Fungi associated with strawberry root rot in Illinois

A qualitative and quantitative study of the fungi associated with apparently healthy and root rot-diseased strawberry main roots was made during a 1-year period. Eighty-one genera were isolated from lesions and stele segments of diseased roots, and tips and segments 5–6 cm from the tip of apparently healthy roots. A diverse mycoflora was isolated from each segment of the root. However, each segment had a typical dominant mycoflora, indicating that a changing mycoflora is associated with the root as it passes from a healthy to a diseased condition.Pythium spp. andRhizoctonia Spp. accounted for 25.09 and 5.67 percent, respectively, of the isolates from Surecrop lesions, and 4.96 and 25.92 percent, respectively, of the isolates from Cyclone lesions.     

Root rot disease incidence and severity on some legume species grown in Samsun and the fungi isolated from roots and soils

Abstract

Root rot disease is very common in the bean, soybean, faba bean and pea plants growing areas in Samsun province. Disease incidence and severity were detected the highest at 93.8% and 55.4% in the bean growing area, and the lowest at 64.0% and 24.3% in the faba bean growing area respectively. In this study, a total of 2714 fungal isolates were obtained from some legume plants and soil samples. The most common fungi isolated from root and soil samples were Fusarium spp., multinucleate Rhizoctonia (MNR), binucleate Rhizoctonia (BNR) and Pythium spp. respectively. Fusarium spp. were isolated at high rates from all the examined areas. MN Rhizoctonia and BN Rhizoctonia were isolated both from inner and coastal areas of the province, whereas Pythium spp. were isolated in costal areas, except for the Vezirköprü district which is situated in the inner area. When looking at the interactions among pathogens causing root rot, it was found the great majority of the samples (30.4%) isolated both Fusarium spp. and MNR-BNR group fungi, whereas Fusarium spp. and Pythium spp. were isolated together from 10.9% of the samples and MNR-BNR and Pythium spp. from only 1.5% of the samples.     

Field evaluation of plant growth-promoting Rhizobacteria amended transplant mixes and soil solarization for tomato and pepper production in Florida

Field trials were performed in Florida to evaluate tomato and pepper transplants amended with formulations of several plant growth-promoting rhizobacteria (PGPR) in a production system that included soil solarization. Transplants grown in five different formulations of PGPR were planted into plots treated by soil solarization, MeBr fumigation, or untreated soil. Treatments were assessed for incidence of several naturally occurring tomato and pepper pathogens including root-knot nematode (Meloidogyne incognita) and species of Pythium, Phytophthora, and Fusarium. Highly significant increases in tomato and pepper transplant growth occurred in response to most formulations of PGPR tested. Transplant vigor and survival in the field were improved by PGPR treatments in both tomato and pepper. Diseases of tomato caused by root-knot nematodes, Fusarium, Phytophthora, and Pythium were not affected by PGPR treatments. PGPR formulation LS261 reduced numbers of root-knot nematode galls on pepper while pepper root condition was improved with formulations LS213, LS256 and LS261. Individual PGPR strains affected the number of Pythium colonies isolated from pepper roots, but did not affect isolation of Pythium from tomato roots. Greater numbers of colonies of Pythium were isolated from pepper roots in the MeBr treatment and fewest in the solarization treatment. Numbers of colony forming units of Fusarium were significantly higher in the untreated soil than in MeBr fumigated or solarized soil with no effect of PGPR on isolation of Fusarium from either crop. Incidence of wilt symptoms on tomato was significantly lower in MeBr treated plots and highest in the untreated plots. Yield of extra large tomato fruit and total yield increased with PGPR formulation LS256. Yield of pepper was increased with formulations LS255 and LS256. Solarization combined with LS256 on pepper produced yields comparable to MeBr.     

Endocarpic Microorganisms of Two Types of Windrow-Dried Peanut Fruit (Arachis hypogaea L.)

