Melaleuca Alternifolia Essential Oil Research Articles

Optimizing the Antimicrobial Synergism of Melaleuca alternifolia (Tea Tree) Essential Oil Combinations for Application against Respiratory Related Pathogens.

Antimicrobial research into the use of Melaleuca alternifolia essential oil has demonstrated broad-spectrum activity; however, much of the research published focuses on identifying the potential of this essential oil individually, rather than in combination for an enhanced antimicrobial effect. This study aimed to determine the antimicrobial activity of four essential oil combinations, all inclusive of M.alternifolia, against nine pathogens associated with the respiratory tract. The minimum inhibitory concentration assay was used to determine the antimicrobial activity of four essential oil combinations, M.alternifolia in combination with Cupressus sempervirens, Origanum majorana, Myrtus communis, and Origanum vulgare essential oils. The interactions between essential oil combinations were analyzed using isobolograms and SynergyFinder 2.0 software to visualize the synergistic potential at varied ratios. The antimicrobial activity of the different combinations of essential oils all demonstrated the ability to produce an enhanced antimicrobial effect compared to the essential oils when investigated independently. The findings of this study determined that isobolograms provide a more in-depth analysis of an essential oil combination interaction; however, the value of that interaction should be further quantified using computational modelling such as SynergyFinder. This study further supports the need for more studies where varied ratios of essential oils are investigated for antimicrobial potential.

Insecticidal activity of Melaleuca alternifolia (Myrtaceae) essential oil against Tribolium castaneum (Coleoptera: Tenebrionidae) and its inhibitory effects on insecticide resistance development

Abstract Pests in stored grains pose a global threat to food security. Tribolium castaneum (Coleoptera: Tenebrionidae) is one of the most serious stored-grain pests in the world, capable of surviving harsh environments and developing resistance to certain classes of insecticides. Fumigation toxicity and the impact of Melaleuca alternifolia Cheel (Myrtaceae) essential oil on T. castaneum were investigated in this study. The 50% lethal concentration (LC50) fumigation toxicity of M. alternifolia essential oil for T. castaneum adults and larvae was 122.7 µL/L at 24 hours and 280 µL/L at 48 hours, respectively. Gas chromatography–mass spectrometry showed that the oil’s major volatile compounds included terpinen-4-ol (31.78%), α-terpineol (20.24%), and terpinolene (17.94%). The treatment disrupted the normal enzymatic activity of acetylcholinesterase, carboxylesterase, and glutathione-S-transferase in T. castaneum adults and caused DNA damage. Melaleuca alternifolia essential oil is a strong fumigant and may be a good substitute for synthetic fumigants used to control pests of stored grain.

Antibacterial and antibiofilm activity of Melaleuca alternifolia (tea tree) essential oil against colistin resistant Salmonella enterica serotypes isolated from poultry environmental specimens

Antibacterial and antibiofilm activity of Melaleuca alternifolia (tea tree) essential oil against colistin resistant Salmonella enterica serotypes isolated from poultry environmental specimens

Super stable Melaleuca alternifolia essential oil Pickering emulsions stabilized with cellulose nanofibrils: Rheological aspects

Melaleuca alternifolia essential oil (MaEO) has attracted technological interest in the pharmaceutical, cosmetic and food sectors for its outstanding and broad antimicrobial spectra. However, its active components are highly susceptible to oxidation due to weathering. Therefore, stabilization of the MaEO components is essential. In this work, we evaluated the stability and rheology of MaEO-in-water Pickering emulsions using cellulose nanofibrils (CNF) as an eco-friendly and sustainable stabilizing agent. Small amplitude oscillatory shear (SAOS) tests brought exciting information about the relationship between internal microstructure strength and the relaxation processes, retardation processes, and viscous flow behavior of the emulsions. Measurements of oil droplet diameter distribution and steady-state rheological tests indicate that the emulsions have super stability under static environmental conditions within 28 storage days. Also, the emulsions present steady-state viscosity suitable for applications in dysphagic foods, presenting a pronounced shear-thinning behavior appropriate to developing cream and lotion skin-care eco-friendly products for the human body.

