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1.
Increased occurrence of cucumber angular leaf spot, Pseudomonas syringae pv. lachrymans, has caused significant losses in cucumber, Cucumis sativus, yield in Poland in recent years. These losses necessitated evaluation of the level of resistance in cucumber cultivars of mainly Polish breeding, cultivated in Eastern Europe, and initiation of a breeding programme for resistance to this disease. Screening for resistance was performed on 84 cucumber accessions under growth chamber conditions using a highly aggressive strain of P. syringae pv. lachrymans. Most of the screened accessions were either susceptible or displayed intermediate resistance. The screening resulted in the identification of five F1 hybrid cultivars moderately resistant to angular leaf spot. The identified F1 hybrids were self-pollinated up to the F4 generation. Individuals resistant to angular leaf spot were identified. These individuals can be used as a source of resistance to angular leaf spot in future breeding efforts.  相似文献   

2.
 In May 1998 leaf spot caused by Septoria chrysanthemella was found on Aster savatieri in Kanagawa Prefecture, Japan. This is the first report of leaf spot on A. savatieri caused by S. chrysanthemella. Received: September 13, 2002 / Accepted: October 18, 2002 Acknowledgments The authors thank Dr. T. Kobayashi, formerly of Tokyo University of Agriculture, for his advice on identifying the fungus.  相似文献   

3.
 The root endophytic fungus Heteroconium chaetospira isolate OGR-3 was tested for its ability to induce systemic resistance in Chinese cabbage against bacterial leaf spot caused by Pseudomonas syringae pv. maculicola and Alternaria leaf spot caused by Alternaria brassicae of the foliar diseases. Chinese cabbage seedlings planted in soil infested with an isolate of H. chaetospira were incubated in a growth chamber for 32 days. The first to fourth true leaves of the seedlings were challenge-inoculated with P. syringae pv. maculicola or A. brassicae. Chinese cabbage planted in soil infested with H. chaetospira showed significant decreases in the number of lesions of bacterial leaf spot or Alternaria leaf spot when compared to the control plants not treated with H. chaetospira. The results indicated that colonization of roots by H. chaetospira could induce systemic resistance in Chinese cabbage and reduce the incidence of bacterial leaf spot and Alternaria leaf spot. Received: April 24, 2002 / Accepted: August 9, 2002  相似文献   

4.
In winter oilseed rape experiments at Rothamsted in 2000/01 to 2002/03 growing seasons, the severity of phoma stem canker epidemics in summer depended on the timing of phoma leaf spot epidemics in the previous autumn, and hence on the timing of Leptosphaeria maculans ascospore release. The first major release of L. maculans ascospores was earlier in 2000 (26 September) and 2001 (18 September) than in 2002 (21 October). Consequently, the autumn phoma leaf spot epidemic was also earlier in 2000 and 2001 than in 2002. The resulting stem canker epidemics were severe by harvest (July) in 2001 and 2002 but not in 2003. No correlation was found between the severity or duration of phoma leaf spotting (lesion days or lesion °C-days) and the subsequent severity of phoma stem canker epidemics. Rates of leaf production and loss were similar in the three growing seasons. Out of ca. 25 leaves produced on plants during each season, leaf numbers 10–14 generally remained on plants for the longest. Treatment with flusilazole + carbendazim in autumn decreased the severity of phoma leaf spotting for several weeks after treatment, decreased the severity of stem canker the following summer and increased yield significantly in 2001 and 2002 but not in 2003. The most effective timings for flusilazole + carbendazim application were when leaves 7–11 were present on most plants and at least 10% of plants were affected by phoma leaf spot. Two half-dose applications of fungicide reduced phoma stem canker and increased yield more than a single full dose application when phoma leaf spot epidemics were early (<800 °C-days after sowing).  相似文献   

5.
A ring spot disease of Aloe vera was found on leaves of potted seedlings of Aloe vera in Hachijojima and Chichijima Islands, Tokyo. From tissue of ring spot lesions, a fungus producing Fusarium-type conidia was consistently isolated. After 1 month, reddish perithecia of nectriaceous fungus had formed on the colonies of this isolate on PDA. These nectriaceous and Fusarium fungi were identified as Haematonectria haematococca and Fusarium sp., respectively. From a single ascospore isolation, the former was confirmed to be the teleomorph of the Fusarium sp. Typical ring spot lesions were reproduced by artificial inoculations using single ascospore and single conidium isolates. Inoculations of five species of genus Aloe revealed that they were highly susceptible except for A. arborescens. This is the first report of a disease on Aloe caused by H. haematococca (anamorph: Fusarium sp.) in Japan, and it was named aloe ring spot.  相似文献   

