Incidence Of Leaf Spot Disease Research Articles

Plant density and variety effect on yield, leaf spot disease, weed species richness and diversity of groundnut production in northern Ghana

AbstractLow plant density and weed infestation are major challenges for groundnut production in northern Ghana. A two‐year on‐farm study was conducted to determine the effect of plant density and variety on grain and fodder yields, incidence of leaf spot disease, weed species diversity and biomass. A factorial treatment combination of 6 varieties and 4 plant densities laid in strip plot design with 4 replications was used. The varieties were (early maturity type: Chinese, Yenyewoso, Samnut 23 and late maturity type: Azivivi, Manipinta, Samnut 22). The plants density included 9, 11, 15 and 22 plants/m2. The late maturity varieties recorded higher (p < .05) canopy cover, grain and fodder yields relative to that of the early maturity varieties. The late maturity varieties also recorded the least sedge weed species frequency, density and incidence of leaf spot disease compared with that of the early maturity varieties. The canopy cover, grain and fodder yields increased with increasing plant density. Broadleaf weed species frequency and density, weed biomass, richness, and diversity declined with increasing plant density. Grain yield showed negative and significant correlation with broadleaf weed species frequency, density and weed biomass. The results suggest that both early and late maturity groundnut varieties can be planted at a density of 22 plants/m2 to increase grain and fodder yields and reduce weed species richness, diversity and growth in northern Ghana and similar agro‐ecology in West Africa.

First Report of Panax notoginseng Leaf spot Disease Caused by Boeremia exigua in China.

Panax notoginseng a perennial herb native to China, is widely grown in the Yunnan Province. (Yang et al. 2022). From July to August 2022, a new leaf spot disease was observed on fully expanded leaves of P. notoginseng from a planting base in the Xundian, Yunnan Province, China. Approximately 250 ha. of P. notoginseng is the cultivated area, and the incidence of leaf spot disease was around 10-15%. Round spots appeared on the infected leaves and as the disease progressed these leaves fell off the plant. A total 21 symptomatic leaves were randomly collected from the planting base to isolate the pathogens and further study in the laboratory. The surface of infected leaves were sanitized with 0.5% sodium hypochlorite for 2 min. and 75% alcohol for 1 min., and then rinsed thrice with sterile water. Once drying, the samples were placed on potato dextrose agar (PDA), plates and incubated at 25 °C for 5 days. The fungus was isolated from the symptomatic tissue, but only three isolates were preserved for further identification. Pure cultures of the representative strain Zhaochanglin 118 were obtained using the singlespore method, and the colonies obtained were dark-green to dark-black in appearance. The pycnidia were dark brown, solitary, or congregated with an inconspicuous neck. The conidia were colorless, ellipsoidal, and measured between 4.5 to 7 × 2 to 3 μm (n = 30). These morphological characteristics were similar to those described for Boeremia exigua (Valenzuela-Lopezi et al. 2018). The genomic DNA of the isolate was extracted using the DN14 cetyltrimethylammonium bromide rapid plant genome extraction kit. The internal transcribed spacer (ITS), RNA polymerase second largest subunit (RPB2) and translation elongation factor 1-alpha (TEF1) genes were amplified via polymerase chain reaction using the primers ITS1/ITS4 (White et al. 1990), Af/Cf (Matheny et al. 2002), and EF1-983F/EF1-2218R (Chen et al. 2015), respectively. All sequences were deposited in GenBank (OQ996531 for ITS; OR291158 for RPB2 and OR291159 for TEF1). A BLASTN homology search using the ITS nucleotide sequence indicated that this has 99.6% identity with the sequence MH859059, named B. exigua from CBS culture collection (517/519 bp); the RPB2 sequence has 97.5% identity with sequence GU371780, named B. exigua from CBS culture collection (704/722 bp); and the TEF1 sequence has 98.4% identity with sequence GU349080, named B. exigua from CBS culture collection (871/885 bp). To test Koch's postulates, a pathogenicity test was carried out on the leaves of six fully expanded P. notoginseng plants in the Xundian planting base. Conidial suspensions were prepared for one isolates at a concentration of 106 spores per milliliter. Three leaflets on different plants were applied with 20µl spore suspension and the other three leaflets were drop of 20 µl sterile distilled water. The whole experiment was repeated three times. The P. notoginseng plants were incubated under sterile conditions at 25°C for 7 days. Inoculated leaves showed the characteristic brown round spots, while control leaves were asymptomatic so, Koch's postulates were fulfilled by re-isolating the pathogen from symptomatic tissue, which was subsequently confirmed as B. exigua through morphological and molecular analyses. Koch's postulates were fulfilled. To our knowledge, this is the first report of B. exigua causing leaf spot disease in P. notoginseng in China, which lays a foundation for further study and developing disease control methods.