The endocarpic microorganisms of peanut fruit dried in either a random windrow (plants left as they fell from the digger) or an inverted windrow (plants inverted to expose fruit to sunlight) were different from that of freshly dug fruit. Chaetomium, Penicillium, Trichoderma, Rhizoctonia, and Fusarium were the dominant fungi found associated with shells (pericarp) of freshly dug fruit. The dominant fungi of shells of windrowed fruit included Chaetomium, Rhizoctonia, Fusarium, Sclerotium, and Alternaria. Seeds of freshly dug fruit were dominated by Penicillium and Aspergillus. The only dominant species in seed of windrowed fruit was Penicillium. Microorganisms were isolated from shells and seed of freshly dug fruit at a frequency of 79% and 52%, respectively. The percentage of infestation was reduced by drying in the field. This was particularly true of the inverted windrow. The proportion of shells and seed infested with a microorganism was reduced 13% and 36%, respectively, after field drying for 5 to 7 days in random and inverted windrows. Microorganisms were isolated much more frequently from shell pieces (73%) than from seed (36%).     

Additional experiences to elucidate the microbial component of soil suppressiveness towards strawberry black root rot complex

Several studies were carried out to investigate the soil microbial components involved in suppressing strawberry black rot root which occurs throughout the Italian strawberry growing region. Quantitative and qualitative evaluation of fungi involved in black root rot were combined with several soil microbial parameters involved in soil suppressiveness towards black root rot agents. The first survey, carried out in an intensively cultivated area of northern Italy, identified Rhizoctonia spp. as the main root pathogen together with several typical weak pathogens belonging to the well‐known black rot root complex of strawberry crop: Cylindrocarpondestructans, Fusarium oxysporum, F. solani, Pestalotia longiseta and others. The root colonisation frequency of strawberry plants increased strongly from autumn to spring at harvesting stage. Rhizoctonia spp. were the only pathogens which followed the rising trend of root colonisation with relative frequency; all the weak pathogens of strawberry black root rot complex did not vary their frequency. Only non‐pathogenic fungi decreased from autumn to spring when at least 60% of colonising fungi were represented by Rhizoctonia. These data suggested that the late vegetative stage was the best time to record the soil inoculum of root rot agents in strawberry using root infection frequency as a parameter of soil health. A further study was performed in two fields, chosen for their common soil texture and pH, but with significant differences in previous soil management: one (ALSIA) had been subjected to strawberry monoculture without organic input for several years; the other (CIF) has been managed according to a 4‐year crop rotation and high organic input. In this study Pythium artificially inoculated was adopted as an indicator for the behaviour of saprophytically living pathogens in bulk soil. Pythium showed a sharp, different response after inoculation in bulk soil from the two soil systems evaluated. Pythium was suppressed only in the CIF field where the highest levels of total fungi and fluorescent bacteria and highest variability were observed. The suppressiveness conditions towards Pythium, observed in the CIF and absent in the ALSIA field, corresponded with the root infection frequency recorded at the late vegetative stage on strawberry plants grown in the two fields: strawberry plants from the CIF field showed lower root colonisation frequency and higher variability than that recorded on those coming from the ALSIA field.     

Fungi Isolated from Flue-cured Tobacco at Time of Sale and After Storage

The fungi isolated from 100 samples of flue-cured tobacco from 12 markets in 2 tobacco belts comprised 11 genera, including 10 species of Aspergillus. The mean percentage per sample isolated from 62 samples of tobacco from Middle Belt markets was Alternaria, 40.6%; Aspergillus niger, 47.8%; Aspergillus repens, 38.0%; and Penicillium, 25.8%. The mean percentage per sample isolated from 38 samples of tobacco from Old Belt markets was Alternaria, 74.0%; Penicillium, 52.5%; Aspergillus repens, 38.0%; and Aspergillus ruber, 36.2%. Damaged (74 samples) and nondamaged (26 samples) stored tobacco yielded species of six genera of fungi, including eight species of Aspergillus. Species of Aspergillus and Penicillium were commonly isolated from both damaged and nondamaged tobacco, whereas species of Alternaria, Cladosporium, Fusarium, and Rhizopus were isoalted more frequently from nondamaged tobacco. The fungi that occurred in the highest population in damaged tobacco were Aspergillus repens, A. niger, A. ruber, and Penicillium species.     

