Results in Figure (4) showed that Streptomyces isolates were distributed into 4 groups according to their antagonistic patterns against fungi involved in cotton seedling disease, group A included four isolates, Qa- 51, Qa53 (from El-Fayoum), Si-1 and Si-4 (from Sinai), group B included 6 isolates, Sc- 2, Sc-11, Ma-13 (from Alexandria), Ps-12 (from Port Said) and Si-6, Si-8 (from Sinai) group C included Qa-44 and Qa-84 (from El- Fayoum), Da-3 (from Damiatta) and Si-9 (from Sinai). However, group D included only one isolate Is-10, which was isolated from Ismailia, according to this isolates distribution, it seems reasonable to conclude that there was no relationship between the Streptomyces geographic origin and their antagonistic pattern against soil-bornefungi involved in cotton seedling disease.
Together, these two studies suggest that pathogenic soil biota, and soil-bornefungi in particular, play an important role in regu- lating the plant diversity–productivity relationship. However, treatments such as soil sterilisation or fungicide application do not resolve the identity of the soil biota involved and, as such, provide only indirect evidence for how they interact with plant species richness. Here, we determined the taxonomic and func- tional diversity of soil-borne fungal communities in roots from a 10-yr-old biodiversity experiment (van Ruijven & Berendse, 2009) using next generation sequencing approaches. We used these data to assess host specificity and negative density depen- dence of the root-associated fungal community. It is important to note that these two factors may have contrasting effects on the relationship between plant and fungal species richness. If host specificity is strong and different plant species accumulate differ- ent fungal species, mixtures of plant species can be expected to harbour a mix of the fungal communities associated with each of the component plant species, potentially leading to an increase in fungal species richness with increasing plant species richness (Rottstock et al., 2014; Dassen et al., 2017). On the other hand, if negative density dependence leads to a reduction in the accu- mulation of host-specific fungal species with increasing plant species richness (i.e. decreasing host density), this may lead to a dilution of host-specific pathogens in mixtures, resulting in a less positive, neutral or even negative relationship between plant species richness and fungal richness.
and T. viride and inoculated with M. phaseolina recorded the highest damage reduction of shoot and root dry weights and the lowest disease severity index values. The develop- ment rate revealed the growth improvement induced by T. harzianum (watermelon, 15%) and A. flavus (melon, 12%). In fact, the application of Trichoderma to the soil as bio- logical control agent in the greenhouse or under field con- ditions not only resulted in reduced disease severity of M. phaseolina but also enhanced plant growth (Srivastava et al. 2008). The efficacy of the three Trichoderma species and A. flavus, applied curatively of watermelon and melon, on growth parameters was studied under pot culture condi- tions. Watermelon plants inoculated with F. solani f. sp. cucurbitae and treated with T. erinaceum, T. viride, and A. flavus showed an improvement of growth parameters. T. helicum and A. flavus were effective on plants inoculated by F. oxysporum f. sp. niveum. The best growth parameters on melon plants inoculated by F. solani f. sp. cucurbitae were obtained in the case of T. erinaceum. Our results sup- ported those of Harman et al. (2004) showing the use of Trichoderma spp. as plant growth enhancers, due to its production of growth hormones and enhanced transfer of minerals to the rhizosphere. The pathogen incidence and disease severity of plant inoculated only with pathogens were higher than the other treatments. Gava and Menezes (2012) revealed that Trichoderma spp. isolates have been Table 10 Comparison of different growth parameters values: shoot and root heights (cm), shoot and root fresh weights (g), and shoot of root dry weights (g) recorded by melon seedlings inoculated by two F. solani f. sp. cucurbitae isolates (FSC 5 and FSC 2) and two F. oxysporum f. sp. melonis isolates (FOM) and treated curatively by three Trichoderma spp. isolates and A. flavus
Abstract: Organophosphorous nematicides are highly toxic pesticides used to control nematodes in agriculture soil. An in vitro Biodegradation study was conducted to determine the biodegradability of, ethoprophos, fenamiphos and triazophos nematicides, using fungi strains isolated from sandy agriculture soil under date palm trees. Five fungi strains labeled as S1 (Fusarium oxysporum), S2(Aspergillus flavus), S3 (Aspergillus fumigatus), S4 (Fusarium moniliforme) and S5 (Trichothecium roseum) were isolated and identified, then incubated with nematicides at successive intervals untill 45 days in liquid medium paralleled with control samples. Recovery rates were performed at two levels 0.1 and 1 mg kg -1 , values were over 90% for all nematicides. Limit of detection values (LOD) were 0.010, 0.012 and 0.011 mg kg -1 and limit of quantitation values (LOQ) were 0.033, 0.040 and 0.036 mg kg -1 respectively. Data indicated that S1 (Fusarium oxysporum) and S2 (Aspergillus flavus) accelerated the degradation rate of all mentioned nematicise, and S2 had the highest impact more than S1, while the other strains had no significant effect. Half-life values (RL 50 ) for nematicides with S1 were 18.15, 16.65 and 15.24 days, respectively,
Laboratory tests made possible to determine the population of soil-bornefungi that are antagonistic towards the studied phytopathogens. Regardless of the experimental treatment, the greatest pop- ulation of antagonistic fungi was found within genus Trichoderma (Figure 2), slightly smaller in Clonostachys spp. and Myrothecium spp., and the smallest in Penicillium spp. Antagonistic fungi most frequently occurred in the soil after using oats (245, 109 and 288 isolates, respectively), and the most rarely in the control (21, 19 and 34 isolates, respectively). Tansy phacelia and vetch used in the cultivation of carrot also caused an increase of the population of antagonistic soil-bornefungi species as compared to the control. An increased population of antagonistic soil-bornefungi species was also observed in the cultivation of scorzonera and root chicory where cover crops were used (Patkowska and Konopiński 2014b, Patkowska et al. 2015).
