Search

Leaf mould caused by Fulvia fulva is a major disease of tomato in Japan. Resistance to several types of fungicides, including succinate dehydrogenase inhibitors (SDHIs), has been reported in isolates from Japan. In this study, we evaluated the sensitivity of F. fulva to SDHI fungicides, SDHI fungicide efficacy in controlling sensitive and resistant isolates, and the presence of mutations in the Sdh B gene, the target site of SDHI fungicides. The minimum inhibitory concentration (MIC) of six SDHI fungicides, excluding isofetamid, ranged from 0.1 to >100 μg/mL against mycelial growth of 45 F. fulva isolates collected in Nara prefecture, Japan, whereas that of isofetamid ranged from 0.1 to only 10 μg/mL. The peak MIC distribution of fluopyram and isofetamid was 10 μg/mL, that of inpyrfluxam was 100 μg/mL and was >100 μg/mL for the remaining SDHI fungicides. In a greenhouse inoculation experiment, only isofetamid controlled the highly resistant isolates with an MIC of 10 μg/mL and the remaining fungicides had MIC >100 μg/mL. In addition, moderately and highly resistant isolates were controlled by the application of isofetamid 6 h or 7 days before inoculation or 3 days after inoculation. Mutations in the Sdh B gene were not observed among sensitive, moderately resistant and highly resistant isolates, suggesting that mutations in other Sdh genes and/or changes in efflux pump expression were involved. Our results indicate the presence of cross‐resistance and different levels of sensitivity reduction among SDHI fungicides. Isofetamid showed the lowest resistance development among the tested SDHI fungicides and is considered effective in controlling tomato leaf mould. [ABSTRACT FROM AUTHOR]

Ein zunehmendes Problem im ökologischen, aber durch die Reduktion anwendbarer Pflanzenschutzmittel auch vermehrt im konventionellen sowie integrierten, Tomatenanbau ist die Samtfleckenkrankheit, verursacht durch den pilzlichen Erreger Fulvia fulva (syn. Passalora fulva, Cladosporium fulvum). Zur Vermeidung von Schäden durch den Erreger mit zum Teil erheblichen Ertragsausfällen wird der Anbau resistenter Sorten empfohlen. In den vergangenen Jahren wurden die monogen bedingten Resistenzen durch die Anpassung und die Bildung offensichtlich neuer Pathotypen des Erregers immer häufiger durchbrochen. Bislang liegen zum Vorkommen von Patho­typen in Deutschland keine Kenntnisse vor. Das Wissen darüber ist essentiell für eine effektive Züchtungsarbeit an neuen Tomatensorten. Das Julius Kühn-Institut hat zusammen mit dem gemein­nützigen Züchterverein Kultursaat e. V. ein im Bundesprogramm Ökologischer Landbau und andere Formen nachhaltiger Landwirtschaft (BÖLN) gefördertes Projekt konzipiert mit dem Ziel, im Pathosystem Tomate-Fulvia fulva eine neue Züchtungsstrategie zu erproben und neue Resistenzquellen zu erschließen. Ein Teil­bereich der Arbeiten befasste sich mit dem aktuellen Auftreten der Pathotypen von F. fulva in Deutschland. Es wurden diverse Isolate aus Einsendungen in eine Pathogenbank aufgenommen und die Pathotypen mit Hilfe eines Differentialsortimentes Tomate (MATREF) in Klima­kammerversuchen identifiziert. Daraus wurde eine Übersicht über das momentane räumliche Vorkommen der Pathotypen in Deutschland erstellt, die für die Züchtungsarbeit im Projekt richtungsweisend ist sowie für den Anbau in der Praxis wichtige Hinweise gibt.