Confectionery Groundnut Genotypes (Arachis hypogaea L.): A Study on Genetic Variability Parameters with Special Reference to Confectionery Traits Improvement

Diverse groundnut parents were used to generate 36 advanced breeding lines to develop into a confectionery genotype for yield, quality, and main biotic stress. Groundnut use is increasing in both food and confectionary due to the steady change in groundnut consumption patterns. Advanced breeding lines evaluated in randomized complete block design including parents and checks during kharif and summer, 2021 respectively. High genetic variability (%) and heritability (%) observed for hundred seed weight (21.08 & 86.34), pod yield per plant (25.37 & 87.66), pod yield (31.63 & 83.71), late leaf spot (32.71 & 79.16), rust disease (39.86 & 87.06), oil content (2.55 & 79.60), Blanchability (18.76 & 97.00), oleic acid (8.52 & 72.90), linoleic acid (16.32 & 73.40) and O/L ratio (24.64 & 73.60) respectively. The correlation between hundred seed weight, sound mature kernels, shelling percentage and pod yield per plant with kernel yield showed positive association. Rust and LLS disease revealed a high positive connection indicating that an increase in late leaf spot disease incidence enhances the incidence of rust disease and vice versa in groundnut. Substantial negative association was found between two crucial quality parameters such as oil content and protein content, as these two characteristics determine the quality of groundnut for confectionary purposes. Path analysis indicates kernel yield had the greatest direct positive effect on pod yield, followed by seed weight, oil content and sound mature kernel and direct selection for these characteristics would be effective. The path analysis of quality attributes revealed that at the genotypic level, oil content, protein content, and O/L ratio have the most direct effect on hundred seed weight.

Analisis Perbandingan Perkembangan Penyakit Bercah Daun (Cercospora capsici) pada Tanaman Cabai Merah (Capsicum annuum L) di Dataran Tinggi dan Dataran Rendah selama Musim Hujan Studi Kasus di Kabupaten Karo dan Deli Serdang

This study aims to analyze the comparison of the development of leaf spot disease (Cercospora capsici) in red chili plants (Capsicum annuum L.) in highland and lowland areas during the rainy season. Leaf spot disease is a serious problem that hinders proper growth in chili plants. The research was conducted in December 2022 using a descriptive survey method, focusing on the issue of leaf spot disease in chili plants in farmers' fields. The results showed that the average percentage of symptomatic chili plants affected by leaf spot disease in the highland area was 50.89%, while in the lowland area, it was 29.77%. The average level of leaf spot disease incidence in the highland was 26.79%, whereas in the lowland, it was 24.61%. From these findings, it can be concluded that leaf spot disease (Cercospora capsici) has a higher incidence rate in red chili plants in the highland compared to the lowland during the rainy season. Knowledge of this difference can assist farmers in taking appropriate preventive or intervention measures to address disease outbreaks in red chili plants in both regions.

