Identification of Alternaria tenuissima causing brown leaf spot on Paris polyphylla var. chinensis in China

Severe brown leaf spot disease was observed on Paris polyphylla var. chinensis in Sichuan Province, China, in 2017 and 2018. The initial symptoms were many light‐brown small spots with necrotic centres, round or irregular in shape, becoming dark brown, gradually enlarging and eventually coalescing, causing extensive leaf senescence. A fungus was isolated from diseased leaves showing typical symptoms of brown leaf spot. The isolates were cultured on potato sucrose agar, and their morphological characteristics of the causal pathogen were observed under a light microscope. Pathogenicity tests revealed that this fungus was the causal pathogen of the disease. Molecular analyses of the sequences of the ribosomal DNA internal transcribed spacer (ITS) region, translation elongation factor 1‐alpha (TEF) and the RNA polymerase II second largest subunit (RBP2) gene were conducted to confirm the identity of the pathogen. The multi‐gene phylogeny indicated that the causal agent was Alternaria tenuissima. To our knowledge, this is the first report of A. tenuissima causing brown leaf sports on P. polyphylla var. chinensis in China.     

TwoAscochyta species onAlthaea officinalis andAralia elata

Two brown zonate leaf spot fungi new to Japan are described.Ascochyta malvicola onAlthaea officinalis andA. marginata onAralia elata were recorded in Kyoto Prefecture in 1988.     

Curvularia asianensis and Curvularia eragrostidis associated with leaf spot of Sansevieria trifasciata in Malaysia

Leaf spot disease was detected on Sansevieria trifasciata in Malaysia. Two Curvularia species namely C. eragrostidis and C. asianensis were isolated as the pathogens. The isolated fungi were identified based on morphology and multigene phylogeny (ITS, GAPDH and TEF1-α). Pathogenicity tests confirmed the roles of both Curvularia isolates in causing leaf spot of S. trifasciata. To our knowledge, this is the first report of C. eragrostidis and C. asianensis causing leaf spot of S. trifasciata in Malaysia.     

Four new species of <Emphasis Type="Italic">Phyllosticta</Emphasis>, one new species of <Emphasis Type="Italic">Pseudocercospora</Emphasis>, and one new combination in <Emphasis Type="Italic">Passalora</Emphasis> from Japan

During a survey of plant-inhabiting fungi in a botanical garden in Japan, some noteworthy fungi were collected from leaf spots of some herbal and arboreal plants. Among them, five new species are described, namely: Phyllosticta. ardisiicola on Ardisia crenata, Phy. aspidistricola on Aspidistra elatior, Phy. kerriae on Kerria japonica, Phy. fallopiae on Fallopia japonica, and Pseudocercospora davidiicola on Davidia involucrata. Passalora pyrrosiae, a new combination for Pseudocercospora pyrrosiae on Pyrrosia lingua, is proposed based on its morphological characteristics designating the neotype specimen.     

Identification of the New Pathogen (Stemphylium lycopersici) Causing Leaf Spot on Pepino (Solanum muricatum)

Pepino (Solanum muricatum var. pepino) plants were found affected by an extensive leaf spot caused by plant pathogenic fungi during a survey in the Cameron highlands, Pahang state, Malaysia. Symptomatic leaf samples were collected from infected pepino plants and cultivated on PDA medium, and the pathogen was isolated and purified; then, consequently, all isolates were identified as Stemphylium lycopersici on the basis of their cultural and morphological characteristics and combined sequences of the internal transcribed spacer (ITS) and glyceraldehyde‐3‐phosphate dehydrogenase (gpd) regions. A pathogenicity assay on detached leaves further confirmed that S. lycopersici causes leaf spot disease. To the best of our knowledge, this is the first report of S. lycopersici causing leaf spot on pepino in Malaysia and worldwide.     

