Optimal Temperature For Mycelial Growth Research Articles

Etiology of Pine Ghost Canker in Southern California Urban Forests.

Pine ghost canker is a recently described disease affecting multiple pine species in urban forests of Southern California. Symptoms include wedged cankers with irregular margins and cryptic discoloration on cross-sections of branches, which can lead to severe dieback and potentially tree death. In this study, we identified and characterized five Neofusicoccum species (N. luteum, N. mediterraneum, N. parvum, N. stellenboschianum, and N. vitifusiforme) as the primary etiological agents of pine ghost canker. These pathogens were consistently isolated from multiple symptomatic pine samples (n = 41) and identified by morphology and phylogenetic analyses using four DNA barcodes (rDNA ITS, tef1, tub2, and rpb2). Pathogenicity was confirmed on healthy branches of 15-year-old Monterey pines, where the five Neofusicoccum species, caused vascular lesions that were not significantly different in length. Secondary fungi (Diaporthe, Diplodia, Neopestalotiopsis, and Pestalotiopsis spp.) were also recovered from symptomatic tissues but did not cause vascular lesions in pathogenicity tests. The optimal temperature for mycelial growth of N. luteum and N. parvum was 30 °C, whereas for N. mediterraneum, N. stellenboschianum and N. vitifusiforme, it was 25 °C. All five species were able to resume growth at room temperature (20 °C) after showing no growth during a 7-day exposure to 5 °C and 40 °C. This study constitutes the first report of N. luteum, N. stellenboschianum, and N. vitifusiforme causing pine ghost canker in California. Environmental factors such as warmer temperatures, irrigation, and pest infestations are discussed as drivers of disease expression in pine trees. Management practices are also proposed.

Heart Rot Disease of Walnut Caused by Nothophoma juglandis sp. nov. and Its Endophytic Biocontrol Agent.

English walnut (Juglans regia L.) is an economically important hardwood tree species cultivated worldwide. Walnut heart rot disease leading to heartwood decay of trees has been frequently observed in a number of plantations in China. To identify the causal agent, 29 diseased stem samples were collected from walnut plantations in Beijing, and 54 fungal isolates were obtained. Koch's postulates were developed, and the results showed that Nothophoma juglandis, a species new to science, was the causal agent of walnut heart rot disease. Granulobasidium vellereum, a notable biocontrol agent, was coisolated with N. juglandis. An antagonistic assay on dual culture and walnut stems (both in the field and detached branches) proved that G. vellereum acted as a potential biocontrol agent against N. juglandis, as it could significantly inhibit the expansion of N. juglandis. The optimal temperature for mycelial growth and pathogenicity of N. juglandis was 26.6 and 27.0°C, respectively, which frequently occur in the summer of the walnut-growing regions in China.

Isolation, Characterization and Phylogenetic Analysis of Stagonospora tainanensis, the Pathogen Causing Sugarcane Leaf Blight in China

Sugarcane leaf blight (SLB), a major fungal leaf disease of sugarcane (Saccharum spp.), has been attributed to Stagonospora tainanensis. In December 2020 and May 2021, signs of leaf blight were observed on sugarcane in the fields of Chongzuo City, in the Guangxi Province of China. Lesions on the leaves were characterized by yellow or dark red spots in the center. Fungal species were isolated, purified and subjected to pathogenicity evaluation on the sugarcane plants. An isolate that caused symptoms the same as those observed in the field was initially identified as S. tainanensis (Leptosphaeria taiwanensis, perfect state) based on its morphological characteristics both of asexual and sexual stages. Dark brown and nearly spherical pycnidia with conidia of long ellipsoidal, hyaline, one to four cells and 29.27 to 54.39 μm long and 9.03 to 16.12 μm wide were found on corn meal agar medium. Ascomata with asci of cylindrical to clavate, a short stipe and eight spores slightly constricted at the septum, with the size of the spore ranging from 36 to 44 μm long and 8.5 to 12 μm wide, were formed on the sugarcane-leaf-decoction saccharose agar medium. The identity of the species was further confirmed by rDNA ITS and TEF-1α sequencing. The optimal temperature for mycelial growth was 25 °C and the optimal pH was 6.0. The pathogen grew well in a medium with oats as the carbon source and yeast extract as the nitrogen source, but poorly in a medium with urea as the nitrogen source. This study is the first to identify the sugarcane leaf blight pathogen in Guangxi, and the first publication describing the biological characterization of S. tainanensis. The occurrence of sugarcane leaf blight should alert sugarcane breeders and plant pathologists to consider integrating control of this potentially important disease into the agenda of their breeding and disease control programs.

