Occurrence and Geographic Distribution of Plant-Parasitic Nematodes Associated with Citrus in Morocco and Their Interaction with Soil Patterns (original) (raw)
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Journal of the Advances in Agricultural Researches, 2020
A survey of plant-parasitic nematodes (PPN) associating citrus trees in Alexandria, El-Behera and Kafr El-Shiekh governorates, northern Egypt was carried-out during 2017-2019 growing seasons. A total of 432 root and rhizosphere soil samples were collected from the surveyed citrus trees. Nematodes were extracted using sieving and Bearmann-pan techniques and, identified to the generic level, based on the morphological characters. Besides, the reaction of mandarine, Citrus deliciosa and lime, C. aurantifolia against the citrus nematode, Tylenchulus semipenetrans, was determined under greenhouse conditions. Results showed that 9 genera of PPN were found in association with the surveyed citrus trees in the three governorates. The citrus nematode, Tylenchulus semipentrans was found to be very common (frequency of occurrence (FO) = 100% in all the surveyed locations, followed by the stubby root nematodes, Trichodorus spp., and the lesion nematodes, Pratylenchus spp. The reaction of the two citrus cultivars; Mandarine, Citrus deliciosa and Lime, Citrus aurantifolia to T. semipenetrans showed that the two cultivars are susceptible to all the tested populations of T. semipentrans with a nematode reproduction factor (RF) was (1.67-2.6).The shoot and root dry weights of these cultivars were reduced as a result of the nematode infection.
Managing nematodes in Egyptian citrus orchards
Bulletin of the National Research Centre
Backed by its Mediterranean climate, fertile soils, cheap labor, and geographic location, Egypt ranks high among citrus producer countries. These factors can collectively offer early fruiting and long harvest season, good quality, low production costs, and closeness of export markets. However, citrus trees are attacked by many plant-parasitic nematode species in Egypt and abroad; all but one, the citrus nematode Tylenchulus semipenetrans, of which are of limited distribution. Tylenchulus semipenetrans impacts the size and quality of citrus yields differently under various conditions, but guidelines have been published to help interpret soil sample results. Other species such as migratory endoparasites (lesion nematodes), sedentary endoparasites (root-knot nematodes), and several species of ectoparasitic nematodes (spiral and stunt nematodes) can damage citrus in Egypt. Yet, due to their limited distribution and very low population densities in citrus orchards, their damaging level i...
2019
A systemic investigation was conducted on February, 2018 to assess the diversity and community structure of plant parasitic nematodes from the soil rhizosphere of ten different citrus species grown at Citrus Research Station, Tinsukia, Assam. Four major plant parasitic nematode species viz., Tylenchulus semipenetrans, Helicotylenchus dihystera, Hoplolaimus indicus and Tylenchorhynchus spp were found prevalent in the rhizosphere of ten different citrus species. In addition to these, several dorylaimid, rhabditid and predatory nematodes were also encountered. Amongst the plant parasitic nematodes, T. semipenetrans was highly abundant (100%) followed by H. dihystera (80%), Tylenchorhynchus spp. (70%) and H. indicus (50%). Among, different citrus species, a higher population of T. semipenetrans was encountered on rough lemon and least number was encountered on trifoliate orange.
2008. Influence of Citrus spp. on the community of soil nematodes in the dry and rainy seasons in Distrito Federal of Brazil. We evaluated the influence of the root system of Citrus spp. on the nematode community in seven equidistant soil cores in a diagonal projection from one plant trunk basis to the center of the nearest plant in the next row. Soil samples were collected at depths of 0-10 cm and 10-20 cm, once during the dry and once during the rainy seasons. The nematode community was represented by 55 genera belonging to 30 families. No significant differences were detected in diversity indices among the sampling points. However, these indices were higher in the dry season and at 0-10 cm deep. Higher values of the disturbance indices were recorded during the wet season. The plant parasites were less abundant in core 1 (0.7 m from trunk), where the bacterial feeders and predators scored higher in this sampling core. The highest number of omnivores was in core 5 (3.5 m from trunk...
A SURVEY OF ROOT-KNOT AND CITRUS NEMATODES IN SOME NEW RECLAIMED LANDS IN EGYPT
A survey was carried out to know the frequency of occurrence of both root-knot nematodes Meloidogyne spp., and citrus nematode Tylenchulus semipenetrans (Cobb, 1913) in the new reclaimed lands in three different governorates in Egypt viz., Behira (El-Tahrir), Minufiya (El-Sadat) and Sharkiya (El-Salhiya) regions as they represent different soil types, crops and climatic conditions. A total of 54 composite soil samples were collected from fields growing different vegetable crops i.e., tomato, potato, eggplant and pepper as well as citrus. Nematodes were extracted and their population density (P.D) and percentage of occurrence were calculated. Results revealed that percentage of occurrence of Meloidogyne spp., was 96.26 % in the surveyed fields, while T. semipenetrans was 85.18 %. Population densities of Meloidogyne spp., greatly differed at all examined locations. The highest P.D was found in El-Tahrir, followed by El-Salhiya regions, whereas El-Sadat region was the lowest one with the values 242, 158, and 114 J2 / 250 g soil, respectively. The highest population densities of T. semipenetrans was found in El-Salhiya, followed by El-Tahrir, whereas El-Sadat region was the lowest by 2881, 1661 and 512 J2 / 250 g soil, respectively. Our survey indicates that Meloidogyne spp., and T. semipenetrans were widely spread in all examined locations in the new reclaimed lands in Egypt and nematode management strategies must become a part of production practices planning program.
