Complete Inhibition Of Spore Germination Research Articles

Combined effects of food additives and heat treatment on fruit rot disease and quality of harvested dragon fruit

The effects of food additives (sodium carbonate, SC and potassium sorbate, PS) at 0%, 1%, 2%, 3% and 4% weight per volume on fungal spore germination of dragon fruit rot diseases, Colletotrichum gloeosporioides, C. capsici and Fusarium sp. were investigated on media. PS at all concentrations showed complete inhibition of spore germination in the three fungi. SC 2% inhibited the germination of C. gloeosporioides by 100% while SC 3% completely inhibited the germination of C. capsici and Fusarium sp. PS solution was selected to study its combined effects with hot water treatment on fruit rot disease and quality of dragon fruit artificially inoculated with C. gloeosporioides. The fruit samples were treated in a heated (55 °C) solution of 1% PS for 5 min and then cooled in tap water at 10 °C (PS-55 °C + cold H2O). Non-treated fruit and fruit treated with the fungicide carbendazim were used as controls. All samples were assessed after being kept at 13 °C for 15 d. The treatment of PS-55 °C + cold H2O reduced the severity of diseases and helped to delay chlorophyll degradation in the dragon fruit bracts, had little impact on the respiration rate, delayed ethylene production and maintained the total ascorbic acid content. However, PS-55 °C + cold H2O treatment, while having little initial effect, did reduce fruit firmness after 15 d of storage. The PS-55 °C + cold H2O treatment did not affect weight loss or the total soluble solids concentration. These findings showed that the PS-55 °C + cold H2O treatment could act as a safe alternative method for suppressing fruit rot disease while maintaining the quality of dragon fruit during cold storage.

Trichoderma species associated with green mould disease of Pleurotus ostreatus and their sensitivity to prochloraz

Green mould disease causes serious economic losses in Pleurotus ostreatus crops worldwide, including in Italy, where prochloraz is the only chemical fungicide allowed to control the disease. The effectiveness of the doses 0.01, 0.05, 0.25 and 1.25 μL L−1 (field dose) of prochloraz (Sponix Flow, 450 g L−1), against colony growth rate and spore germination of Trichoderma pleuroti, T. pleuroticola and T. guizhouense strains on wheat straw extract agar plates were evaluated. Complete inhibition of Trichoderma pleuroti and T. pleuroticola growth was shown by the field dose of prochloraz, and also by the 0.25 μL L−1 dose for T. pleuroti. Complete inhibition of spore germination occurred for all Trichoderma strains at field dose, and at 0.25 μL L−1 for T. pleuroti strains. In in vivo assays, the effect of prochloraz doses 0.05, 0.25 and 1.25 μL L−1 on colonization of straw substrate by T. pleuroti, T. pleuroticola and T. guizhouense inoculated at two spore densities (102 and 105 spores mL−1) immediately after P. ostreatus spawn was studied. Trichoderma pleuroti and T. pleuroticola were both responsible for green mould disease, whereas T. guizhouense was not pathogenic. Trichoderma pleuroti was more aggressive than T. pleuroticola. Prochloraz was effective against T. pleuroti at the field dose, and against T. pleuroticola at 0.25 and 1.25 μL L−1. The study on Trichoderma × Pleurotus interaction type showed that Trichoderma species were active against the mycelial growth of P. ostreatus by competition for space and nutrients, and neither hyphal interaction nor effect by volatile or nonvolatile metabolites occurred.

Use of inductors in the control of Colletotrichum gloeosporioides and Rhizopus stolonifer isolated from soursop fruits: in vitro tests.

Soursop (Annona muricata) is a tropical fruit that can be infected by Colletotrichum gloeosporioides and Rhizopus stolonifer. Traditional methods used for postharvest disease control include the application of fungicides, however due to their excessive use, as well as their persistence in the environment, the development of new strategies that control pathogens are required. The application of chitosan (Chi), salicylic acid (SA) and methyl jasmonate (MJ) is an environmentally-friendly alternative with antimicrobial properties and also induces defense mechanisms in plant tissues. In this study, Colletotrichum was reactivated and Rhizopus was identified using morphological features and molecular tools. In vitro, the application of 0.5 and 1.0% of Chi alone or in combination with SA and MJ decreased mycelial growth and sporulation, a complete inhibition of spore germination was obtained. Thus, the application of Chi in combination with SA and MJ could be a smart strategy to inhibit the development of pathogens that attack soursop fruit.

