Infected Plants Research Articles

Genetic Study and Temporal Dynamics of the Reaction to Ascochyta rabiei Epidemic in Improved Lines and Cultivars of Chickpea (Cicer arietinum L.)

ABSTRACTAscochyta blight is the most devastating worldwide disease of chickpea (Cicer arietinum L.). It is caused by Ascochyta rabiei (teleomorph: Didymella rabiei) an airborne pathogenic fungus which is common in rainy climates and warm temperatures. Despite the efforts deployed by genetic improvement to develop highly resistant varieties, a total resistance to Ascochyta blight is lacking in chickpea. From 2015 to 2019 season, a study was carried out to develop highly resistant lines at the experimental station of the National Agronomical Institute of Tunis (INAT).In this genetic program, four crosses were realized: Nour x ILC154986, Nour x ILC154445, Béja1x ILC155064, and Béja1x ILC154449. Nour and Béja1 varieties were respectively tolerant and susceptible to Ascochyta blight and were used as female parents. The genetic study showed a total of six genes controlling the resistance to Ascochyta blight. The disease progress was analyzed under inoculation in the field on seven dates, and the plant infection rate r was recorded on the parental cultivars and the lines developed from crosses. The temporal progress of the disease was studied by using statistical and mathematical tools. A logistic model was tested and then applied to describe the Ascochyta rabiei progress over time in the field. The fitting adequacy of the logistic model was estimated by the determination coefficient R2 which value exceeded 0.98 and justified this selection. The logistic curves analysis showed a slow blighting and an infection progress decrease of lines issued from Béja1 x desi1 and Nour x Kabuli1 crosses. These lines obtained by transgressive segregation in the Nour x Kabuli1 and Beja1 x Desi2 populations can develop a stable resistance and prevent its overcoming.

Amazonian Bacteria from River Sediments as a Biocontrol Solution against Ralstonia solanacearum.

Bacterial wilt, caused by Ralstonia solanacearum, is one of the main challenges for sustainable tomato production in the Amazon region. This study evaluated the potential of bacteria isolated from sediments of the Solimões and Negro rivers for the biocontrol of this disease. From 36 bacteria selected through in vitro antibiosis, three promising isolates were identified: Priestia aryabhattai RN 11, Streptomyces sp. RN 24, and Kitasatospora sp. SOL 195, which inhibited the growth of the phytopathogen by 100%, 87.62%, and 100%, respectively. These isolates also demonstrated the ability to produce extracellular enzymes and plant growth-promoting compounds, such as indole-3-acetic acid (IAA), siderophore, and ammonia. In plant assays, during both dry and rainy seasons, P. aryabhattai RN 11 reduced disease incidence by 40% and 90%, respectively, while promoting the growth of infected plants. Streptomyces sp. RN 24 and Kitasatospora sp. SOL 195 exhibited high survival rates (85-90%) and pathogen suppression in the soil (>90%), demonstrating their potential as biocontrol agents. This study highlights the potential of Amazonian bacteria as biocontrol agents against bacterial wilt, contributing to the development of sustainable management strategies for this important disease.

Epidemiology and Management of Bean Common Mosaic Virus (BCMV) in Traditional Phaseolus vulgaris L. Landraces within Protected Geographical Indications

Protected geographical indications (PGIs) share health problems related to plant propagation material. The PGI “Faba de Lourenzá” encompasses a 1660 km2 area in northern Galicia, Spain, renowned for its “Faba Galaica” (FG) and Faba do marisco” (FM) bean cultivars. The lack of certified virus-free seeds poses a challenge. From 2019 to 2023, seeds from 60 lots were tested for BCMV. Plants from several plots were tested periodically to develop disease progress curves (DPCs). Control methods (plots out PGI zone, virus-free seedlings, rogueing, corn borders, and intercropping) were tested. Yields in five plots were used to assess BCMV’s economic impact. Seed lots were 22.3% FG-infected and <5% FM-infected. The transmission rate of BCMV from infected FG plants to their seeds was 25.5 ± 5%, while for FM it was 12 ± 3%. FG yield losses were on average 31.6 ± 4.5%. Combining virus-free seedlings and infected plant removal in plots outside the PGI area proved effective at reducing infection rates; combining with intercropping resulted in the lowest incidence in an FG plot. Farmer training and off-site plot selection to produce healthy sowing beans are key to improving results.