Mycoflora isolation and molecular characterization of Aspergillus and Fusarium species in Tunisian cereals

Wheat, barley and maize are the mainly consumed cereals in Tunisia. This study aimed to determine the mycoflora of these cereals with special focus on the mycotoxigenic Aspergillus and Fusarium species. Freshly harvested samples and other stored samples of each type of cereal (31 and 34 samples, respectively) were collected in Tunisia and cultured for fungal isolation and identification. Identification of fungal genera was based on morphological features. Aspergillus and Fusarium species were identified by species specific PCR assays complemented with DNA sequencing. Alternaria (70.83%), Eurotium (62.50%), Aspergillus (54.17%) and Penicillium (41.67%) were the most frequent fungi isolated from wheat. Penicillium (75%), Aspergillus (70%), Eurotium (65%) and Alternaria (65%) were the most frequently recovered genera from barley. The predominant genera in maize were Aspergillus (76.19%), Eurotium (42.86%), and Penicillium (38.09%). Aspergilllus, Penicillium, Fusarium and Alternaria were detected in both stored and freshly harvested grain samples. The frequencies of contamination with Aspergillus, Fusarium and Alternaria were higher in freshly harvested samples, whereas Penicillium species were more frequent in stored samples. The predominant Aspergillus species detected were A. flavus and A. niger. The Fusarium species detected were F. equiseti, F. verticillioides, F. nygamai, and F. oxysporum. This study suggested the potential risk for Aflatoxins and, to a lesser extent, for Ochratoxin A in Tunisian cereals. This is the first survey about mycoflora associated with wheat, barley and maize in Tunisia.     

The effect of fumigants on soil recolonization in the glasshouse by organisms colonizing the spermosphere

Germinating turnip seeds were used as baits to measure changes in colonizing floras of the spermosphere in glasshouse soil boxes following fumigation. The spermosphere mycoflora of the untreated soil was always dominated by Fusarium, Pythium, and Gliocladium spp. Methyl bromide, chloropicrin, and MBC₃₃ (a 67:33 mixture of methyl bromide and chloropicrin), applied in polyethylene bags at a rate of 2·5 ml/cubic foot of soil, greatly reduced colonization by Fusarium and Pythium spp. for 120 days. Fungi and actinomycetes recolonizing treated soils were more active than in untreated soils, and each fumigant induced a characteristic recolonization pattern. The spermosphere of methyl bromide-treated soil was initially dominated by actinomycetes and later by Penicillium spp. In chloropicrin-treated soil, Trichoderma and later Penicillium spp. dominated, and in soil treated with MBC ₃₃, Penicillium and Trichoderma spp. were co-dominant. Dilution plates, made at the same time from the same soil, indicated a close correlation between inoculum density of different fungi in the soil and their inoculum potentials towards the spermosphere.     

Suppression of important pea diseases by bacterial antagonists

The potential for widespreadand severe infection makes ascochyta blight,seedling blight, and root rots major hindrancesto pea production in Alberta, Canada. Over 300bacterial strains were isolated from pea seedand soil samples taken from pea fields. Thesestrains were investigated for their biologicalcontrol potential against four fungal pathogens(Pythium ultimum, Rhizoctoniasolani, Fusarium avenaceum and Ascochyta pisi) of field pea in vitro. Selected bacterial strains were furtherevaluated in vivo. In an initial agarplate bioassay, 30 strains exhibitedantagonistic properties against the fourpathogens, with inhibition zones ranging from 5to 25 mm. Thirteen of these strains, allisolated from soil, inhibited only one or twoof the pathogens, while the remainingseventeen, including nine strains isolated frompea seeds, inhibited either three or all fourpathogens. In a more stringent bioassay, eightof the thirty strains failed to demonstrate theantagonistic features shown in the initialbioassay. Eight strains inhibited only onepathogen, six inhibited two, four inhibitedthree, and four strains inhibited all fourpathogens tested. Two strains ofPseudomonas fluorescens, five strains of Serratia spp. and two strains of Bacillus spp. were further evaluated ingreenhouse experiments. Five of the isolatesreduced the severity of diseases caused byPythium or Ascochyta, two isolatesreduced the severity of Rhizoctonia andone reduced the severity of Fusarium.     