Chlorogenic acid is a fungicide active against phytopathogenic fungi

Plants synthesize diverse types of secondary metabolites and some of them participate in plant protection against pathogen attack. These compounds are biodegradable and renewable alternatives, which may be envisaged for the control of plant pests and diseases. Chlorogenic acid (CGA) is a phenolic secondary metabolite which accumulates in diverse plant tissues and can be found in several agro-industrial by-products and waste. The aim of this work was to determine whether CGA could control the growth of various plant pathogenic fungi, gaining insight into its mechanism of action. Microscopic analysis showed the complete inhibition of spore germination or reduction of mycelial growth for Sclerotinia sclerotiorum, Fusarium solani, Verticillium dahliae, Botrytis cinerea and Cercospora sojina. CGA concentrations that did not completely abolish spore germination were able to produce a partial inhibition of mycelial growth. Viability tests and vital dye staining demonstrate that CGA induces fungal cell lysis. Its fungicidal activity involves an early membrane permeabilization of the spores. These results show the antifungal activity of CGA against phytopathogenic fungi relevant in horticulture and agriculture highlighting the potential of CGA-enriched wastes and by-products to be used as biofungicides.

Synthesis and Biological Evaluation of Bile Acid Analogues Inhibitory to Clostridium difficile Spore Germination.

Standard antibiotic-based strategies for the treatment of Clostridium difficile infections disrupt indigenous microbiota and commonly fail to eradicate bacterial spores, two key factors that allow recurrence of infection. As an alternative approach to controlling C. difficile infection, a series of bile acid derivatives have been prepared that inhibit taurocholate-induced spore germination. These analogues have been evaluated in a highly virulent NAP1 strain using optical density and phase-contrast microscopy assays. Heterocycle substitutions at C24 were well-tolerated and several tetrazole-containing derivatives were highly potent inhibitors in both assays, with complete inhibition of spore germination observed at 10-25 μM. To limit intestinal absorption, C7-sulfated analogues designed to avoid active and passive transport pathways were prepared. One of these derivatives, compound 21b, was found to be a potent inhibitor of C. difficile spore germination and poorly permeable in a Caco-2 model of intestinal epithelial absorption, suggesting that it is likely to be gut-restricted.

Inhibitory effect of gamma irradiation and its application for control of postharvest green mold decay of Satsuma mandarins

Gamma irradiation has been shown to be effective for the control of postharvest fungi in vitro, but little is known regarding antifungal action, responses to gamma irradiation, and its application to fresh produce. Gamma irradiation was evaluated for its in vitro and in vivo antifungal activity against Penicillium digitatum on Satsuma mandarin fruits. Green mold was inhibited in a dose-dependent manner. Gamma irradiation showed a complete inhibition of spore germination, germ tube elongation, and mycelial growth of P. digitatum, particularly at 1.0kGy. To further investigate the mechanisms by which gamma irradiation inhibits fungal growth, the membrane integrity and cellular leakage of conidia were tested, indicating that gamma irradiation results in the loss of plasma membrane integrity, causing the release of intracellular contents such as soluble proteins. In vivo assays demonstrated that established doses can completely inhibit the growth of fungal pathogens, but such high doses cause severe fruit damage. Thus, to eliminate the negative impact on fruit quality, gamma irradiation at lower doses was evaluated for inhibition of P. digitatum, in combination with a chlorine donor, sodium dichloro-s-triazinetrione (NaDCC). Interestingly, only a combined treatment with 0.4kGy of gamma irradiation and 10ppm of NaDCC exhibited significant synergistic antifungal activity against green mold decay. The mechanisms by which the combined treatment decreased the green mold decay of mandarin fruits can be directly associated with the disruption of cell membrane of the fungal pathogen, which resulted in a loss of cytoplasmic material from the hyphae. These findings suggest that a synergistic effect of combining treatment with gamma irradiation with NaDCC has potential as an antifungal approach to reduce the severity of green mold in mandarin fruits.

Antifungal effect of gamma irradiation and sodium dichloroisocyanurate against Penicillium expansum on pears