Inhibitor of cardiolipin biosynthesis-related enzyme MoGep4 confers broad-spectrum anti-fungal activity.

Plant pathogens cause devastating diseases, leading to serious losses to agriculture. Mechanistic understanding of pathogenesis of plant pathogens lays the foundation for the development of fungicides for disease control. Mitophagy, a specific form of autophagy, is important for fungal virulence. The role of cardiolipin, mitochondrial signature phospholipid, in mitophagy and pathogenesis is largely unknown in plant pathogenic fungi. The functions of enzymes involved in cardiolipin biosynthesis and relevant inhibitors were assessed using a set of assays, including genetic deletion, plant infection, lipidomics, chemical-protein interaction, chemical inhibition, and field trials. Our results showed that the cardiolipin biosynthesis-related gene MoGEP4 of the rice blast fungus Magnaporthe oryzae regulates growth, conidiation, cardiolipin biosynthesis, and virulence. Mechanistically, MoGep4 regulated mitophagy and Mps1-MAPK phosphorylation, which are required for virulence. Chemical alexidine dihydrochloride (AXD) inhibited the enzyme activity of MoGep4, cardiolipin biosynthesis and mitophagy. Importantly, AXD efficiently inhibited the growth of 10 plant pathogens and controlled rice blast and Fusarium head blight in the field. Our study demonstrated that MoGep4 regulates mitophagy, Mps1 phosphorylation and pathogenesis in M. oryzae. In addition, we found that the MoGep4 inhibitor, AXD, displays broad-spectrum antifungal activity and is a promising candidate for fungicide development.

Sensitive and rapid determination of tetracycline antibiotic by carrot juice-derived carbon dots as a fluorescent probe.

The antibiotic tetracycline can be efficiently used as medicine for the deterrence of bacterial infections in humans, animals, and plants. However, the unprecedented use of tetracycline is of great concern owing to its low biodegradability, extensive usage, and adverse impacts on the environment and water quality. In this study, a sensitive spectrofluorometric method was proposed for the direct determination of tetracycline, based on biocompatible fluorescent carbon dots (CDs). The synthesis of CDs was performed by adopting a green hydrothermal procedure from carrot juice without requiring surface passivation or outflowing any environmentally hazardous waste. X-ray diffraction analysis and transmission electron microscopy revealed amorphous spherical-shaped CDs that exhibited blue emission under blue illumination. The fabricated fluorescent probe directly detected tetracycline in the concentration range of 4.00 ×10-6 to 1.55 ×10-5mol L-1 with an LOD of 1.33 ×10-6mol L-1. The performance of the probe was assessed in a tap water sample, with recovery values between 80.70 and 103.60%. The method's greenness was evaluated using the Analytical Green metric approach (AGREE) and confirmed to be within the green range. The developed method is facile, rapid, cost-effective, and offers a wide linear range and satisfactory selectivity, making it potentially suitable for determining tetracycline in water applications.

Virus Infected Papaya Plants Differentially affects Oxidative Stress and Survival in Caenorhabditis elegans

Carica papaya (papaya) leaves has significant nutraceutical properties. However, it is speculated that papaya leaf curl virus (PaLCuV) and papaya ring spot virus (PRSV) can severely affect the therapeutic properties and alter the overall nutraceutical potential of papaya leaves. Therefore, we evaluated the bioactivity of the virus infected papaya leaves extract (PLE) compared to healthy PLE in C. elegans. Viruses infection were confirmed by visual inspection and PCR based detection. Anatomical changes and elemental analysis were analyzed through SEM-EDS. PLE were tested for life span extension and ROS scavenging activity on C. elegans. Infected leaves displayed typical symptoms of curling, distortion and anatomical analysis revealed closed and less number of stomata. Healthy PLE extended (24%) the life span of C. elegans with no significant change in ROS generation while in PaLCuV and PRSV infected PLE, were observed to have significant reduction in the mean life span of 15.4% and 17% with 1.2-fold and 1.9-fold increase in ROS generation.

Pest categorisation of Coniella castaneicola.