from 2376 and 2437 (after the use of rye) to 246 and 238 (in control) (Tables 1–5). The present studies enable to state that the use of cover crops (especially rye and white mustard) in the cultivation of Daucus carota L. had a positive effect on the antagonistic activity of soil-bornefungi. A big number of isolates of antagonistic fungi could improve the phytosanitary conditions of the soil. As reported by Gamliel et al. (2000), the development of antagonistic microorgan- isms could be supported by secondary metabolites introduced into the soil of cover crops. Examples of such compounds are glucosinolates, which – after enzymatic hydrolysis – change into different sulphuric compounds (Gamliel et al. 2000). Those compounds are produced inside the plant tissue, and after the microbiological decomposition of plant residues, they are freed into the soil. Isothiocyanates, which appear in the soil during the decomposition of plants roots, are a product of decomposition of glucosinolates (Vig et al. 2009). According to Bending and Lincoln (2000), those compounds are toxic towards plant pathogens, and they can have a synergistic effect on the communities of microorganisms, through which they can favour the development of antagonistic microorganisms.
9. Ulfig, K., Płaza, G., Worsztynowicz, A., Mańko, T., Tienz, A.J. and Brigmon, R. L. Keratinolytic Fungi as Indicators of Hydrocarbon Contamination and Bioremediation Progress in a Petroleum Refinery. Polish Journal of Environmental Studies, 2003; 12(2): 245-250.
As in the CT and NT plots, the highest number of OTUs in HTS came from the Agaricales clade, accounting for ~55% of all OTUs detected in these plots. The second highest number of OTUs in HTS came from Cantharellales and Tulasnellales clades, while the remaining clades accounted for less than 6% of the OTUs. OTUs 517-518 from HTS are strongly linked with the root associates Sebacina and Piriformospora but OTUs 514 and 520-522 from NTS are not strongly linked with any reference taxon in the Sebacinales; the latter three are weakly linked with the saprotrophic Craterocolla. All Cantharellales recovered from KBS LTER are phylogenetically close to saprotrophic species of Minimedusa; isolates T-791 (NTS), X-14 (NT), and X-44 (from soil of a nearby deciduous forest) grew vigorously in culture and are clearly saprotrophic (Thorn, unpublished). PCoA of the data show HTS plots to be not as closely clustered together as NTS plots and the distance between HTS sites in the ordination suggest that HTS
The purpose of the studies was to determine the species composition of fungi and their antagonistic effect towards soil-borne plant pathogens after the cultivation of oats, spring vetch and tansy phacelia as intercrop cover plants. The total population of fungi in the soil after the cultivation of oats was twice as low as after the cultivation of tansy phacelia. A little smaller fungi population was obtained as a result of mulching the soil with spring vetch in com- parison to that after the cultivation of tansy phacelia. The proportion of Fusarium spp., Alternaria alternata, Pythi- um irregulare and Thanatephorus cucumeris isolated from the soil after the cultivation of oats was the lowest one, while being a little higher after the cultivation of spring vetch, and the highest after tansy phacelia. The greatest number of antagonistic fungi occurred in the soil after ploughing in the mulch of oats. Antagonistic fungi isolated from the soil mulched with oats were the most effective in limiting the growth and development of A. alternata, Fusarium culmorum, F. oxysporum, Haematonectria haematococca, P. irregulare and T. cucumeris since the value of their antagonistic effect was the largest. The lowest antagonistic activity of fungi was found out after using tancy phacelia.