Gamma irradiation (GI) was evaluated for its in vitro and in vivo antifungal activity against Penicillium expansum on pear fruits. GI showed a complete inhibition of spore germination, germ tube elongation and mycelial of P. expansum, especially 1·8 kGy. GI affected the membrane integrity and cellular leakage of conidia in a dose-dependent manner. Furthermore, the leakage of protein and sugar from mycelia increased along with the dose. GI was evaluated at lower doses in combination with a chlorine donor, sodium dichloro-s-triazinetrione (NaDCC), to examine the inhibition of P. expansum. Interestingly, only a combined treatment with 0·2 kGy of GI and 70 ppm of NaDCC exhibited significant synergistic antifungal activity. The mechanisms by which the combined treatment decreased the blue mould decay of pear fruits could directly associated with the disruption of the cell membrane of the fungal pathogen, resulting in a loss of cytoplasmic materials from the hyphae. Gamma irradiation (GI) is used as an effective nonchemical approach to inactive pathogens. This study investigated the antifungal effect of gamma irradiation and its combined treatment with a chlorine donor on this fungal pathogen, both in vitro and in vivo. This study emphasized that the integration of low-dose GI and a chlorine donor, NaDCC, exhibited a significant antifungal effect, and that its mechanisms are directly associated with membrane integrity of fungal spores, promising that GI has the potential to be an antifungal approach.

Effect of gamma irradiation and its convergent treatment for control of postharvest Botrytis cinerea of cut roses

Postharvest diseases cause considerable losses to harvested crops. Among them, gray mold (Botrytis cinerea) is a major problem of exporting to cut rose flowers into Korea. Irradiation treatment is an alternative to phytosanitary purposes and a useful nonchemical approach to the control of postharvest diseases. Gamma irradiation was evaluated for its in vitro and in vivo antifungal activity against B. cinerea on cut rose varieties, ‘Shooting Star’ and ‘Babe’. The irradiating dose required to reduce the population by 90%, D10, was 0.99 kGy. Gamma irradiation showed complete inhibition of spore germination and mycelial growth of B. cinerea, especially 4.0 kGy in vitro. Antifungal activity of gamma irradiation on rose B. cinerea is a dose-dependent manner. A significant phytotoxicity such as bent neck in cut rose quality was shown from gamma irradiation at over 0.4 kGy (p<0.05) in both varieties. Although there is no significant difference in both varieties for fresh weight, in the case of flower rate, ‘Babe’ shows more sensitivity than ‘Shooting Star’. In vivo assays demonstrated that established doses in in vitro, over 4 kGy, could completely inactive fungal pathogens, but such high doses can cause severe flowers damage. Thus, to eliminate negative impact on their quality, gamma irradiation was evaluated at lower doses in combination with an eco-friendly chemical, sodium dichloroisocyanurate (NaDCC) to examine the inhibition of B. cinerea. Intriguingly, only the combined treatment with 0.2 kGy of gamma irradiation and 70 ppm of NaDCC exhibited significant synergistic antifungal activity against blue mold decay in both varieties. Together, these results suggest that a synergistic effect of the combined treatment with gamma irradiation and NaDCC can be efficiently used to control the postharvest diseases in cut rose flowers, and will provide a promising technology for horticulture products for exportation.

Study on Antifungal Ability of Water Soluble Chitosan Against Green Mould Infection in Harvested Oranges

Effect of water-soluble chitosan (WSC) on green mould disease caused by Penicillium digitatum P4 was investigated in vitro and in vivo . Results of the experiments showed that P. digitatum P4 growth was much inhibited by WSC and inhibitory effect increased as WSC concentration increased. In vitro test results indicated that complete inhibition of spore germination and mycelial growth were observed in the medium containing 1 mg/ml WSC. In the in vivo study, WSC treatments significantly reduced disease incidence and lesion diameter of green mould disease on orange fruits. After 8 days of inoculation, the lesion diameter of orange fruits coated by 0.5%, 1%, 1.5% and 2% WSC were 5.49 cm, 5.01 cm, 3.22 cm and 1.87 cm, respectively, which smaller than that of control fruits. Biochemical experiments demonstrated that the activities of the main defense-related enzymes in flavedo tissue including chitinase and Beta-1,3-glucanase were enhanced by both P. digitatum P4 infection treatment and challenged with P. digitatum P4 and treated with WSC treatment. However, these enzymes of samples inoculated with P. digitatum only were lower than samples inoculated with P. digitatum P4 and treated with 2% WSC concentration. These findings suggest that the in vitro and in vivo effects of WSC on controlling green mould disease may be associated with direct antifungal activities and the elicitation of biochemical defense responses in fruit.

