Research on basal stem rot (BSR) of ornamental palms caused by basidiospores from <Emphasis Type="Italic">Ganoderma boninense</Emphasis>

Basidiospores were isolated from the fruiting bodies of Ganoderma infecting oil palms from an estate in Johor and from ornamental palms (including oil palms) from Singapore. The spores were then germinated to obtain homokaryotic mycelia. Based on clamp connection formation in paired hyphal fusions, tester strains were identified from the homokaryons isolated. Compatibility tests were then carried out using these testers to determine the relatedness of the homokaryotic Ganoderma isolates, both from Johor and from Singapore. Results from the compatibility tests showed that Ganoderma from both locations belong to the same species, while the Ganoderma isolates from Singapore share some common alleles. The pathogenicity tests carried out on Chrysalidocarpus lutescens seedlings using inoculum growing on rubber wood blocks showed that dikaryotic mycelia can cause basal stem rot infection.     

Selected airborne allergenic fungal spores and meteorological factors in Szczecin,Poland, 2004–2006

Airborne fungal spore concentrations in Szczecin, Poland, were studied between 2004 and 2006 with the objective of determining a seasonal variation in the concentrations of selected fungal spore types in relation to meteorological parameters. The presence of spores of five taxa, namely, Cladosporium, Ganoderma, Alternaria, Leptosphaeria and Didymella, was recorded using a volumetric method (Hirst type). Fungal spores were present in the air in large numbers during the summer, with the highest concentrations recorded mainly in June, July and August. The peak concentrations of two of the studied spore types, Ganoderma and Alternaria, occurred in August, while the concentrations of Cladosporium, Leptosphaeria and Didymella spores were the highest in July. Multiple regression analysis was performed for three fungal seasons—2004, 2005 and 2006. Spore concentration was found to be positively correlated with the minimum temperature. For some spore types, there was also a significant correlation between concentrations, relative humidity and rain.     

Die Bedeutung der Proterosporen: Schlußfolgerungen aus Untersuchungen anGanoderma (Basidiomycetes)

Proterospores are formed exclusively at the beginning of the sporulation period and independently of abiotic factors. They differ both morphologically and physiologically from other spores developed later by the same fruit-body. As seen inGanoderma, proterospores germinate readily, whereas other spores must first pass through a fly larva gut. These proterospores are therefore well adapted to dispersal by air, the other spores, however, to dispersal by animals. In this respect, ontogenesis appears to recapitulate phylogeny. A comparative study of proterospores should further clarify systematic relationships within the fungi.

     

Airborne basidiospores of Coprinus and Ganoderma in a Caribbean region

The present study sought to examine Coprinus and Ganoderma airborne spore counts, analysing seasonal variations, the influence of meteorological variables and intraday behaviour with a view to charting the aerobiological dynamics of both genera in Havana (Cuba) during a 2-year period (November 2010–October 2012). A Hirst-type volumetric air sampler was used as sampling methodology. The spores registered in the air were identified and counted following the model proposed by the Spanish Aerobiological Network based on two longitudinal transects along the slides. Coprinus spores outnumbered those of the Ganoderma (28,468 annual total spores vs. 1,921 spores). Moreover, both genera were recorded in the atmosphere on a large number of days over the two-year study period, with daily maximum concentrations in the rainy months. The daily maximum value for Coprinus was 880 spores/m³ (30 September 2011), whereas for Ganoderma 44 spores/m³ (4 September 2011). The analysis of the Spearman correlation coefficient showed a significant positive correlation of the airborne Coprinus and Ganoderma spores with the temperature, relative humidity and rainfall, whereas the degree of association is negative with the wind speed. Regarding the intraday behaviour, both basidiospores were more abundant in the atmosphere during the night, with a maximum peak at 5–6 a.m.     

