Effects of crop sequences on soil population dynamics of Monosporascus cannonballus ascopsores and Monosporascus root rot and vine decline incidence

[EN] Crop sequences effect on the soil population dynamics of Monosporascus cannonballus ascospores and the incidence of Monosporascus root rot and vine decline (MRRVD), was investigated in a field in which three different cucurbit crops: melon, watermelon, and watermelon grafted onto Cucurbita rootstock, and tomato, were grown during two consecutive growing seasons. Cultivation of melon or watermelon crops in the first growing season resulted in an increase of soil ascopore densities. But, on the contrary, the soil ascospore densities in the second growing season were lower when grafted watermelon or tomatos were cultivated in the first growing season. In the second growing season, MRRVD incidence for each cucurbit crop was significantly different depending on the previous crop, being in general higher when melon or watermelon were the previous crops, slightly lower when the previous crop was grafted watermelon and the lowest when the previous crop was tomato. Disease incidence corresponded with the percentage of isolation of M. cannonballus from the roots, being always significantly lower when the previous crop was tomato. These results demonstrate the potential of crop rotation as a management strategy to reduce infection and reproduction of M. cannonballus, ascospore densities in soil and disease incidence in cucurbits.Ben Salem, I.; M'hamdi, M.; Armengol Fortí, J.; Boughalleb-Mhamdi, N. (2015). Effects of crop sequences on soil population dynamics of Monosporascus cannonballus ascopsores and Monosporascus root rot and vine decline incidence. International Journal of Current Microbiology and Applied Sciences (Online). 4(9):482-500. http://hdl.handle.net/10251/89413S4825004

Fungitoxicity of some fungicides against to pathogens responsible of olive trees decline in the Chebika’s area in Tunisia

The incidence of the disease seems very important on young trees and tends to bemoderate with the aging of the tree. In fact, olive trees have a shallow root system and arestill vulnerable to pathogens especially the irrigated varieties. Chemical and biological control against Fusarium solani, Fusarium oxysporum, Rhizoctonia solani and Verticillium dahliae have revealed that the application in vitro of Prodazim and of Methyl-thiophanatehave showed a very good efficacy up to 100%. Ridomil and Tachigaren have indicated aregular efficiency, while the two bio-fungicides Fungstop and the compost juice havedemonstrated a low efficiency. The two bio-control agents Trichoderma harzianum and Gliocladium virens have showed a relatively high effectiveness in vitro. In vivo, obtainedresults have revealed that the nature of the product, the doses applied and the condition ofthe olive trees are highly correlated factors. The treatment doesn’t appear to have apositive effect on the beginning of stage 1 and on plots presented a good structured soil.Going beyond this stage, whatever the product and the doses used, the attack isirreversible

Morphological and Biological Characterization of Monosporascus cannonballus isolates, responsible of watermelon decline in Kairouan's area

Watermelon grown in Kairouan's region is infected by vine decline disease caused by M. cannonballus. In vitro tests showed that this pathogen produces perithecia with a diameter of 495 μm releasing ascospores with a diameter of 44 μm. The mycelium is very fine, rarely visible in the media KOMADA and TANAKA. The colony of different isolates on substrate culture such as Malt, MS and S, appears very dense. On PDA, the grayish brown color characteristic of this ascomycete was observed. The perithecia production in vitro test for this fungus requires relatively long period of incubation (45 days). The effect of culture media showed that the PDA, MS and Malt are the best for the mycelia development of M. cannonballus. The most favorable culture media for fructification arein descending order MS, S, PDA, Malt. M. cannonballus isolates tested in this study showed an optimum temperature of mycelial growth and reproduction of 30°C. MT15 andMT12 isolates originated from Chebika (Kairouan government) showed a significantmycelial growth at all temperatures of incubation. MT7 and MT14 isolates from the sameregion were the most fertile. The results of pH effect on M. cannonballus developmenthave revealed that the maximum mycelial growth occurred at pH 6 for most of isolates andfor the fructification occurred at pH 4 and pH 8. For the osmotic pression with the addition of NaCl and KCl, the optimal development for majority of isolates is registeredat -0.5 MPa and -2 MPa, with a minimum at -4MPa. The inhibition of the fructification of the M. cannonballus isolates occurred beyond -2MPa

Screening of fungi implicated in the dieback of olive trees (Olea europea) in Chebika’s area

