M. Talavera

Perception of the impact of root-knot nematode-induced diseases in horticultural protected crops of south-eastern Spain

With a surface area of 37 000 ha and an annual yield of 3 × 106 t, the south-east of Spain, predominantly the coast of Almeria, is the largest horticultural growing area under protected cultivation in Europe. A survey on perception of the impact of root-knot nematodes on vegetable production was carried out in this area by face-to-face interviews with 120 farm advisors. The survey was designed to evaluate opinions about prevalence and severity of root-knot nematode-induced diseases, percentage of infested area and effectiveness of root-knot nematode control methods. According to the answers, 17.7% of the fields were infested with root-knot nematode and 18.8% of the cultivable area within each site showed root-knot nematode disease symptoms, which came to 2.0% of the total area used to grow vegetables in the region. Average yield loss was estimated at about 30.8% of total vegetable production, and 38.1% of the farm advisors considered that root-knot nematode infections had increased over the last 5 years. Most farm advisors (78.3%) stated that the most commonly used control method was chemical soil fumigation. Non-fumigant nematicides were cited by 59.8% of them, grafting and resistant cultivars by 42.3%, soil solarisation 38.1%, plant extracts 14.4% and biofumigation 6.2%. The majority of farm advisors considered the application of fumigant nematicides combined with soil solarisation, and grafting onto resistant rootstocks as the most effective methods of root-knot nematode control. In addition to the interviews, plant and soil samples were taken from plastic greenhouses throughout the region to determine species of root-knot nematode present. Meloidogyne javanica was the most prevalent species followed by M. incognita and M. arenaria, but species distribution was linked to the predominating crop sequence in each area, since M. javanica occurred less frequently when sweet pepper rather than tomato appeared in the crop sequence.

Experimental validation of Haldane's hypothesis on the role of infection as an evolutionary force for Metazoans

A common drawback in evolutionary science is the fact that the evolution of organisms occurs in geological timing, completely out of the time scale of laboratory experimental work. For this reason, some relevant hypotheses on evolution of Metazoans are based on correlations more than on experimental data obtained for testing the robustness of those hypotheses. In the current work, we implement an experimental methodology to analyze the role of infections as a driving force in the evolution of Metazoans (Haldanes hypothesis). To that goal, we have used simple models of virulence with short reproduction times, large populations, and that are easily testable in the laboratory. Using the bacteriovirus nematode Caenorhabditis elegans as a model organism under evolution and their infection by the environmental opportunistic bacterial pathogen Pseudomonas aeruginosa as the selective force, we have demonstrated that bacterial infection selects an evolved nematode lineage resistant to infection, with changes in its respiration and capability of consuming novel food resources. Using an experimental approach, we show that infection is a selective force in the evolution of Metazoans as proposed earlier by Haldane.

Effects of dual inoculation of mycorrhiza and endophytic, rhizospheric or parasitic bacteria on the root-knot nematode disease of tomato

The effects of mycorrhisation and inoculation with soil bacteria on the disease caused by Meloidogyne incognita on tomato were studied in pots under greenhouse conditions. Efficacy in promoting plant growth and reducing disease severity and final nematode densities were evaluated for two arbuscular mycorrhizal fungi (AMF; Funneliformis mosseae and Rhizophagus irregularis), three soil bacteria with different living strategies (the endophyte Bacillus megaterium, a rhizospheric Pseudomonas putida and the hyperparasite of nematodes Pasteuria penetrans) and combinations of the fungi and bacteria. In M. incognita-infested plants, F. mosseae increased tomato growth more than R. irregularis, and plants inoculated with B. megaterium presented higher shoot fresh weight than with P. putida or P. penetrans, but dual inoculation did not improve tomato growth more than single inoculations. Disease severity and final nematode densities were reduced by F. mosseae compared to non-mycorrhizal plants. B. megaterium and P. penetrans reduced both the root galling and the final nematode densities compared to treatments without bacteria. P. penetrans reduced final nematode densities more than B. megaterium or P. putida. Dual inoculation of AMF and P. penetrans showed the highest efficacy in reducing the final nematode densities in tomato.

Incidence of plant-parasitic nematodes in natural and semi-natural mountain grassland and the host status of some common grass species

A plant-parasitic nematode survey was undertaken in mountainous pastures of southern Spain. Sixty-three species of plant-parasitic nematodes distributed over 25 genera were associated with pastures and grasslands in southern Spain. Paratylenchus species (P. microdorus, P. similis, P. nanus and P. ciccaronei) were the most abundant and prevalent plant-parasitic nematodes found. Pratylenchus neglectus and P.thornei were widely distributed in 55 and 41% of sites, respectively. Amplimerlinius globigerus, Helicotylenchus digonicus, H. dihystera, H. tunisiensis, Merlinius brevidens, M. microdorus, Rotylenchus unisexus and Scutylenchus quadrifer were found in more than 10% of the fields, on occasion at densities of more than 200 per 100 cm³ of soil. A further 49 species of plant-parasitic nematodes were identified and reported. A pot experiment, using a range of grasses and forage legumes adapted to the zone, ascertained the host status of the most abundant plant-parasitic nematodes. Helicotylenchus digonicus, M. microdorus and P.microdorus populations were maintained or increased by all grasses or legumes tested. In general, grasses were better hosts of P.neglectus and P.thornei than the pasture legumes tested. Medicago minima reduced P.thornei densities after 3 months of growing.

