Blight Disease Severity Research Articles

Glycosyltransferase-Like Toxin of Burkholderia gladioli Strain NGJ1 Is a Potent Antifungal Protein with Potential for Control of Sheath Blight Disease in Rice.

Sheath blight disease caused by the fungal pathogen Rhizoctonia solani poses a great challenge for sustainable rice cultivation. It is important to develop environment-friendly measures for its control. Previously, a rice-associated Burkholderia gladioli strain NGJ1 has been shown to exhibit mycophagous and antifungal activity on R. solani. Here we report that a glucosyltransferase-like (BGT1) protein with a canonical DxD motif that is homologous to glycosyltransferase (GT) toxin of different bacteria is encoded in the antibacterial type VI secretion system (T6SS) encoding gene cluster of NGJ1. The recombinant BGT1 protein purified from Escherichia coli exhibits antifungal activity on R. solani, Magnaporthe oryzae, Fusarium oxysporum, Saccharomyces cerevisiae, and Candida albicans, under laboratory conditions. Using a variant of BGT1 protein (BGT1D168L/D170L), we demonstrate that DxD motif is important for its antifungal activity. The heterologous expression of native BGT1 but not BGT1D168L/D170L protein prevents the growth of yeast cells. Moreover, treatment with BGT1 but not BGT1D168L/D170L significantly reduces sheath blight disease severity in rice. BGT1 treatment does not elicit adverse effects on plants. In conclusion, we emphasize that BGT1 protein-based or transgene-based biotechnological interventions can be exploited for effective control of sheath blight disease in rice.

Evaluating the efficacy of endophytic bacteria in controlling rice sheath blight: In vitro and In vivo studies

Rice production is highly susceptible to various pathogens, including Rhizoctonia solani, Curvularia lunata, and Epicoccum rostratum, which are major threats in Asia. Exploring biological control methods using endophytic bacteria offers promising opportunities to enhance rice resilience against these lethal diseases. Using 16S RNA sequencing, we identified four endophytic isolates of Bacillus spp. from rice roots, stems, and leaves. We evaluated the antagonistic activity of these endophytic bacterial isolates against rice pathogens both in vitro and in vivo. These isolates inhibited the growth of C. lunata by 82%, R. solani by 79%, and E. rostratum by 88% in vitro. The detached leaf assay for sheath blight (ShB) disease severity in strains ranged from 10.4% to 73.3%. In vivo results showed that B. amyloliquefaciens (R-19) exhibited the lowest disease intensity at 7.2% and the highest disease suppression at 78.8%. The fungicide propiconazole at 0.1% treatment showed the lowest disease intensity of 7.7% and the highest disease suppression of 73.4%, compared to the infected control. Besides biocontrol efficacy, endophytic isolates enhance plant growth parameters, including shoot height, root length, fresh and dry weights, number of tillers, and grains per tiller. Plant hormones abscisic acid (ABA) and gibberellic acids (GA3) increased by 35% and 53%, respectively, due to B. subtilis (R-20) and B. amyloliquefaciens (R-19), while flavonoid and indole acetic acid (IAA) concentrations surged by 30%-80%. Similarly, chlorophyll (a, b), carotenoids, antioxidant enzymatic activity, phenolic content, carbohydrates, and proline contents were higher compared to the control. This study provides a foundation for future studies on novel and eco-friendly biocontrol agents. In addition, our study recommends the integration of endophytic bacteria into sustainable agriculture for enhancing rice production and reducing disease impacts.

Classification of Clove Leaf Blister Blight Disease Severity Using Pre-trained Model VGG16, InceptionV3, and ResNet

Clove is one of the precious plants produced in Indonesia. Clove has many benefits for humans, but clove cultivation often experiences problems due to disease attacks, including Leaf Blister Blight Disease(CDC). The handling of CDC disease is carried out based on the severity of the symptoms that can be seen on the affected leaves. This research was conducted to obtain a CDC disease classification model, so appropriate treatment can be carried out. This study used the pre-trained VGG16, InceptionV3, and ResNet models for classification. VGG16 got the highest average accuracy of 96.7%. Aside from that, k-fold cross validation improved the model's accuracy.