Investigations on the causes of upper stem rot (USR) on standing mature oil palms

Three different trials to examine the cause of upper stem rot (USR) infection in oil palm failed to achieve any infection. In the first experiment, inoculum was applied as colonised rubber wood blocks or as spore suspensions. In the second experiment, particular attention was given to ensure that the Ganoderma spores were freshly collected to maintain viability but no infection was observed around the inoculation sites of any of the different oil palm tissues treated. Lastly in the third experiment, both monokaryotic and dikaryotic mycelial cultures were applied directly to cut fronds, which were protected with a moist covering, but no infection was detected after more than two years. Failure to achieve infection by direct inoculation would indicate that USR does not arise from direct infection of living tissues by Ganoderma spores or mycelium, this is probably because of insufficient inoculum potential to cause infection. It is suggested that USR infection is achieved only when a sufficiently large source of inoculum has built up in dead material, probably in frond axils, and this allows invasion of the living tissues.     

Airborne Ganoderma basidiospores in a country with desert environment

Aerobiological studies to identify Ganoderma basidiospores were conducted using Burkard Volumetric 7-Day Recording Sampler (Burkard Manufacturing Co. Ltd., England) at three separate cities in Saudi Arabia. At one site, Jizan, close to the coast of Red Sea, up to 17% of all basidiospores counted were identified as Ganoderma spp. while less than 1% Ganoderma spp. were identified at the two non-coastal sites. A clear seasonal pattern from late autumn to early summer (October-March) with a peak in December was recorded at Jizan and the maximum concentration of Ganoderma basidiospores reached 1.9×10³?m^?3 in December followed by 1.2×10³?m^?3 in January. The diurnal pattern of Ganoderma spore concentrations, when averaged over the year had late-evening maxima (a nocturnal pattern). However, other sites that showed low concentrations of Ganoderma basidiospores did not exhibit any peak or a high maximal level. The study demonstrates that even in a desert environment, airborne activities of Ganoderma basidiospores can be recorded. The impact of Ganoderma on asthmatic patients, particularly in such environments, needs to be investigated.     

Variation in fungal spore concentrations of selected taxa associated

The aim of the study was to determine seasonal variation in concentrations of selected fungal spore types due to meteorological parameters. The presence of spores of thirteen taxa: Cladosporium, Torula, Alternaria, Botrytis, Epicoccum, Stemphylium, Ganoderma, Erysiphales, Entomophthora, Drechslera type, Didymella, Polythrincium and Pithomyces was recorded in Cracow using a Burkard trap. The majority of selected taxa belong to the anamorphic fungi group, the others to Ascomycetes, Basidiomycetes and Zygomycetes. Fungal spores were present in the air in large numbers throughout the summer with the highest levels being reached in June, July and August although their highest concentrations differed with time. For most of the studied spore types: Botrytis, Ganoderma, Alternaria, Epicoccum, Torula, Drechslera type, Polythrincium, Stemphylium and Pithomyces the peak period was recorded in August. Didymella and Entomophthora spores reached their highest concentrations in July while concentrations of Erysiphales and Cladosporium spores were highest in June. Multiple regression analysis was performed for two seasonal periods: pre-peak and post-peak. In the pre-peak period concentrations of 10 spore types: Cladosporium, Botrytis, Epicoccum, Stemphylium, Drechslera type, Pithomyces, Didymella, Erysiphales, Ganoderma and Entomophthora were strongest influenced by minimum temperature while Alternaria, Polythrincium and Torula by maximum temperature (significance level of α=0.05). During the post-peak period the most important factor affecting variation in concentrations of Botrytis, Polythrincium, Didymella, Erysiphales, Ganoderma and Entomophthora spores was the minimum temperature. For Alternaria, Cladosporium, Epicoccum and Torula the maximum temperature appeared to be the most influential, whereas for Drechslera type, Stemphylium and Pithomyces it was sunshine. All correlations between spore concentration, minimum and maximum temperature and sunshine were significant (significance level of α=0.05), and positive although the percentage of explained variation (R²) was low.     