Occurrence of Grey Leaf Spot of Sedum erythrostictum Caused by Cercospora cf. pseudokalanchoes in China

Sedum erythrostictum is a perennial herb in the Crassulaceae family, which is a traditional Chinese medicine used for the treatment of hepatitis, dysentery, herpes zoster and swellings. In 2014, a grey leaf spot disease causing significant damage to plants of S. erythrostictum occurred in the Medicinal Herb Garden of Jilin Agricultural University, Jilin Province, China. The fungus mainly infected the leaves. The necrotic lesions on the leaves were circular or elliptical, amphigenous, greyish brown to brown, slightly concave and surrounded by a dark brown distinct margin. The causal agent from symptomatic tissues was identified as Cercospora cf. pseudokalanchoes based on the symptoms, morphological characteristics, molecular identifications and pathogenicity tests. To our knowledge, this is the first formal report of grey leaf spot of S. erythrostictum caused by C. cf. pseudokalanchoes in China.     

First report of leaf spot disease caused by Phoma eupyrena Sacc. on Aloe vera from Madhya Pradesh,India

A leaf spot disease caused by Phoma eupyrena Sacc. on Aloe vera was reported from Madhya Pradesh, India. Disease symptoms were observed as irregular to elongated, sunken lesion on both leaf surfaces which later turns creamish brown with maroon margin. The fungal colonies were whitish or light pale to dark grey colour. The pycnidia were glabrous and solitary, papillate, and indistinctly uniostiolate averages 100–260 μm in diameter. Conidia were ellipsoidal, 4.5–7.5 × 2.5–3.75 μm in size, with two large guttules. To the best of our knowledge, this is the first report of P. eupyrena causing leaf spot disease on A. vera in India.     

Suppression of Rust and Brown Eye Spot Diseases on Coffee by Phosphites and By‐products of Coffee and Citrus Industries

The rust and brown eye spot, caused by Hemileia vastatrix and Cercospora coffeicola, respectively, are the most important fungal diseases on coffee in South America. Their management is mainly by chemical treatment, and there is no genetic resistance to brown eye spot known so far. Considering the need for developing alternative products for their control, the goal of this work was to evaluate the effects of phosphites and by‐products of coffee and citrus industries on rust and brown eye spot. Formulations of coffee and citrus industry by‐products, phosphites and their combination with fungicide were evaluated in field experiments, and their effect on fungal urediniospores and conidia was evaluated in vitro. In the field, treatments were applied individually or in combination and the in vitro assays were performed with manganese phosphite (Reforce Mn), potassium phosphite and citrus industry by‐product (Fortaleza), copper phosphite and coffee industry by‐product (Fitoforce Full), and fungicide. The severity and incidence of rust and brown eye spot on coffee leaves, yield, and leaf retention were evaluated in the field. Percentage of spore germination was evaluated in vitro for both fungi, whereas mycelial growth was evaluated for C. coffeicola only. The treatments Fortaleza, Reforce Mn and Fitoforce Full suppressed both diseases with a reduction in defoliation. In the year 2012, the plants treated with Reforce Mn and Reforce Mn + Fortaleza showed a yield increase of 72 and 88%, respectively, which was similar to the results shown by the fungicide treatment. In vitro inhibition of germination of H. vastatrix urediniospores and of C. coffeicola conidia was observed and suggests that the products exert some toxic effects to both fungi. Finally, the results observed indicate that the combined use of by‐products of plant‐processing industries and phosphites is an alternative and can be added efficiently to the management of coffee diseases.     

Evidence of Alternaria alternata Causing Leaf Spot of Aloe vera in Iran

A leaf spot and leaf blight disease was observed on Aloe vera plants as small, circular to oval dark brown necrotic sunken spots on leaves. Infected tissues collected from different sites in diseased fields were cultured on potato carrot agar medium, and the pathogen was identified as Alternaria alternata on the basis of morphological and cultural characteristics. The conidiophores were branched, straight, golden brown, smooth‐walled, measuring up to μm long by 3 μm wide with one conidial scar. The conidia were golden brown in colour and produced in long branched chains, obclavate in shape and in short conical flask. Pathogenicity tests conducted on healthy potted aloe plants in a glasshouse showed typical leaf spot symptoms after 4–7 days. The optimal temperature for the growth of A. alternata was 25°C.     