Role of potassium, magnesium, sulphur and copper nutrients on groundnut late leaf spot disease dynamics

Plant protection strategies need an effective alternative mode that reduces chemical load on environment and financial burden on farmers. Mineral nutrition, an integral part of crop production has long since proven to be a promising management strategy. Due to high specificity of host-pathogen-nutrient relationship, precise investigation has to be taken before recommendation. Among the various methods to screen infection frequency and disease tolerance with respect to applied treatments, components of resistance (incubation period, latent period, number of leaf spots, and lesion diameter) studied in hydroponically grown plants under greenhouse conditions are more appropriate than detached leaf assay as disease development of late leaf spot caused by the hemibiotroph., Phaeoisariopsis personata is more akin to the disease development under field conditions. Role of four nutrients i.e., Potassium, Magnesium, Sulphur and Copper deficient conditions as well as supplementation alone and in combination on groundnut late leaf spot disease incidence was compared with fungicidal check (Tebuconazole seed treatment) in terms of components of resistance and anti-oxidant enzyme activities using sand culture. Deficiency of nutrients showed higher disease incidence than control suggesting the role of nutrients in offering resistance to infection. Further it is revealed that CuSO4 and combination of four nutrients were effective in delaying incubation (11.67 days, 12.33days) and latent period (16.67 days, 17.00 days) while MgSO4 followed by combination of four nutrients were effective in reducing lesion number (17.65/leaf, 22.15/leaf) and diameter (0.20 and 0.27 mm) thus lowered AUDPC which showed similar antioxidant enzyme activity as fungicidal check. Nutrient supplementation though inferior to fungicidal check (14 days incubation period, 18.33 dayslatent period, 1.95 lesions/leaf with 0.22mm diameter), wassignificantlysuperior to control (10.33 daysincubation period, 13.67 days latent period, 70.15lesions/leaf with 0.33mm diameter). Hence, application of adequate amount of nutrients improves plants growth as well as resistance to LLS infection.

Aplikasi Pestisida Nabati dan Trichokompos terhadap Penyakit Bercak Daun (Cercospora oryzae) pada Padi Beras Merah di Lahan Basah

Cultivation of brown rice (Oryza nivara L.) in wetlands continues to expand because its consumers continue to increase. This study aims to determine the ability of Trichocompost and a solution of botanical pesticides from kalakai, babadotan and purun tikus in controlling brown spot disease caused by the fungus Cercospora oryzae on brown rice plants in wetlands. Based on the results of observations, the application of trichocompost and purunrat solution was able to reduce the incidence of leaf spot disease from 95.1% in controls to 76.5%. The results of disease intensity showed that the application of trichocompost and kalakai solution was able to reduce disease intensity from 19.55% in controls to 14.10%. The application of trichocompost and babadotan solution increased the number of grains of rice from 216.60 grains in the control to 243.20 grains. The application of Trichocompost and kalakai solution increased the weight of 100 grains from 1.79 g to 2.10 g. The application of only trichocompost, Trichocompost and kalakai solution, trichocompost and babadotan solution, and trichocompost and purunrat solution have the same ability to reduce the incidence and intensity of Cercospora disease. All treatments tested were unable to increase plant height growth.

In vivo and In vitro evaluation of the antifungal activity of the PGPR Bacillus amyloliquefaciens RaSh1 (MZ945930) against Alternaria alternata with growth promotion influences on Capsicum annuum L. plants

