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Youssef K.,University of Bari | Youssef K.,Egyptian Plant Pathology Research Institute | Ligorio A.,University of Bari | Nigro F.,University of Bari | Ippolito A.,University of Bari
Postharvest Biology and Technology | Year: 2012

The role of some salts applied in combination with wax on the development of postharvest rots was examined on 'Tarocco' and 'Valencia late' oranges and 'Comune' Clementines. Sodium carbonate and bicarbonate, potassium carbonate and bicarbonate, ammonium bicarbonate, and potassium sorbate, at 6% concentration (w/v), in combination with a commercial wax, were evaluated for their activity against naturally occurring postharvest decay. Fruit were stored for one month at 4°C ('Tarocco' and 'Valencia late' oranges) or 6°C ('Comune' Clementine), followed by one week of shelf life at 20. ± 2°C and high RH.Most decay was from green and blue moulds, caused by Penicillium digitatum and P. italicum, respectively, with an average incidence of 11% for 'Comune' Clementines and 5% for both 'Tarocco' and 'Valencia late' oranges. Decay caused by Botrytis cinerea and Alternaria spp. was also observed. The incidence of postharvest rots on fruit treated with wax alone (11%) was higher than on those treated with water (7%), whereas in fruit treated with wax combined with different salts, decay incidence was significantly lower than with wax and water controls. In particular, potassium sorbate incorporated in wax significantly reduced the incidence of postharvest decay in all tested cultivars. The incidence of decay on fruit treated with imazalil was low, not exceeding 1%. Salts, except ammonium bicarbonate, interfered with the action of the wax to retard weight loss. The results indicate that the addition of the salts to wax may be an easy and effective mode of their application, since no additional equipment is needed. © 2011 Elsevier B.V.

Youssef K.,Egyptian Plant Pathology Research Institute | Youssef K.,University of Bari | Sanzani S.M.,University of Bari | Ligorio A.,University of Bari | And 2 more authors.
Postharvest Biology and Technology | Year: 2014

The aim of this study was to investigate the ability of two salts, sodium carbonate and bicarbonate, to activate defence mechanisms in citrus fruit against postharvest green mould caused by Penicillium digitatum. In particular, once there was confirmed salt antifungal activity in the absence of direct contact with the pathogen, changes in enzyme activity and expression levels of chitinase, β-1,3-glucanase, peroxidase and phenylalanine ammonia lyase (PAL), and phytoalexin (scoparone, scopoletin, umbelliferone) and sugar (glucose, fructose, sucrose) contents in treated oranges were analyzed. Overall, sodium carbonate and bicarbonate increases the activity of β-1,3-glucanase, peroxidase, and PAL enzymes in orange tissues. Gene expression analyses confirmed PAL up-regulation particularly 12. h after treatment application. HPLC analyses of peel extracts showed increased amounts of the sugars and phytoalexins, compared to control tissues, with sucrose and scoparone being the most represented. The results suggest that, although salts exert a direct antifungal effect on P. digitatum, they are also able to induce citrus fruit defence mechanisms to postharvest decay. The defence response seems correlated with the up-regulation of the phenylpropanoid pathway, which has a role in the adaptation to various stresses. This response could result in natural reaction to wounding and pathogen attack in citrus, enhancing its protective effect. As a consequence, the fruit might have a better chance of successful defence against the decay. © 2013 Elsevier B.V.

Mahmoud M.A.,Egyptian Plant Pathology Research Institute
Foodborne Pathogens and Disease | Year: 2015