The chromosome-level Melaleuca alternifolia genome provides insights into the molecular mechanisms underlying terpenoids biosynthesis

The essential oil of Melaleuca alternifolia is increasingly popular for its naturally occurring pharmacological properties, which is widely used in daily necessities and cosmetics. Understanding the genetic basis of M. alternifolia can also provide useful molecular information that can improve the potential for essential oil yield in breeding. Here, we first reported the genome of M. alternifolia at the chromosome level to anchor the 331.11 Mb sequences into 11 pseudochromosomes with a scaffold N50 of 31.72 Mb. Comparative genomic analysis showed that several genes from the M. alternifolia genome may have evolved toward more terpenoids metabolites by natural selection, including MaSE, MaSDR1, MaKAO, MaGA20ox, MaISPF, MaDXS, MaHMGS, and MaIDI. Metabolomics data showed that sesquiterpenoids and monoterpenoids were the main categories of volatile organic compounds (VOCs), the contents of most of which were significantly higher in leaves than in roots and stems, suggesting that they are important bioactive constituents of essential oils in the leaves of M. alternifolia. Coexpression and ceRNA network results indicated that the identified class of miR156 may affect the biosynthesis of terpenoids by regulating the expression of related genes. Integrated whole-transcriptome and metabolome analyses showed that the members of the CYP450 and terpene synthase (TPS) gene families exhibited a high correlation with terpenoids accumulation, which can be responsible for terpenoids biosynthesis via complex regulatory networks, including MaCYP76F14, MaCYP76B10, MaCYP76A26, MaCYP82G1, MaTPS2, and MaTPS4. These results provide a good insight into the molecular mechanisms of terpenoids biosynthesis in M. alternifolia and will provide basic research and technical support for high yields of essential oils in crop molecular breeding.

Safety assessment and adverse drug reaction reporting of tea tree oil (Melaleuca aetheroleum).

Tea tree (Melaleuca alternifolia) essential oil is widely used as an antiseptic. It mainly consists of monoterpenes with terpinen-4-ol as the major constituent. The aim of this study was to review literature on safety data about tea tree oil and to assess its safety by investigating 159 cases of adverse reactions possibly caused by the oil, reported to the World Health Organization (WHO) from December 1987 until September 2021. To extract these data, VigiBase, the WHO global database of individual case safety reports maintained by the Uppsala Monitoring Centre (UMC), was used. All cases were categorized and analysed and 16 serious cases further assessed. It was concluded that tea tree oil should never be administered orally, as it can lead to central nervous system depression and pneumonitis. Applied topically, skin disorders may occur, especially when the oil had been exposed to light or air. This yields monoterpene oxidation products, being potent skin irritants. Tea tree oil stored under appropriate conditions and not exceeding the expiration date should be considered safe to use by non-vulnerable people for non-serious inflammatory skin conditions, although the occurrence of adverse reactions such as contact allergies is difficult to predict.

Alleviation of hypoxia stress induced oxidative damage, endoplasmic reticulum stress (ERS) and autophagy in grass carp (Ctenopharyngodon idellu) by TTO (Melaleuca alternifolia essential oil)

