几种杀菌剂对梨黑斑病菌抑制作用研究

经室内研究表明,噻菌灵、咪鲜胺、克菌丹、抑霉唑4种杀菌剂对:梨黑斑病菌(Alternaria alternata)均有很好的抑菌效果,其中有效浓度为5×10-8的抑霉唑和6×10-8的咪鲜胺浸泡处理10min能完全杀灭梨黑斑病菌,是极具潜力的浸果处理杀菌药剂。     

百香果疮痂病病原菌鉴定

To identify the pathogen causing scab disease on the fruit of Passiflora Linn. in the passion fruit yard of Cenxi and Nanning cities, Guangxi province. The scab tissues collected from diseased fruits were isolated,purified,and made pathogenicity test,morphological observation, biological and molecular identification. The representive isolate B31, obtained from the diseased fruit, was selected for morphological observation and pathogen identification, and was verified as the causal agent of the scab disease through Koch’s postulates. The result of morphological observation using light microscope showed that the isolate B31 was very similar to Alternaria in terms of hyphae and spore morphology. Phylogenetic analysis results using multiple gene loci showed that identities of sequences of ITS, Alt al, TEF 1 and endoPG genes of isolate B31 were 100% identical to those of Alternaria alternata. This study clarifies that the pathogen causing scab disease of passion fruit in Guangxi is A. alternata, and this is the first report of A. alternate causing scab on passion fruit in China.     

Evaluation of probabilistic risk assessment of pesticides in the UK: chlorpyrifos use on top fruit

The use of probabilistic risk assessment (PRA) for examining chemical impacts has become an important area of debate within the European Union. This paper describes a case study on probabilistic techniques to assess pesticide risks in the UK aquatic environment. The main aim of this paper is to demonstrate both the potential strengths and weaknesses of PRA for assessing pesticides when compared with the conventional deterministic approach, and to examine whether PRA is useful within the European regulatory context. The organophosphate insecticide, chlorpyrifos, was selected as a model compound and toxicity exposure ratios calculated using Monte Carlo analysis and different distributions of spray drift and toxicity values following application to top fruit. Chlorpyrifos is highly toxic to arthropods but less toxic to fishes. Species sensitivity followed a log-normal distribution when fitted to all toxicity data. Toxicity data quantity had little influence on species sensitivity distribution model parameters when n was greater than 10 species. Below this, estimates were less accurate and precise, possibly because of the inclusion of data from many different sources. Estimates of chlorpyrifos exposure derived from the standard spray drift model differed substantially from measurements of chlorpyrifos in European surface waters. When a distribution based on measured concentrations was used in a PRA, the risk of acute fish mortality was low, and the risk of acute arthropod mortality was lower than in other scenarios, although not negligible. If PRA is used to assess pesticides, risk managers need further guidance on how to conduct a PRA and what constitutes 'unacceptable risk' under EC Directive 91/414/EEC, as judgement is required when simple trigger values are no longer used.     

安徽省栝蒌叶枯病菌对4种杀菌剂的敏感性

由致病性链格孢引起的叶枯病是栝蒌生产上出现的一种新病害,在安徽大别山栝蒌生产区发生严重。本研究采用菌丝生长速率法测试了12个代表性栝蒌叶枯病菌菌株对4种常用杀菌剂的敏感性。结果表明,栝蒌叶枯病菌对咪鲜胺敏感性较高,其EC50为0.013 0~0.219μg/mL;代森锰锌和百菌清对栝蒌叶枯病菌均有一定的抑制作用,但各菌株对代森锰锌和百菌清的敏感性差异较大,其EC50分别为0.997~95.64μg/mL和1.66~185.84μg/mL;多菌灵对栝蒌叶枯病菌的菌丝生长抑制作用较差。     

Alternaria Leaf Spot on Three Species of Pelargonium Caused by Alternaria alternata in Japan

A new disease of pelargonium (Pelargonium domesticum Bailey), ivy geranium (P. peltatum (L.) L'Hér. ex Ait.) and scented geranium (P. graveolens L'Hér.), primarily causing brown spots on leaves, was found in Kawasaki-shi in Kanagawa Prefecture and Tachikawa-shi in Tokyo. An Alternaria sp. was consistently isolated from these diseased leaves, and the isolates were pathogenic to their host leaves. Based on morphological characteristics, the causal fungus in all three cases was identified as Alternaria alternata (Fr.) Keissler. Because Alternaria leaf spot of geranium by A. alternata has already been reported, the pathogenicity of isolates from four groups of genus Pelargonium was investigated. The isolates from scented geranium were pathogenic only to their original host, but the isolates from pelargonium, ivy geranium and geranium were pathogenic to all groups of pelargonium. This is the first report of this disease on pelargonium, ivy geranium and scented geranium caused by A. alternata in Japan. We propose the names for these diseases as Alternaria leaf spot of pelargonium (kappan-byo), Alternaria leaf spot of ivy geranium (kappan-byo) and Alternaria leaf spot of scented geranium (kappan-byo). Received 11 December 2000/ Accepted in revised form 19 July 2001     