Intradiurnal periodicity of fungal spore concentrations (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) in Cracow, Poland

Aerobiological monitoring enables the definition of seasonal fungal spore concentrations and also intradiurnal time when the highest concentrations of spores could cause or increase allergy symptoms. These data are useful to estimate symptoms of disease, duration of infection and how advanced the illness is in people suffering from fungal allergens. The aim of the study was to compare the concentrations of fungal spores (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) during dry and rainy periods and to analyse their intradiurnal changes. Average daily spore concentrations in dry and rainy periods were compared, using z test, separately for each taxon, season and for a combined 3-year period. Intradiurnal periodicity of fungal spore concentrations was analysed on the basis of three complementary diagrams. These spore concentrations were presented using three curves for all, dry and rainy days in 1997–1999 (April–November). The spore percentage in particular hours was normalized in relation to the daily spore sum accepted as 100%. Two further diagrams enabled the more precise analysis of the highest concentrations in dry days. Daily Botrytis and Cladosporium spore concentrations did not show significant differences between dry and rainy periods. In the case of Didymella and Ganoderma spore concentrations, there were no significant differences between both weather types in the single years, although there was a significant difference when a 3-year period was considered. The differences between daily concentrations of Alternaria spores in dry and rainy periods occurred in 1997 and in a 3-year period. Intradiurnal periodicity of spore concentrations was different for ‘dry’ and ‘wet’ fungal spores. Dry spores are released from the spore-producing parts of the fungus under conditions of decreasing humidity and increasing airflow. Examples of dry spores are those from Alternaria, Cladosporium and Botrytis. Wet spores, such as those from many Ascomycetes (Didymella) and Basidiomycetes (Ganoderma), are released into the atmosphere by processes related to humidity conditions or rain. The highest concentrations of ‘dry’ spores were observed early in the afternoon, while highest values of ‘wet’ spore concentrations occurred in the predawn hours. Statistically non-significant differences between daily spore concentrations in dry and rainy periods of single seasons were found except for Alternaria. Statistically significant differences could occur when the studied period was longer than one season (Alternaria, Didymella, Ganoderma). The highest concentrations of Alternaria, Botrytis and Cladosporium spores were recorded at noon and early in the afternoon. Concentrations of Didymella and Ganoderma spores were highest in the predawn hours.     

Airborne basidiospores in the atmosphere of Seville (South Spain)

Basidiomycetes produce large quantities of spores that are dispersed by the wind over long distances. Some species can release billions of spores in a day, many of which are important aeroallergens associated with asthma and allergic rhinitis. The results of a survey carried out in the city of Seville during two consecutive years, using a Hirst-type spore trap, showed that airborne basidiospores are present throughout the year, although there is a certain seasonal distribution, with the highest average concentration occurring in November (23,586 basidiospores). Eighteen different types of basidiospores were identified, with Coprinus and Ustilago being the most frequent, followed in descending order of abundance by Agaricus, Phylacteria, Boletaceae, Ganoderma, Cortinarius, Calvatia, Agrocybe, Bovista and Puccinia; the remaining spore types comprised less than 1% of the total basidiospore count.     

Airborne fungal spores in urban and rural environments in Poland

The concentrations of airborne fungal spores were measured during 2001–2002 in two sites in Poland—one in the city and the other in the countryside. The sites differed in habitat characteristics, such as urbanisation level, vegetation and microclimate. The aim of the study was to determine if, and in which way, land use type would affect spore occurrence. The volumetric method was used, and ten easily identifiable spore types were sampled and anyalysed: Alternaria, Botrytis, Cladosporium, Epiccocum, Ganoderma, Pithomyces, Polythrincium, Stemphylium, Torula and Drechslera. The season of spore occurrence was determined using the 90% method. The fungal spores studied were very frequent in the air (in most instances at a frequency higher than 50%). The most common spores were those of Cladosporium, with a frequency range of 83.1–90.5%. In both years the proportion of Cladosporium spores was statistically significantly higher in the city. In both 2001 and 2002 the total seasonal sum of all the spores was higher in the countryside than in the city as was the Seasonal Fungal Index (SFI) values and average concentrations of Botrytis, Ganoderma and Torula. These latter three genera are usually represented as pathogens of plants. The mean spore concentrations of most taxa were significantly higher in the rural environment. Correlation coefficients between daily concentrations at both sites for most of the taxa studied were significant, but with lower correlation values between variables. Such results indicate that the values from the sites are weakly interdependent. The study confirms that land use type may very likely have an impact on the course of spore occurrence, the mean daily concentrations of spores as well as SFI values.     

