Marek Renčo

Soil nematode community changes associated with windfall and wildfire in forest soil at the High Tatras National Park, Slovak Republic

SummaryThe paper presents research findings on the influence of windfall and wildfire on nematode communities in Lariceto-Piceetum forest in the High Tatras in Slovakia. Comparison was made of an intact (REF), affected and extracted (EXT), non-extracted (NEX) and burnt (FIR) forest stand. A total of 55 species belonging to 36 genera were found. The EXT locality harboured the majority of the identified species, but the highest abundance of nematodes was observed in the FIR locality. Bacterial feeders were the dominant trophic group in all investigated plots. In the REF bacterial feeders were followed by root-fungal feeders, fungal feeders and omnivores, in the EXT by omnivores and plant parasites, in the FIR by omnivores and root-fungal feeders and in the NEX by fungal feeders and omnivores. The MI and SI were higher in the REF and the EXT compared to those in the FIR and the NEX, the highest B/F ratio was observed in the FIR and the highest EI was found in the REF. We can conclude that disturbance of forest vegetation and soil has had a clear and demonstrable impact on nematode communities.

Soil nematode community changes associated with compost amendments.

Five composts (C 1 : fresh olive pomace, straw, chicken manure, urea; C 2 : fresh olive pomace, lettuce residues, cow manure, straw, sawdust; C 3 : sewage sludge, municipal green residues; C 4 : grass, leaves, tree branches, soil; C 5 : by-product from penicillin production (mycelium), straw and sawdust) were tested in a pot experiment to investigate their short-term effect on the nematode community of a grassland soil. Composts were mixed with soil at the rates of 10, 25, 50 and 100 g (kg soil) –1 and barley was sown in each potting mixture after a 2-month decomposition period. Nematodes were extracted from each pot 5 months after barley sowing, identified at genus level and grouped into bacterial, fungal and root fungal feeders, predators, omnivores and plant parasites. Bacterial feeders, predators and omnivores were favoured by amendments with composted penicillin substrate and partly by compost from olive pomace, whereas composts from green wastes and sewage sludge suppressed these trophic groups except for predators. All compost treatments suppressed fungal feeders as well as significantly reducing the density of plant-parasitic nematodes compared with non-amended soil. The highest suppressiveness on plant-parasitic nematodes was found for the composts from urban green residues, penicillin substrate and olive pomace plus cow manure. Suppressive effect was hypothesised to be related to ammoniacal nitrogen content of the composts. Composts from fungal mycelium or olive pomace seem to be the most suitable for application in nematode management strategies due to their low impact on beneficial trophic groups.

The effect of soil compost treatments on potato cyst nematodes Globodera rostochiensis and Globodera pallida

SummaryA pot experiment on potato was carried out to verify the nematicidal effect of four composts of different origin (C1: 70 % horse manure + 15 % sugar beet pomace + 5 % poultry manure + 10% grape pomace; C2: 100 % pig manure decomposed by juveniles of Musca domestica; C3: 100 % vermicompost from medical plants wastes; C4: 100% vermicompost from cattle manure) on the potato cyst nematodes G. rostochiensis (Ro1) and G. pallida (Pa2 and Pa3). Composts at different rates (1.0, 2.5 and 5.0 % w/w) were mixed with the nematode infested soils. Pots with unamended soils were used as control. Pots (4 l) were arranged in a glasshouse according to a randomized block design with four replications per each treatment. A significant reduction in number of cysts, eggs and juveniles/cyst and eggs and juveniles/g soil was observed in each compost in comparison to unamended soil. The suppressive nematode effect increased according to the compost NH4+ content and compost rate.