Tomato leaf mold caused by Fulvia fulva (syn. Passalora fulva, Cladosporium fulvum) is an increasing problem in organically grown plants as well as in conventional and integrated cultivation, due to the reduction of applicable plant protection products. To counter the impacts on yield it is recommended to grow resistant varieties. In recent years, however, the frequency of breakdown of the monogenic resistance of these varieties has increased. To date, there is no knowledge of the occurrence of pathotypes in Germany. Nevertheless, knowledge about pathotypes is essential to conduct effective breeding work on new tomato varieties. Together with the non-profit breeders' association Kultursaat e. V., the Julius Kühn-Institute has designed a project supported by the Federal Programme "Organic Farming and Other Forms of Sustainable Agriculture". The aim of the project was to test a new breeding strategy and to select new sources of resistance. An aspect of the project concerned with the current appearance of patho types of Fulvia fulva in Germany. Various isolates from submissions were entered into a pathogen bank and to a large degree identified in climatic chamber tests using a tomato differential set (MATREF). From these results, an overwiew was created which depicts the spatial occurence of different pathotypes in Germany and contains relevant information for breeding work during the project and growing in practice. [ABSTRACT FROM AUTHOR]

Leaf mold disease caused by Cladosporium fulvum appeared on tomato cultivars carrying the Cf-9 resistance gene in Nara Prefecture, Japan, in 2018. We inoculated a differential set of tomato cultivar with six isolates of the fungus and identified two isolates as race 2.9 and four as 2.4.9. We also sequenced their Avr and mating-type genes. All Avr alleles have been found previously in Japanese populations of C. fulvum, but the genotypes of both races were new, suggesting that these isolates have newly emerged in Nara Prefecture. [ABSTRACT FROM AUTHOR]

In order to develop a environmentally friendly control protocol for managing tomato leaf mold disease in the field, we employed bacteria- and fungi-based commercially available microbial preparations. The field experiment was conducted from April to July in 2010. Average incidence rates tomato leaf mold caused by Fulvia fulva were 13.1% at the two plastic houses located in Jangsung, Jeonnam area. Initially 11 microbial preparations were tested for antifungal activity against F. fulva in vitro. Among them, 7 selected preparations showed to be inhibited the mycelial growth of the fungal pathogen over 50%. Four microbes suppressed disease incidence as much 50% under greenhouse condition. Eventually in the field two microbial products including Bacillus subtilis GB-0365 and B. subtilis KB-401 respectively were showed control value up to 71.8% for four times sprays from 20 days to 70 days after transplanting. Furthermore, the control value of three times spray program demonstrated 79.3%. Efficacy of the three and four spray programs was more effective than that of non-spray control treatment. Our results indicated that adjustment of application method of commercially available microbial preparation could be used to control a target plant disease as an effective and efficient crop protection system for organic farming.

This study has been proved that statistical experimental designs offer efficient and feasible approaches for determination of culture medium and fermentation conditions of Streptomyces lavendulae Xjy. Nutrition and cultural conditions have high influence on the antibiotic production of S. lavendulae Xjy. Soya bean meal, NaCl and ( NH4)2 SO4 were identified as the best ingredients for high antifungal activity of Xjy based on single variable experiments. Using response surface methodology, the best concentrations of medium ingredients were 1.46% soya bean meal, 2.25% NaCl and 1.26% ( NH4)2 SO4. The potential components were reduced from seven to three, and the antibiotic activity was increased by 10%. The optimized conditions for Xjy in a 250-ml Erlenmeyer flask were initial pH 5, medium volume 25 ml/250 ml and inoculation volume 10% at 30°C with 200 rpm by response surface methodology. Validation experiments carried out to check the accuracy of the models indicated that the predicted values agreed with the experimental values. The extension of necrosis lesion of Botryosphaeria dothidea was impeded by the application of Xjy in apple fruit. In tomato plants, Xjy showed the 43.7-51.7% curative and protective effects against Fulvia fulva. The optimal medium not only gave a 20% increase in antifungal activity, but it provided a simpler formulation. The results will set a basis for further study on large-scale fermentation volumes using S. lavendulae Xjy and be useful for the development of more advanced control strategies on plant diseases. [ABSTRACT FROM AUTHOR]