6.
Italian ryegrass is a major pasture crop cultivated mainly for feeding cattle in southern Brazil. The choice of crop is based on nutritional quality and the shortage of pastures that occur during the winter in the southernmost part of Brazil. In this region, the production of biomass and seeds are threatened by diseases, in particular fungal diseases that affect the foliage. In this study we identified and monitored the natural occurrence of a complex of leaf spotting diseases and evaluated the effects of combined management practices to reduce the intensity of foliar diseases: seed treatment with Trichoderma atroviride, soil amendment with silicon and cutting frequency (none, one or two cuts). Three diseases were present in a two-season experiment: grey leaf spot (Pyricularia oryzae), brown leaf spot (Bipolaris sorokiniana) and parrot's eye leaf spot (Cercospora sp.). Grey leaf spot had the highest severity, regardless of treatment, during the first season, and was the only disease present in the following season. Grey leaf spot dominated, and plants receiving only one cut were more prone to P. oryzae infection. The treatments with silicon or T. atroviride reduced the relative disease by 40% to 80%, in relation to untreated and uncut regimes. This study showed the main leaf spot diseases associated with L. multiflorum. Moreover, it demonstrates for the first time in the region the effectiveness of reducing leaf spot via the application of silicon in the soil, inoculation of seeds with T. atroviride and managing the cutting regime.  相似文献   

7.
A new disease was observed on Trifolium dasyurum, with symptoms beginning as a halo spot and developing into a leaf blight. The causal organism was identified by microscopy and DNA sequence studies as Botrytis fabae. This strain of B. fabae was also demonstrated to cause disease on foliage of a range of pulse crops, including Vicia faba, Pisum sativum, and Lens culinaris. This study demonstrates the potential of this strain of B. fabae to not only pose a significant threat to T. dasyurum but also to pulses grown in rotation with T. dasyurum that are susceptible to this strain of B. fabae.  相似文献   

8.
甘肃省红豆草病原真菌鉴定及病害发生动态调查   总被引：4，自引：1，他引：3  
为明确甘肃省红豆草的病害种类、发生动态和危害状况,采用病原物分离与培养、形态学及分子生物学鉴定和致病性测定确定红豆草病害种类,于2012—2013年在通渭、渭源、榆中和碌曲4县调查各病害的发病率以确定发生动态,观察病害田间发生特点并结合调查数据评价其重要性。结果表明,4县共发生真菌性病害12种,分别为大茎点霉叶斑病(病原为大茎点霉属真菌Macrophoma sp.)、壳针孢叶斑病(病原为歪头菜壳针孢Septoria orobina)、炭疽病(病原为白蜡树刺盘孢Colletotrichum spaethianum)、黑秆病(病原为红豆草壳二孢Ascochyta onobrychis、菠菜刺盘孢C.spinaciae和链格孢Alternaria alternata混合侵染)、壳二孢叶斑病、茎点霉叶斑病、尾孢叶斑病、柱格孢白斑病、匍柄霉叶斑病、链格孢黑斑病、锈病和白粉病,其中大茎点霉属真菌、白蜡树刺盘孢和菠菜刺盘孢在红豆草上首次发现;尾孢叶斑病和壳针孢叶斑病为甘肃新记录病害;大茎点霉叶斑病为世界新病害,仅于碌曲县发现。白粉病、锈病、链格孢黑斑病发生于红豆草生长后期,其它病害则始于6月;6—9月危害加重的为黑秆病和柱格孢白斑病,发病率最高达89.7%和96.0%;危害渐轻的为茎点霉叶斑病、壳二孢叶斑病和壳针孢叶斑病,发病率最高达88.7%、57.4%和45.1%。黑秆病和茎点霉叶斑病在甘肃省目前危害最重。  相似文献   