Association of Shifting Populations in the Root Zone Microbiome of Millet with Enhanced Crop Productivity in the Sahel Region (Africa)

This study characterized specific changes in the millet root zone microbiome stimulated by long-term woody-shrub intercropping at different sites in Senegal. At the two study sites, intercropping with woody shrubs and shrub residue resulted in a significant increase in millet [Pennisetum glaucum (L.) R. Br.] yield (P < 0.05) and associated patterns of increased diversity in both bacterial and fungal communities in the root zone of the crop. Across four experiments, operational taxonomic units (OTUs) belonging to Chitinophaga were consistently significantly (P < 0.001) enriched in the intercropped samples, and “Candidatus Koribacter” was consistently significantly enriched in samples where millet was grown alone. Those OTUs belonging to Chitinophaga were enriched more than 30-fold in residue-amended samples and formed a distinct subgroup from all OTUs detected in the genus. Additionally, OTUs belonging to 8 fungal genera (Aspergillus, Coniella, Epicoccum, Fusarium, Gibberella, Lasiodiplodia, Penicillium, and Phoma) were significantly (P < 0.005) enriched in all experiments at all sites in intercropped samples. The OTUs of four genera (Epicoccum, Fusarium, Gibberella, and Haematonectria) were consistently enriched at sites where millet was grown alone. Those enriched OTUs in intercropped samples showed consistently large-magnitude differences, ranging from 30- to 1,000-fold increases in abundance. Consistently enriched OTUs in intercropped samples in the genera Aspergillus, Fusarium, and Penicillium also formed phylogenetically distinct subgroups. These results suggest that the intercropping system used here can influence the recruitment of potentially beneficial microorganisms to the root zone of millet and aid subsistence farmers in producing higher-yielding crops.     

Seasonal variation of fungal spore populations in the atmosphere of Zarqa area,Jordan

Fungi are among the most important aeroallergens. The aim of this study was to provide aeromycological baseline information about Zarqa area, Jordan, for the first time. During the entire survey and from 170 settle plate exposures, a total of 735 mould- and 274 yeast colony-forming units (CFU) were collected. mould colonies were assigned to 35 genera and 59 species. The highest abundance was attributed to Cladosporium with a percentage of 29.1% of the total colony count followed by Fusarium 20%, Alternaria 7.7%, Ulocladium 6.5% Penicillium 4.2% and then Aspergillus 3.6%. Cladosporium showed one peak in October while Aspergillus and Penicillium peaked in September. Fusarium peaked in May and August and Alternaria in March and July. However, Ulocladium showed almost the same abundance from March to June and then in September and December. A double peak in total colony count and fungal diversity was found, the first was in March and the second in November–December. Significant differences of total fungal colony counts favouring the 1500 hours collection time over that at 1000 hours were found between November and January while no such significant differences were obtained between February and April. Our results also indicated differences in species composition between the two periods in different months. Spores of the three abundant species, Cladosporium, Fusarium and Alternaria, might favour high release in the 1500 hours period during winter while having a similar incidence during the two periods in the spring months.     