Association of quantitative traits and genetic diversity in Ethiopian sesame (Sesamum indicum L.) genotypes

To enhance sesame yield, it is important to utilize diverse parents in breeding programs and implement an effective selection procedure, which exploits the association of quantitative traits. Therefore, the objective of this experiment was to explore the correlation among quantitative traits and assess genetic variability and diversity using both qualitative and quantitative traits. Correlation coefficients indicated a noteworthy (P<0.001) positive phenotypic (rp) and genotypic (rg) correlation between seed yield and various traits: plant height (rp=0.60; rg=0.58), length of the capsule-bearing zone (rp=0.77; rg=0.80), number of capsules on the main stem (rp=0.80; rg=0.85), primary branches (rp=0.66; rg=0.66), and capsules per plant (rp=0.90; rg=0.91). In contrast, a negative correlation (P<0.001) was observed between yield and bacterial blight disease severity, both phenotypically (rp=-0.60) and genotypically (rg=-0.76). The analysis of path coefficients indicated that the most substantial positive direct effect on yield (0.77) was attributed to capsules per plant, whereas other traits associated with yield exhibited a significant indirect influence on yield through capsules per plant. Qualitative traits exhibited diversity, except for plant growth type, plant growth habit, and stem branching. Shannon-Weaner (H) and Simpson (1-D) diversity indices were higher for interior corolla color (H=1.63; 1-D=0.66), seed color (H=1.50; 1-D=0.46), and capsule beak type (H=1.08; 1-D=0.50). The analysis of variance indicated a notable variation among the examined genotypes regarding quantitative traits, excluding internode length. The plant materials were divided into five clusters through cluster analysis, where clusters I to V consisted of 21, 29, 4, 4, and 6 genotypes, respectively. The current study has shown that the yield of sesame can be enhanced through indirect selection for traits associated with yield, particularly the highest number of capsules per plant. Furthermore, examinations of genetic diversity confirmed the presence of variability within the assessed genotypes, providing valuable insights for upcoming sesame breeding programs.

Survey of rice sheath blight disease incidence and severity across various rice growing states in India

Survey of rice sheath blight disease incidence and severity across various rice growing states in India

Influence of Tuber Seed Size on Susceptibility of Cipira Potato Variety to Aphid (Myzus persicae), and Potato Blight and Bacterial Wilt Diseases

Potato (Solanum tuberosum L.) is one of the most important tuber crops in the world and it is fourth among food crops after rice, wheat and maize. Potato is widely cultivated for its cheap source of carbohydrates, vitamins as well as minerals. In Cameroon, where potato provide a livelihood for most producers, especially in the Western highland, production is challenged by unavailability of appropriate seeds of local varieties or Cameroon improve varieties. Many decades ago, Cipira was released by the Institute of Agricultural Research for Development, Bambui, North West Region, Cameroon as an improved resistant variety. The current study evaluated the performance of Cipira considering seed sizes. Four seed sizes (20mm, 25mm, 30mm and 35mm diameter) were evaluated in a randomized complete block trial in Bambili in 2022 and 2023. Green peach aphid incidence was inversely related to tuber seed sizes (P &lt; 0.05). Aphid population abundance was higher from plants with larger diameter. Late blight and bacterial wilt incidence and disease severity index was significantly higher for plants of smaller tuber seed size. Productivity was 8.06 t ha-1, 6.2 t ha-1, 5.7 t ha-1 and 5.8 t ha-1 from 35mm, 30mm, 25mm and 20mm tuber seed sizes, respectively in 2022. The yield in 2023 was 8.9 t ha-1, 7.8 t ha-1, 7.1 t ha-1, and 6.3 t ha-1, from 35mm, 30mm, 25mm and 20mm, respectively. For improved yield and reduced pest and diseases incidences, Cipira at 30 mm and 35 mm seed sizes are recommended.