Factors affecting incidence and severity of leaf spot disease on lettuce caused by Septoria birgitae

In the 1990s during wet seasons a new disease causing brown leaf spots on lettuce (Lactuca sativa) was found for the first time in many lettuce‐growing areas of Austria and Germany. The causal agent, a new pathogenic species called Septoria birgitae, may be responsible for total crop loss. To study how temperature, inoculum density and leaf wetness period influence disease incidence and severity of leaf spot on lettuce caused by S. birgitae, we carried out in vivo experiments in growth chambers and in the field. Additionally, we evaluated the relevance of infected plant debris acting as a primary inoculum source in soil for subsequent crops. S. birgitae produces spores over a wide temperature range between 5°C and 30°C, and can infect plants at temperatures between 10°C and 30°C, with an optimum between 20°C and 30°C. Spores of S. birgitae at a density of at least 10³ conidia mL^–1 are essential for disease outbreak on lettuce. Because leaf wetness is crucial for releasing conidia from pycnidia, we studied the impact of leaf wetness duration on disease development under various temperature conditions. For relevant leaf spot disease development on lettuce in vivo, a leaf wetness duration of at least 24 h and temperatures higher than 10°C were necessary. Leaf spot disease development in the field required several leaf wetness periods longer than 20 h at approximately 15°C at the beginning of crop cultivation. Incorporating S. birgitae infected plant debris in soil as a primary inoculum was not relevant for leaf spot disease outbreak in the next year. However, in cases of continuous cropping of lettuce on the same field and in the same season, Septoria‐infected lettuce debris may become more relevant.     

Contribution of leaf surface fungi to the air spora

High concentrations of airborne fungal spores frequently occur from spring through fall in temperate areas of the world. Although it is generally assumed that fungi on leaf surfaces are contributors to the air spora, little data are available comparing the types of fungi found on leaf surfaces with those in the atmosphere. Air sampling was carried out with a Burkard Spore Trap located on the roof of a building on the University of Tulsa campus using standard methods. Leaf samples were aseptically collected from Ulmus americana and Quercus palustris trees on campus, placed in sterile plastic bags, and brought to the lab. For each leaf, 4 cm² areas of both upper and lower leaf surfaces were swabbed and plated on malt extract agar with streptomycin. Cultures were incubated at room temperature for 5–7 days and then examined microscopically. Results were expressed as colony forming units (CFU)/cm². Twenty-one fungal taxa were identified from the air samples. The most abundant taxa were Cladosporium, ascospores, basidiospores, and Alternaria; together these four spore types comprised over 90% of the yearly total. Yeasts were the most abundant fungi isolated from both leaf types. Among the mycelial fungi were Phoma species, followed by Cladosporium and Alternaria. Overall twenty genera of filamentous fungi were identified. Yeasts and Phoma are normally splash dispersed and were not identified in the Burkard air samples. However, 10 taxa isolated from leaf surfaces were registered in air samples. Crude estimates of the leaf surface area of each tree suggest that the total fungal load was approximately 5.04×10⁸ CFU for Ulmus and 2.71×10⁸ CFU for Quercus. Of these levels, 19% were from fungi also detected in air samples. The data suggest that some leaf-surface fungi are major contributors to the air spora.     

Identification and Characterization of Pseudocercospora Species Causing Grapevine Leaf Spot in China

Pseudocercospora is an important plant pathogenic genus causing leaf spots on grapevine leaves and other hosts worldwide. A survey of vineyards in four provinces of China was carried out to identify the causal agent of Pseudocercospora leaf spot. A phylogenetic analysis based on a combination of LSU, ITS and ACT loci, coupled with morphology, showed that Pseudocercospora vitis is the sole causal agent of this leaf spot disease. This study represents the first attempt to identify and characterize the cercosporoid species causing Pseudocercospora leaf spot in China using morphological and molecular approaches.     

Index to new names, combinations and emendation appearing in Mycoscience 51 (2)

In this paper, four fungi collected in Nansei Islands are reported. One is Strasseria garciniae, which must be transferred to the genus Phyllosticta. This fungus was collected in Okinawa Main Island and Iriomote Island. The other three fungi are newly added to the Japanese fungal flora. Phyllosticta ghaesembillae on Codiaeum variegatum and Cercospora asplenii on Asplenium antiquum were collected in Yoron Island. The last one, Coniella australiensis on Eucalyptus robusta was collected in Okinawa Main Island. Their morphology and symptoms on the host plant are described, with some mycological notes.     