Neofusicoccum vaccinii: A Novel Species Causing Stem Blight and Dieback of Blueberries in China.

Blueberries (Vaccinium spp.) have been considered to be a superfood because of their health benefits. Stem blight or dieback of blueberry has been frequently observed in commercial plantations, with incidences between 15 and 30% being observed in China. The causal agents of blueberry stem blight and dieback were surveyed at four commercial blueberry plantations in the Shandong, Fujian, Guizhou, and Yunnan Provinces of China during 2017 and 2019. Twenty-eight isolates of Neofusicoccum were obtained from 75 diseased and dead stem samples. Two taxa were identified. Of these, one novel species, Neofusicoccum vaccinii, was identified based on morphological characteristics and DNA sequence analysis of the concatenated internal transcribed spacer, the translation elongation factor-1α gene, and the beta-tubulin gene. Koch's postulates tests indicated that N. vaccinii was pathogenic toward blueberry. N. parvum is the other species isolated in this study. The optimal temperature for mycelial growth was 30°C for both N. vaccinii and N. parvum. N. vaccinii, however, was more virulent than N. parvum in this study at temperatures ranging from 25 to 30°C. Coinoculation of N. vaccinii and N. parvum did not lead to increased disease severity. On the contrary, the aggressiveness of N. vaccinii was suppressed by the presence of N. parvum at 25 to 35°C.

Identification and characterization of Colletotrichum species associated with anthracnose on persimmon in Brazil

Persimmon (Diospyros kaki) anthracnose is a major threat in production areas worldwide. Most of the studies are focused on Colletotrichum horii, but other species have been reported as well. The association of distinct Colletotrichum species present in Brazilian persimmon production regions as well as their host ranges are yet elusive. The aims of this work were to identify and characterize Colletotrichum species associated with the persimmon anthracnose. In a survey performed in four production regions of Brazil, 88.7% and 11.3% out of 231 isolates were identified as members of Colletotrichum gloeosporioides species complex (Cgc) or Colletotrichum acutatum species complex (Cac), respectively. A subset of 18 isolates were identified through multilocus phylogenetic analysis, using ITS-rDNA region and two loci, namely GAPDH and TUB2. This study revealed the presence of four species: C. horii (38.8%) and Colletotrichum fructicola (27.7%) from the Cgc and Colletotrichum nymphaeae (27.7%) and Colletotrichum melonis (5.8%), from the Cac. Additionally, 13 isolates were selected for morphological, physiological, and pathogenic analyses. Contrasting characteristics were observed among species of the Cgc and Cac complexes. The optimal temperature for mycelial growth and germination were higher for Cgc species. The percentage of appressoria melanisation also varied across complexes. All the identified species were able to cause anthracnose-like symptoms on persimmon fruit, leaves, shoots, and sepals. Colletotrichum species from persimmon were also able to infect apple and pear. The findings will support decisions to manage anthracnose of persimmon under high infection risk due to multiple host susceptibility.

