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1.
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
2.
ABSTRACT The effect of treatments with conidial suspensions of Ulocladium atrum and Gliocladium roseum on leaf rot of cyclamen caused by Botrytis cinerea was investigated under commercial greenhouse conditions. Spraying U. atrum (1 x 10(6) conidia per ml) or G. roseum (2 x 10(6) conidia per ml and 1 x 10(7) conidia per ml) at intervals of 2 to 3 weeks during the production period and spraying U. atrum (1 x 10(6) conidia per ml) at intervals of 4 to 6 weeks resulted in a significant reduction of natural infections of petioles by B. cinerea. U. atrum or G. roseum (1 x 10(7)conidia per ml) was as effective as the standard fungicide program. B. cinerea colonized senesced leaves within the plant canopy and infected adjacent petioles and leaves later. The antagonists colonized senesced leaves and reduced B. cinerea development on these leaves. Thus, the inoculum potential on petioles adjacent to necrotic leaf tissues was reduced. The fate of U. atrum conidia on surfaces of green cyclamen leaves during a 70-day period after application was studied. The number of conidia per square centimeter of leaf surface remained relatively constant during the entire experiment. Sixty percent of the conidia sampled during the experiments retained the ability to germinate. When green leaves were removed from the plants to induce senescence and subsequently were incubated in a moist chamber, U. atrum colonized the dead leaves. Senesced leaves also were colonized by other naturally occurring fungi including B. cinerea. On leaves treated with U. atrum from all sampling dates, sporulation of B. cinerea was significantly less as compared with the untreated control. Our results indicate that early applications of U. atrum before canopy closure may be sufficient to achieve commercially satisfactory control of Botrytis leaf rot in cyclamen. 相似文献
3.
Kessel GJ de Haas BH Lombaers-van der Plas CH Meijer EM Dewey FM Goudriaan J van der Werf W Köhl J 《Phytopathology》1999,89(10):868-876
ABSTRACT A technique was developed to localize and quantify the internal mycelial colonization of necrotic leaf tissue of cyclamen (Cyclamen persicum) or lily (Lilium) by pathogenic Botrytis spp. and the antagonist Ulocladium atrum. This technique allows investigation of competitive substrate colonization by both fungi, which is a key process for biological control of Botrytis spp. by U. atrum. A combination of differential fluorescent labeling and image analysis was applied on cryostat sections of necrotic leaf tissue. Botrytis mycelium was labeled specifically by indirect immunofluorescence using a monoclonal antibody specific for Botrytis spp. And an antimouse fluorescein conjugate. Wheat germ agglutinin conjugated to the fluorochrome TRITC was used to label mycelium of both fungi. Image analysis was used to measure the relative surface area of the cryostat section covered by fluorescing hyphae of Botrytis spp. and by fluorescing hyphae of both fungi. A mathematical conversion was derived and used to calculate the relative mycelial volume of each fungal species in the necrotic tissue based on the measured relative surface areas. Temporal aspects of substrate colonization were studied in a short time series. An analysis of components of variance provided insight into spatial colonization patterns for the fungal species involved and allowed the design of efficient sampling strategies for future experiments. 相似文献
4.
ABSTRACT A spatially explicit model describing saprophytic colonization of dead cyclamen leaf tissue by the plant-pathogenic fungus Botrytis cinerea and the saprophytic fungal antagonist Ulocladium atrum was constructed. Both fungi explore the leaf and utilize the resources it provides. Leaf tissue is represented by a two-dimensional grid of square grid cells. Fungal competition within grid cells is modeled using Lotka-Volterra equations. Spatial expansion into neighboring grid cells is assumed proportional to the mycelial density gradient between donor and receptor cell. Established fungal biomass is immobile. Radial growth rates of B. cinerea and U. atrum in dead cyclamen leaf tissue were measured to determine parameters describing the spatial dynamics of the fungi. At temperatures from 5 to 25 degrees C, B. cinerea colonies expanded twice as rapidly as U. atrum colonies. In practical biological control, the slower colonization of space by U. atrum thus needs to be compensated by a sufficiently dense and even distribution of conidia on the leaf. Simulation results confirm the importance of spatial expansion to the outcome of the competitive interaction between B. cinerea and U. atrum at leaf scale. A sensitivity analysis further emphasized the importance of a uniform high density cover of vital U. atrum conidia on target leaves. 相似文献
5.
