Journal of Phytopathology and Pest Management (Al-Azhar University)
Not a member yet
133 research outputs found
Sort by
Control of Alternaria rot disease of pear fruits using essential oil of Viola odorata
Get PDFThe economic losses of fruits due to the post-harvest diseases exceeded 50% of the total production. Although control of post-harvest pathogens still relies mainly on fungicides, but the emergence of fungicide-resistant strains and environmental problems stimulated the search for ecofriendly alternatives. In this study, three isolates of Alternaria alternata were isolated from pear fruits, naturally have symptoms of Alternaria rot disease. The pathogenicity test confirmed that A. alternata AUMC11410 was the most aggressive isolate causing the highest rotted area on the pear fruits. Herein, four tested essential oils of Ocimum basilicum, Eucalyptus globulus, Rosmarinus officinalis and Viola odorata exhibited antifungal impacts against A. alternata AUMC11410. Viola odorata had the highest fungicidal effect on the mycelia growth of the pathogen producing reduction up to 92.50%. By evaluation of the minimum inhibitory concentration (MIC), V. odorata oil showed MIC value at 0.4 µl/ml. Subsequently, application of V. odorata oil (0.4 µl/ml) reduced the percentage of Alternaria rot disease by 75.0 and 62.5% both before and after the pathogen inoculation. The GC-MS analysis of the V. odorata oil revealed that, it was rich in bioactive ingredients such as benzyl benzoate (8.0% of total ingredients), β-ionone (5.04%), α-hexyl cinnamaldehyde (2.93%), 6-methyl γ-ionone (2.29%) and β-linalool (1.16%). Furthermore, it had some monoterpenoids and their derivatives, namely; p-cymene, dihydro-α-terpineol, p-menth-3-en-9-ol, 1,4-cineole, p-menth-6-en-2-one, citronellyl formate, β-citronellol, linalyl acetate and isobornyl acetate that collectively amounted 5.53% of the total ingredients. In conclusion, V. odorata oil included bioactive compounds that may be responsible for this fungicidal effect against the pathogen. Therefore, application of V. odorata oil may be considered as a promising ecofriendly precautionary measure for controlling the post-harvest diseases of pear fruits
Control of charcoal rot disease of okra plants using certain chemical plant resistance inducers
Get PDFThis study was aimed to determine the efficacy of certain chemical inducers on incidence of charcoal rot disease caused by Macrophomina phaseolina (Tassi) in okra okra (Abelmoschus esculentus (L.) under greenhouse and field conditions. Pathogenicity of 12 isolates of Macrophomina phaseolina was carried out on okra under greenhouse conditions. These isolates capable to infect okra plants caused charcoal rot on the basil stem with various degrees of diseases severity. Isolate No. 3 caused the highest charcoal rot severity (70.15%) followed by isolate No. 6 (58.69%). The positive effect of four inducer chemicals, i.e salicylic and ascorbic acids at concentrations 50, 100, 200 ppm; Benzothiadiazole, Bion at 200, 400, 800 ppm and humic acid at 500, 1000, 2000 ppm on the induction of systemic resistance in okra against charcoal rot disease and its effect on growth parameters and green fruit yield components were studied. In vitro, all tested chemical inducers able to suppress growth of M. phaseolina. The highest decrease in linear growth of M. phaseolina was noticed with Bion at concentration 800 ppm (66.96%). Under greenhouse conditions, all the tested chemical inducers significantly decreased charcoal rot severity at all concentrations compared with control. The reduction of charcoal rot in okra was enhanced by increasing chemical inducers concentration. Ascorbic acid was the most effective chemical inducers as they greatly retarded charcoal rot caused by M. phaseolina especially at the higher concentration (200 ppm). While, salicylic acid at 50 ppm recorded the lowest protection of charcoal rot severity. Under field conditions, the percentages of charcoal rot severity were significantly reduced due to soaking the seeds before sowing in any of chemical inducers in both trial seasons (2013 and 2014). The most effective inducer was humic acid at 2000 ppm (84.44 and 85.65% reduction of charcoal rot severity), followed by ascorbic acid at 200 ppm (79.79 and 79.28% reduction of charcoal rot severity) in the first and the second growing seasons, respectively. Also, these treatments significantly increased growth parameters i.e. plant height and number of branches plant-1 as well as, green fruit yield parameters i.e. number of green fruit plant-1; weight of green fruit plant-1 (gm); and total green fruits (ton/acre). Generally, humic acid gave the best results in all growth and green fruit yield parameters under field conditions especially at higher concentration (2000 ppm)
Duration of different developmental stages, mortality rate and adult longevity of rice grain bug Paraeucosmetus pallicornis (Dallas) on rice Oryza sativa (L.) and string beans Vigna sesquipedalis (L.) under controlled condition