EFFECT OF SOME AGRO-INDUSTRIAL RESIDUES ON MYCELIAL GROWTH AND PRODUCTION OF LIGNOCELLULOLYTIC ENZYMES BY A FUNGUS NATIVE TO ALGERIAN FOREST

Valorization of agricultural and agro-food by-products by fermentation constitutes a very interesting biotechnological approach for the production of lignocellulolytic enzymes. This work was carried out to reveal the effect of some lignocellulosic materials on the mycelial growth and lignocellulolytic enzymes production by Bjerkandera adusta BRFM 1916. The strain showed ABTS- and guaiacol-oxidation activities. The optimal temperature for mycelial growth was 28 °C. The maximum growth rate of this fungus was achieved on wheat bran (2.08 ± 0.05 cm day-1), followed by barley bran, with a significant reduction of 6.73%. Several agricultural lignocellulosic residues were used as substrates for enzymes production. All the data indicated differential utilization of the various materials by the fungus. The selected fungus produced good CMCase (690 ± 0.066 UL-1) and β-Glu (253 UL-1) activities on wheat bran and orange peels, respectively. A high level of MnP activity (449.21 ± 3.44 UL-1) was obtained on wheat bran.

Solid-state bioprocessing of sugarcane bagasse with Auricularia fuscosuccinea for phenolic compounds extraction

Sugarcane bagasse is a natural source of phenolic compounds. However, these compounds are bound to lignocellulose components, reducing their ability to function as good antioxidants. These linkages are hydrolyzed by enzymes like β-glucosidases, increasing free phenolics. Auricularia is a food-grade genus capable of producing β-glucosidases. The aim of this work was (I) to determine naturally occurring species of Auricularia and (II) to obtain phenolic compounds through the solid-state bioprocessing of sugarcane bagasse. We have successfully isolated five strains that were assigned to the taxon A. fuscosuccinea. We determined β-glucosidase activity by fluorescence plate assay of the five isolated strains and adjusted an optimal temperature for mycelial growth at 30 °C. A. fuscosuccinea LBM 243 was chosen for solid-state bioprocessing of sugarcane bagasse. β-glucosidase activity (12.2 ± 0.62 U l−1) and protein content (51.58 ± 6.26 mg l−1) were highest on day 20 of culture. The maximum value of total phenolic content (507.5 ± 9.05 mg l−1) was obtained at day 20 and antioxidant capacity (34.44% ± 11.20) was highest at day 10, both in ethanolic extracts. The best performance of ethanol against methanol extraction in this work is highlighted considering ethanol to be a safe, efficient, and low-cost solvent.

Towards an Optimal Methodology for Basidiomes Production of Naturally Occurring Species of the Genus Oudemansiella (Basidiomycetes).

Oudemansiella species are worldwide distributed and they are characterized for having attractive appearance, a soft fleshy context and mild taste and odor, what makes them interesting for mushroom intensive production. However, studies on their cultivation are scarce and there is no information regarding productive and morphological parameters of fruiting bodies obtained in culture. Here, we propose a methodology to determine the best production technique for the cultivation of not only Oudemansiella species but also of other xylophagous species assaying five different mushroom cultivation systems. Also, the optimal temperature of vegetative growth, the optimal lignocellulosic substrates and the nutritional properties of two naturally occurring Oudemansiella species were determined. As a result, bags with holes-system proved to be the most appropriate technique for the production of fruiting bodies, 25°C was determined as the optimal temperature for mycelial growth and wheat straw as the best substrate. The evaluated species showed a higher content of fats and fiber and a lower content of proteins and carbohydrates compared to other mushrooms. Furthermore, this is the first report of the cultivation of O. cubensis on agricultural wastes in the world.

Study of infection process of five species of Colletotrichum comparing symptoms of glomerella leaf spot and bitter rot in two apple cultivars

Bitter rot (BR) and glomerella leaf spot (GLS) occur in all the Brazilian South orchards with different species frequency per region. The main species found in Brazil belong to the Colletotrichum acutatum complex (Cac) and to the C. gloeosporioides complex (Cgc). The objectives of this study were to evaluate the favorable conditions for the germination and growth of five Colletotrichum species and, to compare pathogenicity and aggressiveness among species and between two apple cultivars in fruit, causing BR, and in leaves, causing GLS. The highest germination of conidia (above 90%) was achieved between 15 and 30 °C for Cgc species while for Cac species the highest germination (mean of 71%) was at 25 °C. The optimal temperature for mycelial growth did not differ between complexes and ranged from 23 to 27 °C. Althought, Cgc had a higher estimated maximum temperature then Cac. C. siamense cause BR symptoms regardless of cultivar or type of inoculation. C. nymphaeae and C. melonis caused symptoms in wounded and unwounded fruit but for C. paranaense and C. fructicola the symptoms were observed only in wounded fruit. Leaf symptoms of GLS was more severe in stressed leaves inoculated on the abaxial side compared to non-stressed leaves inoculated on the adaxial side. C. fructicola and C. nymphaeae were able to cause GLS symptoms in leaves with severity varying from 17.5 to 25% (cv. Gala). C. fructicola was the most severe causing GLS symptoms in cv. Gala (severity around 20.5%) and, in cv. Eva (severity around 11%). We discuss the roles that each species plays as a pathogen to better understand BR and GLS in different orchards conditions.