AimsCitrus plants are hosts of numerous plant-parasitic nematodes (PPNs), which are microscopic organisms and hidden enemies for plants. Among the PPNs, the citrus root nematode, Tylenchulus semipenetrans, causes significant damage to citrus plantations in the world. Understanding the citrus nematode population, precise nematode identification, host preference among the citrus species, and damage threshold level are crucially important to control T. semipenetrans. Although some studies have been conducted, minutiae about citrus plant-nematode interactions, nematodes density, and molecular nematode identification have not been well understood. MethodsThis study aimed to reveal nematode identification using molecular and morphological methods, host-nematode interactions, host (citrus species) preference, damage of economic threshold (ET), and economic-injury level (EIL). Therefore, citrus plantations of different provinces located in the Mediterranean region of Turkey were investigate...
Applied Soil Ecology, 2019
Plant-parasitic nematodes (PPN) are the most destructive of all plant pathogens. They are an economically important group of soil pathogens, causing significant annual damages of up to 25% of world crop production. Morocco is considered to be a highly productive country for the colorant/medicinal/spice saffron (Crocus sativus L.). Taliouine and Taznakht regions are the most productive areas of this valuable neutraceutical. Due to its metabolic profile, and growth forms, saffron is susceptible to many plant diseases, including plant-parasitic nematodes (PPN). This work aims to assess the diversity of PPN communities in soils of Taliouine and Taznakht regions to facilitate understanding of links between their assemblages with biotic and abiotic parameters. Herein, nematode communities were characterized in 163 soil samples collected from 11 rural communes characterized by altitudinal gradients in Taliouine and Taznakht regions. Fifteen PPN genera belonging to 12 families were identified, among which the four genera Ditylenchus, Aphelenchoides, Pratylenchus and Helicotylenchus, potentiate serious limiting factors in saffron production. Their frequencies are respectively 92, 49, 48 and 36% in the area of Taliouine, while in Taznakht they represent 95, 69, 33, and 28% respectively. Regarding the assessment of diversity at different sites, the genus richness (R) index ranges from 2 to 10 distinct genera, whereas the Shannon diversity (H') index varies from 0.9 to 1.5 and the Evenness (E) index tends to 1. The Co-inertia analyses revealed a substantial relationship between nematode communities and soil types. Soil texture is the major factor influencing the presence and the abundance of a considerable portion of genera. Multivariate analyses (MBPLS) indicated links between humidity, rainfall, minimum temperature and PPN taxa, though maximum temperature did not have an impact. Ditylenchus, Helicotylenchus, Pratylenchus and Paratylenchus were related to the humidity and silt soil that developed in Taliouine. Aphelenchoides, Tylenchus, Tylenchorynchus and Dorylaimus were more prevalent in rainy locations and clay soils of Taznakht. Suitable nematode controlling approaches may be applied and preventative measures should be considered at nursery and field level.
Egyptian Journal of Agronematology, 2022
This survey was conducted in four locations of Ismailia governorate in the north eastern part of Egypt during the 2020-2022 seasons to investigate occurrence, population density and distribution of plant-parasitic nematodes associated with various crops. A total of 440 soil samples, were collected from infested fruit trees viz. grape (Vitis vinifera L.), guava (Psidium guajava L.), olive (Olea europaea L) and pomegranate (Punica granatum L.) and vegetable crops viz. green bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), strawberry (Fragaria ananassa) and tomato (Solanum lycopersicum L.). Ten plant parasitic nematodes genera have been identified. The root-knot nematodes, Meloidogyne had the highest mean density over any nematode taxa in the tested samples. The highest density values of Meloidogyne were recorded on olive, grape and guava trees that amounted to 800, 640 and 200 juveniles/250 g soil. respectively. However, the maximum densities for Tylenchorhynchus were 160, 180, 120, and 120 juveniles /250 g soil for grape, guava, olive, and pomegranate, respectively. The maximum density values for Helicotylenchus were 180, 120 and 40 juveniles /250 g soil for guava, olive and pomegranate, respectively. Other genera were found at low density i.e. Criconemoides, Trichodorus, Xiphinema, Longidorus, and Pratylenchus. The root knot nematodes have been nearly found in all vegetable crops. The maximum densities for Meloidogyne were 600, 200, 240 and 720 juveniles /250 g soil for green bean, pea, strawberry and tomato, respectively. Generally obtained data indicated that plant-parasitic nematodes are considered as a serious threat to such plant species under variable agronomic and climatic conditions that need to further developed and implemented of control measures.
Plant-parasitic nematodes associated with olive tree in southern Morocco
Plant-parasitic nematodes affect significantly the production of susceptible plants, including olive trees. Knowing that plant production depends on parasite diversity, more information about plant-parasitic nematode communities and about interactions with their habitat is a prerequisite for the development of any control strategy. In this context, nematode communities were determined in soil samples collected from 23 olive growing sites in the Haouz and Souss regions (southern Morocco). These sites corresponded to various modalities: wild (Olea europaea L. ssp. maroccana) (Olea. europaea L. ssp. europaea ), traditional or high-density cropping, rainfed or irrigated,). Ten nematode families and 14 genera were identified, especially spiral nematodes (Helicotylenchus spp. and Rotylenchus spp.), lesion and root-knot nematodes (Pratylenchus spp.) and (Meloidogyne spp.) respectively. Land-use changes (wild vs cropped olive), irrigation and soil physic-chemical characteristics (e.g. pH, t...