Identification of <Emphasis Type="Italic">Ganoderma</Emphasis>, the causal agent of basal stem rot disease in oil palm using a molecular method

From comparison of the alignments of the internally transcribed spacers (ITS) of ribosomal DNA from Ganoderma associated with oil palm basal stem rot (BSR) and other Ganoderma species, two specific primer pairs were selected to provide a specific DNA amplification of pathogenic Ganoderma in oil palm. Each primer pair produced a single PCR product of about 450 bp (for primer pair IT1–IT2) and 334 bp (for primer pair IT1–IT3) when oil palm Ganoderma DNA was used. No PCR amplification product was observed when other Ganoderma species DNA was used in PCR amplification with these primer pairs. Three specific restriction enzyme sites were identified in the ITS and intergenic spacer (IGS1) regions. The restriction enzymes MluI, SacI and HinfI were used to digest the ITS-PCR product and restriction enzymes TfiI, ScaI and HincII were used to digest the IGS1-PCR product. Of the three restriction enzymes used in each rDNA region, MluI specifically digested the ITS regions, and TfiI specifically digested the IGS1 region of oil palm Ganoderma. Analysis of the published ITS nucleotide sequences of 31 Ganoderma species showed that the MluI restriction site was not present in other Ganoderma species. The use of both specific primers and restriction enzyme analysis can be applied as a standard protocol to identify pathogenic Ganoderma in oil palm. In this study, the use of specific primers and PCR-RFLP analyses of the rDNA gave consistent results for the characterisation of pathogenic Ganoderma, and indicated that Ganoderma strains associated with BSR disease in oil palms belong to a single species.     

Airborne Ascomycotina on the island of Crete: Seasonal patternsbased on an 8-year volumetric survey

An 8-year study was conducted on the island of Crete in order to identify airborne ascospores and to determine their seasonal pattern. A Burkard 7-day, volumetric spore-trap was continuously operated in the city of Irakleion – located in the center of the island – from 1994 through 2001. Relatively „high” ascospore counts (20 – 48 spores/m ³) were obtained from mid-spring through summer, while the rest of the year exhibited lower activity (8–16 spores/m³). The predominant ascospores identified were those of Leptosphaeria and Chaetomium; their concentrations varied from 1 or 2 spores up to a few dozens of spores/m³. Other spores encountered sporadically were: Ascobolus, Endophragmiella, Didymella, Diatrypaceae, Leptosphaerulina, Massaria, Pleospora, Sporormiella, Xylaria. The mean daily concentration of all identified ascospores was 30/m³ for the entire study period, corresponding to 13.9% of the total fungal load. Ascospores have been recognized as important inhalant allergens and have been implicated as contributing to symptoms of both rhinitis and asthma.     

Airborne fungal spores in a sawmill environment in Palakkad District, Kerala, India

Concentration of airborne fungal spores inindoor and outdoor environments of a sawmill in Palakkad district of Kerala, India was studied with Burkard Personal Slide Sampler from January to December 1997. Total spore concentration in the indoor and outdoor showed a 3:2 ratio. Higher spore count was observed in indoor in January and in outdoor in October. Thirty three fungal spore types were identified from the indoor and twenty six from the outdoor. Aspergillus/Penicillium, Cladosporium, Nigrospora, Ganoderma, `other basidiospores' and ascospores were the dominant components of the airspora. Aspergillus/Penicillium, the most dominant spore type in the indoor contributed 51.19% and Cladosporium, the most dominant spore type in the outdoor contributed 44.75% of the total spores. The study revealed high prevalence of predominantly allergenic fungal spores in the sawmill environment.     