Alternaria alternata that threatens pepper production and causes major economic harm is responsible for the leaf spot/blight disease. Chemical fungicides have been widely employed; unfortunately, fungicidal resistance is a current concern. Therefore, finding new environmentally friendly biocontrol agents is a future challenge. One of these friendly solutions is the use of bacterial endophytes that have been identified as a source of bioactive compounds. The current study investigates the in vivo and in vitro fungicidal potential of Bacillus amyloliquefaciens RaSh1 (MZ945930) against pathogenic A. alternata. In vitro, the results revealed that RaSh1 exhibited strong antagonistic activity against A. alternata. In addition to this, we inoculated pepper (Capsicum annuum L.) plants with B. amyloliquefaciens RaSh1 and infected them with A. alternata. As a result of A. alternata infection, which generated the highest leaf spot disease incidence (DI), the plant's growth indices and physio-biochemical characteristics significantly decreased, according to our findings. Our results also showed the abnormal and deformed cell structure using light and electron microscopy of A. alternata-infected leaves compared with other treatments. However, DI was greatly reduced with B. amyloliquefaciens RaSh1 application (40%) compared to pepper plants infected with A. alternata (80%), and this led to the largest increases in all identified physio-biochemical parameters, including the activity of the defense-related enzymes. Moreover, inoculation of pepper plants with B. amyloliquefaciens RaSh1 decreased electrolyte leakage by 19.53% and MDA content by 38.60% as compared to A. alternata infected ones. Our results show that the endophyte B. amyloliquefaciens RaSh1 has excellent potential as a biocontrol agent and positively affects pepper plant growth.

Influence of tillage systems and sowing dates on the incidence of leaf spot disease in Telfairia occidentalis caused by Phoma sorghina in Cameroon

The production and leaf quality of Telfairia occidentalis in Cameroon are gravely threatened by leaf spot disease. A field study was conducted in July 2019 and 2020 to determine the influence of tillage systems and sowing dates on the incidence of Telfairia occidentalis leaf spot caused by Phoma sorghina. A randomized block design with three replications and four planting dates was used. The soil physicochemical properties were also determined. Data for disease incidence were registered once every two weeks and submitted to generalized linear model for statistical analysis. The means were separated by Duncan’s multiple range test at a 95% confidence interval. Calculations for disease incidence and statistical analysis were conducted using the Microsoft Excel program and SPSS version 23, respectively. Statistical analysis revealed that the zero tilled field generally registered a lower leaf spot disease incidence than the tilled field, which was highly significant (p ≤ 0.05). In addition, the second sowing date in the zero tilled field proved to be better in terms of low disease incidence than other sowing dates employed in the study. Therefore, to minimize the devastating effects of leaf spot disease, zero tillage coupled with the second sowing date could be exploited.

Influence of Plant Spacing and Intercropping on the Growht and Septoria Leaf Spot of Tomato (Lycopersicon esculentum Mill)

The influence of plant spacing and intercropping on the growth and septoria leaf spot disease incidence and severity of tomato were studied in Owerri, the south east of Nigeria, in the year 2011.The study was designed as a 4x4 factorial in a Randomized Complete Block Design with three (3) replications. Data on growth parameters and septoria leaf spot disease incidence and severity of tomato were collected and statistically analyzed by using Gensat version 4 analytical software, while the means were separated for difference using Fisher’s Least Significant Difference Protocol. The result showed a significant (P<0.05) reduction of septoria leaf spot disease incidence to 0.00% by intercropping at the distance of 75 x 50 cm under tomato sole cropping arrangement. The intercrop combination of tomato/groundnut/soybean also significantly (P<0.05) reduced septoria leaf spot disease incidence (6.7%) under the spacing of 100 x 75 cm. Intercropping significantly (P<0.05) influenced septoria leaf spot disease severity at 6 weeks of transplanting. Similarly, plant spacing of 75 x 50 cm and under the tomato sole crop arrangement significantly reduced the tomato septoria leaf spot disease severity.

Effects of timothy Cladosporium eyespot on photosynthesis and biomass.