Further study on seasonal fluctuations of Egyptian soil fungi

The seasonal fluctuations of fungi were studied in 72 soil samples collected at 10-day intervals between January 1972 and December 1973. The richest periods in the fungal population were January, March and September–December 1972, and April, May, September, November and December 1973. The poorest months were consistently June and July of 1972 and 1973 and August 1973 which are all summer months. Thirty-nine genera were isolated of which Aspergillus, Penicillium, Fusarium, Mucor, Rhizopus and Humicola were of high seasonal occurrence. Seven genera were of moderate occurrence and these were Cochliobolus,Stachybotrys, Paecilomyces, Cunninghamella, Myrothecium, Chaetomium and Sepedonium. The remaining genera were of low or rare seasonal occurrence. Aspergillus showed its highest prevalence during the periods May-September 1972 and April-August 1973. Twenty-four species of Aspergillus in addition to two varieties of A. nidulans were isolated, of which A. niger, A. fumigatus, A. terreus, A. nidulans and A. sydowii were dominant. Thirty species of Penicillium were identified, of which P. notatum, P. funiculosum and P. chrysogenum were of high seasonal occurrence. Penicillium predominated during winter and spring months. Fusarium showed its highest percentage populations during the periods February, March, April, October, November and December 1972 and February, August, September, October and November 1973. Four species of Mucor were recorded of which M. racemosus was the commonest; and its highest percentage populations were recorded in November 1972; and February, March and November 1973 which are moderate temperature months. Rhizopus was represented by two species of which R. nigricans was of high seasonal occurrence. Three species of Humicola were isolated of which H. grisea was the most common.     

Evaluation of five sugar beet varieties for root-knot nematode and root-rot fungal infection

Survey results during 2010–2011 season revealed that the Meloidogyne spp., Helico–tylenchus spp. and Tylenchorhynchus spp. were the common plant parasitic nematodes in the rhizospheres of sugar beet in El-Behera, El-Fayoum and Beni Sueif Governorates. Aspergillus spp., Aspergillus niger, Fusarium spp., Penicillium spp., Penicillium chrysogenum, Penicillium citrinum, Rhizoctonia spp., Rhizopus nigricans, Trichoderma spp. and others were also the common fungi in the same rhizospheres. The rhizosphere of El-Behera Governorate was highly infected with Meloidogyne spp., Fusarium spp. and Rhizoctonia spp., compared to the rhizospheres of El-Fayoum and Beni Sueif, respectively. Evaluation of five of sugar beet cultivars, viz. Chems, Dema-Poly, DS 9001, Manila and Ras-Poly to infection, with Meloidogyne incognita (root-knot nematode), Fusarium solani and Rhizoctonia solani (root rot disease) was carried out under naturally field infection condition in the Nubariya region, Behera Governorate during 2011–2012 season. Host susceptibility rating revealed that the varieties of Ras-Poly, DS 9001 and Manila can be considered as susceptible, while the varieties of Dema-Poly and Chems can be considered as highly susceptible. Pathological results showed that the varieties of Dema-Poly and Ras-Poly were highly infected with F. solani, while not infected with R. solani. The varieties of DS 9001, Manila and Chems were moderately infected with the two pathogens.     

Development of Bursaphelenchus xylophilus Populations in Wood Chips with Different Moisture Contents

Bags of Pinus strobus wood chips with moisture contents of 38, 92, 164, and 217% (oven dry weight) were inoculated with Bursaphelenchus xylophilus and incubated at 30 C in order to determine the effect of wood moisture on nematode population development. Nematodes were extracted after 2, 4, 8, and 12 weeks. Population levels were greatest in wood chips with a moisture content of 38% and decreased successively with each higher moisture content. In chips with the three lower moisture contents, populations peaked at 2 weeks, but at 217% moisture, they peaked at 8 weeks. By 12 weeks, nematode populations had declined in wood chips with 92 and 164% moisture contents. The fungi most frequently isolated from the wood chips were Alternaria, Fusarium, Gliocladium, Graphium, Penicillium, Trichoderma, and Mucorales.     