9.
In June 1995, a disease causing round to irregular-shaped, water-soaked, brown to blackish brown spots on mealycup sage (Salvia farinacea Benth.) was found in Atsugi-shi, Kanagawa Prefecture, Japan. The symptoms were seen only on leaves, not on neither flower petals or stems. The disease was also found in Setagaya-ku, Tokyo, Memambetsu-cho, Hokkaido and Shimoda-shi and Matsuzaki-cho, Shizuoka. An Alternaria sp. was frequently isolated from these diseased plants. The isolates were severely pathogenic to mealycup sage and caused lesions on the inoculated leaves. The isolates were also weakly pathogenic on scarlet sage (S. splendens Sellow ex Roem. and Schult.) but not on any other Labiatae plants tested. Based on morphological characteristics, such as size of conidia, chain number, and the short beak on conidia, the causal fungus was identified as Alternaria alternata (Fr.) Keissler. This report is the first on a mealycup sage disease caused by A. alternata. Because the symptom was restricted to the leaf, the common name of Alternaria leaf spot was proposed. Received 30 August 2002/ Accepted in revised form 18 November 2002  相似文献   

10.
A new defoliating disease with severe leaf spot of Japanese persimmon (Diospyros kaki) was found in Shimane Prefecture. A fungus, isolated from the ascospores that had formed on the leaf spot, was demonstrated to reproduce the symptoms on leaves and described as a new species, Adisciso kaki, based on morphological and molecular phylogenetic analyses. This fungus is characterized by small ascomata without clypeus, obclavate to broadly cylindrical asci with an amyloid apical apparatus, and hyaline ascospores with a submedian septum. We coined the name black leaf spot (Kurohoshi-rakuyo-byo, in Japanese) for the new disease.  相似文献   

11.
In recent years, common bean (Phaseolus vulgaris) and cowpea (Vigna unguiculata) plants in the north of Iran have exhibited symptoms resembling Cercospora leaf spot (CLS) disease. This study was initiated to elucidate the taxonomy and pathogenicity of cercosporoid taxa associated with leaf spot diseases of these two legume crops in Iran. A total of 138 samples with CLS symptoms were collected from cultivated common bean and cowpea species in northern Iran and subjected to microscopic examination, resulting in identification of 98 Cercospora and 59 Pseudocercospora samples. A six-locus phylogenetic analysis (ITS, actA, tef1, gapdh, his3, and cmdA) coupled with examination of the morphology of 42 representative isolates from these samples confirmed that several cercosporoid fungi occur on common bean and cowpea in Iran. Five Cercospora species (C. iranica, C. cf. flagellaris, Cercospora sp. G, Cercospora sp. T, and C. vignigena) and two Pseudocercospora species (P. griseola f. griseola and P. cf. cruenta) were found; of these, C. cf. flagellaris was the dominant species, occurring on both common bean and cowpea. Pathogenicity tests confirmed that all seven species could infect leaves of common bean and/or cowpea. This is the first report of C. iranica, Cercospora sp. G, and Cercospora sp. T associated with common bean and/or cowpea in the world. In addition, C. vignigena was recorded for the first time in Iran. Results achieved in this study will assist strategies for the management of CLS disease of common bean and cowpea.  相似文献   

12.
In vitro detached leaf assays involving artificial inoculation of wounded and unwounded oat and wheat leaves were used to investigate the potential pathogenicity and aggressiveness of F. langsethiae, which was linked recently to the production of type A trichothecenes, HT-2 and T-2 in cereals in Europe. In the first two experiments, two assays compared disease development by F. langsethiae with known fusarium head blight pathogen species each used as a composited inoculum (mixture of isolates) at 10°C and 20°C and found all fungal species to be pathogenic to oat and wheat leaves in the wounded leaf assay. In the unwounded leaf assay, F. langsethiae was not pathogenic to wheat leaves. Furthermore, there were highly significant differences in the aggressiveness of pathogens as measured by lesion length (P < 0.001). In the second two experiments, pathogenicity of individual F. langsethiae isolates previously used in the composite inoculum was investigated on three oat and three wheat varieties. The wounded leaf assay showed that all isolates were pathogenic to all oat and wheat varieties but only pathogenic towards oat varieties in the unwounded assay. Highly significant differences (P < 0.001) in lesion length were found between cereal varieties as well as between isolates in the wounded assay. Significant differences in lesion lengths (P = 0.014) were also observed between isolates in the unwounded assay. Results from the detached leaf assays suggest that F. langsethiae is a pathogen of wheat and oats and may have developed some host preference towards oats.  相似文献   