Use of Poultry Manure Combined with Soil Solarization as a Control Method for Meloidogyne incognita in Carnation

The effectiveness of a combination of soil solarization and poultry manure (raw or pelletized) amendments for the control of root-knot nematode (Meloidogyne incognita) was tested in carnation (Dianthus caryophyllus) crops grown in in-ground beds under plastic-covered greenhouse conditions in southern Spain. Our trials demonstrated that soil solarization alone did not provide sufficient control of root-knot nematode, because the carnation growing season in this region only partly coincides with the most effective period for solarization, resulting in an insufficient duration of treatment during a key period for effectiveness. Chemical fumigation with 1,3-dichloropropene + chloropicrin prior to planting was effective in reducing nematode population densities in soil. Its effects spanned 9 months after planting, resulting in acceptable crop yields. In comparison, the combination of soil solarization and raw or pelletized poultry manure was slightly less effective than chemical fumigation for control of this pathogen but crop yields after 9 months were similar. However, the higher root gall indices observed after 9 months, in comparison with chemically fumigated plots, indicated the need for a reapplication of the organic manure treatment at the start of each successive growing season.

Comparison of different chemical and non-chemical alternatives to Methyl Bromide for strawberry in Huelva (Spain)

“Spain’s Methyl Bromide (MB) Alternatives Project” has been developing/demonstrating alternative fumigants for methyl bromide on strawberry in Huelva since 1997. Here, we describe our research carried out between 2008 and 2010. In all the trials ‘Camarosa’ was grown under high plastic tunnels between October and the end of May every year. Field trials with the same complete randomized block design and 10–12 treatments were performed annually in two locations of Huelva (“Occifresa”-Moguer and “Cumbres Malvinas”-Palos de la Frontera.). In 2007/08 and 2008/09 the following ten treatments were applied: untreated control; MB + chloropicrin (50 : 50 w/w); sodium azide; dazomet + 1,3D(dichloropropene); 1,3D + chloropicrin (61 : 35 w/w); chloropicrin alone; DMDS (dimethyl disulphide) + chloropicrin; methyl iodide + chloropicrin (50 : 50 w/w); acrolein; and furfural. In 2009/10, non-chemical treatments (biosolarization) were included; in comparison with previous year, four additional treatments were applied: biosolarization with fresh poultry manure (25,000 kg/ha), biosolarization with Brassica pellets (2,000 kg/ha), sodium tethathiocarbamate and metam sodium shank-applied with Rotary Spader implement. Black root rot complex (Fusarium spp., Cylindrocarpon spp., Rhizoctonia spp., and Pythium spp.) and nematodes Meloidogyne hapla and Pratylenchus penetrans were the main phytosanitary problems related to the soil, and Macrophomina phaseolina was detected occasionally in the first two seasons. However, plant survival, fruit size and yields were optimal in both locations. In 2009/10 at “Occifresa”-Moguer a higher percentage of dead plants was evidenced, and at an earlier stage than the previous growing seasons, mainly caused by Macrophomina phaseolina and Fusarium oxysporum. DMDS + chloropicrin, 1,3D + chloropicrin and chloropicrin alone were as effective as MB : chloropicrin. Biosolarization with fresh chicken manure (25,000 kg/ha) showed higher production than the untreated control.

Post-anhydrobiotic viability ofpratylenchus thornei andmerlinius brevidens

After natural desiccation in the field, anhydrobiotic populations ofPratylenchus thornei Sher & Allen andMerlinius brevidens (Allen) Sidiqqi were treated in three different ways: some were kept dry to maintain nematodes in the anhydrobiotic stage; some were rehydrated and then allowed to dry again to induce a new desiccation cycle; and some were rehydrated and maintained as such, to reactivate and keep nematodes active.P. thornei populations from the dry treatment had a greater survival rate than the two other treatments. Culturing of the nematodes under wheat revealed that the three treatments did not alter the ability ofP. thornei to penetrate the roots, but nematodes given two cycles of desiccation had a greater rate of reproduction than those exposed to one desiccation cycle and kept in dry soil for a longer period (dry treatment). Survival ofM. brevidens rehydrated and retained in the active state was lower than that of nematodes undergoing the two other treatments.