Characterization of fungi transferred by dust storms in Kuwait and their plant pathogenicity

Dust storms carry large amounts of plant detritus and microorganisms that may cause diseases in humans, animals or plants. These storms are frequent in Kuwait throughout the year. This research was conducted to identify the fungal species carried by the dust storms in Kuwait, originating from the northwesterly direction, with emphasis on plant pathogens. Fungi were isolated from settled dust samples and identified using established microbiological and molecular approaches. Fungal isolates identified as Fusarium oxysporum from settled dust were examined for pathogenicity using a number of crop plants. In total, 17 genera of fungi were identified in the dust samples. These fungi included plant pathogens or facultative plant parasites that were transported in the dust storms as viable propagules. The most common dust-carried fungi belonged to the genera Fusarium, Alternaria, Ulocladium, Phoma, Aspergillus, Acremonium and Penicillium. The F. oxysporum isolates that had been characterized by partial 18S rRNA gene sequencing were pathogenic, causing root and stem rot in tomato, bean and cucumber, but not squash.     

Occurrence of Aspergillus section Flavi and aflatoxin B1 in corn genotypes and corn meal in Argentina

A study has been carried out in Argentina on samples of corn genotypes from a breeding station as well as in commercially available corn meal. All samples were analyzed for fungal infection and aflatoxin B₁.Mycological analysis of corn genotypes showed the presence of three principal genera of filamentous fungi Fusarium (100%), Penicillium (67%) and Aspergillus (60%). In the genus Fusarium three species were identified, F. moniliforme (42%), F. nygamai (56%) andF. proliferatum (1.8%). Eight species ofPenicillium were identified, the predominant species isolated were P. minioluteum, P. funiculosum and P. variabile. In the genus ranked third in isolation frequency, two species were identified, A. flavus and A. parasiticus, the percentage of infection was 78% and 21%, respectively. Only one corn genotype was contaminated with aflatoxin B₁ at a level of 5 ppb. The cornmeal samples showed great differences in fungal contamination, the values ranging from 1 × 10¹ to 7 × 10⁵ cfu g^–1. Fusarium (68%), Aspergillus (35%) and Penicillium (21%) were the most frequent genera isolated. Among the genus, Aspergillus, A. parasiticus (38%) was the most frequent species isolated. All the samples of corn meal were negative to aflatoxin B₁. These results indicate a low degree of human exposure to aflatoxins in Argentina through the ingestion of maize or corn meal.This revised version was published online in October 2005 with corrections to the Cover Date.     

Molecular profiling of fungal assemblages in the healthy and infected roots of <Emphasis Type="Italic">Decalepis arayalpathra</Emphasis> (J. Joseph &amp; V. Chandras) Venter,an endemic and endangered ethnomedicinal plant from Western Ghats,India

Decalepis arayalpathra, an endangered, endemic ethnomedicinal plant from southern Western Ghats, India, is targeted for its aromatic and medicinal properties. This study aimed at to identify fungal endophyte populations associated with healthy and diseased roots of this perennial shrub. Healthy and rotted root samples of D. arayalpathra were collected, fungal endophytes assemblages were identified both by culture-dependent and culture-independent approaches, further sequenced and the retrieved sequences were analysed with the reference sequences in GenBank to know their phylogenetic relationships. Analysis of the ITS rDNA region generated 24 different Ascomycota and three Basidiomycota taxa. Trichoderma sp. was most abundant in healthy and diseased root samples, while Penicillium and Aspergillus were confined to healthy roots. Furthermore, Fusarium solani, Fusarium oxysporum and Mucor velutinosus were found to be the most frequent fungi identified from the rotted root samples, thus substantiated to be the cause for D. arayalpathra decline in the wild. Interestingly, the strains assigned to Fusarium sp. were isolated from diseased roots showing typical clearly visible symptoms, such as a severe brown discolouration on the taproot. Molecular profiling of all the pure fungal isolates, viz., Trichoderma, Penicillium, Aspergillus, Fusarium and Mucor, revealed high sequence similarities (≥ 98 %) to corresponding reference sequences. Sequencing of Trichoderma pure cultures isolated from healthy and diseased roots revealed sequence similarities to Trichoderma harzianum, T. hamatum, T. koningiopsis, T. asperellum, T. pubescens and Hypocrea sp. This confirms the morphological examinations, as Hypocrea is the teleomorph stage of Trichoderma sp. This study signifies the first work pertaining to the taxonomy of the fungal endophytic community of D. arayalpathra, and the results reported in this work may help to ascertain the cause of root rot disease often perceived in D. arayalpathra. Also, it could be useful to identify the promising endophytic communities against the root rot diseases occurring in D. arayalpathra.     

