Basal Rot Disease Research Articles

Suppressive effect of some essential oils on controlling basal rot disease and Biochemistry of garlic cloves

Suppressive effect of some essential oils on controlling basal rot disease and Biochemistry of garlic cloves

Essential Oils as a Control Alternative of Fusarium Falciforme, Responsible for Causing Onion (Allium cepa L.) Basal Rot Disease

Essential Oils as a Control Alternative of Fusarium Falciforme, Responsible for Causing Onion (Allium cepa L.) Basal Rot Disease

Pathogenicity Differentiation of Fusarium spp. Causing Fusarium Basal Rot and Wilt Disease in Allium spp.

Here, 12 Fusarium strains, previously described as F. oxysporum f. sp. cepae (Foc), were examined via multi-locus sequencing of calmodulin (cmdA), RNA polymerase II second largest subunit (rpb2), and translation elongation factor 1-alpha (tef1), to verify the taxonomic position of Foc in the newly established epitype of F. oxysporum. The strains in this study were divided into two clades: F. nirenbergiae and Fusarium sp. To further determine the host specifications of the strains, inoculation tests were performed on onion bulbs and Welsh onion seedlings as potential hosts. Four strains (AC145, AP117, Ru-13, and TA) isolated from diseased onions commonly possessed the secreted in xylem (SIX)-3, 5, 7, 9, 10, 12, and 14 genes and were pathogenic and highly aggressive to onion bulbs, whereas all strains except for one strain (AF97) caused significant inhibition of Welsh onion growth. The inoculation test also revealed that the strains harboring the SIX9 gene were highly aggressive to both onion and Welsh onion and the gene was expressed during infection of both onions and Welsh onions, suggesting the important role of the SIX9 gene in pathogenicity. This study provides insights into the evolutionary pathogenicity differentiation of Fusarium strains causing Fusarium basal rot and wilt diseases in Allium species.

Effectiveness of some plant extracts in biocontrol of induced onion basal rot disease in greenhouse conditions

One of Egypt’s most notable and historically significant vegetable crops is the Liliaceae plant, Allium cepa L. In this study, the effectiveness of methanolic extracts of Artemisia absinthium leaves, Calotropis procera latex, Moringa oleifera seeds, and Syzygium aromaticum clove was investigated in vitro and, in a greenhouse, setting against Fusarium oxysporum, the pathogen that causes onion basal rot in Assiut Governorate, Egypt. The S. aromaticum extract exhibited the inhibition peak (63.3%), whereas the A. absinthium extract had the lowest inhibition impact against F. oxysporum growth (41.1%). The gas chromatography-mass spectroscopy (GC–MS) analysis revealed that 82 important compounds, with abundances ranging from low to high, were present in the tested S. aromaticum’s methanolic extract. The primary components were acetaldehyde, hydroxy- and 2-propanone, 1,1,3,3-tetrachloro-(42.71%), 1,2-ethanediol, and methyl alcohol (34.01%). In comparison to the infected control, the disease severity was significantly reduced by 20% with the use of a plant extracts mixture and Dovex 50% and increased by 62.22% with the use of an extract from A. absinthium. When compared to the infected control, onion plant fresh weight and dry weight were considerably higher under the clove extract therapy. The plant extracts used in this study’s testing contain a number of active ingredients, including amino acids, vitamins, minerals, antioxidants, and enzymes, which is probably why they have such positive impacts. The application of a combination of plant extracts was suggested as a feasible strategy for improving the growth and productivity of onion plants by the study’s findings. More research is needed to comprehend the mechanisms by which plant extracts promote plant development and to optimize the concentration and timing of administration.

Active Prevalence of Fusarium falciforme and F. acutatum Causing Basal Rot of Onion in Maharashtra, India.