Because fish is a vital protein source, fish products are strongly linked to the health of humans. However, the survival of fish is seriously threatened by environmental hypoxia. The present study reported that an additive named tea tree oil (TTO) can prevent damage to the grass carp gill from hypoxia stress. The fish was fed with six graded levels of TTO (0, 40, 80, 120, 160, and 200 mg/kg) diets for 60 days and afterward subjected to a 96-h hypoxia stress trial. Our research elaborated that TTO alleviated the deterioration of serum parameters (cortisol, glucose, lactic dehydrogenase, and lactic acid) and reduced oxidative damage to the gills and apoptosis caused by hypoxia stress, thereby improving the structural integrity of the gills. In addition, TTO relieved gill endoplasmic reticulum stress (ERS), which could be associated with reduced levels of glucose-regulated protein 78 (GRP78) protein and activating its downstream pathways. Furthermore, TTO decreased the levels of LC3-II protein and the related ATG mRNA, suggesting that gill autophagy was suppressed and was probably related to the HIF–BNIP3 pathway. In summary, TTO reduced gill damage caused by hypoxia stress via reducing oxidative damage, endoplasmic reticulum stress (ERS), and autophagy in fish, implying TTO mitigated the negative effects of hypoxia. Based on oxidative damage biomarkers reactive oxygen species (ROS) and malonaldehyde (MDA) contents in the gills, the optimal addictive TTO concentration of grass carp was determined as 89.63 and 90.25 mg/kg, respectively.

In vitro and in vivo antimicrobial activity of an active plant-based quadrocomplex for skin hygiene

Context: The current epidemiological situation causes a new surge of interest to perspective antimicrobial formulations for proper skin hygiene. Aims: To evaluate in vitro and in vivo the antimicrobial activity of a novel active quadrocomplex (QC) for skin hygiene based on Melaleuca alternifolia essential oil, eucalyptol, (-)-α-bisabolol and silver citrate. In addition, to analyze the phytochemical constituents by gas chromatography-mass spectrometry (GC-MS) and to assess the skin irritant potential after regular washing. Methods: The phytochemical analysis was performed using GC-MS. The Minimum Inhibitory Concentrations (MICs) were assessed using a colony-counting method with resazurin. The type of pharmacological interaction was investigated using a modern checkerboard assay. Results: The chemical composition exhibited 18 resolved phytochemicals with the highest concentrations for (-)-α-bisabolol (32.2%) and terpinen-4-ol (31.6%) through the GC-MS analysis. QC agents showed antimicrobial activity against Gram-positive and Gram-negative strains, with MIC values ranging from 1.25 to 40.00 mg/mL. The checkerboard assay demonstrated reduced MIC values for the combinations of QC agents against all reference strains. QC showed significant inhibition of Staphylococcus aureus growth with an average efficiency of 99.91% and Candida albicans 99.94 %. In vivo, the investigation of QC showed higher immediate and prolonged efficiency compared to base formulation (p<0.05). Dermatology evaluation indicated that QC added to the soap base did not affect the skin of hands during regular hand-washing and did not cause any negative effects on the skin. Conclusions: QC exhibits a balanced performance between antimicrobial activity and biological safety and can be considered a promising bioactive composition for regular hand hygiene application. Therefore, additional investigations are needed to study the mechanism of antimicrobial activity.

Antimicrobial effects of Melaleuca alternifolia (tea tree) essential oil against biofilm-forming multidrug-resistant cystic fibrosis-associated Pseudomonas aeruginosa as a single agent and in combination with commonly nebulized antibiotics.

Broth microdilution assays were used to determine minimum inhibitory concentrations (MICs) and fractional inhibitory concentration indices (FICIs) of tea tree oil (TTO), tobramycin, colistin and aztreonam (ATM) against clinical cystic fibrosis-associated Pseudomonas aeruginosa (CFPA) isolates (n = 20). The minimum biofilm eradication concentration (MBEC) and fractional biofilm eradication concentration index (FBECI) were also determined using a similar microbroth dilution checkerboard assay, with biofilms formed using the MBEC device® . TTO was effective at lower concentrations against multidrug-resistant (MDR) CFPA isolates (n = 3) in a biofilm compared to in a planktonic state (MBEC 18·7-fold lower than MIC). CFPA within biofilm was less susceptible to ATM, colistin and tobramycin compared to planktonic cells (MBEC 6·3-fold, 9·3-fold, and 2·1-fold higher than MIC respectively). All combinations of essential oil and antibiotic showed indifferent relationships (FICI 0·52-1·72) when tested against planktonic MDR CFPA isolates (n = 5). Against CFPA isolates (n = 3) in biofilm, combinations of TTO/aztreonam and TTO/colistin showed indifferent relationships (mean FBECI 0·85 and 0·60 respectively), whereas TTO/tobramycin showed a synergistic relationship (mean FBECI 0·42). The antibiofilm properties of TTO and the synergistic relationship seen between TTO and tobramycin against CFPA invitro make inhaled TTO a promising candidate as a potential therapeutic agent.