Microscopic detection of reactive oxygen species generation in the compatible and incompatible interactions of Alternaria alternata Japanese pear pathotype and host plants

 Reactive oxygen species (ROS) generation was examined in the interaction of Alternaria alternata Japanese pear pathotype and host plants using three methods: nitro blue tetrazolium (NBT) method for microscopic detection of O₂ ⁻, diaminobenzidine (DAB) methods for microscopic detection of H₂O₂, and cerium chloride methods for ultrastructural detection of H₂O₂. ROS generation was detected by NBT and DAB methods at appressoria on leaves of susceptible cultivars and heat-shocked leaves of resistant cultivars but not in leaves of resistant cultivars. Ultrastructural detection by the cerium chloride method identified ROS generation at cell walls of appressoria and penetration pegs in susceptible, resistant leaves and heat-shocked leaves. These differences in the ultrastructural and microscopic data in resistant areas were due to the restriction of ROS generation in limited areas, the side facing the plant surface, of appressoria and penetration pegs. Therefore, ROS generation was apparently induced regardless of the resistance or susceptibility of the cultivar with the difference being in the volumes generated. After evaluating the pathological role of ROS generation in fungal structures, such generation was found to be associated with early penetration of cell walls in pear plants. Additionally, ROS generation in plants was also found in degrading pectin layers near infected hyphae and in plasma membrane modification sites in susceptible leaves but not in resistant leaves. ROS generation in susceptible leaves might be accompanied with plasma membrane damage, although the role of ROS generation in the pectin layers is not clear. ROS generation in both fungal and plant cells during their interaction was likely associated with the expression of susceptibility. Received: June 3, 2002 / Accepted: July 31, 2002     

Multiple Alternaria species groups are associated with leaf blotch and fruit spot diseases of apple in Australia

Leaf blotch and fruit spot of apple caused by Alternaria species occur in apple orchards in Australia. However, there is no information on the identity of the pathogens and whether one or more Alternaria species cause both diseases in Australia. Using DNA sequencing and morphological and cultural characteristics of 51 isolates obtained from apple leaves and fruit with symptoms in Australia, Alternaria species groups associated with leaf blotch and fruit spot of apples were identified. Sequences of Alternaria allergen a1 and endopolygalacturonase gene regions revealed that multiple Alternaria species groups are associated with both diseases. Phylogenetic analysis of concatenated sequences of the two genes resulted in four clades representing A. arborescens and A. arborescens‐like isolates in clade 1, A. tenuissima/A. mali isolates in clade 2, A. alternata/A. tenuissima intermediate isolates in clade 3 and A. longipes and A. longipes‐like isolates in clade 4. The clades formed using sequence information were supported by colony characteristics and sporulation patterns. The source of the isolates in each clade included both the leaf blotch variant and the fruit spot variant of the disease. Alternaria arborescens‐like isolates were the most prevalent (47%) and occurred in all six states of Australia, while A. alternata/A. tenuissima intermediate isolates (14%) and A. tenuissima/A. mali isolates (6%) occurred mostly in Queensland and New South Wales, respectively. Implications of multiple Alternaria species groups on apples in Australia are discussed.     

葡萄座腔菌属（Botryosphaeria）引起的果树病害及研究进展

葡萄座腔菌属（Botryosphaeria）真菌在国内外分布广泛,是许多果树常见的病原菌、内生菌和腐生菌,能引起果实腐烂、叶斑、坏死、溃疡和流胶等症状。本文概述了该属真菌引起的果树病害的发生、危害症状、主要病原菌种类、流行学和病害控制、栽培管理策略;展望今后的研究方向。     

Characterization of the host range and sensitivity to fungicides of Trichothecium spp. associated with fruit rot in the field and in storage