Timothy is a forage mainly grown in Min County, Gansu Province, China. In 2021, a leaf spot disease outbreak on timothy grass occurred in Min County, adversely affecting its growth and productivity. Therefore, this study investigated the leaf spot disease incidence in Min County, morphologically and molecularly characterized the disease-causing pathogen, and assessed its effects on the growth, photosynthesis, and biomass of timothy seedlings re-inoculated with the isolated pathogen. In the field, the disease incidence on plants and leaves was 100 and 85%, respectively. Morphologically, young lesions were ellipsoidal-fusiform with dark purple margins and an off-white center, while the mature lesions were eye-shaped spots with a light brown center and dark purple edges. Molecular characterization identified the pathogen as Cladosporium phlei causing Cladosporium eyespot disease. The net photosynthetic rate, transpiration rate, fresh shoot weight, and dry shoot weight of timothy seedlings 14days after inoculation with the pathogen were decreased by 29.77, 56, 45.45, and 46.42%, respectively, implying that Cladosporium eyespot disease is an important timothy grass disease in Min County. Therefore, developing an integrated control strategy is urgent to lessen the economic loss.

INCIDENCE AND YIELD LOSS OF LEAFSPOT DISEASE OF STRAWBERRY IN TASHKENT REGION

The article presents the data on prevalence and development of leafspot (white spot) disease of strawberry in the farms of Tashkent region. The influence of the age of the strawberry plantation on the accumulation of infection of the pathogen has been revealed herein. It has been also noted that strawberry has the highest incidence of leafspot disease during the vegetation period. KEY WORDS: leafspot, fungus, infection, conidium, varieties, incubation period, tissue, pure culture, nutrient media, pathogen, saprophyte.

Agroecological Screening of Copper Alternatives for the Conservation of Soil Health in Organic Olive Production

The efficacy of soil conditioner (vermicompost tea), fertiliser (potassium silicate), and biological control agents (BCAs) as practical agroecological copper alternatives against olive leaf spot (Spilocaea oleaginea (Cast.) Hughe.) disease was investigated between 2018 and 2021 under organic management in a Mediterranean climate. In total, 9 agroecological alternatives to copper oxychloride (vermicompost tea, potassium silicate, Bacillus subtilis EU 007 WP, Platanus orientalis leaf extract, Mycorrhiza mix, seaweed commercial product, Trichoderma citrinoviride TR1, vermicompost tea+Platanus orientalis mix, Penicillium (Mouldy bread pieces)) were applied to olive trees in a randomised block design with 4 replicationsTotal water soluble phenol compounds (TWSP) were found to be the main bioindicator to assess the alternatives and their potential to phase-out copper application. Results related to TWSP indicated that copper oxychloride (control), potassium silicate and vermicompost tea showed significantly higher content of TWSP as we compared zero application of copper and other treatments. These stimulate the antioxidant capacity in olive fruits and reduce the olive leaf spot disease incidence. The pollution effect of copper was monitored during the trial to identify soil pollution in the organic in-conversion experimental land. The total annual ‘active copper’ application was 4.7 kg.ha−1.year−1 and this is in accordance with the legal organic legislation of Turkey. During the conversion period from conventional to organic management, we determined approximately 50% reduced copper content in the soil 0–30 cm depth samples in 2020 (3.70 mg.kg−1) as it is compared to those initial samples (6.43 mg.kg−1) in 2018. We conclude that alternatives to copper that are easily accessible, e.g., vermicompost tea, have a potential for use in organic olive production to replace copper in mitigating olive leaf spots. Furthermore, we find that reduced copper application in organic management with the aim to decrease copper accumulation in soil, fruits and leaves was not yet enough to reduce copper to satisfactory levels. We conclude that further research with the aim of a total replacement of copper fungicide treatments in organic and non-organic systems is needed.