Over the past decade, there have been accumulating reports from researchers, farmers, and field extension personnel on the increasing incidence and spread of onion basal rot in India. Onion basal rot disease is mainly caused by Fusarium spp. This study aimed to validate the information on the active prevalence of F. falciforme and F. acutatum causing Fusarium basal rot (FBR) in Maharashtra. A survey was conducted, and the infected plants/bulbs were collected from fields of 38 locations comprising five districts of Maharashtra, namely, Nashik, Aurangabad, Solapur, Ahmednagar, and Pune, in 2023. This disease was prevalent in high-moisture and high-oil-temperature conditions and the symptoms were observed in most of the fields, with the FBR incidence ranging from 17 to 41%. The available data of basal rot incidence from 1998 to 2022 were analyzed, based on which the prevalence of FBR was 11-50%. Tissue from the infected samples of onion bulbs was used for the isolation. The identification was performed based on colony morphology and microscopic features and confirmed through molecular markers using ITS and Tef-1α gene primers. Of the ten Fusarium isolates collected from selected locations, six species were confirmed as F. acutatum and four as F. falciforme. The pathogenicity tests performed with onion seedlings and bulbs under moist conditions proved that both F. acutatum and F. falciforme independently could cause basal rot disease symptoms but with different degrees of virulence. Koch's postulates were confirmed by reisolating the same pathogens from the infected plants. Thus, the active prevalence of FBR was confirmed in Maharashtra and also, to the best of our knowledge, this is the first report of F. falciforme and F. acutatum causing basal rot of onion independently in Maharashtra, India.

Onion Fusarium Basal Rot Disease Control by Arbuscular Mycorrhizal Fungi and Trichoderma harzianum

Soilborne pathogens reduce 60% of the yield of onion crops. A common fungal pathogen causing wilt disease and severe losses is Fusarium basal rot (FBR). In this study, the combination of Arbuscular Mycorrhizal Fungi (AMF) with Trichoderma harzianum was investigated against FBR. Onion samples were collected from the Ankara–Polatlı region. Among the isolates, isolate S6 was identified as F. oxysporum f. sp. cepae (FOC) using morphological and molecular methods and pathogenicity tests. Different combinations of AMF (Funneliformis mosseae pure strain and the commercial AMF) and T. harzianum were inoculated on susceptible onion cultivars (Seç, Gence, and Şampiyon). The effects of the treatments on FOC biocontrol were studied under growth chamber conditions. The results showed that Şampiyon was the most resistant, while Gence was the most susceptible to basal rot disease. Different colonization rates (8.91–24%), spore densities (16.4–50.4 spore/10 g soil), and the extent to which a plant needs mycorrhizal conditions to grow to its maximum potential (i.e., mycorrhizal dependencies—18.3–51.9%) were recorded by treatment. Both single and combined applications of AMF and Trichoderma applications suppressed FOC. Suppressive effects were more pronounced when the F. mosseae pure strain was used alone (when F. mosseae was used, disease severity decreased from 90 to 68%, p < 0.05). The F. mosseae pure strain also showed the best plant growth promotion and phosphorus content release. The results indicate an interesting potential use of F. mosseae and the combination of AMF with T. harzianum in the management of FOC in onions.

Varietal Screening and Management of Basal Rot Disease of Onion

Onion (Allium cepa L.) belongs to the family Amaryllidaceae. It is known as common onion, bulb onion or biennial herb, and is one of the most important vegetable crops in India. However, the crop faces numerous diseases attack, resulting in losses to both quantity and quality. Among the diseases, the basal rot caused by Fusarium oxysporum f. sp. cepae, is one of the most significant soil-borne diseases. This work aimed to screen various onion varieties for resistance against basal rot in pots under glasshouse condition as well as to assess the efficacy of fungicides against the pathogen under both in vitro and in vivo conditions. It was observed that all onion varieties screened were highly susceptible while Bhima red was just susceptible; none of the varieties were resistant to basal rot. Under in vitro conditions the Fungicides Carbendazim and Tebuconazole, of the given concentration, were cent per cent effective in inhibiting mycelial growth of Fusarium oxysporum f. sp. cepae. For the field condition, the module of [carbendazim (2 g/kg) followed by tebuconazole (0.1 %) followed by azoxystrobin (0.1 %)] was the most effective.