Antifungal Activity of Essential Oil Extracted from <i>Melaleuca alternifolia</i> against Pathogenic Fungi on Mango (<i>Mangifera indica </i>L.) for Mango Postharvest Application

An infection by pathogenic fungi is one of the major problem in post-harvest stage of mangoes. Therefore, the extraction of essential oil from Melaleuca alternifolia is being tested as a natural fungicide for controlling fungus infections of selected mangoes locally known as susu mango. The extraction was performed using Solvent-Free Microwave Assisted Extraction with a yield of 0.57% concentration. The inhibitory effect of this essential oil against isolated fungi from mango was investigated through in-vitro and in-vivo analyses. Distilled water was used as a negative control while chemical fungicide (Globus 5.5) was used as a positive control in the analyses. The mycelial growth inhibition of the extracted essential oil for poisoned food test and disc diffusion method showed 62.50 ± 0.49% and 59.70 ± 0.30% respectively for in-vivo experiment which used unwounded and artificially wounded mangoes. The result also demonstrated that the essential oil applied on the mangoes could decrease the disease incidence from 100% to 61.33% for up to 10 days incubation at room temperature compared to that of the control. Hence, the essential oil of Melaleuca alternifolia can act as a green fungicide and is also a promising alternative to the synthetic chemical fungicide for controlling post-harvest disease on mangoes.

Terpinen-4-ol, the Main Bioactive Component of Tea Tree Oil, as an Innovative Antimicrobial Agent against Legionella pneumophila.

Legionella pneumophila (Lp), responsible for a severe pneumonia called Legionnaires’ disease, represents an important health burden in Europe. Prevention and control of Lp contamination in warm water systems is still a great challenge often due to the failure in disinfection procedures. The aim of this study was to evaluate the in vitro activity of Terpinen-4-ol (T-4-ol) as potential agent for Lp control, in comparison with the essential oil of Melaleuca alternifolia (tea tree) (TTO. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of T-4-ol were determined by broth micro-dilution and a micro-atmosphere diffusion method to investigate the anti-Lp effects of T-4-ol and TTO vapors. Scanning Electron Microscopy (SEM) was adopted to highlight the morphological changes and Lp damage following T-4-ol and TTO treatments. The greatest antimicrobial activity against Lp was shown by T-4-ol with a MIC range of 0.06–0.125% v/v and MBC range of 0.25–0.5% v/v. The TTO and T-4-ol MIC and MBC decreased with increasing temperature (36 °C to 45 ± 1 °C), and temperature also significantly influenced the efficacy of TTO and T-4-ol vapors. The time-killing assay showed an exponential trend of T-4-ol bactericidal activity at 0.5% v/v against Lp. SEM observations revealed a concentration- and temperature- dependent effect of T-4-ol and TTO on cell surface morphology with alterations. These findings suggest that T-4-ol is active against Lp and further studies may address the potential effectiveness of T-4-ol for control of water systems.

Potential Use of Tea Tree Oil as a Disinfectant Agent against Coronaviruses: A Combined Experimental and Simulation Study.

The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.