ABSTRACT Ulocladium atrum (strain 385) consistently reduced Botrytis cinerea sporulation on necrotic fragments of strawberry leaves. On these tissues, two strains of U. atrum (isolates 18558 and 18559) showed lower antagonistic activities than the reference strain 385. Colonization of strawberry leaflets by the three U. atrum strains appeared similar in the absence of B. cinerea, whether quantified by chitin or immunological assays. The second method (based on anti-U. atrum antibodies) revealed that strawberry leaflet colonization by U. atrum 385 was better than by the other U. atrum strains in the presence of B. cinerea. An immunoassay using anti-B. cinerea antibodies revealed that the colonization of B. cinerea in tissues was lower in the presence of U. atrum 385 than with the two other U. atrum strains. The enzymatic activities produced by U. atrum 385 during the colonization phases of necrotic tissues were compared to B. cinerea and U. atrum strains 18558 and 18559. U. atrum 385 had the highest lipase, pectate lyase, and cellobiase activities while B. cinerea had the highest endo-beta-1,4-glucanase activity. The study of lytic activities hydrolyzing the fungal cell wall revealed higher beta-1,3-glucanase activity with U. atrum 385, which was stimulated by B. cinerea on necrotic strawberry leaflets. These results suggest that plant and fungal cell wall-degrading enzymes produced by U. atrum 385 may play a complementary role in the competitive colonization of dead strawberry leaves against B. cinerea. 相似文献
6.
ABSTRACT The colonization of dead onion leaves by Botrytis aclada and the fungal antagonists Aureobasidium pullulans, Chaetomium globosum, Glio-cladium catenulatum, and Ulocladium atrum and the interactions between B. aclada and each of the four antagonists were studied at the microscopic and ultrastructural level. This approach was used in an attempt to understand the colonization pattern of these fungi and the nature of the biocontrol activity of the antagonists that have shown a potential to suppress spore production of Botrytis spp. on necrotic plant tissues. When applied alone, B. aclada and U. atrum were found throughout the leaf tissues in high densities after an incubation period of 6 days at 18 degrees C in a moist chamber. C. globosum and G. catenulatum colonized only the outer portions of the leaf, whereas A. pullulans appeared to be concentrated in the leaf stomata. When pathogen and antagonists were applied together, ultrastructural observations revealed that cells of B. aclada were plasmolyzed in the presence of G. catenulatum, suggesting a reaction to antifungal molecules. Antibiosis also seemed to be involved, albeit to a lesser extent, in the antagonistic interactions between B. aclada and A. pullulans or C. globosum. No evidence of direct parasitism was recorded. On the other hand, U. atrum appeared to completely exclude B. aclada from dead onion tissues when both fungi competed for the substrate. Ultrastructural observations of the in vitro interaction between the two fungi did not reveal parasitism or antibiosis by either fungus. Based on previous records of its biocontrol potential and observations of its colonizing properties, it appears that U. atrum can compete for and utilize necrotic tissues rapidly and extensively, thus, excluding competitors without any other antagonistic action. 相似文献
7.