The European Commission requested the EFSA Panel on Plant Health to conduct a pest categorisation of Coniella castaneicola (Ellis & Everh) Sutton, following commodity risk assessments of Acer campestre, A. palmatum, A. platanoides, A. pseudoplatanus, Quercus petraea and Q. robur plants from the UK, in which C. castaneicola was identified as a pest of possible concern to the EU. When first described, Coniella castaneicola was a clearly defined fungus of the family Schizoparmaceae, but due to lack of a curated type-derived DNA sequence, current identification based only on DNA sequence is uncertain and taxa previously reported to be this fungus based on molecular identification must be confirmed. The uncertainty on the reported identification of this species translates into uncertainty on all the sections of this categorisation. The fungus has been reported on several plant species associated with leaf spots, leaf blights and fruit rots, and as an endophyte in asymptomatic plants. The species is reported from North and South America, Africa, Asia, non-EU Europe and Oceania. Coniella castaneicola is not known to occur in the EU. However, there is a key uncertainty on its presence and geographical distribution worldwide and in the EU due to its endophytic nature, the lack of systematic surveys and possible misidentifications. Coniella castaneicola is not included in Commission Implementing Regulation (EU) 2019/2072 and there are no interceptions in the EU. Plants for planting, fresh fruits and soil and other growing media associated with infected plant debris are the main pathways for its entry into the EU. Host availability and climate suitability in parts of the EU are favourable for the establishment and spread of the fungus. Based on the scarce information available, the introduction and spread of C. castaneicola in the EU is not expected to cause substantial impacts, with a key uncertainty. Phytosanitary measures are available to prevent its introduction and spread in the EU. Because of lack of documented impacts, Coniella castaneicola does not satisfy all the criteria that are within the remit of EFSA to assess for this species to be regarded as potential Union quarantine pest.

Bisifusarium lunatum causing cladode soft rot in pear cactus (Nopalea cochenillifera L. Salm-Dyck) in Brazil.

Cactus pear var. miúda (Nopalea cochenillifera L. Salm-Dyck) is an important crop for the Northeast region of Brazil, composing one of the main sources of animal feed. By April 2021, cladode rot caused death of several cactus pear plants in a production area located in Itaporanga, Paraíba state, Brazil (7°21'55.35" S and 38°11'38.68" W). The infected cladodes showed brown circular necrotic spots, and soft rot with perforations that extended throughout the cladode, followed by tipping over and death of the infected plants. The incidence of the disease ranged from 10 to 30% of the plants. Bisifusarium strains were isolated and cultured on potato dextrose agar (PDA) and syntetic-nutrient-poor-agar (SNA). The colonies showed purple color on PDA. On SNA, macroconidia (n = 100) were abundant, hyaline, slightly falcate, three-septate, measuring 11.0-23.1 x 2.3-4.1 μm. Microconidia (n = 100) were oval, generally aseptate, measuring 4.1-8.7 x 2.3-3.0 μm. Conidiogenic cells formed into short monophialides. Chlamydospores were not observed. According to these morphological features, the pathogen was initially identified as Bisifusarium lunatum (Gryzenhoutm et al. 2017). For further confirmation of the identification, the partial sequences of translation elongation factor 1-alpha (TEF1-α) and the second largest subunit of RNA polymerase II (RPB2) genes were sequenced for a representative isolate (CMA 34: GenBank accession no: TEF1-α: OR536502; and RPB2: OR553509) and compared to other Bisifusarium species from GenBank database. Subsequently, it was subjected to a phylogenetic analysis of maximum likelihood including previously published sequences. According to BLAST searches, the TEF1-α and RPB2 sequences were 99% (637/640 nt) and 100% (312/312 nt) similar to B. lunatum (COUFAL0213: TEF1-α (MK640219), and RPB2 (MK301291)), respectively. The isolate was also clustered in a clade containing the ex-type of B. lunatum with 100% support (SH-aLRT and UFboot), being confidently assigned to this species. The pathogenicity test was performed after Medeiros et al. (2015), by using healthy two months old cactus pear seedlings (n = 10) cultivated in a greenhouse. Sterile toothpicks were distributed over colonies of the representative isolate grown on PDA at 25 ± 2 °C for seven days. Seedling cladodes were stuck with the toothpicks, moistened with sterile water and covered with transparent plastic bags for 24h, thus simulating a humid chamber. Following three months, all control plants (stuck with sterile toothpicks) remained healthy, while those inoculated with the representative isolate exhibited rot symptoms. This test was performed twice. B. lunatum was reisolated from symptomatic cladodes and identified as previously described, thus fulfilling the Koch's postulates. To our best knowledge, this is the first report of B. lunatum causing soft rot on N. cochenillifera in Brazil. Besides N. cochenillifera, this species was also reported on Opuntia ficus-indica in India (Gryzenhoutm et al., 2017), which raises concern regarding its ability to infect other forage sources for cattle feed in Brazilian semiarid regions. The present study highlights that the precise identification of B. lunatum is a key factor to adjust control strategies and management of the disease to prevent the spread of this disease to prevent its spread to other crops.