Importance of thermal adaptation of Amphobotrys ricini in its infection of Asian copperleaf (Acalypha australis)

Amphobotrys ricini and Botrytis cinerea are causal agents of gray mold in euphorbiaceous plants, including Ricinus communis and Acalypha australis. In the present monitoring of epidemics of A. ricini and B. cinerea in A. australis, A. ricini was found in A. australis from August to October, when average temperatures ranged from 17.5 to 32.5 °C. In contrast, B. cinerea was not found in A. australis. This result suggests that A. ricini may adapt better than B. cinerea to warm weather. To test this idea, we examined the effects of temperature on mycelial growth and conidial germination of A. ricini and B. cinerea and their aggressiveness in A. australis and R. communis. Results showed that the optimal temperature for mycelial growth was 20–30 °C for A. ricini and 20 °C for B. cinerea. The optimal temperatures for conidial germination ranged from 26 to 30 °C for A. ricini and from 20 to 26 °C for B. cinerea. At 30–32 °C, A. ricini grew more rapidly, had higher conidial germination percentages and longer germ tubes than B. cinerea. When A. australis and R. communis were inoculated with these fungi, A. ricini was more aggressive than B. cinerea at 28 °C, but less aggressive than B. cinerea at 20 °C, during infection of leaves. These results suggest that thermal tolerance plays an important role in epidemics of A. ricini in A. australis. The study elucidated an ecological mechanism for better understanding about host preference of A. ricini in A. australis.

Leaf blight caused by Curvularia coicis on Chinese pearl barley (Coix chinensis) in Fujian Province, China

Chinese pearl barley (Coix chinensis Tod.) is grown worldwide as a cereal food and medicinal plant. During 2016 and 2017, a severe leaf blight outbreak was observed in Nanjing prefecture, Fujian Province, China. The disease outbreak affected almost 100% of the Chinese pearl barley plants under field conditions. The pathogen was isolated from infected leaves showing typical symptoms of dark brown spots surrounded by yellow halos, and was identified as Curvularia coicis Castellani based on morphological characteristics and sequencing of the ribosomal DNA internal transcribed spacer (rDNA-ITS). The optimal temperature for mycelial growth of C. coicis on potato dextrose agar (PDA) ranged from 25°C to 28°C. Pathogenicity assays were performed using Chinese pearl barley ‘Longyi 1' at the seven- to eight-leaf stage. Overall, C. coicis had a high virulence on these inoculated plants, even in the absence of wounds, and the pathogen was successfully reisolated. The results from this study identified the causal organism of leaf blight on Chinese pearl barley.

Genetic and biological characterization of Macrophomina phaseolina (Tassi) Goid. causing crown and root rot of strawberry

In recent years, crown and root rot of strawberry (Fragaria ×ananassa Duchesne ex Rozier) caused by Macrophomina phaseolina (Tassi) Goid. has affected strawberry production areas worldwide, and in developed countries its emergency has been attributed to the replacement of methyl bromide. The disease was reported in strawberry crop in Chile in 2013, in fields without fumigation. The use of resistant cultivars rises as an alternative to the management of this disease. The objective of this study was to perform a biological and molecular characterization of isolates obtained from two growing regions in Chile and Spain. A total of 35 isolates were characterized for mycelial growth at different temperatures and for chlorate sensitivity. Seven simple sequence repeat loci were used for genetic characterization. Differences were found between Chilean and Spanish isolates in both characterizations. The optimal temperature for mycelial growth was lower in Chilean than in Spanish isolates (30 and 35 °C, respectively). Meanwhile, Chilean isolates were more sensitive to chlorate. In terms of genetic characterization, Polymorphism Information Content (PIC) ranged from 0.38 to 0.85, two main groups were identified, the first group included Spanish isolates and the second group corresponded to Chilean isolates, results were supported by a population structure analysis. This study determined clear differences between two populations of Chilean and Spanish M. phaseolina isolates as causal agent of crown and root rot of strawberry.

