Olive leaf spot (OLS) disease or peacock disease is caused by the fungus Spilocaea oleagina, it is the most destructive disease on olive trees in most regions of Palestine. The disease is controlled by application of copper containing fungicides. Currently, there are more than 20 different fungicides sold in the Palestinian market. The efficacy of these fungicides was not tested on OLS in Palestine. The aim of this work was to test the efficacy of three major fungicides used against the disease. Fungicide solutions containing Fungran, Copper Antracol, and Kocide®101 were prepared by dissolving 0.5 g of each in 200 ml distilled water (DW) according to manufacturer instruction. Five leaves infected with OLS were soaked in each solution for 30 min. Control leaves were placed in 200 ml DW. Leaves were then placed in 9 cm petri dishes containing 3 ml DW to provide high humidity (> 85%). Each day, one leaf was removed, washed in DW and cut into one-cm2 pieces. Leaf pieces holding OLS conidia were printed on olive leaf extract agar media. Results showed that after 24h of fungicide treatment, Kocide®101 was the most effective fungicide followed by Copper Antracol and Fungran with percent conidial germination 2.08, 2.9 and 25.5%, respectively. Interestingly, Fungran efficacy after 48h (2.8% germination) was higher but not significantly different than Kocide®101 and Copper Antracol. This study showed that the efficacy of the three commonly used fungicides against OLS disease in Palestine diminished after four days of treatment. Further studies are needed to test the efficacy of these fungicides under field conditions for a better control planning of peacock disease in Palestine.
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.
Early detection of plant disease requires usually elaborating methods techniques and especially when symptoms are not visible. Olive Leaf Spot (OLS) infecting upper surface of olive leaves has a long latent infection period. In this work, VIS/NIR spectroscopy was used to determine the latent infection and severity of the pathogens. Two different classification methods were used, Partial Least Squared-Discrimination Analysis (PLS-DA) (linear method) and Support Vector Machine (SVM) (non-linear). SVM-classification was able to classify severity levels 0, 1, 2, 3, 4, and 5 with classification rates of 94, 90, 73, 79, 83 and 100%, respectively The overall classification rate was about 86%. PLS-DA was able to classify two different severity groups (first group with severity 0, 1, 2, 3, and second group with severity 4, 5), with a classification rate greater than 95%. The results promote further researches, and the possibility of evaluation OLS in-situ using portable VIS/NIR devices.
The overwintering modes of E. necator were studied on Palestinian vineyards, through observations on the differentiation and maturation of cleistothecia and on the occurrence of flag-shoots (deriving from overwintering mycelium) in vineyards. Field surveys were carried out in 17 vineyards for the presence of Flag shoots and cleistothecia, both forms were not observed. Genetic structure and composition of E. necator populations were investigated by application of already available SCAR (Sequence Characterized Amplified Region) primers specific for the "flag-shoot" and "ascospore" biotypes. These primers were used to evaluate the dynamics of the spatial and temporal distribution of the two biotypes, into fungal populations present in 8 vineyards, with different cultivars and spray histories, in various Palestinian districts (Hebron, Bethlehem, Jerusalem, Ramallah, Jericho, Nablus, Jenin, Tulkarm). 397 samples were analyzed by the uses of the primer pairs UnE-UnF in PCR reactions. All samples were found to be of the ascospore biotypes. This finding shows that the “flag shoot” biotype, appears soon after bud breaking and disappears later, while the “ascospore” biotype is more frequently associated to later infections and bunches damages. Such information would be helpful to understand the reasons underlying possible temporal evolution of the pathogen's populations in vineyards, and can have important implications for powdery mildew rationale control strategies.
Since deuterium 2H (D) is an isotope of hydrogen 1H, the testing of the possibility of photochemical synthesis of marked chlorinated phenol, biphenyl and benzene using normal solvents was studied. The irradiation of full chlorinated compounds dissolved in normal solvents such as MeOH or n-hexane has led to a reaction substitution in which a chlorine atom was substituted by hydrogen atom forming less grade chlorinated chlorophenols, biphenyls and benzenes. The quantum yields of pentachlorophenol, decachlorobiphenyl and hexachlorobenzene under irradiation using polychromatic light were calculated and found to be 5.7 x 10-3, 1.6 x 10-2 and 1.2 x 10-2 Mol·Einstein-1, respectively. Depending on this study the production of marked chlorinated or non-chlorinated compounds using deuterated appropriate solvents such as MeOH d4 or n-hexane d14 is possible. However, more efforts should be made towards chromatographically separation of synthesized standards and byproducts in order to make the use of these marked compounds as standards in residue analysis feasible.
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