Leaf Spot of Hemp Dogbane Caused by Stagonospora apocyni, and its Phytotoxins

Stagonospora apocyni causes a leaf spot disease on hemp dogbane (Apocynum cannabinum L.). The fungus produced phytotoxins citrinin, mellein, tyrosol and α–acetylorcinol in liquid culture. All toxins caused necrosis when placed on leaves of hemp dogbane, and eight other weed species. All four toxins were non–specific phytotoxins. Citrinin showed antimicrobial properties against some bacteria and fungi.     

Effect of Zinc on the Development of Brown Spot in Rice

Brown spot, caused by the fungus Bipolaris oryzae, is one of the most destructive diseases of rice. This study investigated the effect of zinc rates on the development of brown spot in rice. Rice plants (cv. ‘Metica‐1′) were grown in hydroponic culture amended with Zn rates (applied as ZnSO₄^.7H₂O) of 0, 0.5, 1, 2 and 4 μm and inoculated with B. oryzae. The foliar concentration of Zn was determined. Leaf samples were assessed for disease severity, and then, area under brown spot progress curve (AUBSPC) was calculated. The relationship between Zn concentrations on leaf tissues and the rates of this micronutrient was best described by a positive linear regression model, while the relationship between the Zn rates and the AUBSPC was best described with a positive quadratic regression model. The correlation between Zn concentrations on leaf tissues and AUBSPC was positive and significant (r = 0.68, P < 0.05). The results from this study showed that high foliar concentration of Zn was associated with increasing rice susceptibility to brown spot.     

Morphology,phylogeny and pathogenicity of Alternaria species,involved in leaf spot disease of sunflower in northern Iran

Leaf spot disease of sunflower is one of the most important foliar diseases on this crop worldwide. Several fungal groups are known to cause leaf spot disease on sunflower. Species of the genus Alternaria are the most common and serious leaf spot causing fungi on this crop. Leaf spot disease is the most destructive foliar diseases on sunflower in northern Iran; however, the identity of the causal agent remains unknown. The present study was aimed to characterise the identity of the causal agent of the disease by means of morphological and molecular data as well as to evaluate the pathogenicity of the responsible species. For this purpose, a total number of 97 fungal isolates were recovered from sunflower leaves with leaf spot disease symptoms from the sunflower fields in northwestern zone of Iran. All of the isolates were identified as Alternaria alternata based on cultural and morphological characteristics. A subset of isolates was subjected to phylogenetic analysis using sequence data from ITS-rDNA region, gpd and rpb2 genes. Sequence data from ITS-rDNA and gpd did not discriminate A. alternata from the other small-spored Alternaria species. A phylogeny inferred using sequence data from rpb2 gene clustered our isolates in several sub-clades within a single monophyletic clade. Sequence data for the type strain of the other small-spored Alternaria species has to be included in phylogenetic analysis, in order to make sure, whether the observed variations in rpb2 gene sequences are an indication for the population variation in sunflower isolates of A. alternata or define species boundaries among the small-spored Alternaria species. The results of pathogenicity assay on sunflower plants (cultivar Euroflor) under greenhouse condition revealed that A. alternata is pathogenic on sunflower.     

The effects of insect pathogenic soil fungi and ectomycorrhizal inoculation of birch seedlings on the survival of Otiorhynchus larvae

• 1 Weevil larvae of the genus Otiorhynchus are a serious problem in agriculture and forestry, causing damage to a wide range of plant species, primarily by larval feeding on roots. Otiorhynchus larvae are a serious pest in forest plantations in Iceland, causing 10–20% mortality of newly‐planted seedlings.
• 2 We studied the effects of soil fungi on the survival of Otiorhynchus sulcatus larvae. The larvae were introduced into pots with birch seedlings grown in: (i) nursery peat; (ii) nursery peat inoculated with three different species of ectomycorrhizal fungi; (iii) nursery peat inoculated with insect pathogenic fungi; (iv) nursery peat inoculated with ectomycorrhizal fungi and insect pathogenic fungi; and (v) nursery peat inoculated with natural forest soil from Icelandic birch woodland.
• 3 Larval survival was negatively affected by inoculation of: (i) the ectomycorrhizal fungus Laccaria laccata; (ii) the ectomycorrhizal fungus Cenococcum geophylum; (iii) the insect pathogenic fungus Metarhizium anisopliae; and (iv) forest soil. Inoculation with the ectomycorrhizal fungus Phialophora finlandia did not have any significant effect on larval survival. No significant synergistic effect was found between insect pathogenic and ectomycorrhizal fungi.
• 4 It is concluded that ectomycorrhizal and insect pathogenic fungi have a significant potential in biological control of Otiorhynchus larvae in afforestation areas in Iceland. Further studies are needed to establish the effect of these fungi in the field and to analyse how mycorrhizal fungi affect root‐feeding larvae.

