Abstract: Background and Objective: Sesame is an oil crop that has been cultivated in Egypt for hundreds of years. Sesame crop suffers from various soil-borne diseases. Charcoal root rot caused by Macrophomina phaseolina (Tassi.) Goid, is considered one of the main destructive diseases of this crop. The current research was conducted to evaluate the efficacy of biofumigation using the Brassica crops (rocket, cauliflower and radish) on root rot disease of sesame. Materials and Methods: Naturally infected roots of the diseased sesame plants were collected in two successive seasons (2017 and 2018), three biofumigant crops i.e. radish (Raphanus sativus), cauliflower (Brassica oleracea var. Botrytis) and rocket (Eruca sativa) were used as compared with the fungicide Rhizolex-T on mycelial growth of Macrophomina phaseolina in vitro. Obtained data were statistically analyzed using one-way analysis of variance MSTAT. Results: In the first season the cauliflower treatment was not significantly different from that of the fungicide Rhizolex-T in the field experiment. Obtained data showed that Cauliflower biofumigation and Rhizolex-T treatments have resulted in the lowest disease severity levels (2.000, 2.000) 80 days after transplanting. Moreover, Cauliflower-biofumigation and Radish-biofumigation showed the lowest severity levels 2.000, 2.000 at 80 days after transplanting in the second season respectively. There were no significant differences between all tested treatments 60 days after transplanting in 2017. Conclusion: The results of this research demonstrated that biofumigation using the studied brassica crops may provide high efficacy of safe and economical control of charcoal rot of sesame. PubDate: 22 August, 2020
Abstract: Background and Objective: Cassava (Manihot esculenta, Crantz) is one of the most important staple food crops in Togo after maize. Cassava mosaic disease (CMD) is transmitted either through infected cuttings or by whiteflies. This study was to evaluate the incidence of begomoviruses causing CMD in the country’s cassava fields and updating knowledge of these viruses could help to better manage CMD in Togo. Materials and Methods: An initial investigation of viruses which might account for these symptoms was carried out using symptomatic as well as asymptomatic samples collected during epidemiological surveys performed in 2015 (472 samples) and 2017 (300 samples). Virus identification was carried out using PCR. Results: The presence of two strains of cassava mosaic begomoviruses (CMBs): African cassava mosaic virus (ACMV) and East African cassava mosaic virus (EACMV). The CMB incidence was lower in 2017 (12.42%) than in 2015 (26.23%) and ACMV was the dominant CMB across the regions sampled. Conclusion: The results indicate that good cultural practices and introduction of resistant cultivars, together with continuous disease monitoring, are required to reduce the impact of CMD in Togo. PubDate: 22 April, 2020
Abstract: Background and Objective: Bacillus spp. have a wide range of activities in the biocontrol potential against various phytopathogens. This study was focused to identify the antagonistic bacteria and to evaluate for their efficacy against the bacterial pathogens of potato. Materials and Methods: Bacillus sp. strains BB06, BB10, CF58 and CR74 were previously isolated from the rhizosphere. They were identified by 16S rRNA gene and gyrA gene. The strains were tested for hydrolytic enzyme and plant growth-promoting activities. Also, the strains were analyzed the surfactin antibiotic by LCMS-QTOP. Results: Based on the 16S rRNA gene and gyrA gene sequence analyses, the strains were identified as Bacillus velezensis. All strains showed a broad inhibitory spectrum and produced zones of inhibition against bacterial pathogens of potato, included Pectobacterium carotovorum subsp. brasiliense, Dickeya dadantii, Bacillus altitudinis and Ralstonia solanacearum. The results of in vitro assays showed that all isolates can produce protease, amylase, cellulase, lipase, IAA (auxin), siderophores and phosphate solubilization. Further analysis of the surfactin antibiotic by LCMS-QTOP, revealed the characteristic molecular ions mode [M-H-] with an m/z around 1034. The strains showed analogous biofilm formation to support the biocontrol properties. Conclusion: B. velezensis strain BB06, BB10, CF58 and CR74 can be recommended as potential biocontrols. PubDate: 16 November, 2020
Abstract: Background and Objective: Botrytis is a serious fungal pathogen which infects most ornamental plants and its resistance to effective fungicide is a continuous challenge facing disease management. The current research aimed to identify resistant Botrytis spp. from different ornamental plants against fenhexamid. Materials and Methods: About 64 single-spore isolates were collected from different symptomatic and asymptomatic ornamental plants using the modified Kerssies medium, m1KERS. Phenotypic variability was shown in some features including growth texture, sclerotia pattern and conidial dimensions. Pathogenicity and mycelial growth rate tests were statistically carried out using one way analysis of variance (ANOVA). Molecular characterisation was demonstrated by transposable elements (TEs) analysis and fenhexamid resistance was revealed using mycelial growth assay. Results: All isolates were identified as Botrytis spp. according to their morphological and molecular characteristics. Based on phylogenetic analysis, BCLi1 isolate seemed to be distantly related to B. cinerea and other Botrytis species. Significant variation in aggressiveness among isolates was observed on detached lettuce leaves. Four TE genotypes, transposa, boty, flipper and vacuma, were detected in Botrytis populations with TE distribution reached 50, 29.7, 10.9 and 9.4%, respectively. The low virulence level of some Botrytis spp. isolates seemed to be related to vacuma isolates suggesting a possible correlation between virulence and TE genotype. Moreover, a low to moderate resistance of Botrytis spp. isolates was revealed towards the hydroxyanilide fungicide, fenhexamid, in three transposa isolates, BCT6, BCGL2 and BCGL5, with a mean EC50 value of 0.2, 0.3 and 0.5 μg mL–1, respectively. Conclusion: The results demonstrated the first observation of the emergence of resistant isolates of Botrytis from ornamental plants against the highly effective fungicide in Egypt, providing a serious attention towards Botrytis management. PubDate: 09 March, 2020
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