Aspergillus flavus is the main species from section Flavi responsible for aflatoxin accumulation in stored peanuts. Rapid methods to detect A. flavus could help to prevent aflatoxins from entering the food chain. A real-time polymerase chain reaction (RTi-PCR) assay was standardized for rapid, specific, and sensitive detection of A. flavus in stored peanuts. A. flavus was detected in 53.6% and 50% of peanut samples by RTi-PCR and A. flavus and Aspergillus parasiticus agar culture, respectively, with 95% agreement between them. Twenty-two A. flavus isolates were screened using high-performance liquid chromatography for their capacity to produce aflatoxin AFB1 (B1). B1 was produced by >72% of the isolates. Sixteen isolates produced B1 at concentrations ranging from 1.64 to 109.18μg/mL. Four aflatoxin biosynthetic pathway genes (aflD, aflM, aflP, and aflQ) were evaluated using PCR and reverse-transcription PCR in 22 A. flavus isolates from peanut kernels with the aim of rapidly and accurately differentiating toxigenic and atoxigenic isolates. The PCR amplification of genes did not correlate with aflatoxin production capability. The expression of aflD and aflQ was a good marker for differentiating toxigenic from atoxigenic isolates. © Copyright 2015, Mary Ann Liebert, Inc.

Abdel-Monaim M.F.,Egyptian Plant Pathology Research Institute | Abo-Elyousr K.A.M.,Assiut University
Crop Protection | Year: 2012

Rhizoctonia solani and Fusarium solani were isolated from diseased lentil roots showing damping-off and root rot collected from different locations of New Valley governorate. R. solani isolate R-1 and F. solani isolate FS-9 were the highest virulent isolates. The influence of some agricultural factors on severity of damping-off and root rot disease was studied under greenhouse and field conditions. Intercropping cumin, anise, onion and garlic significantly decreased damping-off and root rot disease and increased seed yield. Anise has the greater effect than other crops, while intercropping onion showed the lowest effect. All tested preceding crops planted before lentil decreased disease severity and population of the tested fungi except in case of soybean and groundnut which increased percentage of disease severity as well as populations of the tested fungi in soil. Cowpea and gaur cultivated before lentil gave the highest decrease in disease severity. On the other hand, lentil cultivated after cowpea produced the highest seed yield followed by gaur and millet. Lowest seed yield production was recorded when plants were cultivated after soybean followed by sesame and groundnut. The lowest population of R. solani was recorded when cowpea cultivated before lentil, while, cultivating sorghum before lentil resulted in the lowest population of F. solani. Root exudates of intercropping and preceding crops reduced mycelial dry weight of the tested fungi invitro except groundnut and soybean. © 2011.

Abdel-Monaim M.F.,Egyptian Plant Pathology Research Institute
Mycobiology | Year: 2013

Rhizoctonia solani, Fusarium solani, F. oxysporum, and Macrophomina phaseolina were found to be associated with root rott and wilt symptoms of faba bean plants collected from different fieldes in New Valley governorate, Egypt. All the obtained isolates were ableto attack faba bean plants (cv. Giza 40) causing damping-off and root rot/wilt diseases. R. solani isolates 2 and 5, F. solani isolate 8, F. oxysporum isolate 12 and M. phaseolina isolate 14 were the more virulent ones in the pathogenicity tests. Biocontrol agents (Trichoderma viride and Bacillus megaterium) and chemical inducers (salicylic acid [SA] andhydrogen peroxide) individually or in combination were examined for biological control ofdamping-off and root rot/wilt and growth promoting of faba bean plants in vitro and in vivo. Both antagonistic biocontrol agents and chemical inducers either individually or in combination inhibited growth of the tested pathogenic fungi. Biocontrol agents combined with chemical inducers recorded the highest inhibited growth especially in case SA + T. viride and SA + B. megaterium. Under green house and field conditions, all treatments significantly reduced damping-off and root rot/wilt severity and increased of survival plants. Also, these treatments increased fresh and weights of the survival plants in pots compared with control. The combination between biocontrol agents and chemical inducers were more effective than used of them individually and SA + T. viride was the best treatment in this respect. Also, under field conditions, all these treatments significantly increased growth parameters (plant height and number of branches per plant) and yield components (number of pods per plant and number of seeds per plant, weight of 100 seeds and total yield per feddan) and protein content in both seasons (2010~2011 and 2011~2012). Faba bean seedssoaked in SA + T. viride and SA + B. megaterium were recorded the highest growth parameters and yield components. Generally, the combination between biocontrol agents and chemical inducers recorded the best results for controlling damping-off and root rot/wilt diseases in greenhouse and field with addition improved plant growth and increased yield components in field. © The Korean Society of Mycology.

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