Mechanism underlying the response of fungi and their Fusarium symbiotic networks to the rotations of soybean and corn

Fusarium oxysporum and Fusarium solani are the main soybean root rot pathogens in northern China. We investigated the distribution and driving factors of Fusarium under different cropping systems to evaluate and regulate soil health. The factors affecting Fusarium in soybean cropping systems were assessed using high-throughput sequencing of ITS1 to identify soil microbial population diversity, and then the soil physicochemical properties were assessed to determine the levels of various elements present in the environment. According to the results, the abundance of Fusarium was obviously reduced in the corn–soybean rotation and uncultivated soil systems. The relative abundance of Fusarium in the soil and the abundance and diversity of fungal communities were significantly positively associated with the abundance of Ascomycota. Additionally, the relative abundance of Fusarium was significantly positively correlated with the zinc (Zn) content. When the Zn content was high, the abundance of Fusarium increased, and the correlations with Chaetomium, Cryptococcus, Penicillium and Trichoderma significantly decreased. Soybean yield was significantly negatively correlated with fungal community abundance and diversity. Based on our results, the uncultivated soil and corn–soybean rotation cropping systems improved the organizational structure of the soil fungal community and were conducive to the health and production of soybean.     

Environmental Isolates of Fungi from Aquarium Pools Housing Killer Whales (Orcinus orca)

Systemic mycoses in killer whales (Orcinus orca) are rare diseases, but have been reported. Two killer whales died by fungal infections at the Port of Nagoya Public Aquarium in Japan. In this study, the fungal flora of the pool environment at the aquarium was characterized. Alternaria spp., Aspergillus spp. (A. fumigatus, A. niger, A. versicolor), Fusarium spp. and Penicillium spp. were isolated from the air and the pool surroundings. The other isolates were identified as fungal species non-pathogenic for mammals. However, the species of fungi isolated from the environmental samples in this study were not the same as those isolated from the cases of disease in killer whales previously reported.     

Isolation and molecular characterization of causal agent of blue mold on Allium cepa L. and its control by Pennisetum flaccidum Griseb

Blue mold pathogen, isolated from infected Allium cepa L., was identified as a Penicillium species through morphological and molecular characterisation. Internal Transcribed spacer (ITS) region of ribosomal DNA (rDNA) was utilised for DNA sequencing. Basic Local Alignment Search Tool (BLAST) analysis has found the maximum similarity index of the fungus to be 82.39% with the Uncultured Penicillium clone (Accession: MF535522). So, the isolated Penicillium specie is the first reported specie of the genus that infects onion. A phylogenetic tree was constructed to establish a relationship of the isolated fungus with the most relevant species reported on GenBank. Extracts of Pennisetum flaccidum Griseb. were evaluated against the isolated fungus as a potential biocontrol agent. Among the five tested methanol concentrations (0.5%, 1%, 1.5%, 2% and 2.5%) of each plant part (root, inflorescence and foliage), 0.5% root extract showed maximum growth retardation, i.e. 89%. For bioassay-guided fractionation, the root extract was partitioned in n-hexane, chloroform, n-butanol and ethyl acetate. Ethyl acetate (1%) was proved to be the most potent one. Phytochemical screening has confirmed the occurrence of terpenoids, tannins, saponins and alkaloids. The applied molecular approach has deduced that the Penicillium specie collected from Pakistan might be novel. This study can be concluded that P. flaccidum contains potent phytochemicals which might be used as antifungal agent against Penicillium species.