The effect of five composts of different origin on the survival and reproduction of Globodera rostochiensis

Five composts of different origin (C1: fresh olive pomace, straw, chicken manure and urea; C2: fresh olive pomace, cow manure, lettuce residues, straw and sawdust; C3: sewage sludge and municipal green residues; C4: grass, leaves, tree branches and soil; C5: by-product from penicillin production (mycelium), straw and sawdust, were tested for the control of the cyst nematode, Globodera rostochiensis, on potato in pot experiments. Composts were mixed with the nematode-infested soil at the rates of 1.0, 2.5, 5.0 and 10.0% w/w. A significant reduction in the number of eggs and juveniles was observed at all concentrations of the tested composts; compost from olive pomace mixed with urea resulted in the greatest decrease.

The effect of two compost soil amendments, based on municipal green and penicillin production wastes, on plant parasitic nematodes

SummarySuppressive effect of two composts, applied at five doses (0 %, 1 %, 2.5 %, 5 % and 10 % w/w), was studied on spring barley to control different genera of plant parasitic nematodes in potting mixtures. Amendment of soil with these materials resulted in a significant decreasing effect of plant parasitic nematode populations. The best reduction of number of plant parasitic nematodes was found for the nematode genera Bitylenchus, Helicotylenchus, Heterodera, Paratylenchus and Rotylenchulus by a municipal green compost (C1) and nematode genera Bitylenchus, Geocenamus, Helicotylenchus, and Rotylenchulus by a compost derived from penicillin production residues (C2). The compost C1 with a lower C:N ratio was more effective in the nematode control than the compost C2. The analysis of variance showed a significant interaction among all factors involved in the experiment: type of compost, different doses and nematode genera. Relationship between applied doses and number of nematodes showed a significantly high negative correlation.

Organic amendments of soil as useful tools of plant parasitic nematodes control

SummaryUse of organic soil amendments is a traditional agricultural practice for improving physical and chemical soil properties, soil structure, temperature and humidity conditions as well as nutrients content which are needful for plants growth. Application of organic materials to soil can cause a change in soil microflora and microfauna including soil nematodes. Nematodes, are the most ample and varied group of soil fauna. They are ever-present habitants of all soil types with high population densities. The changes in soil nematodofauna can results in an increase in the number of beneficial nematodes such as bacterial or fungal feeders and decrease and/or suppression in the occurrence of economically important plant parasitic nematodes. A variety of organic amendments, such as animal and green manure, undecomposed (raw) or decomposed materials (compost) are used for this purpose. Generally, plant parasitic nematodes have been controlled mainly by chemical soil fumigants and nematicides, agricultural practices or resistant cultivars. However, organic amendments can provide an environmentally friendly alternative to the use of chemical nematicides, which are often expensive, of limited availability in many developing countries and above all environmentally hazardous.

Seasonal fluctuations of the nematode communities in a hop garden soil

SummaryA study on the seasonal fluctuation of nematode population was conducted during three vegetation periods (2005 – 2007), at 20 and 40 cm soil depth, from May to October, in a hop garden at Nemšová (Slovak Republic). The seasonal fluctuation of the nematode population was related to temperature and rainfall. At 20 cm soil depth of each year, the largest nematode population was recorded in July, and the smallest from July to October. At 40 cm soil depth, nematode abundance was not significantly different between the years 2006 and 2007. In general, at the same depth, a decrease of nematode abundance was observed from May to October. The soil nematode community was rich in bacteriovorous nematodes, especially in the top 20 cm soil. The genus Rhabditis was the eudominant taxon at both soil depths. This genus with the genera Cephalobus, Heterodera, Merlinius and Aglenchus represented the 50 % of the total nematode population at 20 cm soil depth and with the genera Cephalobus, Helicotylenchus, Heterodera and Merlinius represented the 52 % of total nematodes abundance at 40 cm depth.

