Chapitre 14: Phytopathogènes et stratégies de contrôle en aquaponie

peer reviewedAmong the diversity of plant diseases occurring in aquaponics, soil-borne pathogens, such as Fusarium spp., Phytophthora spp. and Pythium spp., are the most problematic due to their preference for humid/aquatic environment conditions. Phytophthora spp. and Pythium spp. which belong to the Oomycetes pseudo-fungi require special attention because of their mobile form of dispersion, the so-called zoospores that can move freely and actively in liquid water. In coupled aquaponics, curative methods are still limited because of the possible toxicity of pesticides and chemical agents for fish and beneficial bacteria (e.g. nitrifying bacteria of the biofilter). Furthermore, the development of biocontrol agents for aquaponic use is still at its beginning. Consequently, ways to control the initial infection and the progression of a disease are mainly based on preventive actions and water physical treatments. However, suppressive action (suppression) could happen in aquaponic environment considering recent papers and the suppressive activity already highlighted in hydroponics. In addition, aquaponic water contains organic matter that could promote establishment and growth of heterotrophic bacteria in the system or even improve plant growth and viability directly. With regards to organic hydroponics (i.e. use of organic fertilisation and organic plant media), these bacteria could act as antagonist agents or as plant defence elicitors to protect plants from diseases. In the future, research on the disease suppressive ability of the aquaponic biotope must be increased, as well as isolation, characterisation and formulation of microbial plant pathogen antagonists. Finally, a good knowledge in the rapid identification of pathogens, combined with control methods and diseases monitoring, as recommended in integrated plant pest management, is the key to an efficient control of plant diseases in aquaponics.Cos

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Not AvailableThe parasitic fungus, Paecilomyces lilacinus (Thom.) Samson is one of the most promising and practicable biological control agents for the management of plant parasitic nematodes. The organism adapts to diverse environmental conditions and is compatible with many fungicides and nematicides (Villanueva and Davide, 1983). Its effectiveness in managing Meloidogyne (J atala et al., 1980), Globodera (Franco et al., 1981), Tylenchulus (Herrera et al., 1985) and Nacobbus (de Sisler et al., 1985) species affecting important crops has been determined. No work has so far been undertaken to evaluate its efficacy for the control of the reniform nematode, Rotylenchulus reniformis Linford et Oliveira. Hence, the present glasshouse studies were undertaken to evaluate P. lilacinus for the biological control of R. reniformis infecting tomato, as compared with carbofuran.Not Availabl

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Not AvailableThe effect of Paecilomyces lilacinus (Thom.) Samson alone and in combination with carbofuran@ 0.5 and 1.0 kg ai per ha was studied on the management of reniform nematode, Rotylenchulus reniformis Linford and Oliveira infecting brinjal, Solanum melangena L. Inoculation of plants with P. lilacinus grown on 4 g sterilized rice was effective in increasing plant height and root weight and in reducing the nematode population both in soil and roots. The fungus gave least reproduction factor and increased the percentage of ...Not Availabl

Biochemical changes in <i>Glomus fasciculatum </i>colonized roots of <i>Lycopersicon esculentum </i>in presence of <i>Meloidogyne incognita</i>

721-727Glasshouse experiments were conducted to elicit biochemical substantiation for the observed difference in resistance to nematode infection in roots colonized by mycorrhiza, and susceptibility of the fresh flush of roots of the same plant that escaped mycorrhizal colonization. Tomato roots were assayed for their biochemical profiles with respect to total proteins, total phenols, indole acetic acid, activities of polyphenol oxidase, phenylalanine ammonia lyase and indole acetic acid oxidase. The roots of the same plant (one set) received Glomus fasciculatum and G. fasciculatum&nbsp; plus juveniles of Meloidogyne incognita separately; and half the roots of second set of plants received G. fasciculatum while the other half of roots did not receive any treatment. Roots colonized by G. fasciculatum recorded maximum contents of proteins and phenols followed by that of the roots that received G. fasciculatum plus M. incognita. However, IAA content was lowest in the roots that received mycorrhiza or mycorrhiza plus juveniles of root-knot nematode and correspondingly. Roots that received juveniles of root-knot nematode recorded maximum IAA content and per cent increase over healthy check and mycorrhiza-inoculated roots. The comparative assay on the activities of PPO, PAL and IAA oxidase enzymes in treated and healthy roots of tomato, indicated that PAL and IAA oxidase activities were maximum in G. fasciculatum colonized roots followed by the roots that received mycorrhiza plus juveniles of root-knot nematode, while the activity of PPO was minimum in these roots. The roots that received juveniles of root-knot nematode recorded minimum PAL and IAA oxidase activities and maximum PPO activity. Since the roots of same plant that received mycorrhiza and that did not receive mycorrhiza; and the plant that received nematode alone and mycorrhiza plus nematode recorded differential biochemical contents of proteins, total phenols and IAA, and differential activities of enzymes under study, it was evident that the biochemical defense response to mycorrhizal colonization against root-knot nematodes was localized and not systemic. This explained for the response of plant that differed in root galling due to nematode infection in presence of mycorrhizal colonization. The new or fresh roots which missed mycorrhizal colonization, got infected by nematodes and developed root galls