ABSTRACT The effect of preliminary nutrient activation on the ability of conidia of the antagonist Trichoderma harzianum (atroviride) P1 to suppress Botrytis cinerea was investigated in laboratory, greenhouse, and field trials. Preliminary nutrient activation at 21 degrees C accelerated subsequent germination of the antagonist at temperatures from 9 to 21 degrees C; at >/=18 degrees C, the germination time of preactivated T. harzianum P1 conidia did not differ significantly from that of B. cinerea. When coinoculated with B. cinerea, concentrated inocula of preactivated but ungerminated T. harzianum P1 conidia reduced in vitro germination of the pathogen by >/=87% at 12 to 25 degrees C; initially quiescent conidia achieved this level of suppression only at 25 degrees C. Application of quiescent T. harzianum P1 conidia to detached strawberry flowers in moist chambers reduced infection by B. cinerea by >/=85% at 24 degrees C, but only by 35% at 12 degrees C. Preactivated conidia reduced infection by >/=60% at 12 degrees C. Both quiescent and preactivated conidia significantly reduced latent infection in greenhouse-grown strawberries at a mean temperature of 19 degrees C, whereas only preactivated conidia were effective in the field at a mean temperature of 14 degrees C on the day of treatment application. An antagonistic mechanism based on initiation of germination in sufficiently concentrated inocula suggests that at suboptimal temperatures the efficacy of Trichoderma antagonists might be improved by conidia activation prior to application. 相似文献
8.
G.J.T. Kessel B.H. de Haas C.H. Lombaers-van der Plas J.E. van den Ende M.G. Pennock-Vos W. van der Werf J. Köhl 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(3):273-284
Biological control of Botrytis spp. by the fungal antagonist Ulocladium atrum is based on their interaction in plant tissue. U. atrum is effective against B. cinerea in commercial cyclamen crops but not effective against B. elliptica in lily crops. Based on the necrotrophic nature of the Botrytis spp. and the saprophytic nature of U. atrum it is hypothesised, and experimentally confirmed, that the interaction between Botrytis spp. and U. atrum, resulting in a biocontrol effect, only takes place in necrotic plant tissue. The role of necrotic tissue in the epidemiology of B. cinerea in cyclamen and B. elliptica in lily was found to be different. Removal of symptomless senescing leaves resulted in a significant reduction of the area under the disease severity progress curve (AUDPC) for B. cinerea in cyclamen but had no effect on the disease severity in lily. U. atrum applications significantly reduced B. cinerea AUDPC values in cyclamen but were less efficient than the removal of senescing leaves. In lily, disease severity was not affected by applications of U. atrum. It is concluded that necrotic cyclamen tissue, not killed by B. cinerea, plays an important role in the onset of disease. Colonisation of this tissue by U. atrum prevents saprophytic colonisation of those leaves by B. cinerea. In contrast, conidia of B. elliptica directly infect healthy lily leaf tissue. U. atrum applications aimed at blocking the infection pathway from a saprophytic base are therefore not effective against B. elliptica. Control options based on competitive interactions in and around B. elliptica lesions resulted in a reduced production of conidia by B. elliptica but proved ineffective against disease development. The potential of U. atrum as a biocontrol agent against Botrytis spp. and possibly against other necrotrophs appears to be determined by the competitive saprophytic ability of the antagonist in mutual substrates of pathogen and antagonist and by the role of these substrates in disease epidemiology. 相似文献
9.
J. Salinas D. C. M. Glandorf F. D. Picavet K. Verhoeff 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(1):51-64
In recent years, spotting of ray florets of gerbera flowers has become an important problem. This type of small necrotic lesions may occur before, but especially shortly after harvesting the flowers.Botrytis cinerea was easily isolated from such lesions. Inoculation withB. cinerea only gave typical necrotic lesions, when dry conidia were dusted on the flowers with a short period of high rh after inoculation. At 18–25 °C a high rh for at least 5 hours was necessary. Rotting of ray florets and receptacles byB. cinerea occurred when inoculated flowers were kept wet for a few days. Spots consist of one to several necrotic, usually epidermal cells. A single conidium could give rise to a necrotic lesion after germination. Germination of conidia and lesion formation occurred between 4 and 25 °C; at 30 °C, germination and lesion formation did not occur. Between 18 and 25 °C, many lesions became visible within 1 day after inoculation; at 4 °C it took 2 to 3 days before lesions could be seen. If kept dry, conidia ofB. cinerea remained ungerminated on ray florets of gerbera flowers and could be removed from the ray florets. Within 1 day at high rh, germination occurred and lesions were produced. Conidia ofB. cinerea, stored dry, were able to survive much longer than the lifetime of a gerbera flower. Even after storage at room temperature for up to 14 months, some conidia were able to germinate in vitro and on ray florets and induce the formation of lesions. Addition of gerbera pollen diffusate stimulated germination and lesion formation. 相似文献
10.