Hybridization of Chitosan and Biosynthesized Silver Nanoparticles to Enhance Antimicrobial Activity against Phytopathogens in Tomato (Solanum lycopersicum)

Chitosan-hybridized biogenic silver nanoparticles (Ch@BSNP) were synthesized with the extracellular metabolites of Trichoderma viride. Chitosan hybridization- and T. viride-derived compounds associated with the particles were confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM)-energy dispersive X-ray analysis (EDX), and gas chromatography–mass spectrometry (GC–MS) analysis. The particles had a ζ-potential 19.2 mV and a hydrodynamic size of 97.74 nm with a polydispersity index (PDI) of 0.198. TEM analysis revealed particles of spherical shape and actual size range between 30 and 35 nm. The antimicrobial activity of these particles was compared to chitosan alone and nonhybridized particles against three bacterial phytopathogens, viz, Pseudomonas syringae, Erwinia chrysanthemi, and Xanthomonas campestris. The zone size was 50.0, 29.75, and 34.00 mm with Ch@BSNP, respectively, while the corresponding values for BSNP were 29.75, 23.5, and 18.00 mm. In a liquid culture assay, exposure to Ch@BSNP significantly decreased the size of bacterial cells from 3905.00 to 2711.00 nm for P. syringae, from 3484.00 to 3386.00 nm for E. chrysanthemi, and from 7823.33 to 5956.33 nm for X. campestris. Similar increased activity of Ch@BSNP was also observed against four fungal plant pathogens, viz, Sclerotium rolfsii, Rhizoctonia solani, Alternaria alternata, and Alternaria brassicicola. The Ch@BSNP also demonstrated lower toxicity on noncancerous human cell lines than antimicrobial efficacy. In a greenhouse study, Ch@BSNP reduced the leaf spot disease incidence in tomato by up to 60% and also enhanced several physical and physiological attributes, viz, root and shoot lengths, fresh and dry weights, and chlorophyll and carotenoid contents compared to the diseased plant. These observed beneficial effects and overall biocompatibility of Ch@BSNP suggest that this material may be a safe and effective antimicrobial bioagent for sustainable nano-enabled agriculture.

In vitro antioxidant and antifungal activities of different solvent extracts of leaf peel and gel of Aloe succotrina and their bio-control of leaf spot disease of Phaseolus vulgaris seedlings

Phytochemical constituents, in vitro antioxidant and antifungal activities of leaf peel and gel of Aloe succotrina (Xanthorrhoeaceae) using different solvents, n-butanol, ethylacetate, water and methanol, were evaluated. The antifungal effects of these different solvent extracts against pathogenic fungi, Alternaria alternata, Cladosporium cladosporioides and Cochliobolus specifer, causing leaf spot disease of seedlings of Phaseolus vulgaris were evaluated. In addition, their effects on different growth attributes and metabolite content of treated P. vulgaris seedlings were measured. Highest flavonoid content was measured in the ethylacetate extract, while, the highest concentrations of saponins and tannins were measured in butanol extract. Water and methanol exhibited higher phenolic content. All solvent extracts of leaf peel and gel of A. succotrina could be categorized as strong radical scavengers based on their respective inhibitory concentration at 50% scavenging activity (IC50) values. The highest total antioxidant capacity (TAC) was measured for the methanol leaf peel extract [194.04 mg ascorbic acid (AA) equivalent /g dry weight (DW)]. Alternaria alternata was the most resistant species showing the least growth inhibition percentages in vitro antifungal assays. All plant extracts exhibited considerable growth inhibition (> 70%) with C. cladosporioides referring to its pronounced susceptibility. The leaf spot disease incidence of P. vulgaris seedlings was completely disappeared after seedlings treatment by the methanol leaf peel extract of A. succotrina. Moreover, most measured seedlings growth attributes, e.g., the shoots and roots lengths, the contents of photosynthetic pigments and carbohydrates were significantly enhanced. The methanol extracts of leaf peel of A. succotrina could be considered as potential sources of antioxidant as well as antifungal compounds to control A. alternata leaf spot disease. Treatment of P. vulgaris with water leaf and gel extracts of A. succotrina improved its growth attributes and resistance against leaf spot caused by Cladosporium cladosporioides and Cochliobolus specifer.