Suppression of root-knot nematodes in potting mixes amended with different composted biowastes

SummarySuppressiveness of soil amendments with different rates of composted biowaste materials, olive pomace, municipal green wastes, sewage sludge and spent mushroom substrate, was evaluated against the root-knot nematode Meloidogyne incognita on tomato in potting mixtures. Soil amendments were applied at 0, 10, 25, 50 and 100 g kg−1 soil, according to a randomized block design with five replications for each treatment. Sixty days after tomato transplanting, nematode population density on plant roots and in soil and root gall infestation were assessed on each root system, and plant top and root weight were also recorded. Soil pH, dry and organic matter content, total and ammoniacal nitrogen were analyzed at the same time. Olive pomace-based composts resulted in the highest nematode suppression (73–97 %, according to the rate) and significantly reduced gall formation on tomato roots. Olive-waste compost affected positively tomato growth only in combination with sheep wool wastes, but it caused phytotoxicity when mixed with chicken manure and urea. Soil amendments with composted mushroom substrate also provided a consistent nematode suppression and a significant increase of plant growth, whereas composted municipal green wastes were more suppressive and positively affected tomato growth when combined with sewage sludge. Soil chemical parameters were scarcely affected by compost amendments, as organic matter was significantly increased only by the olive pomace-derived composts and nitrogen content only at the highest rate of the five composts. Data from the experiment confirmed the potential of compost amendments for sustainable management of root-knot nematodes both in field and greenhouse container media, though their technical effectiveness and economic convenience are strictly dependent on a correct proportion and local availability of raw materials used in the composting process.

Communities of free living and plant parasitic nematodes in hop gardens in Slovakia

SummaryA total of 61 nematode species belonging into 48 genera was identified in soil of nine localities of hop gardens in Slovakia. From free living soil nematodes the most abundant were the genus Rhabditis-eudominant taxon, species Aphelenchus avenae — dominant taxon, the species Cephalobus persegnis, Chiloplacus propinquus, Aglenchus agricola, Nothotylenchus acris, Aporcelaimellus obtusicaudatus and genus Eudorylaimus were subdominant taxa. Only ten species of plant parasitic nematodes were observed — Ditylenchus dipsaci, Bitylenchus dubius, Merlinius brevidens, Rotylenchus robustus, Helicotylenchus canadensis, H. digonicus, Pratylenchus penetrans, P. pratensis, Heterodera humuli, and Paratylenchus bukowinensis. Bitylenchus dubius and Merlinius brevidens belonged to dominant taxa, the species Heterodera humuli and Helicotylenchus digonicus to subdominant taxa. The occurrence of Heterodera humuli cysts was recorded at all localities studied, and the occurrence of H. humuli larvae in soil during autumn indicates that possibly more than one generation of the parasite have developed within one vegetation period. The proportion of individual trophic groups in nematode communities of hop gardens was characterised by the prevalence of bacterial feeders followed by plant parasites. The ecological characteristics used for ecological evaluation, especially Maturity Index and Plant Parasitic Index/Maturity Index, indicate a more disturbed environment. Although hop is a perennial plant, the structure and ecology of its nematode communities is more similar to the agricultural ecosystems with a higher level of agricultural practices.

Nematicidal effect of chestnut tannin solutions on the potato cyst nematode Globodera rostochiensis (Woll.) Barhens

SummaryRecently, tannins have been reported for their nematicidal activity against the root-knot nematode Meloidogyne javanica both in vitro and in pot experiments in addition to a biocidal effect on a wide range of fungi, bacteria and yeasts. However, no information is available on the effect of these polyphenols on plant parasitic cyst nematodes. Therefore, an in vitro and a pot experiments on potato were undertaken to investigate the nematicidal activity of tannin aqueous solutions at different concentrations on the potato cyst nematode Globodera rostochiensis. In the in vitro experiment different tannin concentrations in a geometric scale (from 0.32 to 20.48 g/l) were tested for their effect on the egg hatch of the nematode. All tested tannin concentrations were effective to reduce egg viability from 56 to 87%, in comparison to the untreated control. In the pot experiment, tannins, as aqueous solutions at rates of 100, 250 and 450 g/m2, were applied to soil at two different application times (at sowing and at sowing and two weeks later). All tested doses were effective to reduce the number of cyst/100 g soil, eggs and juveniles/g soil and reproduction rate in comparison to untreated control. The number of eggs and juveniles/cyst was not influenced by the different applied rates of tannins.