Estimating the maydis leaf blight disease severity of maize in Southern Karnataka and identifying potential resistant varieties

Estimating the maydis leaf blight disease severity of maize in Southern Karnataka and identifying potential resistant varieties

The integrated disease management of early blight in organically grown tomato under hill condition of Sikkim, India

Tomato (Lycopersicon esculentum Mill.) is the most widely cultivated vegetable crop in the world and early blight caused by Alternaria spp. is one of the major production constraints. Survey was conducted during kharif seasons of 2018-19 &amp;2019-20 in four districts of Sikkim. Maximum early blight disease severity was recorded in south district of Sikkim. Pathogenicity test of isolates collected from different location were established. Morphological, cultural, and molecular identification of the pathogen reveal pathogen as Alternaria spp. Five different bio-control agents i.e., Trichoderma harzianum, T. Viride, Pseudomonas fluorescens, Bacillus subtilis and Bacillus cereus were evaluated against the test pathogens. Among the bio-control agents tested, Trichoderma harzianum (74.89%) and Trichoderma viride (69.41%) showed maximum percent growth inhibition. Open field experiment was conducted with eleven treatments formulated by integrating the different organic inputs, biocontrol agents and copper-based fungicide as chemical check. Organic treatment T9 {Susceptible Variety + Soil treatment with Trichoderma harzianum @1:25(1kg Trichoderma + 25 Kg of FYM) + cow dung slurry 10% + Nimbicidine 0.3% + Panchagavya 10% + Cow Urine 10%} consistently showed the best result among the bioresources tested. Keywords: Tomato, Organic, Bio agent and Integrated disease management

Elevated CO2 Can Worsen Fusarium Head Blight Disease Severity in Wheat but the Fhb1 QTL Provides Reliable Disease Resistance.

Fusarium head blight (FHB) is a destructive fungal disease of wheat that causes significant economic loss due to lower yields and the contamination of grain with fungal toxins (mycotoxins), particularly deoxynivalenol (DON). FHB disease spread and mycotoxin contamination has been shown to worsen at elevated CO2, therefore, it is important to identify climate-resilient FHB resistance. This work evaluates whether wheat with the Fhb1 quantitative trait locus (QTL), the most widely deployed FHB resistance locus in wheat breeding programs, provides reliable disease resistance at elevated CO2. Near-isogenic wheat lines (NILs) derived from either a highly FHB susceptible or a more FHB resistant genetic background, with or without the Fhb1 QTL, were grown in growth chambers at ambient (400 ppm) and elevated (1000 ppm) CO2 conditions. Wheat was inoculated with Fusarium graminearum and evaluated for FHB severity. At elevated CO2, the NILs derived from more FHB-resistant wheat had increased disease spread, greater pathogen biomass and mycotoxin contamination, and lower rates of DON detoxification; this was not observed in wheat from a FHB susceptible genetic background. The Fhb1 QTL was not associated with increased disease severity in wheat grown at elevated CO2 and provided reliable disease resistance.

INDUCTION OF SYSTEMIC RESISTANCE BY BIOTIC AND ABIOTIC COMPOUNDS AGAINST ALTERNARIA BLIGHT OF CAULIFLOWER CAUSED BY ALTERNARIA BRASSICAE

Alternaria blight of cauliflower is initiated by Alternaria brassicae, is considered as one of the significant diseases caused in cauliflower crop cultivated in all the growing areas of the world. Alternaria blight disease severity in cauliflower occurs after initiation of curd formation and continues till seed pods are set. Several opportunities include improvement of resistant cultivars; crop rotation, biological control, chemical pesticides, and tillage are used to control this particular disease. By using chemical pesticide mostly diseases can be controlled. In present investigation the three abiotic (salicylic acid, oxalic acid, benzothiadiazole and two biotic compound Trichoderma harzianum, and T.viride lab formulations were used to control this disease. Treatments were evaluated for their ability to reduce illness and prevent the production of conidia, a hallmark of pathogen proliferation. However, the disease control was maximum in variety Doctor II and under post inoculation technique. The maximum disease control was observed with the treatment of bion (93.86%) followed by salicylic Aacid (90.93%) and oxalic acid (89.06%) @ 50 mg.L concentration. The biotic compound T. harziaznum (4g/Kg seeds) also showed effective disease control (87.2%) followed by T.viride (84.53%). Although, the disease initiation in variety SV40551AC was two days later and the infection index was lower in Doctor II due to its tolerance nature. Keywords: Alternaria brassicae, cauliflower, Alternaria blight, entry routes, pathogen.