Three layers of blotting paper (9 cm diameter) were cut plate, placed at the bottom and water. Excess water was plates were autoclaved for 121 ° C for around 20 min. at 15 psi. Seed samples were surface disinfected with 1% sodium hypochlorite solution for about 2 min. at room temperature and placed 10 seeds per petri plates. plates were incubated for seven days at 25±2 ° C in alternating cycles of 12 hours darkness and 12 hours light. After seven days of incubation, fungi were detected by their growth and spore morphology by following the keys outlined Barnett and Hunter, 1972, Watanabe,
Ten species of fungi viz., Fusarium graminearum, F. oxysporum, Aspergillus flavus, A niger, A. terreus, Penicillium sp, Curvularia lunata, Drechslera halodes, Alternaria alternata and Cladosporium cladosporides isolated from maize seeds were used as test fungi for antifungal activity assay.
Previous research has suggested that cover crops may be a viable option for disease control (Brown and Morra, 1997; Treonis et al., 2010; Weller et al, 2002; Zasada et al., 2007; Zhou and Everts, 2004). However, significant cover crop biomass is needed to prove these theories. The more cover crop biomass that is incorporated into the soil, more “food” will become available to the microbial populations. This will allow for antagonistic or synergistic relationships to develop as the microbes compete for the same food source (Eastburn 2010). Due to the poor establishment of the cover crops in the field experiment, a greenhouse assay was developed to further explore the differences in the microbial populations between cover crop treatments. The cover crops in the field experiment were not planted early enough in the fall to allow for adequate growth before the first frost. This late planting did not allow the cover crops to become established well enough to survive the winter months and therefore, the overall cover crop biomass across the plots was quite low. By not having enough biomass, the microbial populations were not significantly different from those detected in the fallow treatment plots. Since many previous studies have proven that cover crops contain disease suppressive qualities, further research was initiated.
After the degradation process, the soil (weight of 1 g) was placed in a centrifuge tube and immersed in 10 ml of acetone-phosphoric acid solution (99.5:0.5). Then, the solution was placed into an intermittent ultrasonic water bath at a low temperature for 2 h and was centri- fuged for 5 min. The upper extract liquid was transferred to a separating funnel, supplemented with 15 % sodium chloride. The centrifuge tube was washed with 10 ml of acetone twice and the wash solution was poured into the separating funnel. The solution was extracted with 10 ml ethyl acetate twice and the mixture was stratified into two liquid phases at rest. The upper layer of ethyl acetate was transferred to a culture vessel and then 10 ml of methanol was added after evaporation of ethyl acetate. Finally, the mixed solution was introduced into an HPLC sampling bottle through a syringe of the organic microporous membrane in a volume of 0.5 ml for the measurement of chlorpyrifos.
The lack of national scale monitoring during the last thirty years exposes Europe to infestations of new nematode species as a direct consequence of climate change (Neilson and Boag, 1996) and an unknown pathogen burden exacerbated in the short term by removal of approved nematicides (91/414/EEC). The move to field scale monitoring rather than national scale moves the burden of responsibility from policymakers to individual landowners and growers to test soil prior to crop planting. Such pre-plant tests are only available in European member states that have the nematological infrastructure to process large sample numbers and a dissemination pipeline between researcher and farmer. One example which has been in operation for 10+ years occurs in Scotland, where farmers through agronomy companies submit soil samples for nematode testing prior to planting of potato, soft fruit and root vegetables. Results determine whether the selected crop and/or the choice of a resistant cultivar is made, thereafter the nematode data is passed to the supermarket multinationals who make decisions on nematicide application thus determining which branding the product can be sold e.g. “green” label. Other nematode services are provided in the UK mainly by SRUC, SASA and FERA. In the Netherlands commercial laboratories process nematode samples and run advisory services based on the Dutch nematode scheme (Molendijk and Mulder, 1996) and decision support systems like NemaDecide (Been et al., 2007). Following Eurofins acquisition of a Dutch commercial laboratory, nematode analyses will be offered as a new service for Swedish farmers and the former Swedish nematode laboratory at SLU has been acquired by a private company offering analyses.
Increased SF diversity in contrast to decreased AMF diversity by most fertilization regimes. In addition to the alternation of fungal quantity, the diversity of SF and AMF were differentially regu- lated by the long-term fertilization. SF diversity increased in all fertilization treatments compared to control (Figure 4), probably due to the increased contents of soil nutrients such as SOC, TN, MN and TP (Figure 7). Previous study on AMF commu- nities under different practices has demonstrated that organic management enhances the diversity of AMF assemblages, compared to conventional management practice (Verbruggen et al. 2010). However, we observed either a negative (1/2OMN) or no effect (OM) of long-term organic fertiliza- tion on the diversity of AMF, whereas mineral fertilization treatments (NP, PK, NK and NPK) caused a decrease in AMF diversity, compared to CK (Figure 4). Additionally, SOC, TN, MN and TP had a less negative impact on the diversity of AMF than the quantity of AMF (Figure 7), suggesting that the diversity and quantity of AMF respond to the nutritional status in the different manners.