Reactions of Short, Intermediate and Long Day Onion Genotypes in Turkish National Onion Breeding Program to Fusarium Basal Rot Disease

Onion basal rot (Fusarium oxysporum f. sp. cepae) disease exerts serious threats on global onion (Allium cepa L.) production and trade. Present breeding programs mostly focus on development of cultivars resistant to onion basal rot disease. Characterization of breeding material in breeding gene pool is the first step of breeding. This study was conducted to determine the susceptibility of 4 onion cultivars, 30 long-day, 1 intermediate-day and 21 short-day onion genotypes to onion basal rot disease. Significant differences were seen in disease susceptibility of the genotypes (P<0.01 ) in both onion seedling and bulb tests. Onion seedling and bulb tests revealed that resistance was not detected in short and intermediate-day onion genotypes and cultivars, while two of long-day onion genotypes (ACLD 7 and 8) were found to be tolerant. Based on present finding, 3 cultivars, 28 long-day, 1 intermediate-day and 21 short-day genotypes were identified as sensitive. ACLD 7 and 8 long-day onion genotypes, which were identified as promising in seedling tests, were also identified as tolerant in bulb tests and such findings proved the compliance of seedling and bulb tests. Bulbs were obtained from the long-day onion lines (ACLD 7-8 genotypes) that were found to be promising and survived in seedling tests and seeds were obtained from these genotypes to ensure progress of generation and they were included in breeding gene pool.

Pathogenicity chromosome of Fusarium oxysporum f. sp. cepae

Fusarium oxysporum f. sp. cepae (Foc) is the causative agent of Fusarium basal rot disease in onions, which leads to catastrophic global crop production losses. Therefore, the interaction of Foc with its host has been actively investigated, and the pathogen-specific (PS) regions of the British strain Foc_FUS2 have been identified. However, it has not been experimentally determined whether the identified PS region plays a role in pathogenicity. To identify the pathogenicity chromosome in the Japanese strain Foc_TA, we initially screened effector candidates, defined as small proteins with a signal peptide that contain two or more cysteines, from genome sequence data. Twenty-one candidate effectors were identified, five of which were expressed during infection. Of the expressed effector candidates, four were located on the 4-Mb-sized chromosome in Foc_TA. To clarify the relationship between pathogenicity and the 4-Mb-sized chromosome in Foc_TA, nine putative 4-Mb-sized chromosome loss strains were generated by treatment with benomyl (a mitotic inhibitor drug). A pathogenicity test with putative 4-Mb-sized chromosome loss strains showed that these strains were impaired in their pathogenicity toward onions. Genome analysis of three putative 4-Mb-sized chromosome loss strains revealed that two strains lost a 4-Mb-sized chromosome in common, and another strain maintained a 0.9-Mb region of the 4-Mb-sized chromosome. Our findings show that the 4-Mb-sized chromosome is the pathogenicity chromosome in Foc_TA, and the 3.1-Mb region within the 4-Mb-sized chromosome is required for full pathogenicity toward onion.

Biological Control of Fusarium oxysporum, the Causal Agent of Fusarium Basal Rot in Onion by Bacillus spp.