Erratum to: Mycena kentingensis, a new species of luminous mushroom in Taiwan, with reference to its culture method

Mycena kentingensis, a new luminous mushroom, was discovered in the tropical forest of Kenting National Park in Taiwan. The pileus of M. kentingensis is 3–8 mm in diameter and emits green light in the dark. The dorsal surface of the pileus is covered with short and white spines. The lamellae are nearly free. The stipe is puberulous with a white basal disc about 2 mm broad. Cheilocystidia are clavate to obpyriform, 16–40 × 4–8 μm, and have dense excrescences on the upper half or two-thirds of the cell. The pileus lacks cherocyte, and the stipe lacks caulocystidium. To further identify the species by the DNA barcode method, the internal transcribed spacer (ITS) DNA sequence of M. kentingensis was amplified by polymerase chain reaction, sequenced, and searched for in the GenBank. The hit with the maximum score was an uncultured fungus clone KFRI2121 (accession number HQ662846) with 88 % sequence identity. For those ITS sequences associated with Latin binominal names in the GenBank, the hit with the maximum score was Mycena stylobates with 87 % sequence identity. Phylogenetic analyses by Bayesian and maximum likelihood methods showed that M. kentingensis is close to M. stylobates and M. adscendens. To develop its culture method, mycelia of M. kentingensis were isolated. The optimal temperature for mycelial growth on potato-dextrose agar (PDA) medium was 24 °C. Commercial compost with the addition of 20 % rice bran and 50 % water was appropriate for fruit-body formation. The new species of Mycena kentingensis brings the total of luminous fungi in the world to 74 species.

The effect of environmental factors on infection of blueberry fruit by Colletotrichum acutatum

Anthracnose fruit rot of blueberries caused by Colletotrichum acutatum is a serious problem in humid blueberry‐growing regions of North America. In order to develop a disease prediction model, environmental factors that affect mycelial growth, conidial germination, appressorium formation and fruit infection by C. acutatum were investigated. Variables included temperature, wetness duration, wetness interruption and relative humidity. The optimal temperature for mycelial growth was 26°C, and little or no growth was observed at 5 and 35°C. The development of melanized appressoria was studied on Parafilm‐covered glass slides and infection was evaluated in immature and mature blueberry fruits. In all three assays, the optimal temperature for infection was identified as 25°C, and infections increased up to a wetness duration of 48 h. Three‐dimensional Gaussian equations were used to assess the effect of temperature and wetness duration on the development of melanized appressoria (R2 = 0·89) on Parafilm‐covered glass slides and on infection incidence in immature (R2 = 0·86) and mature (R2 = 0·90) blueberry fruits. Interrupted wetness periods of different durations were investigated and models were fitted to the response of melanized appressoria (R2 = 0·95) and infection incidence in immature (R2 = 0·90) and mature (R2 = 0·78) blueberry fruits. Additionally, the development of melanized appressoria and fruit infection incidence were modelled in relation to relative humidity (R2 = 0·99 and 0·97, respectively). Three comprehensive equations were then developed that incorporate the aforementioned variables. The results lay the groundwork for a disease prediction model for anthracnose fruit rot in blueberries.