Chemical composition and bioactivities of Melaleuca alternufolia essential oil and its main constituents against Spodoptera littoralis (Boisaduval, 1833)

BackgroundSpodoptera littoralis is mostly controlled by the use of synthetic insecticides. Nonetheless, the use of these insecticides causes a slew of issues. On this pest, the antifeedant activity of Melaleuca alternifolia essential oil (EO) and its two principal components was investigated.ResultsThe gas chromatography–mass spectrometry (GC/MS) analysis revealed that the M. alternifolia EO was composed of eleven compounds. Terpinen-4-ol (40.1%) and γ-terpinene (21.9%) were chosen as the major constituents. In terms of antifeedant efficacy, treatment with M. alternifolia EO and these components reduced leaf consumption and the efficiency of food conversion in larvae in a concentration-dependent manner. When compared to untreated larvae, weight, growth, and pupation percentage were all significantly lower.ConclusionsThe findings show that M. alternifolia EO and its components, terpinen-4-ol and γ-terpinene can be effectively combined for cotton leafworm management.

The strategic use of water additives for tambaqui Colossoma macropomum transport: New insights of bacteriosis and productivity approach

The transport of live fish is a major sanitary issue for aquaculture. This study addresses two critical steps regarding natural recurrent mortality outbreaks after transport of tambaqui Colossoma macropomum. At first, five mortality outbreaks post-transport of juveniles showing clinical signs suggestive of columnaris were investigated. Flavobacterium columnare was ascertained as the etiological agent in all outbreaks, causing massive mortality up to 72 h after transport. Based on these findings, the next step consisted of a trial to investigate the use of three additives (8 g/L sodium chloride, 11.12 mg/L Melaleuca alternifolia essential oil and 60 mg/L oxytetracycline) in the water of transport, simulating fish farmers' practices to prevent disease outbreak. Juveniles (≅ 8 cm) were transported for 3 h under trade-mimicking conditions, then transferred to 20 tanks (5 groups, 4 replicates) and monitored for 30 days for analysis of health status. Zootechnical parameters (weight gain, total feed intake, feed conversion, specific growth rate and growth analysis) were assessed on days 1, 15 and 30. The best health status was attributed to the group transported with 0.8% NaCl, which showed 100% survival, in addition to being the only group that did not show behavioral changes and clinical signs, indicating the absence of any infectious biological source after transport. A poly-infection (Aeromonas jandaei and F. columnare) was detected in fish from all other groups (M. alternifolia, oxytetracycline and control). Furthermore, fish exposed to sodium chloride showed better weight gain and feed conversion compared to those transported with oxytetracycline (p ≤ 0.05). Then, the pathogenicity of the two isolated strains (A. jandaei and F. columnare) was ascertained by Koch's Postulate assay, which established two emerging pathogens for C. macropomum. This study addresses fundamental information for the development of fish farming and suggests the addition of salt at 0.8% in the water of transport to prevent columnaris and motile Aeromonas septicemia (MAS) associated disease.

Dietary tea tree (Melaleuca alternifolia) essential oil as alternative to antibiotics alleviates experimentally induced Eimeria tenella challenge in Japanese quails.

Coccidiosis is one of the most common infectious diseases seen in Japanese quails. The current study was conducted to evaluate the impact of tea tree essential oil (TTEO) on growth performance and intestinal health of quails in response to Eimeria tenella challenge. A total of 250 Japanese quails were divided into five treatments: untreated uninfected (negative control); untreated infected (positive control); infected + Amprolium; infected and 1% TTEO; infected and 2% TTEO. Except negative control, all groups were orally dosed with 5 × 104 sporulated oocysts of E. tenella. The results revealed that supplementation of 1% TTEO and treatment of amprolium improved feed intake, weight gain and feed conversion ratio in infected quails compared to the positive control. Similarly, lesion score and mortality was significantly (p < 0.01) reduced in quails supplemented with 2% TTEO and amprolium treated birds. Moreover, oocysts counts and histological features of caecum in infected birds were reversed in 1% TTEO and amprolium treatment. The histological findings of amprolium and 1% TTEO supplemented quails showed intact intestinal villi with mild sloughed epithelium. In conclusion, 1% TTEO can be safely used to control coccidiosis in Japanese quails as natural effective compound.