<i>Fusarium oxysporum</i> is the main pathogen causing Fusarium basal rot in onion (<i>Allium cepa</i> L.), which incurs significant yield losses before and after harvest. Among management strategies, biological control is an environmentally safe and sustainable alternative to chemical control. In this study, we isolated and screened bacteria for antifungal activity against the basal rot pathogen <i>F. oxysporum</i>. Isolates 23-045, 23-046, 23-052, 23-055, and 23-056 significantly inhibited <i>F. oxysporum</i> mycelial growth and conidial germination. Isolates 23-045, 23-046, 23-052, and 23-056 suppressed the development of Fusarium basal rot in both onion seedlings and bulbs in pot and spray inoculation assays. Isolate 23-055 was effective in onion seedlings but exhibited weak inhibitory effect on onion bulbs. Based on analyses of the 16S rRNA and <i>rpoB</i> gene sequences together with morphological analysis, isolates 23-045, 23-046, 23-052, and 23-055 were identified as <i>Bacillus thuringiensis</i>, and isolate 23-056 as <i>Bacillus toyonensis</i>. All five bacterial isolates exhibited cellulolytic, proteolytic, and phosphate-solubilizing activity, which may contribute to their antagonistic activity against onion basal rot disease. Taken together <i>B. thuringiensis</i> 23-045, 23-046, 23-052, and 23-055 and <i>B. toyonensis</i> 23-056 have potential for the biological control of Fusarium basal rot in onion.

The SIX5 Protein in Fusarium oxysporum f. sp. cepae Acts as an Avirulence Effector toward Shallot (Allium cepa L. Aggregatum Group).

Fusarium oxysporum f. sp. cepae (Foc) causes basal rot disease in Allium species, including onions (Allium cepa L.) and shallots (A. cepa L. Aggregatum group). Among Allium species, shallots can be crossbred with onions and are relatively more resistant to Foc than onions. Thus, shallots are considered a potential disease-resistant resource for onions. However, the mechanisms underlying the molecular interactions between shallots and Foc remain unclear. This study demonstrated that SIX5, an effector derived from Foc (FocSIX5), acts as an avirulence effector in shallots. We achieved this by generating a FocSIX5 gene knockout mutant in Foc, for which experiments which revealed that it caused more severe wilt symptoms in Foc-resistant shallots than the wild-type Foc and FocSIX5 gene complementation mutants. Moreover, we demonstrated that a single amino acid substitution (R67K) in FocSIX5 was insufficient to overcome shallot resistance to Foc.

Molecular Real-Time PCR Monitoring of Onion Fusarium Basal Rot Chemical Control.

Fusarium basal rot disease (FBR) is a destructive threat to onion crops around the globe. It causes seedlings' death, development disruption, and pre- and post-harvest bulb infection and rotting, with a concern for toxin infestation. It is an emerging disease in Israel, with new reports from farms nationwide. Recently, we reported on a full-season pot experiment to protect two leading commercial cultivars against FBR chemically. Here, we present new real-time qPCR molecular tracking of the pathogens inside the host plant and compare the infection levels to a deep analysis of the impacts of this experiment's treatments on plant growth and health indexes. The new findings reveal variations within each treatment's effectiveness regarding sprout development and bulb ripening stages. For instance, in the yellow Orlando cv., high protection was obtained with Azoxystrobin + Tebuconazole (Az-Te) in sprouts against F. oxysporum f. sp. cepae and with Fludioxonil + Sedaxen in mature plants against Fusarium acutatum. Thus, combining these fungicides may protect plants throughout their lifecycle. Also, Prochloraz at low dose was highly efficient in the Orlando cv. Still, to shield red Noam cv. plants from both pathogens, increasing this fungicide concentration towards the season-ending should be preferred. The qPCR tracking showed that all chemical treatments tested could reduce infection from pathogens by 80-90%, even with compounds such as Az-Te that were less effective. This implies that the pesticide was effective but probably phytotoxic to the plants, and thus, lower dosages must be considered. The molecular-based analysis discloses the high infection ability of F. oxysporum f. sp. cepae compared to F. acutatum in both cultivars. It also indicates an antagonism between those species in the Orlando cv. and synergism in the Noam cv. The current work reveals weak and strong points in chemical FBR protection and offers new ways to improve its application. The qPCR-based method enables us to closely monitor the pathogenesis and efficacy of chemical-preventing treatments and optimize crop-protection protocols.