Evaluation of Antagonists and the Effectiveness of Application Methods against Sheath Blight Disease of Rice under Pot Conditions

Rice sheath blight caused by Rhizoctonia solani is one of the main disease of rice in the Chhattisgarh region. Three potential Trichoderma species were evaluated against sheath blight disease of paddy under pot conditions. The Trichoderma spp. Obtained/ isolated from three discrict Rajnandgaon, Raipur and Durg of Chhattisgarh were compared for their efficacy with check fungicide hexaconazole for foliar sprays. This experiment was conducted under pot condition in completely randomyzed design (CRD) with three replications during kharif 2016 and 2017. Among the three potential Trichoderma spp., highly effective species against sheath blight pathogen was evaluated. The disease severity was recorded 14 days after inoculation. The results of comparative foliar application of Raipur, Durg and Rajnandgaon Trichoderma isolates showed that all isolates of Trichoderma spp. significantly reduced the sheath blight disease severity in rice under pot conditions at 30 DAT and 60 DAT planting. Among the Trichoderma isolates, foliar spray of Durg isolate (TD3) was effectively showed 26.24% reduction in disease severity at 30 DAT and 24.85% reduction in disease severity at 60 DAT over control treatment. The highest disease severity was reduced by check fungicide hexaconazole. The Durg isolate (TD3) at 30 DAT and 60 DAT also increased the yield per plant as compared to Raipur (TR2) and Rajnandgaon isolates (TR1).

Antimicrobial Traits of Beauveria bassiana Against Rhizoctonia solani, the Causal Agent of Sheath Blight of Rice Under Field Conditions.

Beauveria bassiana, an entomopathogenic fungus, has recently drawn attention worldwide not only as a potential biocontrol agent against insect pests but also for its other beneficial roles as plant disease antagonist, endophyte, plant growth promoter, and beneficial rhizosphere colonizer. In the present study, 53 native isolates of B. bassiana were screened for antifungal ability against Rhizoctonia solani, the causal agent of sheath blight of rice. Also, the mechanisms underlying such interaction and the responsible antimicrobial traits involved were studied. Following this, potential B. bassiana isolates were assayed against the reduction of sheath blight of rice under field conditions. The results showed that B. bassiana exhibited antagonistic behavior against R. solani with a percent mycelial inhibition recorded maximum of up to 71.15%. Mechanisms behind antagonism were the production of cell-wall-degrading enzymes, mycoparasitism, and the release of secondary metabolites. The study also deciphered several antimicrobial traits and the presence of virulent genes in B. bassiana as a determinant of potential plant disease antagonists. Under field conditions, combined application of the B. bassiana microbial consortium as a seed treatment, seedling root dip, and foliar sprays showed reduced sheath blight disease incidence and severity up to 69.26 and 60.50%, respectively, along with enhanced plant-growth-promoting attributes. This is one of the few studies investigating the antagonistic abilities of the entomopathogenic fungus B. bassiana against phytopathogen R. solani and the underlying mechanisms involved.

Isolation and characterization of three bacteriophages infecting Erwinia amylovora and their potential as biological control agent

BackgroundFire Blight, incited by Erwinia amylovora, is one of the most damaging pear and apple diseases in the world. Fire blight was introduced to Egypt in the 1960 and threatens the Egypt’s costs for pear industry. Currently, Phage therapy is considered to be secured biological method for controlling plant bacterial diseases. This investigation aimed to isolate and identify molecularly for bacteria causing fire bright disease. As well as isolation and identification bacteriophages via spot and plaque assay techniques from pear fire blight lesions and soil. On the other hand, bacteriophages were identified based on plaque morphology, virion morphology, physical characters, profile of DNA restriction and protein.ResultsPathogenicity test revealed that healthy seedlings and pear fruits were responsive to fire blight E. amylovora. Considering the relatively wide host range and greatest protein and genetic variability, using restriction enzyme pattern, the three diversity phage isolates named, EAP1, EAP2 and EAP3 showed a lack of diversity out of five were fatherly characterized. The phages confirmed the close relation of EAP1, EAP2 to Siphoviridae (hexagonal head and long flexible non-contractile tail) and EAP3 to Myoviridae (icosahedral head and contractile tail). The phages retained higher lytic competence of 90.4; 92.68 and 95.25% for EAP1, EAP2 and EAP3, respectively. The phages were stable at strong alkaline (pH 10) 2% salt solution conditions and UV spectra. While EAP3 phage revealed the hexagonal head and very short tail that belongs to Myoviridae family. Bacteriophages were characterized by digestion of the phage DNA with three restriction endonucleases and were placed into three groups based on the patterns. Bacteriophages were 9 used for reducing bacterial infection populations and severity on pear. In a bioassay, the biocontrol of E. amylovora was evaluated using disks of immature pear fruit. On the pear disk surface, bacterial exudate was considerably suppressed by all phage isolates. According to measurements of the bacterial population still present on the disk surface, phage therapy could reduce it by up to 97%. Bacteriophages reduced pear fire blight disease severity on pear fruit trails.ConclusionThe results indicated that bacteriophage isolates may demonstrate variable reactivity against E. amylovora. Bacteriophages reduced pear fire blight disease severity on pear fruit trials. The results indicated that bacteriophage isolates may demonstrate variable reactivity against E. amylovora.