Airborne pollen and spores on the Arctic island of Jan Mayen

A survey of airspora collected on Jan Mayen, an isolated North Atlantic island (71°N, 8°30′W), using a Burkard seven-day volumetric trap from 24th April to 31th August, 1988, revealed only very small concentrations. A total of 10 different pollen types were recorded, constituting a seasonal sum of 29 pollen grains. The local pollen season was confined to July, with Oxyria digna and Salix as the most numerous pollen types recorded. Exotic pollen grains, namely Betula, Pinus and Castanea type, were recorded in three periods during June and July. Studies of back trajectories indicate North America and/or Iceland and Greenland as possible source areas for the Betula pollen. There were more diatoms than pollen in the local airspora. Fungal spores mainly occurred in late July and August. Cladosporium constituted less than 5% of the total seasonal sum of fungal spores, while basidiospores contributed nearly 12%. The highest diurnal average of Cladosporium was 27 spores m^?3 air. The seasonal maximum of unidentified fungal spores reached a diurnal average of 639 spores m^?1 air on 27th August.     

The impact of nutrition on spore yields for various fungal entomopathogens in liquid culture

Spore yields were measured for various fungal entomopathogens grown in six nutritionally different liquid media with low and high carbon concentrations (8 and 36 g l^–1, respectively) at carbon-to-nitrogen (C:N) ratios of 10:1, 30:1 and 50:1. Six fungi were tested: two Beauveria bassiana strains, three Paecilomyces fumosoroseus strains and one Metarhizium anisopliae strain. Spore yields were examined after 2, 4 or 7 days growth. In general, highest spore yields were obtained in media containing 36 g/l and a C:N ratio of 10:1. After 4 days growth, highest spore yields were measured in the three Paecilomyces isolates (6.9–9.7 × 10⁸ spores ml^–1). Spore production by the B. bassiana isolates was variable with one isolate producing high spore yields (12.2 × 10⁸ spores ml^–1) after 7 days growth. The M. anisopliae isolate produced low spore concentrations under all conditions tested. Using a commercial production protocol, a comparison of spore yields for the coffee berry borer P. fumosoroseus and a commercial B. bassiana isolate showed that highest spore concentrations (7.2 × 10⁸ spores ml^–1) were obtained with the P. fumosoroseus isolate 2-days post-inoculation. The ability of the P. fumosoroseus strain isolated from the coffee berry borer to rapidly produce high concentrations of spores prompted further testing to determine the desiccation tolerance of these spores. Desiccation studies showed that ca. 80% of the liquid culture produced P. fumosoroseus spores survived the air-drying process. The virulence of freshly produced, air-dried and freeze-dried coffee berry borer P. fumosoroseus blastospores preparations were tested against silverleaf whiteflies (Bemisia argentifolii). While all preparations infected and killed B. argentifolii, fresh and air-dried preparations were significantly more effective. These results suggest that screening potential fungal biopesticides for amenability to liquid culture spore production can aid in the identification of commercially viable isolates. In this study, P. fumosoroseus was shown to possess the production and stabilization attributes required for commercial development.     

The specific transport system for lysine is fully inhibited by ammonium in Penicillium chrysogenum: An ammonium-insensitive system allows uptake in carbon-starved cells

The regulation exerted by ammonium and other nitrogen sources on amino acid utilization was studied in swollen spores of Penicillium chrysogenum. Ammonium prevented the L-lysine, L-arginine and L-ornithine utilization by P. chrysogenum swollen spores seeded in complete media, but not in carbon-deficient media. Transport of L-[¹⁴C]lysine into spores incubated in presence of carbon and nitrogen sources was fully inhibited by ammonium ions (35 mM). However, in carbon-derepressed conditions (growth in absence of sugars, with amino acids as the sole carbon source) L-[¹⁴C]lysine transport was only partially inhibited. Competition experiments showed that L-lysine (1 mM) inhibits the utilization of L-arginine, and vice versa, L-arginine inhibits the L-lysine uptake. High concentrations of L-ornithine (100 mM) prevented the L-lysine and L-arginine utilization in P. chrysogenum swollen spores. In summary, ammonium seems to prevent the utilization of basic amino acids in P. chrysogenum spores by inhibiting the transport of these amino acids through their specific transport system(s), but not through the general amino acid transport system that is operative under carbon-derepression conditions.     