<em>Allium cepa </em>L. (Onion) Storage Diseases and Effect of <em>Trichoderma asperellum </em>and <em>Trichoderma virens </em>Pre-harvest Treatments on Postharvest Quality

Substantial yield losses have been reported during the storage of Allium cepa L., and effective methods to minimize postharvest losses are currently lacking. Therefore the objectives of this study were to investigate the impact of pre-treatment with Trichoderma asperellum and Trichoderma virens on post-harvest losses during storage and to evaluate factors associated with these losses. The storage behaviors of Allium cepa L. bulbs after different field treatments with Trichoderma spp. were examined using a complete randomized design. The common onion bulb diseases encountered during storage were basal rot and black mould diseases, with Fusarium sp., Mucor sp., Penicillium sp., Aspergillus niger and Aspergillus flavus being associated with diseased bulbs. The results regarding the percentage of diseased bulbs showed that pre-harvest treatments with Trichoderma asperellum and Trichoderma virens did not have a significant effect on disease control during storage. Furthermore, storage losses of onions were attributed to sprouting, rooting and wilting, which were exacerbated by the prevailing temperature (~30-32°C) and relative humidity (~77%-79%) during the storage period.

Seasonal variations in the composition and diversity of rhizosphere soil microbiome of bamboo plants as infected by soil-borne pathogen and screening of associated antagonistic strains

As the occurrence and severity of soil-borne diseases are strongly season-dependent, the ecological processes that shift plant microbiome compositions and functions upon pathogen infection in different seasons are rarely studied. In this study, we compared the differences in fungal and bacterial communities in rhizosphere soil between healthy and diseased bamboo plants throughout the four seasons at the main bamboo production site in China and investigated how basal rot disease caused by Fusarium proliferatum affected the composition, structure and ecological functions of rhizosphere-associated microorganisms. The results showed that diseased bamboo plants enriched the highest abundance of Fusarium genus in rhizosphere soil while receiving largely increased stem lesion area in summer. Microbiome analysis further proved that healthy bamboo plants harbored more ecologically beneficial microbial taxa that might function as biological protectants in their rhizosphere soil than diseased plants at the same season. Three individual strains with biocontrol potentials were further isolated and identified as Trichoderma spirale, Bacillus velezensis and Streptomyces mirabilis. The antagonistic tests further demonstrated their inhibition effects on the growth and pathogenicity of the pathogenic fungus F. proliferatum in vitro and in vivo. This study advances our understanding of soil-borne pathogen mediated changes in microbiome structure and function in plant rhizosphere soil and provides potential biocontrol strains for increasing plant resistance against basal rot disease.

Management of basal rot disease ("moler") of shallot with biomanci fertilizer

Management of basal rot disease ("moler") of shallot with biomanci fertilizer

First report of Fusarium falciforme causing basal rot of onion (Allium cepa) in India.