Characterization of biologically synthesized copper nanoparticles by Aspergillus carbonarius and evaluation of their activity in reducing the pathogenic stress of tomatoes infected with Fusarium oxysporum

This study was conducted to evaluate the efficiency of the fungus Aspergillus carbonarius in the synthesis of copper nanoparticles (CuNPs) from copper chloride solution, with the characterization of these nanoparticles and the demonstration of their effectiveness in inhibiting the pathogenic fungus Fusarium oxysporum causing tomato root rot disease. The results indicated that the treatment of copper chloride solution at 150 mM with A. carbonarius filtrate led to the production of CuNPs which characterized by a color change from blue to green, with the highest absorbance observed at 300 nm. X-ray diffraction (XRD) results revealed the crystalline structure with peaks at angles 28.47286, 47.43258, and 56.20644 ◦ corresponding to (111), (220), and (311) planes, respectively, matching the JCPDS card number 01-081-1841. Scanning electron microscopy images showed cubic, pyramidal, and prismatic shapes with dimensions ranging from 15 - 84.291 nm. In laboratory experiment, CuNPs inhibited the growth of the pathogenic fungus, with an inhibition zone of 1.6 cm, compared to copper chloride which recorded 0.9 cm. In the field, , the treatment of CuNPs led to an increase in the stress resistance indicators, reaching the highest values for CuNPs when combined with the fungicide Medazim in the American tomato cultivar. The concentrations of total phenols and glutathione in this treatment were 2.56 mg/g and 0.322 µg/g, respectively. The lowest concentration of proline was recorded as 4.31 µg/g in the treatment involving CuNPs against the fungal infection. CuNPs with the fungicide medazim, significantly outperformed other treatments, registering lowest disease severity at 12.22% in the American cultivar, compared to the highest disease severity was recorded in the treatment with the pathogenic fungus alone, reaching 91.16% in the Dutch cultivar. CuNPs significantly increased tomato fruit weight, both in healthy and infected plants. The American, Turkish, and Dutch tomato cultivars infected with the pathogenic fungus and treated with under + medazim showed higher productivity, reaching 6432.55, 6334.34, and 6305.73 g.plant-1, compared to the lowest productivity in the treatment of these cultivars with the pathogenic fungus, reaching 1008.34, 977.45, and 833.78 g.plant-1, respectively

Частота встречаемости гетеродеза на масличных культурах семейства Капустные в Краснодарском крае

A beet cyst nematode Heterodera schachtii Schmidt is an obligate parasite, which infected many kinds of agricultural crops in different countries. It penetrates into internal tissues of plant root and causes mechanical destructions of cells. The disease manifests itself in a form of plant wilting. Yield decrease can reaches up to 50%. The purpose of the research was to determine frequency of occurrence of the beet cyst nematode Heterodera schachtii Schmidt in sowings of winter and spring oil crops from a Brassicaceae family in the Krasnodar region. The observations of sowings of the studied crops were conducted in phases of a vegetative period 2–4 true leaves and green pod on fields of the V.S. Pustovoit All-Russian Research Institute of Oil Crops in 2010–2023. In these phases, 20 plants were selected on ten equidistant plots diagonally across the sowings of each crop. The frequency of occurrence of Heterodera schachtii was calculated as a ratio between numbers of sick and healthy plants expressed as a percentage, and then divided into groups: infected plants are absent; low (to 10% of infected plants); average (from 11 to 50% of infected plants); high (51% and more of infected plants). The beet cyst nematode was allocated in plants of all studied crops, besides winter and spring false flax. In years, when the disease was stated in sowings of oil crops from the Brassicaceae family, the frequency of the diseases occurrence was low (up to 10%) in both phases of plant development 2021. And in 2021, it increased to average level (11–18%) on winter and spring rapeseed and brown mustard. An infection degree of plants of all studied groups was equal 1–3 points with a predominance of 1 point.

