Biological control of Peacock spot disease caused by Spilocaea oleagina on Olive using bacteria.

2020 ◽  
Vol 8 (1) ◽  
pp. 12-20
Author(s):  
Mazen Salman
Keyword(s):  
Leaf Spot ◽  
Latent Infection ◽  
Conidial Germination ◽  
Leaf Spot Disease ◽  
Olive Leaf ◽  
Olive Leaves ◽  
Spot Disease ◽  
Before And After ◽  
Olive Trees ◽  
Chemical Fungicides

The olive leaf spot disease caused by the fungus Spilocaea oleagina (Cast.) Hughes (syn. Cycloconium oleagina) is one of the most destructive diseases on olive trees causing losses that may reach 20% of the yield. The disease is controlled by the application of chemical fungicides which is not always feasible in providing proper protection against the pathogen. In this work we report the efficacy of Pseudomonas fluorescenc isolate ORS3 and Bascillus atrophaeus isolate Bat in controlling the disease under field conditions. An Olive field in, Tulkarm governorate, Palestine was selected. The olive trees were 5-10 years old and were highly infected with the olive leaf spot. Trees were sprayed with bacteria formulated in oil. Control trees were sprayed with water. For evaluation of bacterial efficacy against the disease, olive leaves were collected before and after application of the bacteria. Germination of conidia latent infection and severity were determined. In addition to that, bacterial viability was assessed. Results of the work revealed that the bacteria were able to inhibit conidial germination of the fungus. The percent of reduction in conidial germination (85.8 and 70.2%) in the presence of P. fluorescenc isolate ORS and B. atrophaeus isolate Bat, respectively was significantly lower than that in the control or in leaves sprayed with 10% oil (69.1 and 56.1%, respectively). After two weeks of spraying, the percent of latent infectoin (figure 4) was significantly (p<0.05) lower on leaves sprayed with P. fluorescenc isolate ORS3 and B. atrophaeus isolate BAT (5.1 and 3.8% latent infection, respectively). However, bacterial shelf life on the surface of olive leaves was reduced after three days of spraying (i.e no bacteria were re-isolated). The results indicated that the bacteria can be used for control of the leaf spot disease. Further studies are required to evaluate the efficacy of the bacteria under different environmental conditions.

Biological control of Peacock spot disease caused by Spilocaea oleagina on Olive using bacteria.

2020 ◽  
Vol 8 (1) ◽  
pp. 12-20
Author(s):  
Mazen Salman
Keyword(s):  
Leaf Spot ◽  
Latent Infection ◽  
Conidial Germination ◽  
Leaf Spot Disease ◽  
Olive Leaf ◽  
Olive Leaves ◽  
Spot Disease ◽  
Before And After ◽  
Olive Trees ◽  
Chemical Fungicides

The olive leaf spot disease caused by the fungus Spilocaea oleagina (Cast.) Hughes (syn. Cycloconium oleagina) is one of the most destructive diseases on olive trees causing losses that may reach 20% of the yield. The disease is controlled by the application of chemical fungicides which is not always feasible in providing proper protection against the pathogen. In this work we report the efficacy of Pseudomonas fluorescenc isolate ORS3 and Bascillus atrophaeus isolate Bat in controlling the disease under field conditions. An Olive field in, Tulkarm governorate, Palestine was selected. The olive trees were 5-10 years old and were highly infected with the olive leaf spot. Trees were sprayed with bacteria formulated in oil. Control trees were sprayed with water. For evaluation of bacterial efficacy against the disease, olive leaves were collected before and after application of the bacteria. Germination of conidia latent infection and severity were determined. In addition to that, bacterial viability was assessed. Results of the work revealed that the bacteria were able to inhibit conidial germination of the fungus. The percent of reduction in conidial germination (85.8 and 70.2%) in the presence of P. fluorescenc isolate ORS and B. atrophaeus isolate Bat, respectively was significantly lower than that in the control or in leaves sprayed with 10% oil (69.1 and 56.1%, respectively). After two weeks of spraying, the percent of latent infectoin (figure 4) was significantly (p<0.05) lower on leaves sprayed with P. fluorescenc isolate ORS3 and B. atrophaeus isolate BAT (5.1 and 3.8% latent infection, respectively). However, bacterial shelf life on the surface of olive leaves was reduced after three days of spraying (i.e no bacteria were re-isolated). The results indicated that the bacteria can be used for control of the leaf spot disease. Further studies are required to evaluate the efficacy of the bacteria under different environmental conditions.

scholarly journals Evaluation of garlic, BAU-biofungicide, bion and chemical fungicides in controlling leaf spot of Taro