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
11.
The mode of action of soluble silicon against strawberry powdery mildew (Sphaerotheca aphanis var. aphanis) was investigated in four experiments. First, silicon-treated leaves from plants grown with silicate (Si+) and control leaves
were excised, inoculated with conidia, and subsequent germination and formation of appressoria in a petri dish was assessed
after 24 h. The germination rate was 49.7% on Si+ leaves, and was 67.2% on control leaves (t-test, P < 0.01). Second, we soaked cellulose membranes in various solvents and then placed the membranes on 4% water agar, dusted
the membranes with conidia, and examined after 12 h. No difference was apparent between any treatment and the control (distilled
water). Third, strawberries growing hydroponically with additional silicon in the medium were inoculated with conidia, and
leaves were observed with a scanning electron microscope 1–2 days after inoculation. Germ tubes and secondary hyphae were
shorter and had fewer branches on Si+ leaves than on the control. Moreover, penetration appeared to be inhibited. Fourth,
the cuticle was separated from leaves from plants grown as in the third experiment, placed on water agar, and dusted with
conidia. Germination of conidia, observed with a light microscope, on Si+ leaves was suppressed markedly to 40%–60% of that
of the control. These results suggested that soluble silicon induced physiological changes in the cuticle layer after absorption
by the plant. In addition, soluble silicate reduced germination of conidia, formation of appressoria, and possibly the penetration
of powdery mildew. 相似文献
12.
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
13.
Bailey BA Apel-Birkhold PC Akingbe OO Ryan JL O'Neill NR Anderson JD 《Phytopathology》2000,90(8):812-818
ABSTRACT The fungus Pleospora papaveracea and Nep1, a phytotoxic protein from Fusarium oxysporum, were evaluated for their biocontrol potential on opium poppy (Papaver somniferum). Four treatments consisting of a control, P. papaveracea conidia, Nep1 (5 mug/ml), and P. papaveracea conidia plus Nep1 (5 mug/ml) were used in detached-leaf and whole-plant studies. Conidia of P. papaveracea remained viable for 38 days when stored at 20 or 4 degrees C. Nep1 was stable in the presence of conidia for 38 days when stored at 4 degrees C or for 28 days at 20 degrees C. The presence of Nep1 did not affect conidia germination or appressoria formation. Nep1 was recovered from drops applied to opium poppy leaves in greenhouse and field studies 24 h after treatment. Opium poppy treated with the combination of Nep1 and P. papaveracea had higher necrosis ratings than the other treatments. There were changes in the intercellular protein profiles, determined by sodium dodecyl sulfate gel electrophoresis and silver staining, due to application of treatments; the most intense occurred in response to the combination of Nep1 and P. papaveracea. The combination of Nep1 and P. papaveracea enhanced the damage caused to opium poppy more than either component alone. 相似文献
14.
ABSTRACT Trichoderma biocontrol isolates are most effective as highly concentrated inocula. Their antagonism to other fungi may be a result of pregermination respiration. In a nutrient-rich medium, almost all Trichoderma atroviride P1 (P1) conidia initiated germination processes and increased respiration, even in dense suspensions. When 1 x 10(7) P1 conidia/ml were coinoculated with 1 x 10(5) Botrytis cinerea conidia/ml, dissolved oxygen fell to <1% within 2 h and the pathogen failed to germinate. More dilute P1 suspensions consumed oxygen slowly enough to allow coinoculated B. cinerea to germinate. On nutrient-poor media, fewer P1 conidia initiated germination. Oxygen consumption by the inoculum and inhibition of B. cinerea were enhanced when P1 conidia were nutrient activated before inoculation. Pregermination respiration also affected competitive capacity of the antagonist on solid substrates, where respiratory CO(2) stimulated germination rate and initial colony growth. These parameters were directly correlated with inoculum concentration (R(2) >/= 0.97, P < 0.01). After initiating germination, Trichoderma conidia became more sensitive to desiccation and were killed by drying after only 2 h of incubation on a nutrient-rich substrate at 23 degrees C. These results indicate that nutrient-induced changes preceding germination in Trichoderma conidia can either enhance or decrease their biological control potential, depending on environmental conditions in the microhabitat. 相似文献
15.