Comparison of Optimal Control Effect from Fungicides and Pseudomonas Fluorescens on Downy Mildew in Corn

Downy mildew is a disease that continues to infect corn crops in Timor Tengah Utara regency, reducing the amount of crop production and making corn farmers suffer losses. Farmers continue to look for ways to control downy mildew. Two treatments are commonly used by farmers, namely spraying Fungicides and Pseudomonas Fluorescens simultaneously in one unit of time, but have not resulted in optimal production. Therefore, this research is important to get a more optimal way to control find downy mildew. In this paper, we determine the optimal model of downy mildew control in corn plants by comparing the use of Fungicides and Pseudomonas Fluorescens. This research begins by forming a dynamic mathematical model consisting of six populations, namely four corn populations (Sh, F , P , Ih) and two populations of infecting fungi (Sv , Iv ). Then they obtained the basic reproduction number (R0) and two equilibrium points, namely the disease-free equilibrium and the disease-endemic equilibrium which has asymptotic stability. Numerical simulation results based on optimal control analysis with the minimum Pontryagin principle show that using fungicides can reduce the number of plants infected with downy mildew. Therefore, control by using fungicides is necessary and recommended increasing the number of downy mildew infected plants.

In vitro potential control of white root fungus in nutmeg (Myristica fragrans) based on botanical fungicide of coconut shell liquid smoke

Nutmeg (Myristica fragrans) is spice plant which has an important position as a source of essential oils. An important problem in nutmeg cultivation is white root disease which can reduce nutmeg production. Until now, white root disease is still a problem in nutmeg plantations in South Aceh district. One of the solution that can be explored as an environmentally friendly control measure is to use the botanical fungicide coconut shell liquid smoke. This research aims to determine the potential of coconut shell liquid smoke in controlling white root fungus in vitro. The research was carried out in the Plant Protection Laboratory, Faculty of Agriculture, Teuku Umar University. The research design used was a non-factorial Completely Randomized Design (CRD) consisting of nine levels of liquid smoke concentration treatment; control 0%, 0.5%, 1%, 2%, 3%, 4%, 6%, 8%, 10%. Each treatment involved three replications. Data analysis was carried out using analysis of variance and Tukey's least significant difference (HSD) test.The research stages carried out consisted of producing coconut shell liquid smoke, isolating white root fungus from the roots of infected nutmeg plants and potential assay of liquid smoke in inhibiting the growth of white root fungus. In vitro bioassay result showed that liquid smoke treatment 3% was the best treatment because it was the lowest concentration causing total inhibition of the growth of white root fungus.

IDENTIFICATION OF RESISTANCE TO MELON FUSARIUM WILT IN SEVEN HYBRID COMBINATIONS OF PUMPKINS

Melon wilt disease, also known as wilt disease, occurs from the seedling stage to the adult stage of plants. According to previous research, grafting is an effective means to improve the resistance of melons and Solanaceae vegetables to soil borne diseases and pests. With the popularization of vegetable grafting, the demand for rootstocks has rapidly increased. Therefore, this experiment takes seven pumpkin hybrid combinations as the research object, studies the resistance of different hybrid combinations to wilt disease, selects pumpkin hybrid combination rootstocks with strong resistance, and provides reference for grafting cultivation in production. The research results indicate that 10 days after inoculation with pathogens, the overall plant infection in the early stage was not significantly affected by the pathogens, and there was no significant difference between the various hybrid combinations. On the 20th day of inoculation with pathogens, Yanbian-3×360-3 showed significant differences in plant height and chlorophyll indicators compared to other pumpkin rootstock hybrid combinations. On the 30th day of pathogen inoculation, Yanbian-3×360-3 showed significantly higher plant stem diameter indicators than other pumpkin rootstock hybrid combinations, showing significant differences from other pumpkin hybrid combinations. Therefore, it can be concluded that Yanbian-3×360-3 had the optimal relative growth rate. Moreover, on the 30th day of pathogen inoculation, the leaf disease index was 52.67%, and the stem disease index was 37.92%, indicating that Yanbian-3×360-3 was less affected by pathogen infection and has stronger resistance to wilt disease. On the 30th day after inoculation with pathogenic bacteria, the investigation showed that the disease index of leaves in Yanbian-2×041-1 was 54.67%, and the disease index of stem dissection was 45.83%. Hetoua2×041-1, with a leaf disease index of 95.33% and a stem cutting disease index of 87.92%. Among the seven pumpkin hybrid combinations, Yanbian-3×360-3 and Yanbian-2×041-1 have the best disease resistance and are neutral disease resistant combinations; Hetoua2×041-1 has the most severe incidence and is a highly susceptible combination. The two pumpkin rootstocks, Yanbian-3×360-3 and Yanbian-2×041-1, have good resistance to melon wilt disease and can be used as grafting rootstocks for melon wilt disease resistance. Considering the affinity between grafting rootstocks and scions and the impact on yield after grafting, further verification is needed in the later stage.