줄버섯 피해 표고골목의 특성 및 표고균과의 대치배양

A harmful fungus occurred seriously in bed-log of shiitake(Lentinula edodes) in Jangheung-Gun, Korea. The fungus was identified as Bjerkandera adusta by its morphology and ITS(Internal Transcribed Spacer) analysis. The fungus was reported as causal agent of stem-rot of Populus euramericana in Korea, but not reported in bed-log of shiitake until this notification. Thus, studies were made to investigate inside condition of bed-log of shiitake damaged by B. adusta, physiological characteristics of B. adusta and antagonism between these two fungi. First of all, B. adusta is white-rotting fungus like shiitake and wood-rotting condition is similar to that of shiitake. But, there are a lot of small spots in damaged wood tissue under bark which are not seen in case of shiitake. Optimal temperature for mycelial growth of B. adusta is ca. 30 o C while that of shiitake is ca. 25 o C. When confrontation cultures were made between these two fungi under 15 o C, 20 o C, 25 o C and 30 o C, B. adusta has antagonistic ability against shiitake in all the temperatures. From the results of experiments, if the bed-logs of shiitake are exposed to high temperature, there should be mass propagation of B. adusta, and shiitake mycelia will be seriously injured by the fungus. Therefore, to prevent the damage by B. adusta, it is needed to grow the mycelia of shiitake fast in the bed-log, and to avoid exposure of the bed-log to high temperature in summer.

Botrytis cinerea에 의한 야콘 잿빛곰팡이병의 발생

The gray mold disease occurred on tuberous roots of yacon in storage facilities in Gangneung, Korea, in March 2010. Symptoms typically appeared as in the form of dark brown discoloration on the surface of tuberous roots and water-soaked brown lesions in cross sections of the affected portions. A total of five isolates of Botrytis sp. were obtained from the symptomatic portions. All isolates on potato-dextrose agar (PDA) produced abundant conidia which were pale brown, one-celled, mostly ellipsoid or ovoid in shape and in size. Large numbers of round to irregular, smooth, black, hard sclerotia were produced on PDA over time. The optimal temperature for mycelial growth and sclerotia formation of the fungal isolates was . On the basis of morphological and cultural characteristics, all the fungal isolates were identified as Botrytis cinerea. Pathogenicity test on host plants showed that the fungus could infect not only tuberous roots but also leaves and petioles of yacon. This is the first report on gray mold of yacon (Smallanthus sonchifolius) caused by Botrytis cinerea in Korea.

노루궁뎅이버섯류의 톱밥재배와 항산화물질 비교 연구

As a preliminary study in order to develop new varieties of Hericium species, this study was carried out to investigate the optimal temperature for mycelial growth, to figure out the applicability to sawdust cultivation on Quercus mongolica substrate, and to analyze the antioxidant capacity of ergothioneine and polyphenols in Hericium strains preserved in Korea Forest Research Institute (KFRI). In the results of optimal temperature for mycelial growth of eight Hericium erinaceus, it was in a strain (KFRI 842), in five strains (KFRI 507, 508, 509, 843, 845), and in two strains (KFRI 582, 844). Optimal temperature for mycelial growth of H. coralloides (KFRI 713) was . Four strains (KFRI 508, 843, 844, 713) out of the total nine Hericium strains showed full mycelium growth within 20 days at the optimal temperature on PDA medium in petri-dish (85 mm in diameter). The other strains have need of more time for full mycelium growth. Mushroom production of H. erinaceus ranged from 215 to 384 g of fresh weight and its dry weight was 7 to 9% of it, whereas that of H. coralloides was 299 g of fresh weight and its dry weight was 10% of it. The contents of ergothioneine and polyphenols of H. erinaceus strains were different by strains and those were in the range of mg/g dw. and mg/g dw., respectively. On the other hand, those of H. coraloides were in the range of 1.7 mg/g dw. and 3.9 mg/g dw., respectively. From the results of correlation (