Effects of fungicides and antagonistic marine-derived fungi on rice seedling promotion and rice sheath blight control

Fourteen fungicides and three marine-derived fungi were tested for their activities in the promotion of rice seedling development and their efficacy in controlling rice sheath blight disease in two rice varieties, RD43 and KMDL105, under greenhouse conditions. The results showed that the rice seeds treated with carbendazim 50%SC and azoxystrobin 25%SC displayed the best promotion of rice growth in root length and shoot height at seven and 14 days in rice var. RD43. Rice seeds from var. KMDL105 treated with thiophanate-methyl 70%WP exhibited significant stimulation of rice seedling growth resulting in the greatest increase in root length and shoot height at seven and 14 days. In pot experiments with rice var. RD43, spraying with triforine 19%EC, propiconazole 25%EC, trifloxystrobin 50%WG, and validamycin 3%SL showed a high level of fungicidal activity in controlling sheath blight disease, with this evidenced by significant suppression of the disease severity by 71–75% and 61–73% at seven and 14 days after inoculation, respectively. The treatment of rice var. KMDL105 with validamycin 3%SL exhibited the best activity in controlling sheath blight disease by reducing disease severity by up to 62% and 64% at seven and 14 days, respectively. The antagonistic marine fungi tested in this study displayed low activity against sheath blight disease and low effects on rice seedling promotion compared to fungicides. Specifically, Trichoderma harzianum KUFA 0689 and T. asperellum KUFA 0677 reduced sheath blight disease severity by 42–46% and 27–37% at seven and 14 days, respectively.

Endogenous Salicylic acid Estimation in Wheat leaves treated with Salicylic acid and infected with Alternaria triticina

This study was aime to measure the accumulation of endogenous salicylic acid, as indicator for systemic acquired re-sistance of wheat plants of “Utique” variety. The plant was sprayed with salicylic acid (SA) or water as control, at the five-leaf stage, later infected with leaf blight caused by Alternaria triticina. Leaf samples were removed after 10, 20, and 30 days of inoculation to test their endogenous content of salicylic acid as it is the primary internal signal indicating the emergence of systemic acquired resistance in plants, by the spectrophotometer measuring. Endogenous SA values were ascending dramatically from 10 days to 20 days and maximum with 30th day significantly, while control plants exhibit lower values in all day periods, insignificantly. SA treatments proved reduction in disease incidence after 10 days with 54% and after 20 days with 64%, while after 30 days the reduction recorded high percentage of 80%. In comparison between the time intervals, disease severity was clearly reduction and reached to 83% after 10 days of inoculation then decreased to 72% for both 20th and maintained its stability on the 30th day of inoculation by 72%. This study was proved the reduction of wheat leaf blight incidence and disease severity as a result of treatment by using 1Millimolar (mM) of SA was leading to accumulation of significant levels of endogenous SA as indicator for internal induced resistance in plant.