Frontiers in bacterial-based green synthesized nanoparticles (NPs): A sustainable strategy for combating infectious plant pathogens

The excessive use and inappropriate application of synthetic pesticides on essential agricultural crops, intended to them from harmful pests, have resulted in severe environmental pollution. Additionally, the penetration of these toxic pesticide residues into the edible parts of plants has raised significant health concerns for humans and animals by developing respiratory problems, neurological disorders, and cancers. In response, nanotechnology has emerged as a promising alternative, enabling the development of highly reliable, minuscule nanoparticles (NPs) in size of 1–100 nm (nm) with diverse morphologies. These NPs offer an alternative approach to managing plant pathogens compared to traditional pesticides. Although various synthetic NPs have been produced using different elements, their persistence in plant tissues, soil, and water presents significant challenges. Conversely, the synthesis of biologically-derived green NPs, particularly those from bacteria, is considered a safer method for controlling plant pathogens. Bacteria-based green NPs are advantageous due to the rapid growth proliferation of bacteria and their resilience to extreme conditions. However, their synthesis and application remain limited, with scant research exploring against infectious plant pathogens. This study reviews recent literature on the synthesis of bacteria-based NPs, detailing their morphological, structural, chemical, optical, electronic, electrical, and magnetic properties, along with their thermal characteristics. By elucidating the mechanisms by which these NPs combat phytopathogens, this research provide crucial insight for future applications, enhancing our understanding of bacteria-based NPs research. The wealth of recent research on bacteria-based green NPs is anticipated to enrich future applications and deepen our understanding of this emerging field.

High temperatures reduce growth, infection, and transmission of a naturally occurring fungal plant pathogen.

Climate change is rapidly altering the distribution of suitable habitats for many species as well as their pathogenic microbes. For many pathogens, including vector-borne diseases of humans and agricultural pathogens, climate change is expected to increase transmission and lead to pathogen range expansions. However, if pathogens have a lower heat tolerance than their host, increased warming could generate so-called thermal refugia for hosts. Predicting the outcomes of warming on disease transmission requires detailed knowledge of the thermal tolerances of both the host and the pathogen. Such thermal tolerance studies are generally lacking for fungal pathogens of wild plant populations, despite the fact that plants form the base of all terrestrial communities. Here, we quantified three aspects of the thermal tolerance (growth, infection, and propagule production) of the naturally occurring fungal pathogen Microbotryum lychnidis-dioicae, which causes a sterilizing anther-smut disease on the herbaceous plant Silene latifolia. We also quantified two aspects of host thermal tolerance: seedling survival and flowering rate. We found that temperatures >30°C reduced the ability of anther-smut spores to germinate, grow, and conjugate in vitro. In addition, we found that high temperatures (30°C) during or shortly after the time of inoculation strongly reduced the likelihood of infection in seedlings. Finally, we found that high summer temperatures in the field temporarily cured infected plants, likely reducing transmission. Notably, high temperatures did not reduce survival or flowering of the host plants. Taken together, our results show that the fungus is considerably more sensitive to high temperatures than its host plant. A warming climate could therefore result in reduced disease spread or even local pathogen extirpation, leading to thermal refugia for the host.

First report of Fusarium oxysporum f. sp. lactucae causing wilt on greenhouse-grown lettuce in North Carolina.