Plant parasitic nematodes from a forest tree nursery in southern Spain with some notes about the influence of soil storage on the quantitative recovery of Meloidogyne arenaria

A nematological survey was carried out in a forest tree nursery in Andujar, southern Spain. Meloidogyne arenaria was found in soil and roots samples from Acacia sp., Biota sp., Juglans regia, Pinus spp., Salix babilonica and Sophora japonica. Pratylenchus vulnus was found in Acacia sp., Cupressus macrocarpa, Juglans regia, Ligustrum japonica, Morus sp., Pinus spp., Populus sp., Salix babilonica and Ulmus pumila. Helicotylenchus sp., Xiphinema americanum and Tylenchorhynchus sp. were found in all the plant species planted in the nursery. Paratylenchus sp., Criconemella sp. and Zygotylenchus guevarai host ranges are also given. The influence of soil storage on the recovery of M. arenaria was studied. At storage temperatures similar to those of the nursery (10-15°C), densities of M. arenaria in soil increased until the sixth week after sampling and were then maintained until the thirteenth week of storage. Incubation temperatures below 16°C during the migration of nematodes through a cottonwool filter, reduced the number of M. arenaria juveniles recovered after 15 h, but increasing migration time up to 39 h could counterbalance this reduction. Pflanzenparasitare Nematoden aus einer sudspanischen Forstbaumschulemit einigen Bemerkungen uber den Einfluss der Probenlagerung auf den quantitativen Nachweis von Meloidogyne arenaria - In einer Forstbaumschule in Andujar, Sudspanien, wurde eine nematologische Untersuchung durchgefuhrt. Meloidogyne arenaria wurde in Boden- und Wurzelproben von Acacia sp., Biota sp., Juglans regia, Pinus spp., Salix babilonica und Sophora japonica gefunden. Pratylenchus vulnus konnte an Acacia sp., Cupressus macrocarpa, Juglans regia, Ligustrum japonica, Morus sp., Pinus spp., Populus sp., Salix babilonica und Ulmus pumila nachgewiesen werden. Helicotylenchus sp., Xiphinema americanum und Tylenchorhynchus sp. wurden an allen Pflanzenarten gefunden, die in der Baumschule angebaut wurden. Ferner werden die Wirtspflanzen von Paratylenchus sp., Criconemella sp. und Zygotylenchus guevarai genannt. Dann wurde auch der Einfluss der Probelagerung auf den Nachweis von M. arenaria untersucht. Bei Lagerungstemperaturen von 10-15°C, die ahnlich waren wie die in der Baumschule, nahmen die Dichten von M. arenaria bis zur sechsten Woche nach der Probenahme zu und hielten sich dann bis zur 13. Woche der Lagerung. Temperaturen unter 16°C wahrend der Wanderung durch ein Baumwollwattefilter verminderten die Anzahl der nach 15h wiedergefundenen Juvenilen, doch konnte eine Verlangerung der Wanderzeit auf 39h diese Verminderung ausgleichen.

Fumigant Use for Strawberry Production in Europe: The Current Landscape and Solutions

ABSTRACT The impact of methyl bromide (MB) phase-out on important fruit and nursery industries in the EU (2005/2008) has been significant. Under EU Regulation 1107/2009, MB fumigant alternatives 1,3-dichloropropene and chloropicrin were also phased out (in 2010 and 2013, respectively) while dazomet, metam sodium, and potassium were re-approved with crucial restrictions of rates and years of application. However, currently an EU Member State may authorize use of these phased-out fumigants for 120 days/year. This exemption has been used for strawberry (fruit and nursery production) and other crops in Spain, Italy, Belgium, France, UK, Cyprus, Malta, and Greece in recent years. To provide an update of the current situation, a comprehensive survey of 41 European and other industries has been completed. Most of them use crop rotation as the main pest management solution. Non-chemical solutions, in particular soilless cultivation, are important in the UK, Ireland, France, the Netherlands, and Belgium. Chemical fumigation is still important in Spain, Italy, Morocco, Turkey, France, and Belgium.

Fungi recovered from root-knot nematodes infecting vegetables under protected cultivation

Abstract A survey was conducted in root-knot nematode-infested plastic houses to determine the diversity and frequency of occurrence of fungi associated with the nematode. The relationships between percentage fungal parasitism and physicochemical properties of soil were also investigated. Fifty-nine plastic houses were sampled in southeastern Spain, 42 treated with nematicides and 17 left untreated. Eleven fungal genera and unidentified fungi were isolated from nematode eggs or juveniles. Fungal parasitism occurred more frequently in untreated (82.4%) than treated (50%) soils. The species richness in untreated soils ranged from 0 to 5, the Shannon–Wiener diversity index (a measurement of how many different fungi there are in site taking into account how evenly they are distributed among the site) from 0 to 2.01, and the evenness index from 0.46 to 0.99. In treated soils, species richness ranged from 0 to 4, the Shannon–Wiener diversity index from 0 to 1.61, and the evenness index from 0.81 to 1. Of the sites with nematophagous fungi, Arthrobotrys dactyloides (34%), Cylindrocarpon sp., Neosartoria hiratsukae (17%), and Fusarium solani (14%) were the fungi most frequently found. Physicochemical properties of soil were similar in nematicide treated and untreated soils. Percent fungal parasitism in untreated soils correlated positively with lime, silt and carbonate content of soil.