During 2017–2019, we observed Trichothecium spp. causing fruit rot in the field and in storage. This study was conducted to examine morphological differences of the species from different hosts, reveal the species’ potential host range, and evaluate the efficacy of five fungicides. Six strains of Trichothecium spp. isolated from nectarine, peach and walnut were selected. Although the colony morphology, mycelial growth rate and spore size differed among hosts, phylogenetic analysis based on the internal transcribed spacer and part of the 5ʹ end of the β-tubulin gene showed that all tested strains belonged to Trichothecium roseum. For its host range, 23 kinds of fruit were examined using T. roseum strain YT-1 as an inoculum; 10 kinds of fruit, including pear, apple, mango, Chinese chestnut, pepino melon, fig and durian, were susceptible to T. roseum, with minimum inoculation concentrations ranging from 10⁴ to 10⁵ spores/ml. The fungicides that most effectively inhibited the six isolates were fluazinam and fludioxonil, with EC₅₀ values of 0.07–0.1 and 0.01–0.04 μg/ml, respectively, followed by difenoconazole (0.81–2.96 μg/ml), boscalid (5.43–13.51 μg/ml) and azoxystrobin (9.18–27.25 μg/ml). Improvement of the shelf life of nectarines held in plastic trays was explored using allyl isothiocyanate (AITC) against T. roseum YT-1. The application of 10 μl/L AITC significantly suppressed disease symptoms. The findings provide useful information for future disease emergency management in the field and for food preservation.     

河北省苹果果实黑点病的症状与病原研究初报

为明确河北省苹果果实黑点病的症状类型及其对应的病原菌,本研究对河北省6个市的果园进行了病害调查和样品采集,并对引起不同症状类型的病果进行了病原菌的分离和鉴定.结果表明,河北省的套袋苹果黑点病可以分为四大类型,分别是萼洼黑点型、果面黑点型、果面晕斑型和梗洼褐斑型.除了果面晕斑型为单一病原侵染之外,其他类型的病斑均分离获得...     

Identification of putative defense-related genes in Japanese pear against <Emphasis Type="Italic">Alternaria alternata</Emphasis> infection using suppression subtractive hybridization and expression analysis

The Japanese pear pathotype of Alternaria alternata, a toxin-dependent necrotrophic pathogen, causes black spot of Japanese pear by producing the host-specific AK-toxin. Pre-inoculation with nonpathogenic A. alternata or pretreatment with an elicitor prepared from A. alternata reduced disease symptoms caused by the pathogen. Salicylic acid- and jasmonic acid-dependent signaling pathways are not involved in the induced resistance to infection by the pathogen. The expression of multiple defense-related genes in Japanese pear leaves inoculated with nonpathogenic A. alternata was examined using suppression subtractive hybridization. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank database as accessions DC993229–DC993535.     

Internal fruit rot of netted melon caused by <Emphasis Type="Italic">Pantoea ananatis</Emphasis> (=<Emphasis Type="Italic">Erwinia ananas</Emphasis>) in Japan

An internal fruit rot with a malodor was found in netted melons (Cucumis melo L.) in commercial greenhouses in Kochi Prefecture, Japan, in 1998, despite their healthy appearance and lack of water-soaking or brown spots on the surface. A yellow bacterium was consistently isolated from the affected fruits. To confirm the pathogenicity of eight representative isolates of the yellow bacterium, we stub-inoculated ovaries (immature-fruits) 5–7 days after artificial pollination, with a pin smeared with bacteria. After the melon fruits had grown for 60 more days, an internal fruit rot resembling the natural infection appeared, and the inoculated bacterium was reisolated. The melon isolates had properties identical with Pantoea ananatis, such as gram-negative staining, facultative anaerobic growth, indole production, phenylalanine deaminase absence, and acid production from melibiose, sorbitol, glycerol, and inositol. Phylogenetic analysis based on 16S rDNA sequences showed that the melon bacterium positioned closely with known P. ananatis strains. The melon bacterium had indole acetic acid (IAA) biosynthesis genes (iaaM and iaaH) and a cytokinin biosynthesis gene (etz). The bacterium could be distinguished from the other ‘Pantoea’ group strains by rep-PCR genomic fingerprinting. From these results, the causal agent of internal fruit rot was identified as a strain of P.ananatis [Serrano in (Philipp J Sci 36:271–305, 1928); Mergaert et al. in (Int J Syst Bacteriol 43:162–173, 1993)]. The nucleotide sequence data reported are available in the DDBJ database under accessions AB297969, AB373739, AB373740, AB373741, AB373742, AB373743 and AB373744.