In August 2023, butterhead lettuce (Lactuca sativa L.) presented wilting, chlorosis, and about 2 cm of reddish-tan internal discoloration in the crown from a commercial greenhouse in Orange County, North Carolina. Plant collapse beginning with the outer leaves near the soil surface was observed with 25% disease incidence. Symptomatic lettuce plants were submitted to North Carolina State University's Plant Disease and Insect Clinic. Vascular tissue from symptomatic crowns were cut into pieces, and surface-sterilized in 10% NaOCl for two minutes. The tissue was rinsed in sterile deionized water three times, blotted dry, and placed on acidified potato dextrose agar (APDA). Three isolates, each from a different symptomatic plant, were transferred to APDA and Spezieller Nährstoffarmer agar (SNA) with pieces of sterile filter paper on the surface of the SNA media and incubated for 14 days at 23°C in the dark. Each isolate produced micro and macroconidia consistent with the morphological description of Fusarium oxysporum Schlechtendahl emend. Snyder & Hansen (Leslie and Summerell 2006). DNA was extracted from 15-day-old fungal colonies grown on APDA media using the DNeasy Plant Mini Kit (Qiagen, Germantown, MD, U.S.A.). The intergenic spacer locus was amplified using two primer pairs, iNL11/CNSa and iCNS1/NLa, and sequences were aligned together to form a single contig (O'Donnell et al., 2009). Primers EF1/EF2 were used to amplify the elongation factor 1-alpha region (O'Donnell et al., 1998). Each isolate was deposited into GenBank with accession numbers PP216479, PP216480, PP216481, PP235836, PP235837, and PP235838. Individual isolates revealed a 100% query cover and identity match with sequences of F. oxysporum f. sp. lactucae (FOL) and >99% identity with F. oxysporum CBS 144134 type material accessions in GenBank using BLASTn. A comparison with previously described lettuce isolates showed a homologous match with FOL race 1 isolates from California (MH412701), Arizona (DQ837658), and Greece (OQ466116), and race 4 isolates from Italy (MK801787) and Spain (OP903519). Each isolate was verified as FOL using specific primers FLA0001F/FLA0001R for FOL based on sequence tagged site markers designed by Shimazu et al. (2005). To confirm Koch's postulates, fifteen 21-day-old lettuce cv. Red Tide plants were inoculated with FOL (isolate FOLNC_660). During transplanting, lettuce roots were submerged in a 1 × 105 conidia/mL suspension for five minutes, following an inoculation protocol from Schmale and Gordon (2003). The lettuce plants were placed separately in 8.9 × 8.3 cm pots containing potting soil and maintained in a greenhouse with 31°C daytime and 25°C nighttime temperature, relative humidity of 60%, and 12-hour photoperiod. After 15 days, 80% and 86.7% of infected plants exhibited wilting, chlorosis, and vascular discoloration. The fifteen control plants remained symptomless for both experimental runs. FOL was recovered from the vascular tissue of all symptomatic plants. To our knowledge, this constitutes the first report of FOL infecting lettuce in North Carolina. Fusarium wilt of lettuce has been reported in California (Hubbard and Gerik 1993), Arizona (Matheron and Koike 2003), and most recently in Florida (Murray et al., 2020). The presence of FOL in North Carolina may result in significant crop loss for commercial growers. One of the most effective management strategies is to plant lettuce cultivars that are resistant against FOL.

Electronic Nose and GC-MS Analysis to Detect Mango Twig Tip Dieback in Mango (Mangifera indica) and Panama Disease (TR4) in Banana (Musa acuminata)

Volatile organic compounds (VOCs), as a biological element released from plants, have been correlated with disease status. Although analysis of VOCs using GC-MS is a routine procedure, it has limitations, including being time-consuming, laboratory-based, and requiring specialist training. Electronic nose devices (E-nose) provide a portable and rapid alternative. This is the first pilot study exploring three types of commercially available E-nose to assess how accurately they could detect mango twig tip dieback and Panama disease in bananas. The devices were initially trained and validated on known volatiles, then pure cultures of Pantoea sp., Staphylococcus sp., and Fusarium odoratissimum, and finally, on infected and healthy mango leaves and field-collected, infected banana pseudo-stems. The experiments were repeated three times with six replicates for each host-pathogen pair. The variation between healthy and infected host materials was evaluated using inbuilt data analysis methods, mainly by principal component analysis (PCA) and cross-validation. GC-MS analysis was conducted contemporaneously and identified an 80% similarity between healthy and infected plant material. The portable C 320 was 100% successful in discriminating known volatiles but had a low capability in differentiating healthy and infected plant substrates. The advanced devices (PEN 3/MSEM 160) successfully detected healthy and diseased samples with a high variance. The results suggest that E-noses are more sensitive and accurate in detecting changes of VOCs between healthy and infected plants compared to headspace GC-MS. The study was conducted in controlled laboratory conditions, as E-noses are highly sensitive to surrounding volatiles.

Harnessing Walnut-Based Zinc Oxide Nanoparticles: A Sustainable Approach to Combat the Disease Complex of Meloidogyne arenaria and Macrophomina phaseolina in Cowpea.