Onion (Allium cepa, L) is a very important vegetable crop in India. India is the second largest producer of onion in the world and the crop is grown on more than 1.22 million hectares. Fusarium Basal Rot (FBR) is an economically important diseasef onion that causes considerable losses in onion production up to 50% in field and 30-40% during post-harvest storage of bulbs (Gupta and Gupta 2013; Rajamohan et al. 2019). Onion plants showing chlorosis, twisting, wilting, necrosis, bulb discoloration, rot in the basal parts of bulb and roots typical to FBR were observed, in a field trial of 36 onion cultivars during October 2020 in Bangalore, Karnataka. FBR incidence varied from 30-100% in this field (Fig 1 a-d). Symptomatic bulbs were washed with water, basal plate and fleshy leaves cut into 0.5 to 1 cm-size, surface disinfected with 1.5% sodium hypochlorite (NaOCl) for 3 min, and rinsed with sterile distilled water. Twenty pieces were placed on potato dextrose agar (PDA) in Petri plates and incubated at 25°C for 7 days. Colonies from single-spore isolates on PDA showed abundant white aerial mycelium. Colonies showed light pink or purple coloration on the reverse side of the culture plate with brown center (Fig 1e-f). Macroconidia were 19.13 to 28.35 (mean= 24.2) × 4.29 to 6.06 (mean= 5.05) µm, hyaline, falcate, with slightly curved apexes, and three to five septa. Microconidia were cylindrical to ellipsoid, aseptate, hyaline 8.20 to 12 (mean=10.0) × 3.55 to 4.79 (mean= 4.29) µm (Fig 1g). Chlamydospores were round, intercalary, hyaline, single or in chains (Fig 1h). Two isolates (IBFF-09 & IBFF-10) were analyzed for internal transcribed spacer-ITS (White et al. 1990) and translation elongation factor 1-α (tef1) gene (O'Donnell et al. 1998) by polymerase chain reaction (PCR) and sequenced. ITS and partial tef1 gene sequences of isolates IBFF-09 and IBFF-10 were submitted to the NCBI database (GenBank accession # ON394614&ON026859; # ON409480, ON093166 respectively). Phylogenetic analysis of tef1 gene placed the isolates with F. falciforme (Fig 1i). A pathogenicity test was performed by dipping roots of 28 days old healthy onion seedlings of a susceptible genotype 16/7Y GR3 into a conidial suspension (1 × 104 conidia/ml) of isolate IBFF-10 for 15 min and then transplanting the plants into pots containing sterilized potting mix. Inoculated plants developed typical symptoms of FBR and were all dead by 20 days post inoculation (Fig 1j) while the non-inoculated controls remained healthy. Pathogen was re-isolated from infected plants and showed the same morphology, ITS and tef1 sequence similarity as the original isolate, thus fulfilling Koch's postulates. Basal rot of onion by F. falciforme is reported from Mexico (Tirado-Ramírez et al. 2021). Till date, only F .oxysporum, F. proliferatum and F. solani have been implicated in onion FBR in India (Lee et al. 2021; Rathore and Patil, 2019). F. falciforme however, i prevalent in India and is reported to infect other crops (Gangaraj et al. 2022; Gupta et al. 2019; Homa et al. 2018). There is a high probability that this pathogen is contributing significantly to basal rot disease but it has not been reported yet. To our knowledge, this is the first report of F. falciforme infecting onions in India. In order to develop FBR resistant onion cultivars it is critical to identify and study the response of onion genotypes to different Fusarium spp causing the disease.

Physiological characteristics and effectiveness of some trichoderma isolates against fusarium basal rot of shallot

Trichoderma is one of the fungal biological agents used to control fusarium basal rot disease on shallot. The use of Trichoderma sp. can reduce the negative impact on the environment and humans due to the use of synthetic chemical fungicides. This study aimed to characterize the physiological characteristics of some Trichoderma sp. and assess the potential in controlling Fusarium oxysporum on shallot. This research consisted of various tests, such as phosphate solubilization, chitinolytic activity, antibiosis, IAA production, and growth promoting tests, including germination percentage, plant height, and root length. There were eight isolates of Trichoderma originating from various species of plants in the field. They were T. hamatum 1, T. hamatum 2, T. asperellum, T. harzianum, T. pseudokoningii, Trichoderma rice, Trichoderma T01, and Trichoderma T02. All isolates did not react positively to the indole acetic acid (IAA) and antibiosis tests. Conversely, all isolates showed a positive reaction in the chitinolytic activity, except T. hamatum. Isolates Trichoderma T01 and Trichoderma T02 reacted positively to phosphate dissolution. Trichoderma T02 had the best germination rate and plant height compared to all isolates, with values of 90% and 6.00 ± 0.96, respectively. Trichoderma rice has the best root length compared to all isolates 8.