Several surveys were conducted during spring 2008 in Chebika’s area in Tunisia. Samples were collected from infected plants showed different types of symptoms and they have been the subject of mycological analysis. The morphological identification of fungal colonies isolated from roots, crown and stems of two olive varieties Koroneiki and Chemlali Sfax, revealed the presence of a fungi complex including Fusarium oxysporum, Fusarium solani, Rhizoctonia solani, Verticillium dahliae, Cladosporium fulvum, Alternaria solani, Alternaria tenuis, Bispora punctata. and Cylindrocarpon .sp; Although,those fungi Fusarium oxysporum, Fusarium solani, Rhizoctonia solani and Verticillium dahliae are ubiquitous and the predominant one. Pathogenicity results revealed that the fungi isolated from olive trees exhibited typical symptoms on Koroneiki variety incontrolled conditions

Security and Privacy Issues in Wireless Mesh Networks: A Survey

This book chapter identifies various security threats in wireless mesh network (WMN). Keeping in mind the critical requirement of security and user privacy in WMNs, this chapter provides a comprehensive overview of various possible attacks on different layers of the communication protocol stack for WMNs and their corresponding defense mechanisms. First, it identifies the security vulnerabilities in the physical, link, network, transport, application layers. Furthermore, various possible attacks on the key management protocols, user authentication and access control protocols, and user privacy preservation protocols are presented. After enumerating various possible attacks, the chapter provides a detailed discussion on various existing security mechanisms and protocols to defend against and wherever possible prevent the possible attacks. Comparative analyses are also presented on the security schemes with regards to the cryptographic schemes used, key management strategies deployed, use of any trusted third party, computation and communication overhead involved etc. The chapter then presents a brief discussion on various trust management approaches for WMNs since trust and reputation-based schemes are increasingly becoming popular for enforcing security in wireless networks. A number of open problems in security and privacy issues for WMNs are subsequently discussed before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the author's previous submission in arXiv submission: arXiv:1102.1226. There are some text overlaps with the previous submissio

Nonlinear fractional differential equations in nonreflexive Banach spaces and fractional calculus

The aim of this paper is to correct some ambiguities and inaccuracies in Agarwal et al. (Commun. Nonlinear Sci. Numer. Simul. 20(1): 59-73, 2015; Adv. Differ. Equ. 2013: 302, 2013, doi:10.1186/1687-1847-2013-302) and to present new ideas and approaches for fractional calculus and fractional differential equations in nonreflexive Banach spaces

Student performance assessment using clustering techniques

The application of informatics in the university system management allows managers to count with a great amount of data which, rationally treated, can offer significant help for the student programming monitoring. This research proposes the use of clustering techniques as a useful tool of management strategy to evaluate the progression of the students’ behavior by dividing the population into homogeneous groups according to their characteristics and skills. These applications can help both the teacher and the student to improve the quality of education. The selected method is the data grouping analysis by means of fuzzy logic using the Fuzzy C-means algorithm to achieve a standard indicator called Grade, through an expert system to enable segmentation.Universidad de la Costa, 2 Universidad Nacional Experimental Politécnica “Antonio José de Sucre”, Universidad Simón Bolívar, Corporación Universitaria Latinoamericana, Corporación Universitaria Minuto de Dios

Retention of health workers in Malawi: perspectives of health workers and district management

<p>Abstract</p> <p>Background</p> <p>Shortage of human resources is a major problem facing Malawi, where more than 50% of the population lives in rural areas. Most of the district health services are provided by clinical health officers specially trained to provide services that would normally be provided by fully qualified doctors or specialists. As this cadre and the cadre of enrolled nurses are the mainstay of the Malawian health service at the district level, it is important that they are supported and motivated to deliver a good standard of service to the population. This study explores how these cadres are managed and motivated and the impact this has on their performance.</p> <p>Methods</p> <p>A quantitative survey measured health workers' job satisfaction, perceptions of the work environment and sense of justice in the workplace, and was reported elsewhere. It emerged that health workers were particularly dissatisfied with what they perceived as unfair access to continuous education and career advancement opportunities, as well as inadequate supervision. These issues and their contribution to demotivation, from the perspective of both management and health workers, were further explored by means of qualitative techniques.</p> <p>Focus group discussions were held with health workers, and key-informant interviews were conducted with members of district health management teams and human resource officers in the Ministry of Health. The focus groups used convenience sampling that included all the different cadres of health workers available and willing to participate on the day the research team visited the health facility. The interviews targeted district health management teams in three districts and the human resources personnel in the Ministry of Health, also sampling those who were available and agreed to participate.</p> <p>Results</p> <p>The results showed that health workers consider continuous education and career progression strategies to be inadequate. Standard human resource management practices such as performance appraisal and the provision of job descriptions were not present in many cases. Health workers felt that they were inadequately supervised, with no feedback on performance. In contrast to health workers, managers did not perceive these human resources management deficiencies in the system as having an impact on motivation.</p> <p>Conclusion</p> <p>A strong human resource management function operating at the district level is likely to improve worker motivation and performance.</p