Experiments were conducted to determine the effects of temperature, relative humidity (RH) and duration of wetness period on in vitro germination of conidia and infection of detached pear leaves by Venturia nashicola , the causal agent of pear scab. Conidia germinated only in near-saturation humidity (RH > 97%). The final percentage germination (24 h after inoculation) at 100% RH without free water was less than half that in free water. Conidia germinated over the range of temperatures tested (5–30°C); the optimum temperature for germination was ≈21°C. Changes in percentage germination of conidia over time were fitted by logistic models at each individual temperature. Polynomial models satisfactorily described the relationships between two (rate and time to 50% of maximum germination) of the three logistic model parameters and temperature. The minimum length of the wetness period for successful infection of detached pear leaves by conidia was observed at several temperatures. The shortest length of wetness period required for infection was 7 h at 22°C. Two polynomial models fitted well the relationship between the minimum wetness duration required for infection, and temperature. 相似文献
16.
Pedro Boff Pieter Kastelein Joop de Kraker Matthijs Gerlagh Jürgen Köhl 《European journal of plant pathology / European Foundation for Plant Pathology》2001,107(6):615-624
The epidemiology of Botrytis cinerea was studied in five annual strawberry crops using waiting-bed transplants, a system widely adopted in the Netherlands. On dead leaves of transplants the incidence of B. cinerea varied from 26.7% to 52.6%, but the leaf area with potential sporulation was low (3.5–15.6%). During each crop cycle, the availability of necrotic leaf substrate for spore production of B. cinerea was generally low and varied between seasons and with the quality of transplants. B. cinerea sporulated on a maximum of 15.5 cm2 of leaf area per plant, measured as potential sporulation. The aerial concentration of B. cinerea conidia in untreated plots did not differ from the concentration in plots where all dead leaves had been removed, nor from the concentration at 25–50 m distance from the strawberry plots. B. cinerea incidence on flowers ranged from 5% to 96%, but no correlation was found with the potential spore production on necrotic leaves. Grey mould at harvest varied from 1.4% to 11.3% and was correlated with the average precipitation during the harvesting period but not with B. cinerea incidence on flowers. Post-harvest grey mould ranged from 2.1% to 32.6% and was correlated with petal colonisation by B. cinerea. The results suggest that in the annual cropping system with waiting-bed transplants, necrotic leaves are not a significant source of B. cinerea inoculum, unlike in other strawberry production systems. Therefore, control measures of grey mould in this annual system should focus on protection of flowers and young developing fruits, and not on the reduction of inoculum production on leaf debris. 相似文献
17.
稻曲病菌分生孢子的生物学研究 总被引：47，自引：5，他引：47
本文对稻曲病菌分生孢子的一些生物学特性进行了研究,结果表明,基质养分对分生孢子萌发影响较大,纯水不利于孢子萌发,PSA最适于孢子萌发,葡萄糖则强烈抑制孢子萌发,马铃薯煮汁既可抵消葡萄糖的抑制作用,又可刺激孢子萌发。分生孢子在琼脂面上比在液滴中萌发率高。分生孢子萌发的适宜温度为22~31℃,以28℃最好。分生孢子萌发对pH值敏感,以pH 6~7最适宜。用振荡培养法获取分生孢子,培养10 d后,孢子的萌发力开始下降。分生孢子的存活对水的依赖性强,在水中保存8 d萌发力不变,在100% RH中8 d萌发力略有降低,而在25% RH中5 h萌发力即迅速下降。根据这些特性,作者对分生孢子在田间的动态作了一些推测。 相似文献
18.
