Podosphaera xanthiiis the main causal agent of cucurbit powdery mildew in Southern Italy. Illumina sequencing of mRNA from twoP. xanthiiisolates of opposite mating types (MAT1-1andMAT1-2) and their sexual cross was used to obtain a detailedde novoTrinity-based assembly of the transcriptome of the fungus. Over 60 million of high-quality paired-end reads were obtained and assembled into 71,095 contigs corresponding to putative transcripts that were functionally annotated. More than 55% of the assembled transcripts (40,221 contigs) had a significant hit in BLASTx search and included sequences related to sexual compatibility and reproduction, as well as several classes of transposable elements and putative mycoviruses. The availability of these new transcriptomic data and investigations on potential source of genetic variation inP. xanthiiwill promote new insights on the pathogen and its interactions with host plants and associated microbiome.

Surface DBD (SDBD) discharge maintained in moist air in the immediate vicinity of the water surface is an effective source of reactive species for the production of plasma-activated water (PAW). In this work, we investigated the water activation process for two different DBD energization methods; i.e. using periodic HV pulses with nanosecond risetimes and amplitude-modulated HV AC. We combined UV–vis–NIR ICCD spectroscopy with electrical characteristics to determine the basic characteristics of SDBD microfilaments. Formation of N₂O₅/NO₂/N₂O/H₂O₂/NO₂ ⁻/NO₃ ⁻ species was followed and the production yields of species generated in PAW (H₂O₂/NO₂ ⁻/NO₃ ⁻) were determined in a flow-through reactor under well-defined and stable discharge conditions. Both energization methods reached comparable energy efficiencies of nitrogen fixation in the range of 1–6 g kWh⁻¹ with minimal concentrations of H₂O₂ (10 s μM). However, the AC-powered SDBD produced mainly NO₃ ⁻ with minimal NO₂ ⁻ (1/10 of NO₃ ⁻), while in the case of pulsed SDBD the better-balanced NO₂ ⁻/NO₃ ⁻ ratio was achieved.

The plasma filaments propagating along the air–water interface offer a useful approach to enhance the transport of reactive species from plasma into the liquid medium. In this work, we investigated the novel streamer-spark discharge geometry, where both electrodes are submerged in water, inside a continuous flow-through reactor as a source of plasma-activated water (PAW) that can be used as a nitrogen-enriched water fertilizer and/or antimicrobial agent. We have inspected the efficiency of nitrogen fixation by varying the external parameters such as airflow and discharge repetition rate at fixed water flow through the reactor. The concentrations of generated NO_x species exhibit linear dependence on input power in both gaseous and dissolved forms, with the production rate of NO_x ⁻ reaching as high as 48.5 μmol min⁻¹ with standard energy efficiencies of around 16 mmol MJ⁻¹. Biocidal efficiency was tested on three selected fungal species (Botrytis cinerea, Penicillium italicum, Aspergillus carbonarius), which are usually more resilient than bacteria. The best efficacy in conidia germination inhibition has been achieved for Penicillium italicum (nearly 40%). The results presented also indicate that the energy efficiency of NO₃ ⁻ synthesis is tied to the characteristics/parameters of individual streamer-spark discharge events, while the total NO₃ ⁻ concentration and production throughput are determined by the overall discharge power.

The application of Low-Temperature Plasmas has shown great potential as an effective and alternative tool for microbial inactivation in recent years. Nevertheless, further investigations are required to fully understand the possible factors influencing these processes. The present study aims to investigate the effectiveness of square wave modulated Volume Dielectric Barrier Discharge on the direct inhibition of conidial germination in five different fungal species, various discharge conditions, and medium composition. The five different fungal species used were Botrytis cinerea, Monilinia fructicola, Aspergillus carbonarius, Fusarium graminearum, and Alternaria alternata. On water agar, the inhibition of Botrytis cinerea was influenced by the applied voltage, which mainly reflects the uniformity of the treatment. Under the selected voltage condition, the inhibition increased with treatment duration and decreased with fungal spore complexity. B. cinerea and M. fructicola, with unicellular conidia and low melanin content, showed similar behaviour and high sensitivity to the treatment. F. graminearum and A. alternata, both having multicellular conidia, were more resistant to the plasma treatment and showed different sensitivity likely due to different content in melanin. However, after 1 min of treatment, complete inhibition of conidial germination was achieved for all the tested species. Inhibition of A. carbonarius conidia on different agarized media containing dextrose or malt extract was influenced by the complexity and composition of the medium, being potato dextrose agar that more hindered the plasma efficacy. Each medium exhibited a different electrical response studied by Electrical Impedance Spectroscopy and morphology observed by Scanning Electron Microscopy images. These differences translated into a different response to the applied electrical field, influencing plasma generation and uniformity.

The quarantine bacterium Xylella fastidiosa was first detected in Salento (Apulia, Italy) in 2013 and caused severe symptoms in olives, leading to plant death. The disease, named Olive Quick Decline Syndrome (OQDS), is caused by the strain “De Donno” ST53 of the subspecies pauca of this bacterium (XfDD), which is spread by the insect Philaenus spumarius. The epidemic poses a serious threat to the agricultural economy and the landscape, as X. fastidiosa infects several plant species and there is yet no recognized solution. Research on OQDS is focused on finding strategies to control its spread or mitigate its symptoms. As a perspective solution, we investigated the efficacy of the low-temperature plasma and plasma-activated water to kill bacterial cells. Experiments were conducted in vitro to test the biocidal effect of the direct application of a Surface Dielectric Barrier Discharge (SDBD) plasma on bacteria cells and Plasma Activated Water (PAW). PAW activity was tested as a possible biocidal agent that can move freely in the xylem network paving the way to test the strategy on infected plants. The results showed a high decontamination rate even for cells of XfDD embedded in biofilms grown on solid media and complete inactivation in liquid culture medium.

Powdery mildew is one of the most common and severe diseases of cucurbits, causing heavy yield losses in all growing areas when not successfully controlled. Two different fungal species, Podosphaera xanthii and Golovinomyces orontii , are generally recognized as causal agents. The results of monitoring carried out in 2016 and 2018 confirmed that P . xanthii is the exclusive pathogen causing cucurbit powdery mildew (CPM) in southern Italy. P . xanthii is a bipolar heterothallic fungus; a PCR‐based method for distinguishing MAT1 ‐ 1 and MAT1 ‐ 2 idiomorphs was applied for assessing mating type distribution in fungal populations present on cucurbits in different sites. The idiomorph MAT1 ‐ 2 was prevalent over the MAT1 ‐ 1 in 2016, whereas they were approximately in a 1:1 ratio in 2018; this finding corroborated the hypothesis that the MAT1 ‐ 1 idiomorph was more recently introduced in the area. Cyflufenamid‐resistant isolates were widespread in commercial greenhouses and field plantings even though use of this fungicide had been drastically reduced by the farmers 1 year before the monitoring due to the effectiveness losses observed in CPM control. Occurrence of cyflufenamid resistance and its impact on efficacy were evaluated in a field trial comparing different fungicide spray schedules. Cyflufenamid‐resistant isolates were detected even at the first appearance of symptoms on leaves, increasing over time. Isolates resistant to cyflufenamid showed a resistance factor as high as 900. Generally, P . xanthii was better controlled when cyflufenamid was used in integrated strategies rather than in spray schedules based on the exclusive use of the fungicide.