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Not AvailableThe parasitic fungus, Paecilomyces lilacinus (Thom.) Samson is one of the most promising and practicable biological control agents for the management of plant parasitic nematodes. The organism adapts to diverse environmental conditions and is compatible with many fungicides and nematicides (Villanueva and Davide, 1983). Its effectiveness in managing Meloidogyne (J atala et al., 1980), Globodera (Franco et al., 1981), Tylenchulus (Herrera et al., 1985) and Nacobbus (de Sisler et al., 1985) species affecting important crops has been determined. No work has so far been undertaken to evaluate its efficacy for the control of the reniform nematode, Rotylenchulus reniformis Linford et Oliveira. Hence, the present glasshouse studies were undertaken to evaluate P. lilacinus for the biological control of R. reniformis infecting tomato, as compared with carbofuran.Not Availabl

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Not AvailableNematode interactions are important biological phenomena and of great significance in agriculture. It is a fascinating subject which is multidisciplinary by nature, and concerns any scientist involved with plant health. There have been marked advances in our knowledge of various aspects of the subject in the last two decades. This study area has been the subject of several reviews, but there was no exclusive text on the subject. This has stressed the need to document the information, developing a unifying theme which treated nematode interactions in a holistic manner. This book is about the inter­ action of plant-parasitic nematodes with other plant pathogens or root symbionts, the nature of their associations, their impact on the host and con­ sequential interactive effects on the involved organisms. Since nematodes are at the centre of the theme, the responsibility of understanding of other plant pathogens dealt with in this book is largely delegated to the reader. I have limited the book content to interactions with biotic pathogens and root symbionts only, for various reasons. The book embodies 16 chapters, and attempts to present balanced infor­ mation on various aspects of nematode interactions with other plant pathogens and root symbionts. Some chapters describe general aspects of the subject. Interactions of nematodes with specific groups of organisms are addressed in the remaining chapters.Not Availabl

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Not AvailableAbstract Accurate and reliable identification of plant parasitic nematodes is fundamental to many aspects of their effective management. Control programmes using either resistant cultivars or crop rotation are usually directed at specific species of parasitic nematodes. Since different species of a particular genus are important pathogens on different crops, the species present in a field must be accurately and often rapidly identified. The same speed and reliability in the identification of races would be helpful. Biochemical analyses offers ...Not Availabl

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Not AvailableThirteen citrus rootstocks and hybrids belonging to six species were evaluated to determine their reaction to the citrus nematode, Tylenchulus semipenetrans, under glasshouse conditions. Resistance ratings were assigned based on the reproduction factor. The rootstock Poncirus trifoliate and hybrids between Citrus limonia and P. trifoliata viz., CRH-3, CRH-5 and CRH-41 were rated resistant; while Forida rangpur 8747 was found moderately resistant to the citrus nematodeNot Availabl

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Not AvailableOil-cakes of castor (Ricinus communis), karanj (Pongamia glabra [P. pinnata]) and neem (Azadirachta indica) at 20 g per plant and the parasitic fungus, Paecilomyces lilacinus at 8 g infected rice seeds per plant alone and in combination at half the dosages were evaluated for the management of T. semipenetrans infecting acid lime under glasshouse conditions. Neem cake + P. lilacinus gave maximum shoot length and shoot weight, while castor cake + P. lilacinus gave maximum root length and root weight. Maximum reduction in soil nematode population was obtained with neem cake + P. lilacinus, while castor cake + P. lilacinus gave the least nematode population in the roots.Not Availabl

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Not AvailableOne hundred and twenty-nine banana cultivars were evaluafed to determine their reaction to the burrowing nematode, Radopholus similis (Cobb) Thome. The resistance ratings were given based on the nematode populaton per JOg roots. Nine cultivars viz., Adakka Kunnan, Attikol, Ayiramka Poovan, Elakki Bale. Kunnan, Pacha Chingan, Pedali Moongil, Poovan and Thatilla Kunnan were rated resistant, while 28 cultivars were found moderately resistant to R. similis. All the other cultivars tested showed varying degrees of susceptibility.Not Availabl