Soilborne plant pathogenic fungi cause heavy crop losses all over the world. Agriculture has been facing the destructive activities of numerous pests and pathogens from an early time, which leads not only to the reduction of yield of the crops but also the aesthetic value. Chemical control of such plant pathogens disturbs the environment, subverts ecology, degrades soil productivity, and mismanages water resources [1, 2]. In addition to this, due to the growing cost of pesticides, particularly in the less affluent region of the world and consumer demands for pesticide-free food has led to the search for the substitutes for these products. Biological control of plant diseases, especially those caused by soilborne plant pathogens and nematodes, by microorganisms has been considered a more natural and environmentally acceptable alternative to the existing chemical treatment methods . The renewed interest in biocontrol among agriculture biologists is due to its eco-friendly protection against weeds, insects, and plant diseases, a long lasting effect, and safety features. Some of the bacterial antagonists, however, also have been found to show direct growth promoting effects on crop plant inoculants [4, 5].
The main objective of the present study was to evaluate the disease-suppressive effect of brassica and non-brassica cover crops of interest in Swedish agriculture. Two species were chosen from the Brassicaceae (oilseed radish, which has high GSL content, and mustard, which has low GSL content) and compared with two non-brassicas (rye and Westerwoldian ryegrass). The three soil-borne pathogens chosen as model organisms (Sclerotinia sclerotiorum, Fusarium culmorum and Rhizoctonia solani) are responsible for economically important diseases in oilseed rape, cereals and potatoes, respectively. The starting hypothesis for the investigation was that growing the biomass from four different cover crops (two brassicas and two non-brassicas), cutting and chopping it and immediately incorporating it would suppress three important soil-borne plant pathogens. In the case of the brassica cover crops, the mechanism behind the suppression could be either direct toxicity through the transformation of glucosinolate into isothiocyanate or an indirect result of changes in the structure of the soil microflora.
After the antifungal evaluation analysis of Eupatorium odoratum, Vernonia amygdalina and disinfectants, Izal was found to be the most effective disinfectant against airborne fungi isolates. The results of this study showed that Izal will be more effective in disinfection of poultry houses followed by Polidine. Whereas, ethanolic extracts of Eupatorium odoratum was found to be the most effective herbal extract in disinfecting poultry houses as it had more activity against all the test isolate except Candida akabenensis. Aqueous extract of Vernonia amygdalina may not be considered effective in disinfecting poultry houses due to poor activity recorded across the test isolates.
affect symbiotic relations of these fungi, which in turn affect glomalin production. In a pot culture experiment, the sterile soil was treated with 0, 100, 200 mg N kg -1 soil as urea or 0, 20, 40 mg P kg -1 soil as triple superphosphate, in two separate factorial experiment based on completely randomized design with three replications. Corn plant (Zea mays L.) was inoculated with Rhizophagus clarus (formerly, Glomus clarum) or Rhizophagus intraradices (formerly, Glomus intraradices) in each set of experiment. Easley extractable glomalin (EEG) and total glomalin (TG) in soil were determined by Bradford method at the end of experiment. Root colonization by both fungi increased EEG and TG compared to the non-mycorrhizal control (p<0.05). Nitrogen levels of 100, 200 increased EEG by 75 and 112% and TG by 59 and 76%, respectively, compared to the no nitrogen treatment. P levels of 20, 40 caused 27% increase and 6% decrease in EEG, and 24% increase and 13% decrease in TG, respectively, compared to the zero addition of phosphorus. Regarding glomalin production in this condition, R. clarus was more efficient than R. intraradices. Application of 20 mg P kg -1 increased root colonization, dry weights of shoot and root, chlorophyll index, leaf area, amount of shoot and root nitrogen and potassium compared to the 40 mgP. kg -1 and control. Thus, application of 100 mg N kg -1 increased root colonization, dry weights of
that it is difficult to estimate the effects of low concentrations of heavy metals on the soil mi- crobial population since soil microorganisms may be more strongly affected by other physi- cal, chemical, and biological factors, such as soil water content, organic matter content, fertilizer application, and cropping. In addition, some of the effects, even in the highly contaminated ar- eas, include indirect effects of heavy metal pollu- tion. 7,9 The present study aims on the effects of