signatures and highlighted how pollinator identity, behavioural ecology, and life history traits shape epibiont composition.

Sclerotia play an important role in the disease cycle of Sclerotinia sclerotiorum . Traditional control measures do not effectively suppress germination and viability of sclerotia. This study performed a series of in-vivo bioassays to investigate the effect of biofumigants produced by Brassica juncea Caliente 199, biological control by Paraphaeosphaeria minitans ( Coniothyrium minitans ) , and calcium cyanamide (as Perlka®) on carpogenic germination and sclerotial viability. Paraphaeosphaeria minitans resulted in complete inhibition of carpogenic germination and high sclerotial mortality. Calcium cyanamide applied at the equivalent field rates of 400 and 300 kg ha ⁻¹ Perlka resulted in 100% and 77% reduction in sclerotial germination, respectively, but viability remained high (> 95%). The combination of P. minitans and calcium cyanamide at the rate of 400 kg ha ⁻¹ Perlka achieved complete inhibition of sclerotial germination and ≥ 97.5% mortality. Biofumigation resulted in ≥ 91.0% viable sclerotia and 45–46% of sclerotia germinating carpogenically. These results showed that of the treatments tested, P. minitans significantly reduced the carpogenic germination and the viability of sclerotia. Paraphaeosphaeria minitans was identified as a good candidate for use in an integrated pest management program to achieve sustainable control of the pathogen. Further studies are needed to assess the effectiveness and potential of integrating these non-pesticide measures with other control methods to achieve better control of S. sclerotiorum in the field.

In a previous study of fungal endophytes associated with grapevine trunk disease (GTD) in New Zealand vineyards, Botrytis cinerea was recovered from the inner trunk tissues of vines that were symptomatic or asymptomatic for GTD. The effect of B. cinerea , considered an endophytic latent pathogen, on colonisation and symptom development by the grapevine trunk pathogens Neofusicoccum parvum and Diplodia seriata was investigated. B. cinerea isolates recovered from both GTD symptomatic and asymptomatic grapevine trunks, and isolates from infected berries, were pathogenic on green shoots and berries. In planta interactions between B. cinerea and N. parvum or D. seriata were evaluated on detached green Sauvignon Blanc shoots and woody stems of 2‐year‐old potted Sauvignon Blanc vines. Lesion length and colonisation of the shoots by the pathogens was determined by reisolation, 2 and 12 weeks post‐inoculation for detached and attached shoots, respectively. D. seriata did not produce lesions but was shown to endophytically colonise, being recovered from inoculated shoots. Reisolation of D. seriata was unaffected by co‐inoculation with B. cinerea in both detached and attached shoots. For N. parvum , co‐inoculation with B. cinerea did not affect lesion lengths in detached shoots. In contrast, in attached shoots co‐inoculation by B. cinerea inhibited N. parvum lesion development. This was hypothesised to be due to contrasting infection mechanisms by the two Botryosphaeriaceae species and alteration in the host response between detached and attached tissues. The findings indicate that B. cinerea is involved in the GTD complex and affects symptom expression.

Dieback of blackcurrants ( Ribes nigrum ) is an increasing problem worldwide with several pathogens including the Botryosphaeriaceae species, Neofusicoccum ribis , reported as being associated with dieback. To identify the species of Botryosphaeriaceae associated with blackcurrant dieback in New Zealand, isolations were carried out from plant samples with dieback symptoms collected from blackcurrant orchards in the main growing areas in the South Island of New Zealand. For one site, symptomatic grapevines in an adjacent vineyard were also sampled as they are known hosts of these species. The pathogenicity of representative isolates from each of the species recovered was determined on detached blackcurrant shoots. Of the 242 symptomatic plant materials collected, 29% were infected by Botryosphaeriaceae. Species of Botryosphaeriaceae were recovered from plant samples from all four orchards sampled. Of the 70 Botryosphaeriaceae isolates recovered from blackcurrant, Diplodia seriata (43 isolates) and D. mutila (17 isolates) were the most prevalent species, with Neofusicoccum australe (6 isolates), N. cryptoaustrale (3 isolates) and one isolate of D. sapinea also recovered. D. seriata , D. mutila , N. australe and N. cryptoaustrale were also recovered from symptomatic grapevine tissues sampled from the adjacent vineyard and all but N. cryptoaustrale were found in the blackcurrant crop adjacent to this vineyard. All species were pathogenic on detached green shoots, with N. australe and N. cryptoaustrale the most pathogenic, producing the longest lesions compared with D. seriata and D. mutila . This is the first study on the incidence and pathogenicity of species of the Botryosphaeriaceae infecting blackcurrant plants in New Zealand.

Arbuscular mycorrhizal fungi (AMF) are obligate biotrophs that form a symbiotic and mutualistic relationship with most terrestrial plants, playing an important role in plant growth, nutrient acquisition, and ecosystem stability. This review synthesizes current knowledge on AMF colonization in plants within New Zealand ecosystems, including the challenges and opportunities of molecular identification techniques used in characterizing AMF communities in natural and managed systems. The ecosystem services provided by AMF, such as improved growth parameters, enhanced nutrition, and disease control, are discussed in detail, highlighting their significance in sustainable agriculture and natural ecosystems. Additionally, the role of AMF in invasion ecology was examined, revealing their dual potential to either facilitate or hinder invasive plant species. Despite significant advances in understanding AMF biology, future research is needed to explore the underlying mechanisms of AMF-plant interactions and to address the challenges caused by changing environmental conditions. This review focused on the importance of AMF in promoting ecosystem resilience and suggests avenues for future research to harness their full potential in agricultural and ecological contexts.

Sclerotia of Sclerotinia sclerotiorum germinate carpogenically developing apothecia and release ascospores which act as an inoculum in the field. Identifying the factors influencing the carpogenic germination of sclerotia is important in management of the pathogen. This study assessed the effect of medium and cold preconditioning on in vitro carpogenic germination of sclerotia and development of apothecia. Carpogenic germination was tested in sand, water agar and potting mixture and the effect of preconditioning of sclerotia at 4°C was assessed for isolates originating from different locations in New Zealand. Sclerotia germination and number of apothecia per plate were greater in water agar compared with potting mix. Development of stipes into apothecia was greater in compost compared with water agar. The isolates from sub‐tropical Auckland region showed greater carpogenic germination than most of the isolates from temperate Canterbury region under the experimental conditions used in the study. A few isolates showed a positive or negative response to cold preconditioning hence, no conclusions as to possible ecological adaptation of S. sclerotiorum to the field conditions in which the isolates originated could be made. The prominent isolate effect on all aspects of carpogenic germination assessed highlights the need to include several isolates in future studies.