Abstract: The protective, curative and eradicant activity of the strobilurin fungicide trifloxystrobin against Cladosporium fulvum on tomatoes was determined under growth chamber and greenhouse conditions. In growth chamber experiments chlorothalonil applied at 100μgml−1 was used as standard fungicide treatment. Seven-week-old tomato plants, hybrid Alma F1, were inoculated by conidial suspension. Protective treatments were carried out by spraying plants 24, 48 and 96h before inoculation at the doses of 5, 10 and 20μga.i.ml−1. Curative treatments were carried out with the same doses, at the same time intervals after inoculation. Additionally, spray treatments were applied after the appearance of the symptoms to evaluate the anti-sporulant activity of the fungicides tested. Protective treatments of trifloxystrobin applied 24 and 48h before inoculation provided disease control higher than 88% at all the application doses tested, while only the dose of 20μga.i.ml−1 was highly effective when applied 96h before the inoculation of the plants (IOP). The curative treatments were less effective than the protective treatments. Post-inoculation treatments of trifloxystrobin at 10 or 20μgml−1 were efficacious only when applied 24 or 48h after IOP, with limited activity when applied 96h after inoculation. Eradicant treatments of trifloxystrobin provided satisfactory anti-sporulant activity when applied at the dose rate of 20μgml−1. Applications of trifloxystrobin at the rates of 5 or 7.5ga.i.100l−1 of spray solution carried out during a 2-year period (2004–2005), in the greenhouse, demonstrated the validity of the above findings, providing control efficacy values higher >90%. Moreover, during both years of the study, applications of trifloxystrobin either at 5 or 7.5ga.i.100l−1, reduced spore production significantly on diseased tomato leaves. The results of the study showed that trifloxystrobin may play a crucial role as part of an integrated chemical control programme for tomato leaf mould caused by C. fulvum. [Copyright &y& Elsevier]

A procedure for producing high yields and high regeneration frequencies of protoplasts from Fulvia fulva is described. This procedure was devised by systematic trials of various parameters, such as culture age and osmotic support, which are known to affect protoplast yield and regeneration. Mycelium from liquid cultures of 24-48 h, incubated with Novozym 234 in buffered 1.0 M MgSO4, gave the best conditions for protoplast release. Regeneration frequencies up to 50% were obtained with a complete medium containing 0.8 M sucrose for osmotic support. [ABSTRACT FROM AUTHOR]

Auxotrophic and drug resistant mutants have been isolated in five of the seven races of Fulvia fulva (syn. Cladosporium fulvum) following UV mutagenesis. Drug resistant mutants have also been isolated by genetic transformation using vectors conferring resistance to hygromycin B and phleomycin. Protoplasts of complementing auxotrophs or mutants with different drug resistances have been fused to form diploids as demonstrated by growth characteristics and microfluorimetry. Some of the diploid fusion products remained stable but most went on to haploidise spontaneously. Using this technique it is now possible to perform both complementation and linkage analysis in an imperfect fungal plant pathogen. [ABSTRACT FROM AUTHOR]

Leaf mold symptoms were found on tomato varieties carrying the Cf-9 resistance gene against Passalora fulva, the causal agent of leaf mold, in Japan in 2008. Disease symptoms and morphological characteristics of the isolates were similar to those of P. fulva. After inoculating a set of tomato differentials with the isolates, all isolates were identified as race 2.9 of P. fulva, previously unreported. [ABSTRACT FROM AUTHOR]

Leaf mold of tomato was found on cv. Momotaro-fight in 2003 in Ehime Prefecture. The symptoms were marginal indefinite yellowing on the upper leaf surface, and downy, gray to brown sporulation on the lower surface underneath the spots. The symptoms and morphology were the same as seen with Passalora fulva. The fungal isolates were identified as races 2.4, 2.4.11, 4, and 4.11 by inoculation tests. Races 4 and 4.11 have never before been found in Japan. [ABSTRACT FROM AUTHOR]