Production of Bio Fortified Vermicompost and its Efficacy Against Onion Basal Rot Disease Caused by Fusarium oxysporum f. sp. cepae

Production of Bio Fortified Vermicompost and its Efficacy Against Onion Basal Rot Disease Caused by Fusarium oxysporum f. sp. cepae

Gas Chromatography Mass Spectrometry (GCMS) analysis of the antagonistic potential of <i>Trichoderma hamatum</i> against <i>Fusarium oxysporum</i> f. sp. cepae causing basal rot disease of onion

Fusarium oxysporum f. sp. cepae causing basal rot disease of onion is a destructive phytopathogen resulting in 30-50% yield loss and remains as a major constraint in onion productivity. The management of disease through application of fungicide is not feasible and economically viable. Hence, the present study is focused on investigation of effective Trichoderma sp. and identifying the effective volatile organic compounds produced by it against the basal rot pathogen in onion. A total of ten Trichoderma spp. were isolated from rhizospheric soil of healthy onion plants and tested against virulent Fusarium oxysporum f. sp. cepae isolate FCIM1. The Trichoderma isolate (TIM2) showed 77.40% inhibition on mycelial growth of pathogen followed by the isolate (TIV1) with 70.36% inhibition. The molecular identification of effective Trichoderma isolate through the analysis of the rDNA of Internal Transcribed Spacers (ITS) region revealed isolate TIM2 as Trichoderma hamatum. The GC-MS analysis of Trichoderma hamatum unravelled the important volatile organic compounds like Methyl stearate, n-Hexadecanoic, Eicosane, 9-cyclohexy, Heptadecane, Dodecane, 2-cyclohexyl, to 2H-Pyran-2-one, 6-pentyl, 5-Hydroxymethylfurfural, Tetrapentacontane, 1-Dodecanol, 2-Propenoic acid, pentadecyl ester, Benzene, (2-methylbutyl) and 1,2-Dimethyltryptamine with peak area and retention time. These bioactive compounds exert a strong antifungal activity against Fusarium oxysporum f. sp. cepae. The scanning electron micrographs of Fusarium paired with effective Trichoderma (TIM2) showed the swollen hyphae with cell wall damage which is clear evident of antagonistic interaction of volatile compounds produced by Trichoderma hamatum.

Prevention and Control of Fusarium spp., the Causal Agents of Onion (Allium cepa) Basal Rot

Fusarium basal rot disease (FBR) is considered a serious threat to commercial onion production in Israel and worldwide. Today, coping means applied in Israel against the disease have limited efficiency and include a four-year crop cycle and disinfecting the soil with metam sodium. At the same time, agricultural tools (harrows, plows, etc.), contaminated equipment and workers facilitate spread of the disease to new growth areas, and the field disease incidence in Israel now reaches 8% of yields in heavily infected areas. Infected onions do not always show disease symptoms and the problem worsens if they arrive at storage facilities, especially since this pathogen genus produces known toxins. The current study aims at examining the potential of chemical control to reduce the damage caused by this disease. To this end, nine commercial fungicides were scanned in plate sensitivity assay against the main pathogens involved, Fusarium oxysporum f. sp. cepae and Fusarium acutatum. Several fungicides were found to be highly effective against the two pathogens, especially the mixtures Azoxystrobin + Difenoconazole, Fluopyram + Trifloxystrobin, or the Fluazinam compounds. Three selected preparations previously tested in seedlings were evaluated here in a full growing season. Prochloraz successfully protected the Orlando variety (white onion, Riverside cv.) and the Noam variety (red onion) at all growth stages against F. oxysporum f. sp. cepae. At the same time, this treatment was ineffective against F. acutatum in Noam cv. Another anti-fungal preparation, Fludioxonil + Sedaxen mixture, showed a wider range of effectiveness at the season’s end against the two Fusarium species tested in both onion cultivars. These results are an important step towards developing FBR control in commercial onion fields. Follow-up work is needed to optimize the pesticides’ concentrations and their application methods and to test them on a field scale. Interestingly, these pathogens were more aggressive towards the cultivar from which they were isolated: F. oxysporum f. sp. cepae to the red onion Noam cv. and F. acutatum to the white Orlando cv. Infecting the plants with both pathogens reduced disease symptoms in the white Orlando cv, suggesting antagonistic interactions in this onion genotype.