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M. Gerlagh J.J. Amsing W.M.L. Molhoek A.I. Bosker-van Zessen C.H. Lombaers-van Der Plas J. Köhl 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(4):377-386
In two successive seasons, the effect of treatment of geranium stock plants with the competitive saprophytic fungus Ulocladium atrum as a biocontrol agent against Botrytis cinerea was compared to a fungicide treatment with Euparene M. B. cinerea incidence and severity on the stock plants, B. cinerea spore load in the air around stock plants and death of cuttings due to B. cinerea were scored. B. cinerea incidence and severity were much stronger in the second than the first experiment. This was quantitatively expressed by higher numbers of conidia of B. cinerea monitored in the second than the first year, both on necrotic (a maximum for the control of 27.5 × 106 spores per sample - all necrotic leaves of five plants - in experiment 1 against 86 × 106 in experiment 2) and green leaves, but numbers of conidia of B. cinerea recovered from the air were only slightly different. The death rate of cuttings was moderate in the first and extremely high in the second experiment. For the fungicide treatment, maximum sample values of 7% and 76% of 6-week old cuttings were killed in the first and the second experiment respectively. Treatment with U. atrum was effective in reducing all parameters studied. With the exception of the spore load of B. cinerea in the air and the success of cuttings, the effect of U. atrum varied from as good as the fungicide to half as effective. In the first trial, only Euparene M reduced spore load in the air, in the second trial only U. atrum consistently did so. In the first trial U. atrum reduced death of 4-week old cuttings, though less than fungicide (1.2, 20 and 38% killed with fungicide treatment, U. atrum treatment and control respectively). In the second trial only the fungicide reduced loss of cuttings. The impact of the data on the integration of U. atrum in a control system of B. cinerea in geranium is discussed. 相似文献
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A. Overeem G. J. H. Buisman J. T. P. Derksen F. P. Cuperus L. Molhoek W. Grisnich C. Goemans 《Industrial Crops and Products》1999,10(3):102-165
In the work described, seed oils rich in linolenic acid were used for the synthesis of aliphatic oxiranes. The oils studied were linseed (Linum usitatissimum) oil, Canadian linseed oil and the oil of Lallemantia iberica. The oils contained 54.1, 60.2 and 68.0% of linolenic acid, respectively, and showed high theoretical iodine values of 211, 226 and 236 g/hg. Unsaturations in the oils were used to introduce epoxides by epoxidation with in situ generated peroxyacetic acid. The epoxidized oils, showing high percentages of oxirane oxygen (9.4, 10.0 and 10.7%), were applied as crosslinkers in powder-coating formulations. The major advantage of these types of crosslinkers is that they are neither toxic nor mutagenic, in contrast with the widely applied synthetic triglycidyl isocyanurate (TGIC) crosslinkers. However, two potential problems exist when aliphatic oxiranes are compared with conventional TGIC systems. A decrease in glass transition temperature (Tg) of the powder formulation and a higher degree of yellowing of the coating are often observed. In this paper the effects of using oils containing high linolenic acid contents on the yellowing of the coating and the Tg of the powder, are studied. It appeared that aliphatic oxiranes are suitable as environment-friendly crosslinkers in powder-coating systems. 相似文献
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van Dijk A Molhoek EM Bikker FJ Yu PL Veldhuizen EJ Haagsman HP 《Veterinary microbiology》2011,153(1-2):27-36
The broad-spectrum defense system based on host defense peptides (HDPs) is evolutionary very old and many invertebrates rely on this system for protection from bacterial infections. However, in vertebrates the system remained important in spite of the superposition of a very sophisticated adaptive immune system. The cathelicidins comprise a major group of HDPs in mammals. About six years ago it was first described that cathelicidins are also present in birds. Here we review the properties and biological activities of the recently discovered avian cathelicidins and their potential to be used as a paradigm for the development of anti-infectives. Like the mammalian cathelicidins, avian cathelicidins exert direct antimicrobial activities but can also selectively boost host immune responses by regulation of cytokine production and recruitment of immune cells. In addition, it was found that chicken cathelicidins bind endotoxins and dampen the endotoxin-mediated inflammatory response. Molecular dissection has allowed identification of different structural elements involved in bacterial killing and immunomodulation. These studies have enabled the design of small HDP-based antibiotics with specific functions, i.e. having primarily immunomodulatory or antimicrobial activities. Since the immunomodulatory effects may, to a certain degree, be species-specific, we hypothesize that poultry-specific antibiotics can be developed based on avian cathelicidins. 相似文献