Incidences of fungal leaf spot disease in buffel grass (Cenchrus ciliaris) in some selected pasture farms in Tanzania

Buffel grass (Cenchrus ciliaris L.) is one of the important perennial forage grasses in the pasture farms of Tanzania. It is highly nutritious, drought-resistant, grazing-tolerant, and with rapid growth characteristics. Field observation of leaf spot disease in buffel grass was conducted during the months of April, May, and July 2012 at three pasture farms in Tanzania. Laboratory and greenhouse fungal pathogenicity studies for buffel grass seedlings were conducted at Sokoine University of Agriculture, Morogoro, Tanzania. This study was set to investigate the health status of buffel grass from selected pasture seed farms for screening seed-borne fungal species of economic importance. It was also set to establish the pathogenic fungi effects on leaves of buffel grass seedlings.The incidence of leaf spot disease in buffel grass was 54%. Fungal pathogens of economic importance that were detected in this study include Phoma spp (28.5%), Curvularia lunata (17.34%), Alternaria alternata (14.1%), and Bipolaris spp. (12.2%). Pathogenicity of Bipolaris spp. Phoma spp., Pyricularia grisea, Fusarium pallidoroseum, Exserohilum rostratum, and Nigrospora oryzae were confirmed on C. ciliaris seedlings. The highest disease incidence was observed on buffel grass seedlings sprayed with Bipolaris spp (40%), while the lowest disease incidence was observed on plants sprayed with E. rostratum (27.5%). In particular, the order of virulence of the pathogenic fungal species was Bipolaris spp > P. grisea > Phoma spp. > F. pallidoroseum > E. rostratum (40%, 37.5%, 35.0%, 32.5%, and 27.5%, respectively). All identified pathogenic fungi species are seed-borne and with reported ability to cause leaf spot diseases in several other tropical forage grass species. Further research on innovative technologies and practices for controlling fungal infectious diseases in buffel grass seeds and leaves is suggested.

Diversity, biocontrol, and growth promotion potential of culturable endophytic fungi isolated from root, shoot, and leaf of wild Phoebe bournei Yang across seasons

Endophytic fungi were isolated from Phoebe bournei (Hemsl.) Yang, and their diversity and antimicrobial and plant-growth-promoting activities were investigated. Of the 389 isolated endophytic fungi, 88.90% belonged to phylum Ascomycota and 11.10% to phylum Basidiomycota. The isolates were grouped into four taxonomic classes, 11 orders, 30 genera, and 45 species based on internal transcribed spacer sequencing and morphologic analysis. The host showed a strong affinity for the genera Diaporthe and Phyllosticta. The diversity of the fungi was highest in autumn, followed by spring and summer, and was lowest in winter. The fungi exhibited notable tissue specificity in P. bournei, and the species richness and diversity were highest in the root across all seasons. Five isolates showed antimicrobial activity against eight plant pathogens and reduced the incidence of leaf spot disease in P. bournei. Additionally, nine biocontrol isolates showed plant-growth-promoting activity, with five significantly promoting P. bournei seedling growth. This is the first report on the endophytic fungi of P. bournei and their potential applicability to plant disease control and growth promotion.

English

The study was conducted to test the antifungal efficacy of J. curcas leaf extracts against Phaeoisariopsis personata (causal pathogen for groundnut late leaf spot disease) under in vivo conditions, and to identify important phytochemical constituents exhibiting antifungal properties. The results showed that the greatest reduction of late leaf spot disease incidence was achieved by all the Jatropha curcas leaf extracts at the highest concentration (0.5 mg mL-1) as 36.89, 36.59 and 24.67% for chloroform, ethyl acetate and methanolic extracts, respectively. Subsequently, J. curcas leaf extracts treatments enhanced the growth and yield of groundnut compared with the control (untreated). The antifungal effects of J. curcas were supported by the presence of phytochemical constituents identified by GC-MS. Hexadecane; n-hexadecanoic acid; phenol, 2, 4 bis (-dimethylethyl); phytol and hexadecanoic methyl ester were detected as major phytocompounds in J. curcas leaf extracts that were possibly responsible for the antifungal activity. © 2021 Friends Science Publishers

Antifungal potential of zinc against leaf spot disease in chili pepper caused by Alternaria alternata.