2017 ◽  
Vol 28 (3) ◽  
pp. 167-173
Author(s):  
MAS Sohag ◽  
MT Hossen ◽  
MS Monjil
Keyword(s):  
Field Experiment ◽  
Plant Height ◽  
Leaf Spot ◽  
Disease Incidence ◽  
Foliar Spray ◽  
Leaf Spot Disease ◽  
Spot Disease ◽  
Maximum Reduction ◽  
Before And After ◽  
Chemical Fungicides

The field experiment was conducted to evaluate the efficacy of Garlic extract @ 10%, BAU-Biofungicide @ 2%, Bion@ 0.2%, Bavistin DF (Carbendazim) @ 0.1% and Proud 250EC (Propiconazole) @ 0.1%  for controlling leaf spot disease of taro (Colocasia esculenta). Performance of these treatments was assessed by applying as cormel treatment and foliar spray. Cormel treatment under field experiment was found effective for BAU-Biofungicide and Proud 250EC. Bavistin DF and Proud 250EC was more effective than other treatments in increasing plant height and healthy leaves, and in decreasing spotted and dead leaves. Before foliar spraying, BAU-Biofungicide as cormel treatment reduced the disease incidence (46.19%) and severity (25.28%) of taro leaf spot at 180 days after sowing. As foliar spray all the treatments has significant effect on taro leaf spot. Among the treatments BAU-Biofungicide was found superior to control leaf spot of taro. BAU-Biofungicide resulted maximum reduction of disease incidence and severity and increase in number of healthy leaf followed by Bion and Proud 250EC. BAU-Biofungicide showed enhanced results in terms of disease incidence and severity of leaf spot of Taro before and after foliar spraying.Progressive Agriculture 28 (3): 167--173, 2017

scholarly journals Identification of Genetic Markers in Olive Linked to Olive Leaf Spot Resistance and Susceptibility

2001 ◽  
Vol 126 (3) ◽  
pp. 305-308 ◽  
Author(s):  
Genet Teshome Mekuria ◽  
Graham Collins ◽  
Margaret Sedgley ◽  
Shimon Lavee
Keyword(s):  
Leaf Spot ◽  
Bulked Segregant Analysis ◽  
Screening Tools ◽  
Leaf Spot Disease ◽  
Olive Leaf ◽  
Base Pairs ◽  
Spot Disease ◽  
Susceptible Bulk ◽  
Improvement Programs ◽  
Segregating Population

Olive leaf spot is a disease of olive (Olea europaea L.) caused by the fungal pathogen, Spilocea oleaginea Cast. Progeny derived from crosses among susceptible, resistant, and semiresistant parental lines were assessed in the field for 8 years and classified as either resistant or susceptible. DNA from some of the progeny of this segregating population was used to identify molecular markers linked to olive leaf spot disease using the randomly amplified polymorphic DNA (RAPD) technique and bulked segregant analysis (BSA). Two DNA bulks were constructed, each containing 13 progeny showing either resistance or susceptibility for the disease, and screened for polymorphisms using 100 primers. One primer produced two polymorphic bands, one of ≈700 base pairs (bp) from the susceptible bulk and the other of ≈780 bp from the resistant bulk. The 780 bp marker appeared in 70.6% of the segregating progeny and 100% of parents showing resistance to leaf spot disease, while the 700 bp marker appeared in 47.1% of the segregating progeny and 100% of the parents showing susceptibility. These markers can be used as screening tools in olive improvement programs.

scholarly journals Sources of variation in a field evaluation of the incidence and severity of olive leaf spot

2005 ◽  
Vol 58 ◽  
pp. 273-277 ◽  
Author(s):  
E.O. Obanor ◽  
M. Walter ◽  
E.E. Jones ◽  
M.V. Jaspers
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Field Evaluation ◽  
Leaf Spot Disease ◽  
Olive Leaf ◽  
Mean Values ◽  
Spot Disease ◽  
Sources Of Variation ◽  
The Mean ◽  
Over Time

Incidence ( infected leaves) and severity (number of lesions/leaf) of olive leaf spot disease caused by Spilocaea oleagina were assessed every 2 weeks on 20 trees in a Canterbury olive grove for 12 weeks during summer 2003/04 All the trees were infected by olive leaf spot disease (OLS) and although disease incidence and severity varied between trees (Plt;0001) it did not vary between branches over time (P0088) There was a strong correlation (R20869) between disease incidence and severity It was estimated that at least five trees and 50 leaves/tree were required to correctly estimate the mean values of the parameters measured Throughout the duration of the experiment no new leaf lesions formed and although old lesions increased in size (Plt;0001) spore numbers decreased from 5104 to 1102 conidia/cm2 of lesion and viability of conidia declined from 55 to 10

scholarly journals Evaluation of Two Predictive Models for Forecasting Olive Leaf Spot in Northern Greece

