Strawberry is an important horticultural crop in Victoria, Australia. Grey mould caused by Botrytis cinerea reduces marketable yield and post-harvest quality of strawberry fruit in the region. We conducted two field experiments in Victoria (Coldstream and Warburton) to evaluate the effectiveness of a commercial seaweed extract from Durvillaea potatorum and Ascophyllum nodosum (Seasol®) on the yield, revenue, and post-harvest rot of strawberry fruit. We applied the extract to strawberry crops (cv. Albion) monthly as a combined drench (10 L ha^-1) and foliar spray (1:400), with water as a control. Application of the seaweed extract significantly increased strawberry fruit yields by 8-10% and revenue by AU$0.37-0.59 per plant. Furthermore, the extract significantly reduced the incidence and severity of post-harvest rots in strawberry fruit by 52-87%, respectively. The extract did not affect the firmness, soluble solids concentration (SSC), titratable acidity, or SSC:acid of strawberry fruit. In a separate laboratory experiment, we found that growing strawberry in the seaweed extract (1:400) increased the concentration of peroxidase by 50% and doubled H₂O₂ in roots soon after treatment. Increases in reactive oxygen species are an indicator of a suite of pathways associated with resistance and tolerance of biotic and abiotic stresses. Overall, the results demonstrate that the seaweed extract can act as a commercially-viable biostimulant for strawberry fruit production in south-eastern Australia.

Knowledge of the factors structuring populations of pathogenic fungi is fundamental to disease management efforts and basic biology. However, this crucial information is missing for many important pathogens, including broad-host-range and drought-associated pathogens from the globally distributed Macrophomina genus. The objectives of this work were to evaluate the evidence for host specialization, geographic adaptation, and recombination using a global survey of Macrophomina isolates from diverse geographic, temporal, and host sources. We obtained high-quality short-read sequence data for 463 Macrophomina spp. isolates, representing four putative species, collected from 91 host plant species and soil in 23 countries. Analysis of bi-allelic, single-nucleotide polymorphisms revealed high diversity, admixture, and equal mating type ratios, suggesting ongoing recombination. Although most tested isolates asymptomatically colonized strawberry, only strawberry-derived isolates caused disease on this host. These isolates were all in a single lineage, suggesting that the ability to cause disease on strawberry is not widespread among M. phaseolina. Significant associations were also found between isolations from soybean plants and specific population clusters, suggesting that specialization for virulence or reproduction has also occurred for soybean. Geography × isolate genotype associations were weak, suggesting that Macrophomina spp. were frequently trafficked between regions. Reference-free whole-genome comparisons support current boundaries among four Macrophomina species, and new molecular markers were designed to specifically identify each species. Contrary to expectations, M. phaseolina should be considered a single species with both specialist and generalist populations in which meiosis can maintain genetic diversity. [ ] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Strawberry (Fragaria x ananassa) production has increased around the world, but crop quality and yield are threatened by fungal pathogens. Botrytis cinerea is a filamentous fungus that infects over 1400 species of crops, causing gray mold disease with devastating losses to horticulture worldwide, including strawberry. The heavy reliance on synthetic fungicides in the strawberry industry has led to the emergence of fungicide resistance in B. cinerea. Therefore, understanding the fundamental biology of B. cinerea is an important step in the search for novel antifungals. Although B. cinerea is one of the most serious pathogens of strawberry, this pathosystem is understudied compared to other plant hosts. Consequently, further evidence is needed on pathogen penetration and early disease development in strawberry tissues. Here, we adapted and advanced assays using detached strawberry leaves, fruits, and petals to study B. cinerea infection. These assays allow the comparison of the treatment effect on the same fruit, avoiding confounding from differential ripening, and facilitate the screening of fungicides or biocontrol agents. Through chlorophyll fluorescence analysis and scanning electron and confocal microscopy, we quantified lesions caused by B. cinerea in the early stages of infection in fruit and petals, and demonstrated that B. cinerea penetrates through the stomata of strawberry achenes, revealing a previously unrecognized infection route in this host. These data provide a deeper understanding of the B. cinerea–strawberry interaction and will serve as a foundation for future studies seeking novel antifungal treatments against B. cinerea.

Charcoal rot of strawberry caused by the soilborne pathogen Macrophomina phaseolina has increased in importance in Australia and many other countries since 2005. Several factors might explain the increase in the disease in Australia, including the withdrawal of the soil fumigant methyl bromide in 2005 due to its adverse effect on the stratospheric ozone. We conducted a field experiment to test the hypothesis that soil disinfestation with methyl bromide could eliminate charcoal rot in a strawberry field severely affected by the disease. The results showed that a single application of methyl bromide/chloropicrin reduced M. phaseolina in infected strawberry crowns buried in soil by 98% and DNA concentrations in soil at planting by 100% compared with the untreated control. The use of methyl bromide/chloropicrin also reduced charcoal rot in the strawberry crop by 99.7% and increased marketable fruit yields by 86% and revenue by A$2.81 per plant. In contrast, the adopted substitute fumigant, 1,3-dichloropropene/chloropicrin, controlled M. phaseolina and charcoal rot considerably less effectively than methyl bromide/chloropicrin. The results add weight to the premise that the phase-out of methyl bromide was an important factor that contributed to the increase in charcoal rot in strawberry in Australia and possibly in other countries. The benefits of methyl bromide withdrawal for the environment are significant and well documented, so the ongoing need to identify suitable alternatives for managing soilborne diseases such as charcoal rot remains vitally important. [ ] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY 4.0 International license .

Crown rot diseases have become increasingly important in strawberry production following the withdrawal of key pesticides due to environmental and human health concerns. The principal causal agents, Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae , can persist for extended periods in infected crown tissues and residual plant material in soil, serving as inoculum sources for subsequent crops. In some regions, crop termination using drip fumigants has been adopted to simultaneously destroy residual strawberry plants and the pathogens within them. In this study, we evaluated microwave heating as a non-chemical alternative for crop termination and pathogen suppression in strawberry. Pot experiments were used to quantify the thermal sensitivity of the two pathogens within infected crown tissue in microwave-heated soil. The estimated LD ₅₀ and LD ₉₀ temperatures for M. phaseolina were 63.1 °C and 86.2 °C, and for F. oxysporum f.sp. fragariae 72.3 °C and 87.3 °C, respectively. A field experiment showed that heating a strawberry crop to 80–90 °C using microwaves terminated plants as effectively as a herbicide treatment (glufosinate-ammonium + triclopyr). Microwave treatment also reduced the viability of M. phaseolina and F. oxysporum f.sp. fragariae in infected strawberry crowns by an average of 97%, decreased the emergence of the weed Senecio vulgaris by 73%, and reduced DNA concentrations of M. phaseolina and Pythium spp. (clades I and F) in soil by 95% and 80%, respectively. The results demonstrate the potential of microwaves as a non-chemical strategy for thermo-management of residual plant material and pathogen inoculum in strawberry production systems.