The fungal pathogen, Alternaria alternata is responsible for causing leaf spot disease in many plants, including chili pepper. Zinc (Zn) an essential micronutrient for plant growth, also increases resistance in plants against diseases, and also acts as an antifungal agent. Here, in vitro effects of ZnSO4 on the propagation of A. alternata were investigated, and also in vivo, the effect of foliar application of ZnSO4 was investigated in chili pepper plants under disease stress. In vitro, ZnSO4 inhibited fungal growth in a dose-dependent manner, with complete inhibition being observed at the concentration of 8.50mM. Hyphae and conidial damage were observed along with abnormal activity of antioxidant enzymes, Fourier-transform infrared spectroscopy confirmed the major changes in the protein structure of the fungal biomass after Zn accumulation. In vivo, pathogen infection caused the highest leaf spot disease incidence, and cumulative disease index, which resulted in a significant reduction in the plant's growth (length and biomass), and physiochemical traits (photosynthetic pigment, activity of catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase). The heat map and principal component analysis based on disease, growth and, physico-chemical variables generated useful information regarding the best treatment useful for disease management. Foliar Zn (0.036mM) acted as a resistance inducer in chili pepper plants that improved activities of antioxidants (CAT and POX), and defense compounds (PPO and PAL), while managing 77% of disease. The study indicated foliar ZnSO4 as an effective and sustainable agriculture practice to manage Alternaria leaf spot disease in chili pepper plants.

Detection of leaf spot disease of banana caused by Alternaria sp. in Gujarat, India

A symptomatic leaf spot diseased samples were collected and responsible pathogenic fungus was isolated from the banana field near Bakrol, Gujarat, India. The morphological and molecular characterisation identified this fungus to be Alternaria sp. The pathogenic fungus was repeatedly isolated from symptomatic leaf spot in detached banana leaf assay which fulfilled the Koch’s postulates for this pathogen. To the best of our knowledge, this is the first report of incidence of leaf spot disease caused by Alternaria sp. on banana plant in Gujarat, India.

Canola Growth Stage at Time of Infection Determines Magnitude of White Leaf Spot (Neopseudocercosporella capsellae) Impact.

White leaf spot (Neopseudocercosporella capsellae) is a persistent and increasingly important foliar disease for canola (Brassica napus) across southern Australia. To define the role of plant growth stage in the development of disease epidemics, we first investigated the response of different canola cultivars (Scoop and Charlton) at five Sylvester-Bradley growth stages against N. capsellae. White leaf spot disease incidence and severity was dependent on plant growth stage and cultivar (both P < 0.001), with plants being most susceptible at plant growth stage 1.00 (cotyledon stage) followed by plant growth stage 1.04 (fourth leaf stage). Then, to quantify the impact of this disease on canola yield, we investigated the in-field relationship of white leaf spot disease incidence and severity with seed yield loss following artificial inoculation commencing at growth stage 1.04 (fourth leaf stage). White leaf spot significantly (P < 0.001) reduced seed yield by 24% in N. capsellae inoculated field plots compared with noninoculated field plots. To our knowledge, this is the first time that serious seed yield losses from this disease have been quantified in the field. The current study demonstrates that N. capsellae disease incidence and severity on canola is determined by host growth stage at which pathogen infestation occurs. Emerging seedling cotyledons were highly susceptible, followed by less susceptibility in first true leaves to emerge, but then increasing susceptibility as plants subsequently aged toward the fourth leaf stage. This explains field observances where white leaf spot readily establishes on emerging seedlings and subsequently becomes more prevalent and severe as plants age.