Management of Phytophthora Blight of Pigeon Pea (Cajanus cajan L. Hugh) Through the Use of Neem (Azadirachta indica) Plant Parts Aqueous Extracts

This study is focused on the management of phytophthora blight, a fungal disease of “pigeon pea” by the application of some aqueous extracts of neem plant parts. The aim of the study was to manage the phytophthora blight of pigeon pea using the plant parts extract of neem. The study was conducted in the year, 2021, at the Demonstration Farms (both field and laboratory) of the Department of Crop Science and Technology, School of Agriculture and Agricultural Technology, Federal University of Technology, Owerri, Imo State, Nigeria. The experiment was designed as Randomized Complete Block Design (RCBD) with five replications. Data on pigeon pea growth parameters and disease incidence and severity, were statistically analyzed by the use of Analysis of Variance (ANOVA) software as outlined by Wahua. The means were separated for difference using the Fisher’s Least Significant Difference (FLSD). Results indicated that aqueous extract of neem seed application caused the tallest Pigeon pea height (103.30 cm), the highest number of pigeon pea leaves (99.40), the lowest phytophthora blight disease incidence (11.00%) and also the lowest phytophthora blight disease severity (1.00).

Intercropping chickpea–flax for yield and disease management

AbstractAscochyta blight (caused by Ascochyta rabiei) is a primary concern of chickpea production worldwide. Intercropping chickpea with a non‐host crop has the potential to suppress this disease and improve resource use efficiency for enhanced crop yield. This study aimed to evaluate the effects of seeding rate and row configuration of chickpea (Cicer arietinum L.)–flax (Linum usitatissimum L) intercropping on (1) yield and seed quality, (2) disease incidence and severity of Ascochyta blight of chickpea, and (3) land productivity of this intercropping system. Field trials were conducted at the Eastern Agricultural Research Center, Sidney, MT, and the Southern Agricultural Research Center, Huntley, MT, in 2020 and 2021. Chickpea was planted with flax in four intercropping configurations (70% chickpea–30% flax in mixed rows, 50% chickpea–50% flax in alternate rows, 50% chickpea–50% flax in mixed rows, and 30% chickpea–70% flax in mixed rows). Chickpea yield decreased with increased flax proportion in the mixed rows intercrop. Flax displayed higher competitiveness than chickpea, resulting in decreased yield and protein concentration in chickpea but increased yield and protein content in flax. Land equivalent ratio of intercropping was greater than one, showing improved land productivity (2%–23% greater than monocropping). Intercropping reduced Ascochyta blight disease incidence and severity; the 50% chickpea–50% flax and 30% chickpea–70% flax intercropping configurations could reduce the disease severity to 50% (in Huntley) and 67% (in Sidney) of that in the monocropping. These results indicated that seed ratio and planting configurations of chickpea–flax intercropping may be manipulated to increase land use efficiency and reduce Ascochyta blight in chickpea. Canadian Development Center ‘CDC Leader’ yielded greater than Royal in the higher disease pressure environment in Huntley indicated that selection of disease resistant cultivars is important for managing Ascochyta blight in chickpea.

Antifungal potential of volatiles produced by Bacillus subtilis BS-01 against Alternaria solani in Solanum lycopersicum.

Bacterial biocontrol agent/s (BCAs) against plant diseases are eco-friendly and sustainable options for profitable agricultural crop production. Specific beneficial strains of Bacillus subtilis are effective in controlling many fungal diseases including Alternaria blight caused by a notorious pathogen "Alternaria solani". In the present study, the biocontrol attributes of a newfangled strain of B. subtilis (BS-01) have been investigated and its bioactive compounds were also identified against A. solani. The volatile organic compounds (VOCs) produced by BS-01 in organic solvents viz., n-hexane, dichloromethane, and ethyl acetate were extracted and their antifungal efficacy has evaluated against A. solani. Also, the preventive and curative biocontrol method to reduce the fungal load of A. solani was estimated by both foliar and seed applications on infected tomato (Solanum lycopersicum) plants as determined by quantitative PCR assays. Growth chamber bioassay revealed that both foliar and seed application of BS-01 on tomato plants previously or subsequently infected by A. solani significantly reduced the pathogen load on inoculated tomato foliage. Results showed that antifungal bioassays with various concentrations (10-100 mg mL-1) of extracted metabolites produced by BS-01 in ethyl acetate fraction showed the highest inhibition in fungal biomass (extracellular metabolites: 69-98% and intracellular metabolites: 48-85%) followed by n-hexane (extracellular metabolites: 63-88% and intracellular metabolites: 35-62%) and dichloromethane (extracellular metabolites: 41-74% and intracellular metabolites: 42-70%), respectively. The extracted volatile compounds of BS-01 were identified via GC-MS analysis and were found in great proportions in the organic fractions as major potent antifungal constituents including triphenylphosphine oxide; pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl); pyrrolo[1,2-a] pyrazine-1,4-dione, hexahydro-3-(phenylmethyl); n-hexadecanoic acid; n-tridecan-1-ol; octadecane; octadecanoic acid; eicosane and dodecyl acrylate. Separate or mixture of these bioactive VOCs had the potential to mitigate the tomato early blight disease severity in the field that would act as a sustainable plant protection strategy to generate profitable tomato production.