13.
Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of three rambutan postharvest diseases, stemend rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits to control the diseases were investigated: application of potassium metabisulphite (250 ppm) or culture filtrate ofTrichoderma harzianum (TrH 40) followed by controlled atmosphere storage (CA) at 13.5°C and 95% r.h. Potassium metabisulphite at 250 ppm under CA effectively controlled the incidence and severity of the three postharvest diseases and maintained the eating quality and color of the fruit for 21 days. The greatest effect of this treatment was on brown spot disease, caused byG. microchlamydosporum. Application of TrH 40 was less effective than potassium metabisuphite. http://www.phytoparasitica.org posting July 8, 2002.  相似文献   

14.
In May 1998 and 1999, two types of leaf spot (black type and brown type) caused by Phoma spp. were found on Farfugium japonicum in Tokyo and in Gunma Prefecture, Japan. The fungus isolated from black-type lesions caused only black-type lesions, and the fungus from brown-type lesions caused only brown-type lesions. We propose to name these diseases black leaf spot of F. japonicum (kokuhan-byo in Japanese) for the disease with black lesions and circular leaf spot of F. japonicum (rinmon-byo in Japanese) for the disease with brown lesions. This is the first report on leaf diseases of F. japonicum caused by Phoma spp.  相似文献   

15.
Tomato leaves showing severe leaf spot symptoms have been observed and sampled in the central west and southwest Taiwan during 2015 and 2016. The symptoms were similar to those of bacterial leaf spot/late blight diseases, but only Stemphylium-like fungi were consistently isolated from the diseased tomato. Upon spray inoculation of tomato, Stemphylium-like isolates caused leaf spot symptoms identical to those of naturally infected plants, and the pathogenic isolates were successfully re-isolated from inoculated leaves. The tomato-pathogenic isolates were identified as S. lycopersici based on morphological characterization and molecular identification. S. lycopersici has been previously reported to cause gray leaf spot of tomato in the temperate regions, but the majority of S. lycopersici-caused lesions were black/dark brown rather than gray in our surveillance. Accordingly, it is suggested that S. lycopersici-caused disease of tomato is named Stemphylium leaf spot of tomato more appropriately than tomato gray leaf spot. Moreover, S. lycopersici-caused leaf spot disease on tomato has been distributed in major tomato production regions in Taiwan. The information provided by our study will be important for future breeding of tomato cultivars, especially for tomato producers in Taiwan.  相似文献   

16.
Sugar beet root infection by Cercospora beticola, the causal agent of Cercospora leaf spot (CLS), was studied in a climate chamber and in the field. In the climate chamber, root incubation of susceptible seedlings with a conidial suspension resulted in disease incidences that were significantly different for two sugar beet cultivars (Auris: 0.8 ± 0.14 and A00170: 0.5 ± 0.18; P < 0.05) with regard to the control treatment 35 days after root incubation in a standard potting soil-fine river sand mixture. In a field trial with susceptible cv. Savannah with soil-incorporated CLS-infested leaf material, disease developed four weeks earlier in the infested plots than in the control plots. The probability that disease develops in the field was significantly higher for the infested than for the control plots (P < 0.05). Symptomless plants from infested field plots transferred to the glasshouse to induce leaf spot symptoms showed a significantly higher probability to induce symptom development (0.4 ± 0.08), than plants from control plots (0.02 ± 0.02) (P <0.05) 14 days after transfer. This probability was significantly higher than for plants that remained in three of the infested field plots (0.2 ± 0.04; 0.2 ± 0.05 and 0.2 ± 0.04 respectively), except for one infested field plot (0.4 ± 0.05) on July 5. We conclude that C. beticola is able to infect sugar beet seedlings through their roots and that latent CLS infections in sugar beet lead to symptom development at high temperatures (> 20 °C) and high relative humidity (> 95) in our climate chamber or after canopy closure in the field. Quantification of root infection and long term survival in soil is necessary to assess its contribution to the epidemiology and life cycle of Cercospora beticola. Cultural methods such as a wider crop rotation, management of crop debris and ploughing systems may provide control strategies alternative to or reducing fungicide input.  相似文献   