Therapeutic ultrasound and essential oil of melaleuca alternifolia interfere with muscle regeneration?

Currently the Essentials oil of Tea Tree is used in healing, for possessing various medicinal properties. Phonophoresis is a method used in physiotherapy, where pharmacological substances associated with a coupling agent, are induced by ultrasonic waves in the underlying tissues. Our objectives are aimed at monitoring and qualitative analysis of the lesion treated with the compound and the method accuracy phonophoresis. We used twenty (20) rats, which are divided into two (2) different groups: Group I: Rats harmed without intervention and Group II: Rats victims treated with the compound by Phonophoresis. Histological analysis showed the material collected in samples from animals in group I, an extensive and diffuse inflammation, unconnected with large amounts of inflammatory cells, as in group 2 inflammation comes in mild areas with limited, there is also muscle fiber regeneration. The results seem to demonstrate the efficacy of Melaleuca alternifolia essential oil by phonophoresis in the muscle fiber in the lesion region.

Melaleuca alternifolia formulations in the treatment of experimental pythiosis.

Essential oils (EO) are aromatic compounds from the plant secondary metabolism. Melaleuca alternifolia EO is well known for its medicinal properties and promising use as an antimicrobial agent. Pythiosis is a difficult-to-treat and emerging disease caused by the oomycete Pythium insidiosum. This study evaluated a nanoemulsion formulation of M. alternifolia (NEMA) in topical and intralesional application to treat experimental pythiosis. Dermal toxicity tests were performed on M. alternifolia EO in Wistar rats. Pythiosis was reproduced in rabbits (n = 9) that were divided into groups: group 1 (control), cutaneous lesions with daily topical application of a non-ionizable gel-based formulation and intralesional application of sterile distilled water every 48 h; group 2 (topical formulation), lesions treated daily with topical application of a non-ionizable gel-based formulation containing 5 mg/ml of NEMA; and group 3 (intralesional formulation), lesions treated with NEMA at 5 mg/ml in aqueous solution applied intralesionally/48 h. The animals were treated for 45 days, and the subcutaneous lesion areas were measured every 5 days. M. alternifolia EO showed no dermal toxicity. The lesion areas treated with intralesional NEMA reduced at the end of treatment, differing from groups 1 and 2 (P < 0.05). In the topically treated group, the lesion areas did not differ from the control group, although the number of hyphae significantly reduced (P < 0.05). Under the experimental conditions of this study, the NEMA formulations presented a favorable safety profile. However, further studies are required to evaluate if this safety applies to higher concentrations of NEMA and to validate its use in clinical pythiosis.

Chemical and Biological Characterization of Melaleuca alternifolia Essential Oil.

The essential oil of Melaleuca alternifolia, commonly known as tea tree oil, has many beneficial properties due to its bioactive compounds. The aim of this research was to characterize the tea tree essential oil (TTEO) from Slovakia and its biological properties, which are specific to the chemical composition of essential oil. Gas chromatography/mass spectroscopy revealed that terpinen-4-ol was dominant with a content of 40.3%. γ-Terpinene, 1,8-cineole, and p-cymene were identified in contents of 11.7%, 7.0%, and 6.2%, respectively. Antioxidant activity was determined at 41.6% radical inhibition, which was equivalent to 447 μg Trolox to 1 mL sample. Antimicrobial activity was observed by the disk diffusion method against Gram-positive (G+), Gram-negative (G−) bacteria and against yeasts, where the best antimicrobial activity was against Enterococcus faecalis and Candida albicans with an inhibition zone of 10.67 mm. The minimum inhibitory concentration showed better susceptibility by G+ and G− planktonic cells, while yeast species and biofilm-forming bacteria strains were more resistant. Antibiofilm activity was observed against Pseudomonas fluorescens and Salmonella enterica by MALDI-TOF, where degradation of the protein spectra after the addition of essential oil was obtained. Good biological properties of tea tree essential oil allow its use in the food industry or in medicine as an antioxidant and antimicrobial agent.