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ABSTRACT The saprophytic fungus Ulocladium atrum was selected for its ability to competitively exclude Botrytis spp. from aboveground necrotic plant tissues which can play a crucial role in the epidemiology of diseases caused by necrotrophic Botrytis spp. Fungal growth in necrotic aboveground tissues can be hampered by fluctuating water availability. Adaptation to these adverse conditions is a key factor for the successful establishment of an antagonist population in this niche. Conidia of U. atrum germinated at water potentials between -1 and -7 MPa on water agar. Germinated conidia survived one to three interruptions of moist incubation by periods at -10 or -42 MPa. The speed of germination was significantly slower with interruption of the moist period as compared with the control, which had continuously moist incubation. However, the maximum germination percentage was the same for conidia incubated with or without interruption of the moist incubation. In bioassays with necrotic cyclamen leaves at -1, -3, and -7 MPa, U. atrum significantly reduced the sporulation of B. cinerea by more than 80%. The results demonstrate that U. atrum tolerates water stress during competitive substrate colonization with B. cinerea. The antagonist is, therefore, an attractive candidate for field applications on aboveground tissues. 相似文献
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Jürgen Köhl Wilma M. L. Molhoek Carin H. van der Plas Nyckle J. Fokkema 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(3):251-259
In this study, the hypothesis was tested that removal of substrate for sporulation ofBotrytis spp. may lead to a retardation of an epidemic if the majority of the inoculum is produced inside the treated crop. Suppression of sporulation ofBotrytis spp. could be an attractive option for biological control ofBotrytis leaf spot in onions. In a field experiment, necrotic leaf tissue was removed to simulate the effect of a biocontrol agent. By this means, the amount of substrate on whichBotrytis spp. sporulates was reduced. In the experiment, the spore load above the onion plots was significantly reduced and the epidemic of onion leaf spot was retarded. At the end of the growing season, the number of leaf lesions in the green leaf area was lower in plots with substrate removal than in control plots (0.6 and 1.1 cm–2, respectively). The results demonstrated that an epidemic of onion leaf spot largely depends on the rate of inoculum production inside a crop. Thus, suppression of sporulation on necrotic leaf tissue is a valid control strategy that could be applied by using sporulation suppressing antagonists. 相似文献
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Jürgen Köhl Carin H. van der Plas Wilma M. L. Molhoek Nyckle J. Fokkema 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(6):627-637
Saprophytic antagonists were evaluated for suppression of sporulation ofBotrytis allii andB. cinerea on artificially killed segments of onion leaves that were pre-inoculated with the pathogens. During incubation of the antagonisttreated leaf segments in moist chambers, periods of leaf wetness and leaf dryness were alternated to simulate conditions in the field. Interruption of humid conditions with dry periods had a differential effect on antagonists.Alternaria alternata, Chaetomium globosum, Ulocladium atrum andU. chartarum suppressed sporulation ofB. allii almost completely under continuously wet conditions, and when the leaf wetness periods were interrupted with drying periods of 9h imposed 16, 40, and 64 h after the antagonists were applied. When leaf wetness was interrupted 16 h after antagonist application, the number of conidia ofB. allii produced cm–2 leaf surface after eight days was under the detection limit of 5.2 × 103 conidia on leaves treated with these antagonists compared to 3.7 × 105 conidia on leaves that were not treated. On the other hand,Gliocladium roseum, G. catenulatum andSesquicillium candelabrum, all highly efficient under continuously wet conditions, were of low to moderate efficiency when leaf wetness periods had been interrupted 16 h after application of the antagonists. The antagonists showed the same differentiation and sensitivity to interrupted wetness periods when tested withB. cinerea. 相似文献
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Jürgen J. Köhl Wilma W. M. L. Molhoek Belia B. H. Groenenboom-de Haas Helen H. M. Goossen-van de Geijn 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(4):401-414
Apple scab caused by Venturia inaequalis is a major disease in apple production. Epidemics in spring are initiated by ascospores produced on overwintering leaves
whereas epidemics during summer are driven by conidia produced on apple leaves by biotrophic mycelium. Fungal colonisers of
sporulating colonies of V. inaequalis were isolated and their potential to reduce the production of conidia of V. inaequalis was evaluated on apple seedlings under controlled conditions. The four most effective isolates of the 63 screened isolates
were tested subsequently under Dutch orchard conditions in 2006. Repeated applications of conidial suspensions of Cladosporium cladosporioides H39 resulted in an average reduction of conidial production by V. inaequalis of approximately 40%. In 2007, applications of conidial suspensions of C. cladosporioides H39 reduced conidial production by V. inaequalis by 69% on August 6 and by 51% on August 16, but no effect was found on August 20. However, viability of available conidia
of C. cladosporioides H39 was low at the end of the experiment. Epiphytic and endophytic colonisation by Cladosporium spp. of leaves treated during the experiment with C. cladosporioides H39 was significantly higher than on control leaves sampled 6 weeks after the last application. It is concluded that C. cladosporioides H39 has promising potential as a biological control agent for apple scab control. More information is needed on the effect
of C. cladosporioides H39 on apple scab epidemics as well as on mass production, formulation and shelf life of conidia of the antagonist. 相似文献
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