Influence of Dimilin on a microsporidian infection in the gypsy moth Lymantria dispar (L.) (Lepidoptera: Lymantriidae)

Bioassay studies were conducted to investigate the influence of Dimilin (diflubenzuron), a chitinsynthetase inhibitor used for insecticidal control of the gypsy moth, Lymantria dispar, on the development and viability of a microsporidian pathogen of L. dispar. Before or after an infection with a Nosema species, L. dispar larvae were fed Dimilin in sublethal dosages. Dimilin fed to L. dispar larvae at 0.65 ng/cm² diet surface resulted in a total larval mortality of 53%. Although the microsporidian infection alone did not cause high mortality rates (9%), mortality increased to 96% when L. dispar larvae were inoculated with both Dimilin and Nosema spores. When Dimilin was fed to the larvae 24 h before or 6 days after inoculation with the microsporidium, the number of mature spores produced was significantly reduced. When Dimilin was fed to the larvae 24 h after microsporidian inoculation, the number of spores produced was not significantly reduced. Spores that were produced in larvae after Dimilin had been ingested with the diet were less infectious than spores produced in control larvae; the experimental infection rate decreased from 94% when spores obtained from control larvae were used, to 48 or 10% when spores obtained from larvae fed Dimilin 24 h or 6 days after Nosema inoculation, respectively, were used. Mature microsporidian spores washed in Dimilin solution prior to oral inoculation, however, were as infectious as spores stored in liquid nitrogen. We have shown that Dimilin interferes with the establishment of the parasite in its host. In addition, when Nosema sp. succeeds in infecting the L. dispar host despite treatment with Dimilin, the microsporidium does not develop optimally and spore production is reduced.     

Application ofVerticillium lecanii for the control ofAphis gossypii by a low-volume electrostatic rotary atomiser and a high-volume hydraulic sprayer

Verticillium lecanii (Fungi: Deuteromycete) blastospores were applied to a chrysanthemum crop by an ULV electrostatically charged rotary atomiser (APE-80). The deposition of spores and subsequent control ofAphis gossypii were compared to high volume hydraulic application. A full rate treatment (2×10¹³ blastospores per ha.) was applied by the APE-80 at week 1 and reduced spore rates of 1/6^th and 1/12^th applied by both the APE-80 and the hydraulic sprayer once and twice a week respectively for weeks 1 to 6. Untreated plots served as controls. Initial deposits of spores were higher with the electrostatic sprayer and better distributed with respect to the position of the target aphids. Significantly lower aphid populations were recorded on the electrostatically treated plots in week 4. The single full rate treatment had significantly fewer aphids than the untreated plots from week 3 and all treatments had significantly fewer aphids than the untreated plots from week 5 onwards. The proportion of the aphid population killed byV. lecanii was higher on the electrostatically treated plots until week 6.      

On the mortality ofTribolium castaneum adults treated sublethally as larvae with pirimiphos methyl,Nosema whitei and pirimiphos methyl—N. whitei doses

NeonateTribolium castaneum larvae were treated with 0.5 ppm pirimiphos methyl, 1.6×10⁴ spores/gNosema whitei alone and 0.5 ppm+1.6×10⁴ spores/g combined and the resulting adult mortality recorded. All treatments increased the mortality of the beetles significantly (P<0.01), though the combined dose gave a lower mortality than either the microsporidian or the insecticide alone.      

An insight into spore dispersal of <Emphasis Type="Italic">Ganoderma boninense</Emphasis> on oil palm

The disease of oil palm caused by Ganoderma boninense, although universally referred to as Ganoderma basal stem rot, occurs in three very distinct phases, with basal stem rot only part of the disease cycle. G. boninense also causes a seedling disease and an upper stem rot. An understanding of spore dispersal provides an insight into where spores of G. boninense have a role in the infection process. This role will be discussed in relation to each of these three infection phases. This understanding is a critical component of developing a successful disease control strategy.