     

桃树根部内生真菌ZJ-4的分离鉴定及其对桃褐腐病的抑制效果

自桃树根部组织中分离能够防治桃褐腐病害的内生拮抗真菌,并从细胞学水平对其抑制机理进行了初步的探究。采用两点对峙法筛选抑制桃褐腐病菌Monilinia fructicola的内生拮抗真菌,通过菌落形态学特点观察及ITS基因测序分析,初步鉴定内生拮抗真菌的系统发育学地位;采用果实离体实验检测内生拮抗真菌的抗菌效果;使用电子显微镜观察被内生拮抗真菌抑制的桃褐腐病菌丝、孢子的形态以及细胞结构的变化。分离得到的内生真菌ZJ-4对桃褐腐病防效高且稳定,初步鉴定为篮状菌属Talaromyces;果实离体试验表明,内生真菌ZJ-4明显降低了桃褐腐病的发病率;通过电子显微镜观察到被内生真菌ZJ-4抑制的桃褐腐病菌丝及孢子表面粗糙凹陷,畸形现象严重,胞质溶胶收缩凝聚,细胞内部出现大量的空腔。本研究筛选的ZJ-4对桃褐腐病原菌的生长有明显的抑制作用,为开发应用该菌株提供参考。     

<i>Aspergillus tubingensis</i> Causes Leaf Spot of Cotton (<i>Gossypium hirsutum</i> L.) in Pakistan

Cotton (Gossypium hirsutum L.) is a key fiber crop of great commercial importance. Numerous phytopathogens decimate crop production by causing various diseases. During July-August 2018, leaf spot symptoms were recurrently observed on cotton leaves in Rahim Yar Khan, Pakistan and adjacent areas. Infected leaf samples were collected and plated on potato dextrose agar (PDA) media. Causal agent of cotton leaf spot was isolated, characterized and identified as Aspergillus tubingensis based on morphological and microscopic observations. Conclusive identification of pathogen was done on the comparative molecular analysis of CaM and β-tubulin gene sequences. BLAST analysis of both sequenced genes showed 99% similarity with A. tubingensis. Koch’s postulates were followed to confirm the pathogenicity of the isolated fungus. Healthy plants were inoculated with fungus and similar disease symptoms were observed. Fungus was re-isolated and identified to be identical to the inoculated fungus. To our knowledge, this is the first report describing the involvement of A. tubingensis in causing leaf spot disease of cotton in Pakistan and around the world.     

Physiological responses to folivory and phytopathogens in a riparian tree,Brabejum stellatifolium,native to the fynbos biome of South Africa

The canopies of many tree species sustain a large diversity of folivorous arthropods and phytopathogenic fungi. These organisms are thought to influence overall tree and stand productivity. Leaf diseases caused by Phyllosticta owaniana and Periconiella velutina, phytopathogenic fungi commonly found on the native riparian tree Brabejum stellatifolium (wild almond), like any other leaf disease, can potentially reduce a plant's photosynthetic efficiency. In addition to these two phytopathogens, the weevils Setapion provinciale and Setapion quantillum are abundant in wild almond canopies. Despite their pervasive occurrence, the impacts of these phytopathogens and arthropods on host tree leaf physiology have not been examined. The gas exchange response of wild almond leaves to phytopathogens and folivore damage was assessed. Leaf nitrogen, phosphorus and water content were also determined. Declines in photosynthetic rates and other physiological parameters were associated with increasing damage severity by weevils and phytopathogens in leaves of B. stellatifolium. Nitrogen and phosphorus contents were negatively associated with disease severity. Water and phosphorus contents were also negatively correlated with increased weevil damage, while nitrogen content was positively correlated with it. The observed responses of B. stellatifolium metabolic functioning to fungal pathogen and folivory indicate a possibility of suppressed wild populations of wild almond.