17.
Leaf spot of tomato, incited by Pseudomonas syringae pv. syringae, has been reported recently in Italy on grafted and non-grafted tomato plants (scion Cuore di Bue, rootstock Solanum lycopersicum x Solanum hirsutum cv. Beaufort). In some greenhouses, more than 80% of plants were affected, with a marked reduction in yield. This work was undertaken in order to understand the effect of the number of hours of incubation at high relative humidity (r.h.) and temperature as well as the effect of the presence of wounds at infection time on the development of leaf spot. A difference in sensitivity to leaf spot was observed in the various cultivars tested, in terms of severity of P. syringae pv. syringae, with “Cuore di Bue” being the most susceptible of these cultivars. The development of leaf spot is mostly favored by the presence of wounds, at temperatures between 15 and 20°C. The severity of the disease is lower at 10 and 25°C and very low at 30°C. Under the most favorable temperature conditions, the presence of wounds is sufficient to allow the development of the pathogen immediately upon incubation at high r.h. The effect of wounds and the relatively low requirement of hours of incubation at high r.h. suggest the need for careful management and handling of plants when temperatures range between 15 and 25°C, and particularly within 15 and 20°C. All operations carried out, particularly at transplant and immediately after, should avoid the creation of wounds.  相似文献   

18.
Rapeseed (Brassica napus) production in Australia relies heavily on triazine-or glyphosate-tolerant cultivars. For 14 triazine-tolerant cultivars, disease development of Neopseudocercosporella capsellae (white leaf spot), Alternaria brassicae and A. japonica (Alternaria leaf spot), and Hyaloperonospora brassicae (downy mildew) were all dependent upon herbicide application timing (p < 0.001), with significant differences between cultivars (p < 0.001) and a significant interaction (p < 0.001) between herbicide application timing and cultivars. Atrazine applied preinfection by N. capsellae, A. brassicae, or A. japonica enhanced disease incidence, severity, and leaf collapse, while atrazine application postinfection for these same pathogens reduced all three disease parameters. However, for H. brassicae, application of atrazine after, and especially prior to, infection resulted in lower disease incidence, severity, and leaf collapse. Application of glyphosate on five glyphosate-tolerant cultivars for N. capsellae resulted in significant differences (p < 0.05) between glyphosate application treatments, and between host cultivars in terms of incidence and consequent leaf collapse. For A. brassicae, A. japonica, and H. brassicae, glyphosate resulted in significant differences (p < 0.001) across application timings between cultivars, and a significant interaction (p < 0.001) between herbicide application timings and cultivars. Glyphosate applied on glyphosate-resistant rapeseed after, and especially prior to, attack by H. brassicae, reduced downy mildew. These are the first studies to highlight how the timing of application of triazine or glyphosate in relation to pathogen infection is critical to the susceptibility of rapeseed to white leaf spot, Alternaria leaf spot, and downy mildew. This new understanding offers fresh possibilities for improved management of these diseases in herbicide-tolerant rapeseed crops.  相似文献   

19.
Brown leaf spot disease caused by Cylindrocladium was found on Howea belmoreana on Hachijojima Island, Tokyo, Japan, in December 2001. Typical symptoms were incited after artificial inoculation. A culture of white mycelia, isolated from leaf spot symptoms, produced reddish perithecia of a nectriaceous fungus. Based on morphological and molecular analyses, this fungus was identified as Calonectria ilicicola (anamorph: Cylindrocladium parasiticum). Pathogenicity of this fungus on five plants cultivated on Hachijojima Island was confirmed by artificial inoculation. This report is the first on Cylindrocladium brown leaf spot of H. belmoreana caused by C. ilicicola (anamorph: Cy. parasiticum).  相似文献   

20.
A new disease was found in Japan, on celery (Apium graveolens var. dulce) having severe chlorotic leaf spot, stunt, and dwarf with leaf curl. A spore suspension from the fungus isolated from affected plants induced identical symptoms 14 days after plants were sprayed. Identification and molecular characterization showed that the causal agent is Colletotrichum simmondsii. This report is the first of stunt anthracnose on celery caused by C. simmondsii. We propose the name “stunt anthracnose” for the new disease. Colletotrichum acutatum sensu lato, as reference pathogen of celery anthracnose, should be changed to C. fioriniae based on morphological and molecular characteristics.  相似文献   

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