Botrytis cinerea에 의한 초석잠 잿빛곰팡이병 발생

2005년 3월경 경남농업기술원 움막저장고에서 저장중이던 초석잠의 덩이줄기에 이상증상이 발생하였다. 병징은 초석잠 덩이줄기 부분이 수침상으로 물러지고 썩으면서 병반부위에 회색의 곰팡이가 많이 생겼다. 분생포자는 무색, 단포자이며 난형 또는 타원형으로 크기는 <TEX>$5{\sim}16{\times}4{\sim}12{\mu}m$</TEX>였다. 분생포자경은 갈색으로 격막이 있고 나무가지 모양이며, 폭은 <TEX>$14{\sim}30{\mu}m$</TEX>였다. 균사생육과 균핵형성 적온은 <TEX>$20^{\circ}C$</TEX>였다. 초석잠에서 병징과 병원균의 균학적 특징, 병원성을 조사한 결과 Botrytis cinerea Persoon:Fries에 의한 초석잠 잿빛곰팡이병으로 동정하였다. In March of 2005, gray mold disease caused by Botrytis cinereu on Stachys sieboldii Miq. was occurred in the mud cellar storage of Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The symptoms started with water-soaked and rotten in the tubers. The conidia were one celled and mostly ellipsoid or ovoid in shape and light gray in color. The conidia were <TEX>$5{\sim}16{\times}4{\sim}12{\mu}m$</TEX> in size and the conidiophores were <TEX>$14{\sim}30{\mu}m$</TEX> in length. The pathogen formed conidia and sclerotia abundantly on PDA. The optimal temperature for mycelial growth and sclelotia formation was <TEX>$20^{\circ}C$</TEX>. On the basis of symptom, mycological characteristics and pathogenicity test on host plants, the fungus was identified as Botrytis cinerea Persoon: Fries. This is the first report on gray mold of S. sieboldii caused by B. cinerea in Korea.

Doenças do milho causadas por fungos do gênero Stenocarpella

Os fungos Stenocarpella macrospora e Stenocarpella maydis podem causar podridão de semente, morte de plântula, podridão da base do colmo e da espiga e mancha foliar em milho, sendo comumente detectados nos grãos ardidos quando as espigas são infectadas. Os danos no rendimento e na qualidade de grãos causados especificamente por Stenocarpella ainda não foram devidamente quantificados. Os patógenos são encontrados praticamente em todas as regiões produtoras de milho do Brasil. A doença ocorre com maior intensidade em lavouras de monocultura, principalmente em pequenas propriedades rurais, e em lavouras produtoras de semente, onde o cereal é freqüentemente cultivado na mesma área. Os restos culturais de milho e as sementes infectadas constituem-se na principal fonte de inóculo primário. O inóculo constituído de picniosporos, produzido nos resíduos culturais, é disseminado à curta distância pelo vento e respingos d'água. A disseminação à longa distância ocorre pelas sementes. A infecção das plantas pode ser sistêmica, com inóculo na forma de micélio oriundo das sementes, e/ou pela penetração direta com germinação dos conídios nos sítios de infecção, como bainha foliar, lâmina foliar, pedúnculo e palha da espiga. A temperatura ótima para crescimento do micélio e germinação dos conídios de ambas espécies ocorre na faixa de 23 ºC a 28 ºC. As principais estratégias de controle baseiam-se na eliminação e/ou redução da fonte de inóculo primário, como uso de semente sadia, tratamento de sementes com fungicida do grupo dos benzimidazóis e rotação de culturas. Pouca informação existe sobre a tolerância da doença em híbridos comerciais no Brasil. A adubação equilibrada do solo e evitar elevada densidade de plantas também podem reduzir a infecção.

Effect of temperature on the mycelial growth of the fungus Sphaeropsis sapinea

Effect of temperature on mycelial growth was tested on 11 isolates from six pine species - P. nigra, P. sylvestris, P. halepensis, P. heldreichii, P. pinaster and P. pinea, originating from Serbia and Montenegro. The optimal temperature for mycelial growth of the fungus S. sapinea on potato-dextrose agar (PDA) and malt-extract agar (MEA) media was 28?C. However, a very similar colony growth occurred also at 25?C. The growth of all the tested isolates was better on PDA than on MEA. In addition to faster growth, on PDA the fungus showed the physiological activity in the wider temperature interval - between 4?C and 40?C. On MEA, all isolates grew in the temperature interval between 10?C and 35?C. However, colony formation or inoculum growth of a low number of isolates occurred also at 4?C. The differences in growth among the isolates occurred only at the temperatures which are closer to cardinal.