Get PDFParaeucosmetus pallicornis Dallas, locally known as Rice grain bug (RGB) is considered a new pest of rice in the Philippines. Originally RGB is a pest attacking string beans which is commonly planted along the bunds of rice field. This study was conducted to be able to establish the effect of string beans and rice plant on the duration of each developmental stage and adult longevity P. pallicornis Dallas under controlled condition. The duration of egg incubation and adult longevity of RGB both on rice and string beans in laboratory and screenhouse were not significant. Although there were nymphal instars that were found to be significantly different, it does not affect the total developmental period of RGB on rice and string beans under laboratory conditions. In the screenhouse, the total development period of RGB was significant on rice and string beans wherein RGB reached adult stage on the average of 30.75 days on rice plants compared to an average of 43.59 days those on string beans. This suggests the possibility that a second generation of RGB will be produced by the new batch of RGB adults bred on rice plants. Considering that the reproductive to ripening phase of rice is about 65 days, the duration of this phase could accommodate a second generation of RGB nymphs and adults. Percent mortality of RGB in rice and string beans was 23.33% under laboratory condition while in screenhouse, 76.66% was recorded in rice and 55% in string beans
Effect of Azadirachta indica extract on the radial growth of some test fungi isolated from two varieties of cocoyam (Colocasia esculenta L.) corms and cormels in some markets in Plateau State, Nigeria
Get PDFAntifungal effect of aqueous and ethanol extracts of Azadirachta indica on the radial growth of fungal pathogens of stored cocoyam corms and cormels was investigated. Four different extract concentrations were used from the plant leaves. Pathogenicity test showed that: Alternaria alternata, Fusarium oxysporum, Verticilium lateritium, Botrydiplodia theobramae, Colletotricum coccoides, Phythium myriotylum, Fusarium verticillioides, Rhizopus stolonifer and Geotricum candidum induced rot in both varieties of healthy cocoyam corms and cormels after 7 days of inoculation. The highest aqueous extract inhibition recorded was 81.11% on V. lateritium at 10% while the least inhibitory effect was 18.35% observed at 2.5% on G. candidum. Meanwhile, the ethanol extract gave a highly significant (P<0.05) inhibitory effect of 87.21% at 10% and the least was 26.80% at 2.5% on A.alternata and V. lateritium respectively compared to the rest as recorded in aqueous extract at the same level of concentrations (10%). The fungitoxic potential of this plant extract on rot inducing fungi of stored cocoyam corms and cormels is indicative of its use to farmers as alternative to commercial or synthetic fungicides destroying our ecosystem and health.Â
Influence of preharvest spraying with the chemical salts on grey mold disease and keeping quality of table grapes during storage
Get PDFThe efficacy of calcium chloride, calcium nitrate, potassium metabisulfate, calcium carbonate and sodium bicarbonate to protect grape bunches during harvesting was studied under storage conditions. This experiment was carried out in a private vineyard, El-Khatatba region, Alexandria desert road, Egypt during 2014 and 2015 growing seasons on Thompson seedless variety. The chemical used at 0.1 and 0.2% g /liter water. The healthy grape bunches of all treatments were harvested at proper ripeness, packed in perforated plastic bags, put inside carton boxes and stored at 0oC under 90-95% R.H. for 36 days. Other grape bunches either treated or untreated with the salts were artificially inoculated with spore suspension of Botrytis cinerea at a concentration of 3x106 spores/ml before packing and cold storage. Disease severity of grape bunches with B. cinerea was estimated after 36 days of cold storage. All treatments exhibited disease reduction under field conditions of Thompson seedless grape variety. The field applications of salts gave a significant reduction of botrytis rot during storage. In this respect, the grape rots were significantly reduced when sprayed by the salts three times
Evaluation of certain neonicotinoid insecticide seed treatments against cereal aphids on some wheat cultivars
Get PDFField experiment was conducted to find out the comparative efficacy of four commercial neonicotinoid insecticide seed treatments imidacloprid, thiamethoxam, acetamiprid and dinotefuran against cereal aphids, Rhopalosiphum padi L., Schizaphis graminum Rondani, and  Rhopalosiphum maidis Fitch (Homoptera: Aphididae) infesting three wheat cultivars Bani Suef, Sids 1 and Misr 1 at Assiut Governorate, Egypt during 2014/2015 season. R. padi was the most abundant species with an average (62.33, 32.50 and 25.00), followed by S. graminum (28.40, 22.67 and 19.00) and R. maidis (9.17, 8.16 and 6.17aphids/tiller) on the three wheat cultivars respectively. There were significant differences in the number of aphids among the wheat cultivars, Bani Suef, Sids 1 and Misr 1. In early season until the second week of March imidacloprid, thiamethoxam, acetamiprid and dinotefuran seed treatments reduced significantly the aphid population densities. After the second week of March there were no significant differences between all insecticide treatments compared to the untreated control. The application of neonicotinoid insecticides as seed treatments under field conditions to suppress the wheat aphid’s population increased the yield production of wheat cultivars about 23.04–64.98%. In addition, it was an incontrovertible notice that imidacloprid and thiamethoxam seed treatments caused a significant increase in the average yield/feddan in the three wheat cultivars compared to untreated control, whereas acetamiprid and dinotefuran gave a lower increase in the yield production. It might be concluded that, imidacloprid and thiamethoxam had a better efficienÂcy against wheat aphids than acetamiprid and dinotefuran. As a result of which, neonicotinoid insecticide seed treatments are an integral component and friendly tactic of integrated pest management programs for aphids control in wheat.Â