Zinc oxide nanoparticles (ZnO NPs) exhibit diverse applications, including antimicrobial, UV-blocking, and catalytic properties, due to their unique structure and properties. This study focused on the characterization of zinc oxide nanoparticles (ZnO NPs) synthesized from Juglans regia leaves and their application in mitigating the impact of simultaneous infection by Meloidogyne arenaria (root-knot nematode) and Macrophomina phaseolina (root-rot fungus) in cowpea plants. The characterization of ZnO NPs was carried out through various analytical techniques, including UV-visible spectrophotometry, Powder-XRD analysis, FT-IR spectroscopy, and SEM-EDX analysis. The study confirmed the successful synthesis of ZnO NPs with a hexagonal wurtzite structure and exceptional purity. Under in vitro conditions, ZnO NPs exhibited significant nematicidal and antifungal activities. The mortality of M. arenaria juveniles increased with rising ZnO NP concentrations, and a similar trend was observed in the inhibition of M. phaseolina mycelial growth. SEM studies revealed physical damage to nematodes and structural distortions in fungal hyphae due to ZnO NP treatment. In infected cowpea plants, ZnO NPs significantly improved plant growth parameters, including plant length, fresh mass, and dry mass, especially at higher concentrations. Leghemoglobin content and the number of root nodules also increased after ZnO NP treatment. Additionally, ZnO NPs reduced gall formation and egg mass production by M. arenaria nematodes and effectively inhibited the growth of M. phaseolina in the roots. Furthermore, histochemical analyses demonstrated a reduction in oxidative stress, as indicated by decreased levels of reactive oxygen species (ROS) and lipid peroxidation in ZnO NP-treated plants. These findings highlight the potential of green-synthesized ZnO NPs as an eco-friendly and effective solution to manage disease complex in cowpea caused by simultaneous nematode and fungal infections.

A random forest-based analysis of cassava mosaic disease-related factors affecting the on-farm livelihoods of cassava farmers

This study aimed to identify key CMD-related factors affecting Cameroon cassava farmers’ incomes originating from both the sale of cassava cuttings (V215) and the sale of cassava roots (V216). To achieve this, nine CMD-related variables were used to independently train two Random Forest models. These models were later employed for regression-based prediction of both financial targets V215 and V216. The Random Forest (RF)-based mean absolute percentage error for targets V215 and V216 were 0.19 and 1.25 respectively. The RF-based mean Gaussian deviance for targets V215 and V216 were 0.07 and 0.51 respectively. Based on RF feature importance scores (RFFI), the top 3 factors affecting income originating from the sale of cassava cuttings were found to be: late appearance of symptoms as a difficulty associated with regular field monitoring (RFFI of 0.2594), removal of infected plants as a method of controlling frequent occurrence of viral diseases in respondents’ cassava fields (RFFI of 0.1633) and lack of healthy planting material due to frequent occurrence of viral diseases in respondents’ cassava fields (RFFI of 0.1495). Also, the top 3 factors affecting income originating from the sale of cassava roots were found to be: the replacement of infected plants with healthy cuttings as a method of controlling the frequent occurrence of viral diseases in respondents’ cassava fields (RFFI of 0.1974), decrease in yield due to frequent occurrence of viral diseases in respondents’ cassava fields (RFFI of 0.1530) and poor plant growth due to frequent occurrence of viral diseases in respondents’ cassava fields (RFFI of 0.1388).

Identification of Plant Leaf Disease Using CNN and Image Processing

Agriculture is an important sector for the growing people of the world to fulfil the minimum requirements of food. Identifying plant infection in the agricultural sector is complex. If the detection is wrong, there is more damage to crop production and economic loss of the market. Leaf infection identification need a large number of labors, command of plant disorders and requires a lot of observing time. Therefore, this analysis explains detection of plant leaf disease by utilizing CNN and image processing. Alex Net and ResNet-50 are Convolutional Neural Network (CNN) models. First, this method is performed on Kaggle datasets of potato and tomato plants to examine the characteristics of an infected leaves. Then, feature extraction and categorization method is executed on dataset pictures to observe leaf disorders using Alex Net and ResNet-50 models by executing image processing. Observational outputs demonstrate potential of described method, in which it reaches a complete accuracy of 98% and 95% of Alex Net and ResNet50. The output shows that described model particularly predicts defective plant leaves from healthy leaf images.