Effect of fungicides and biological products in controlling rust and gray mold in grapevines

Grape rust and gray mold are diseases in grapevines with high destructive potential. In this study, the effectiveness of different fungicides and biological products in controlling these diseases was evaluated using the cultivar “Niágara Rosada” in the municipality of Louveira-SP, from February to April 2017. A randomized block design was used, with 10 treatments and four replicates and five plants per plot. Each treatment was applied nine times at weekly intervals, with application volumes in the range of 400–1000 L/ha. The evaluation criterion for rust was the severity, based on the percentage of leaf area affected by the disease (0 to 100%), whereas gray mold was evaluated using the incidence of diseased bunches (0 to 100%). All treatments were effective in controlling both diseases and significantly reduced the disease incidence in the experimental plot compared with that in the control plots. The best rust control was obtained by treating the plants with boscalide+pyraclostrobin (1 L c.p./ha), which was superior to fluxapyroxade+pyraclostrobin (0.5 L) + Bacillus amyloliquefaciens (0.5 kg), B. amyloliquefaciens (0.5 kg), Melaleuca alternifolia essential oil (1.5 L), and dimoxystrobin+boscalide (1 L). The plants treated with fluxapyroxad+pyraclostrobin (0.5 L) + B. amyloliquefaciens (0.5 kg) had a lower incidence of gray mold than did those treated with dimoxystrobin+boscalide (1 L), boscalide+kresoxim methyl (0.5 L), and piremethanil (1.5 L). These results suggest that the use of M. alternifolia essential oil and B. amyloliquefaciens may represent an important tool for the management of rust and gray mold in grapevines.

𝘚𝘰𝘳𝘨𝘩𝘶𝘮 𝘴𝘶𝘥𝘢𝘯𝘦𝘯𝘴𝘦 AS COVER CROP AND BIOLOGICAL PRODUCTS ON INCIDENCE OF 𝘚𝘤𝘭𝘦𝘳𝘰𝘵𝘪𝘯𝘪𝘢 𝘴𝘤𝘭𝘦𝘳𝘰𝘵𝘪𝘰𝘳𝘶𝘮 AND YIELD OF TOBACCO

Brazil is the world's second largest producer of tobacco (Nicotiana tabacum) with part of its production concentrated in Santa Catarina. The incidence of Sclerotinia sclerotiorum in tobacco areas has promoted a decrease in productivity, and control alternatives are needed due to the limited use of agrochemicals for the crop. With the hypothesis that the sudan grass (Sorghum sudanense) and Trichoderma harzianum reduce the attack of S. sclerotiorum in tobacco crops on the coast of Santa Catarina; the objective here was to test the incidence of S. sclerotiorum and the use of sudan grass associated with biological products on tobacco yield. A study with application of straw from sudan grass (SG); SG + Trichoderma harzianum (TH); SG + TH + Melaleuca alternifolia essential oil; SG + TH + Bacillus subtilis Bacillus licheniforimis; and SG + TH + Bacillus subtilis in a conventional system of tobacco were carried out in São João do Sul and Santa Rosa do Sul, Santa Catarina. Results showed that in São João do Sul, there was no difference between the treatments in yield and incidence of S. sclerotiorum. However, in Santa Rosa do Sul, the association of SG + TH, SG + TH + B. subtilis B. licheniforimis, and SG + TH + B. subtilis presented greater yields than others. In both sites, sudan grass and associations promoted a higher financial return compared to control. More studies are requested to elucidate the physiological effect of biological products and sudan grass as a cover crop on tobacco.