Effects of Combination of Copper Fungicide and Plant Activator on Late Blight and Quality Criteria of Potato

Late blight caused by Phytophthora infestans is one of the most important fungal diseases that cause damage to both the green parts and tuber of the potato plant and limits potato cultivation. Systemic fungicides are mostly preferred by farmers in the control of potato late blight. The fact that systemic fungicides cause health problems in terms of human and environmental health has revealed the need for research on control methods that do not threaten environmental health. In recent years, successful results have been obtained in the control of many diseases with plant activators known as Induced Systemic Resistance (ISR) promoters. This study was carried out in the spring season of 2016-2017 to observe the effect of copper fungicide and plant activator (Lactobacillus acidophilus fermentation product) combination on the control of potato late blight disease and some quality criteria of potato tubers in the experimental plots of Ege University Ödemiş Vocational School in Ödemiş district of İzmir province. The experiment was planned as two separate experiments with Marabel and Melody potato cultivars. The experiment was established according to a split-plot experimental design with four replications. In this study, the effect of the treatments on potato quality and yield criteria such as tuber number, tuber width, tuber length, single tuber weight, yield per decare, and the effects of the pesticides on potato late blight disease and disease severity parameters were evaluated. When the data obtained as a result of the study were evaluated, it was determined that the combination application had a positive effect on the control of potato late blight disease in both potato cultivars compared to the control plots. When the quality criteria of potato tubers were evaluated, the highest number of tubers was obtained from the plots where copper fungicide and plant activator (Isr-2000) combination was applied. Significant increase was obtained in potato quality and yield criteria such as tuber width, tuber length, average tuber weight and yield per decare when the combination plots were compared with the control plots. In conclusion, the use of contact fungicides and plant activator combinations in the control of late blight in the spring period within the scope of sustainable agriculture is promising as an application alternative in the control of plant diseases in organic agriculture.

Biocontrol and plant growth promotion potential of endophytic Bacillus subtilis JY-7-2L on Aconitum carmichaelii Debx.

Aconitum carmichaelii Debx. is a famous medicinal plant rich in alkaloids and widely used to treat various human diseases in Asian countries. However, southern blight caused by Sclerotium rolfsii severely hampered the yield of A. carmichaelii. Beneficial microbe-based biological control is becoming a promising alternative and an environmentally friendly approach for the management of plant diseases. In this study, we evaluated the biocontrol potential of an endophytic bacterial strain JY-7-2L, which was isolated from the leaves of A. carmichaelii, against southern blight in vitro and by a series of field experiments. JY-7-2L was identified as Bacillus subtilis based on multi-locus sequence analysis. JY-7-2L showed strong antagonistic activity against S. rolfsii in vitro and on A. carmichaelii root slices by dual-culture assay. Cell-free culture filtrate of JY-7-2L significantly inhibited the hyphal growth, sclerotia formation, and germination of S. rolfsii. In addition, volatile compounds produced by JY-7-2L completely and directly inhibited the growth of S. rolfsii. Furthermore, JY-7-2L was proved to produce hydrolytic enzymes including glucanase, cellulase, protease, indole acetic acid, and siderophore. The presence of bacA, fenA, fenB, fenD, srfAA, and baeA genes by PCR amplification indicated that JY-7-2L was able to produce antifungal lipopeptides and polyketides. Field trials indicated that application of the JY-7-2L fermentation culture significantly reduced southern blight disease severity by up to 30% with a long-acting duration of up to 62 days. Meanwhile, JY-7-2L significantly promoted the fresh and dry weights of the stem, main root, and lateral roots of A. carmichaelii compared to non-inoculation and/or commercial B. subtilis product treatments. Taken together, JY-7-2L can be used as a promising biocontrol agent for the control of southern blight in A. carmichaelii.