Field performance of second generation (BG-II) Bt cotton genotypes against bollworm complex under rainfed conditions
Get PDFA field experiment was conducted at Main Agricultural Research Station, Dharwad, Dharwad (Karnataka, India) to investigate the performance of second generation Bt cotton genotypes under rainfed condition. All second generation Bt genotypes with cry1Ac + cry2Ab genes have shown high level of resistance to all the three species of bollworms. The incidence of bollworms did not cross economic threshold in BG-II hybrids. First generation Bt genotypes with cry1Ac genotypes bollworms crossed economic threshold level for two times. Compared with BG-I and non Bt genotypes all the BG-II genotypes were found to be better with respect to larval incidence and damage by bollworms.MRC-7351 BG-II recorded highest seed cotton yield of 20.37 q/ha being at par with KDCHH-621 BG-II (19.75), MRC-7201 BG-II (19.13), and Bunny Bt BG-II (18.60), but superior to BG-I genotypes without any protection against bollworms.Â
Detection of Clavibacter michiganensis subsp. sepedonicus the causal agent of potato ring rot, in the breeding and propagation materials of the three-stage control process
Get PDFTo maintain Clavibacter michiganensis subsp. sepedonicus-free (Cms-free) potato genetic resources, a three-stage process of checking limited lots of initial and new breeding potato materials was designed for small breeders in terms of costs, personnel and facilities. For an intensified evaluation of the presence of Cms in different vegetative stages within one growing season a mixture of 10 randomly selected artificially infected and healthy tubers of individual cultivars and breeding materials were prepared. In the first stage, a visual assessment of the vascular vessels of mother tubers was performed and at least 20% of each material was deemed positive, indicating that it should be discarded. In the second stage, one half of mother tubers were grown in the greenhouse and the other in a netting house. Plants in bloom and daughter tubers were evaluated. Within the second stage 1.4%–28% of each individual potato material could be excluded based on double-antibody sandwich enzyme-linked immunosorbent assays and SYBR Green real-time PCR assays, including a melting point analysis using PSA 1/R and CelA F/R primer sets and biological tests on aubergines. In the third stage, in vitro plants transferred from potato resources that tested negative in the previous stages were evaluated using the methods used in the second stage. The specificity of the antibodies and the two primer sets, PSA1/R and CelA F/R, were evaluated with 100% success
Ampelomyces quisqualis Ces. – a mycoparasite of Euphorbia hirta powdery mildew in Himachal Pradesh, India
Get PDFMycoparasitism is defined as the association of two fungi where one acts as parasite over the other. In October 2015, a powdery mildew infection was observed on Euphorbia hirta during the routine mycological survey in district Mandi the central region of Himachal Pradesh, India. During the course of microscopic examinations infection was found mixed with another unknown fungus. Upon morphological and microscopic examinations of infection on leaves, Podosphaera euphorbiae-hirtae was identified as powdery mildew fungus mixed with a mycoparasite Ampelomyces quisqualis. To the best of our knowledge, this is the first report of mycoparasitism of Ampelomyces quisquali on powdery mildew of Euphorbia hirta in India
Role of certain bioagents against Guava decline disease and in enhancement of the growth of guava trees
Get PDFBiocontrol agents, Bacillus subtilis, Pseudomonas fluorescens and Trichoderma harzianum were evaluated against fungi causing guava (Psidium guajava) decline disease caused by Botryodiplodia theobromae, Fusarium oxysporum, and Rhizoctonia solani. Generally, our results showed high antagonistic effects of tested biocontrol agents against previous pathogens. T. harzianum isolates showed an average of 58% inhibition against all pathogens. T. harzianum T4 was the most prominent isolate in inhibiting the growth of guava pathogenic fungi. Based on the secretion of volatile substances, T4 had the most significant inhibition ability as compared to other Trichoderma isolates. By using B. subtilis, the radial growth of R. solani and F. oxysporum was significantly decreased as compared to B. theobromae. In case of P. fluorescens, the radial growth of R. solani was decreased more than B. theobromae followed by F. oxysporum. Different densities of T4 significantly decreased the disease severity and increased plant height, dry weight of shoots and roots and total pigments (chlorophyll a and b, and carotenoids) in guava trees in comparison with infected trees only. We concluded that the application of biocontrol agents decreased guava decline disease and improved the growth of guava trees