Plants ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1200
Author(s):  
Thomas Thomidis ◽  
Konstantinos Michos ◽  
Fotis Chatzipapadopoulos ◽  
Amalia Tampaki
Keyword(s):  
Predictive Models ◽  
Leaf Spot ◽  
Conidial Germination ◽  
Polynomial Model ◽  
Leaf Wetness ◽  
Generic Model ◽  
Olive Leaf ◽  
Northern Greece ◽  
Disease Symptoms ◽  
Olive Trees

Olive leaf spot (Venturia oleaginea) is a very important disease in olive trees worldwide. The introduction of predictive models for forecasting the appearance of a disease can lead to improved disease management. One of the aims of this study was to investigate the effect of temperature and leaf wetness on conidial germination of local isolates of V. oleaginea. The results showed that a temperature range of 5 to 25 °C was appropriate for conidial germination, with 20 °C being the optimum. It was also found that at least 12 h of leaf wetness was required to start the germination of V. oleaginea conidia at the optimum temperature. The second aim of this study was to validate the above generic model and a polynomial model for forecasting olive leaf spot disease under the field conditions of Potidea Chalkidiki, Northern Greece. The results showed that both models correctly predicted infection periods. However, there were differences in the severity of the infection, as demonstrated by the goodness-of-fit for the data collected on leaves of olive trees in 2016, 2017 and 2018. Specifically, the generic model predicted lower severity, which fits well with the incidence of the disease symptoms on unsprayed trees. In contrast, the polynomial model predicted high severity levels of infection, but these did not fit well with the incidence of disease symptoms.

scholarly journals The Application of Trichoderma Strains or Metabolites Alters the Olive Leaf Metabolome and the Expression of Defense-Related Genes

2020 ◽  
Vol 6 (4) ◽  
pp. 369
Author(s):  
Roberta Marra ◽  
Mariangela Coppola ◽  
Angela Pironti ◽  
Filomena Grasso ◽  
Nadia Lombardi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Phenolic Compounds ◽  
Plant Growth ◽  
Plant Pathogens ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Leaf Spot Disease ◽  
Olive Leaf ◽  
Olive Leaves ◽  
Olive Trees

Biocontrol fungal strains of the genus Trichoderma can antagonize numerous plant pathogens and promote plant growth using different mechanisms of action, including the production of secondary metabolites (SMs). In this work we analyzed the effects of repeated applications of selected Trichoderma strains or SMs on young olive trees on the stimulation of plant growth and on the development of olive leaf spot disease caused by Fusicladium oleagineum. In addition, metabolomic analyses and gene expression profiles of olive leaves were carried out by LC–MS Q-TOF and real-time RT-PCR, respectively. A total of 104 phenolic compounds were detected from olive leave extracts and 20 were putatively identified. Targeted and untargeted approaches revealed significant differences in both the number and type of phenolic compounds accumulated in olive leaves after Trichoderma applications, as compared to water-treated plants. Different secoiridoids were less abundant in treated plants than in controls, while the accumulation of flavonoids (including luteolin and apigenin derivatives) increased following the application of specific Trichoderma strain. The induction of defense-related genes, and of genes involved in the synthesis of the secoiridoid oleuropein, was also analyzed and revealed a significant variation of gene expression according to the strain or metabolite applied.

scholarly journals Effects of Postemergence Herbicides on Cercospora arachidicola Hori and Early Leaf Spot of Peanut1

1999 ◽  
Vol 26 (1) ◽  
pp. 4-8 ◽  
Author(s):  
J. A. Baysinger ◽  
H. A. Melouk ◽  
D. S. Murray
Keyword(s):  
Arachis Hypogaea ◽  
Leaf Spot ◽  
Untreated Control ◽  
Conidial Germination ◽  
Leaf Spot Disease ◽  
Common Disease ◽  
Cercospora Arachidicola ◽  
Spot Disease ◽  
Arachis Hypogaea L ◽  
Postemergence Herbicides

Abstract Early leaf spot is a common disease of peanut caused by the fungus Cercospora arachidicola Hori. Experiments were conducted to evaluate the effect of postemergence herbicides on the conidial germination of C. arachidicola and on the incidence of early leaf spot disease in peanut (Arachis hypogaea L.) in a greenhouse. Conidial germination was enhanced (≥ 100%) at concentrations of 1, 100, and 1000 mg/L of 2,4-DB compared with the untreated control. Lactofen reduced conidial germination by 42% compared with the control at concentrations as low as 100 mg/L and completely inhibited germination at concentrations ≥ 5000 mg/L. A concentration of 10,000 mg/L acifluorfen and 2,4-DB completely inhibited conidial germination. Acifluorfen, acifluorfen plus 2,4-DB, and lactofen decreased the sporulation of early leaf spot lesions. Lactofen reduced leaf spot incidence 12% and decreased sporulation of lesions 22% compared with the control. None of the herbicides increased the incidence of early leaf spot on peanut plants or the number of early leaf spot lesions per leaflet when compared with plants that received no herbicide.

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