The effect of microclimate variables on development ofClonostachys rosea and biocontrol ofBotrytis cinerea was investigated on rose leaves and crop residues. C.rosea established and sporulated abundantly on inoculated leaflets incubated for 7–35 days at 10°, 20° and 30°C and then placed
on paraquat—chloramphenical agar (PCA) for 15 days at 20°C. On leaflets kept at 10°C, the sporulation after incubation on
PCA increased from 60% to 93% on samples taken 7 to 21 days after inoculation, but decreased to 45% on material sampled after
35 days. A similar pattern was observed on leaves incubated at either 20° or 30°C. The sporulation ofC. rosea on leaf disks on PCA was not affected when the onset of high humidity occurred 0, 4, 8, 12 or 16 h after inoculation. However,
sporulation was reduced to 54–58% on leaflets kept for 20–24 h under dry conditions after inoculation and before being placed
on PCA. The fungus sporulated on 68–74% of the surface of leaf disks kept for up to 24 h at high humidity after inoculation,
but decreased to 40–51% if the high humidity period before transferral to PCA was prolonged to 36–48 h. The growth ofC. rosea on leaflets was reduced at low inoculum concentrations (103 and 104 conidia/ml) because of competition with indigenous microorganisms, but at higher concentrations (105 and 106 conidia/ml) the indigenous fungi were inhibited. Regardless of the time of application ofC. rosea in relation toB. cinerea, the pathogen’s sporulation was reduced by more than 99%. The antagonist was able to parasitize hyphae and conidiophores
ofB. cinerea in the leaf residues. AsC. rosea exhibited flexibility in association with rose leaves under a wide range of microclimatic conditions, and in reducingB. cinerea sporulation on rose leaves and residues, it can be expected to suppress the pathogen effectively in rose production systems. 相似文献
19.
During March and April of 1993 and 1994, surveys on the incidence and severity of cashew powdery mildew ( Oidium anacardii ) were conducted in the Newala, Mtwara, Nachingwea and Tunduru areas of southern Tanzania to determine the variation in perennation between localities. Only immature cashew shoots, panicles and fruit can be infected by O. anacardii conidia. Cashew trees at sites in each district were assessed for shoot and panicle production and cashew powdery mildew. Survival of O. anacardii between seasons, in any area, was determined by the degree of production of shoots that were within the canopy and by the incidence of infection. Immature shoots produced from the main branches within the tree canopy were the main source of active powdery mildew in all districts; trees in the Newala district had the highest numbers of infected immature shoots in comparison with survey sites in the other areas. During the 1994 cashew-growing season (June–August), powdery mildew developed more rapidly and affected more shoots on the inside of the tree canopy than on the outside. Germination of conidia was reduced after aqueous suspension for 3 h. Germination on cashew leaves submerged under 2 mm of water was not affected. Appressorial and hyphal formation by germinating conidia on leaves decreased with increasing duration under water. Germination of conidia on glass slides at 100% r.h. was higher at 25 and 30°C than at 15°C and there was no germination at 35°C. 相似文献
20.
U. Ma&#;olepsza† 《Plant pathology》2005,54(3):317-324
Pretreatment of detached tomato leaves with o -hydroxyethylorutin reduced the percentage leaf area affected, and delayed the appearance of necrosis, following inoculation with conidial suspensions in droplets of the grey mould fungus Botrytis cinerea . o -Hydroxyethylorutin delayed, but did not inhibit, in vitro germination of conidia, although overall percentage germination was reduced compared with water controls. Both the reactive oxygen species (ROS) – superoxide anions and hydrogen peroxide – increased twice as much in o -hydroxyethylorutin-treated leaf tissue 2 and 6 h postinoculation with B. cinerea conidia in tissues under inoculation drops, as well as in surrounding tissues, whereas in plants not pretreated with the compound ROS generation was noticed later, and only in tissues under inoculation drops. Compared with these compounds, changes in the levels of hydroxyl radicals, lipid peroxidation and the activity of the enzymes superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and catalase were largely unchanged. In stimulating ROS in inoculated tomato tissue, B. cinerea appeared to be affected directly pre- and postinfection, but indirect effects increasing host resistance cannot be excluded. 相似文献