Fungitoxic activity of fruit extracts of Syzygium cumini (L.) Skeels against plant pathogenic fungi Alternaria alternata and Fusarium oxysporum

This study was aimed to evaluate the effectiveness of the aqueous and ethanolic extracts of fruits of Syzygium cumini, against the mycelial growth of Alternaria alternata and Fusarium oxysporum. The results showed that ethanolic extract at the concentrations of 7.5 and 9 mg/ml completely inhibited the mycelial growth of A. alternata and F. oxysporum, respectively. While the aqueous extract at a highest tested concentration (37.5 mg/ml) exhibited only 27.86 and 37.23% inhibition of mycelial growth of A. alternata and F. oxysporum, respectively. The spore germination assay also showed the complete inhibition of spore germination of A. alternata and F. oxysporum by ethanolic extract at 50 and 60 mg/ml concentrations, respectively. Minimum inhibitory concentration was recorded as 0.039 and 0.156 mg/ml in ethanolic extract and 20 and 6.25 mg/ml in aqueous extract against A. alternata and F. oxysporum, respectively. Phytochemical analysis also showed the presence of high amount of phenolics, tannins, flavonoids, alkaloids and saponins.

Effect of Cymbopogon martinii, Foeniculum vulgare, and Trachyspermum ammi Essential Oils on the Growth and Mycotoxins Production by Aspergillus Species.

This study was performed to investigate effect of essential oils on Aspergillus spore germination, growth, and mycotoxin production. In vitro antifungal and antiaflatoxigenic activities of Cymbopogon martinii, Foeniculum vulgare, and Trachyspermum ammi essential oils were carried out on toxigenic strains of Aspergillus species. Plant materials were hydrodistilled for 4-5 h in Clevenger apparatus. 0.25 μL/mL, 0.5 μL/mL, 1 μL/mL, 2 μL/mL, and 4 μL/mL concentrations of each essential oil were prepared in 0.1% Tween 80 (V/V). T. ammi oil showed highest antifungal activity. Absolute mycelial inhibition was recorded at 1 μL/mL by essential oils of T. ammi. The oil also showed complete inhibition of spore germination at a concentration of 2 μL/mL. In addition, T. ammi oil showed significant antiaflatoxigenic potency by totally inhibiting toxin production from A. niger and A. flavus at 0.5 and 0.75 μL/mL, respectively. C. martinii, F. vulgare, and T. ammi oils as antifungals were found superior over synthetic preservative. Moreover, a concentration of 5336.297 μL/kg body weight was recorded for LC50 on mice indicating the low mammalian toxicity. In conclusion, the essential oils from T. ammi can be a potential source of safe natural food preservative for food commodities contamination by Aspergillus species.

Epidemiology of cutaneous mycosis in the Medina region of Saudi Arabia correlated with studying the effect of light-induced gold nanoparticles on the growth of dermatophytes in vitro

A total of 145 clinical cases were diagnosed, 137 were found to be positive cases of cutaneous fungal infection. Among all one hundred and thirty seven positive cases, superficial mycoses cases of tinea versicolor caused by Malassezia furfur were found to be the most frequent representing (42.3%) of the total, the remaining (51.1%) and (6.6%) were cases of cutaneous mycoses caused by dermatophytes and Candida albicans respectively. Tinea capitis was the most frequent among clinical case caused by dermatophytes representing (21.2%) of the total, followed by tinea pedis (9.5%) and tinea corporis (8.1%), the rest of the clinical tinea cases recorded were of low occurrence. The most frequently isolated causal agents of cutaneous mycoses caused by dermatophytes were Microsporum canis (15.4%), Trichophyton metagrophytes (11.7%), and Trichophyton violaceum (11%). Screening for keratinolytic activity showed that Microsporum canis and Tinea verrucosum recorded the highest value, while the rest of the dermatophytes gave lower values. When light-induced gold nanoparticles was tested against dermatophytes in vitro inhibitory effect on spore germination of dermatophyte isolates was observed, the percentage of inhibition in spore germination ranged from 87.5% to complete inhibition of spore germination.

Inhibition of Spore Development and Mycelial Growth of Rhizopus stolonifer by Essential Oil of Satureja richingeri from Iran

There is a great interest in the use of natural antifungal compounds for the control of fungi such as Rhizopus stolonifer in the postharvest agricultural system and food industry. In this study, the inhibitory effect of essential oil extracted from Satureja richingeri and its major compound, Carvacrol, on spore development and mycelial growth of R. stolonifer was investigated. Mycelium exhibited higher sensitivity to the oil and Carvacrol than that observed for spores. Spore treatment with oil and Carvacrol for 2 and 3 h led to a complete inhibition of spore germination, after 4 h of incubation. However, continuing the incubation to 6 h resulted in germination of 4.67% of the spores treated with the oil but no germination was detected for those treated with Carvacrol. It could be concluded that treatment with S. richingeri essential oil for 3 h would extend the shelf life of agricultural product considerably via inhibition of spore germination.

Identification of the Solanum nigrum Extract Component Involved in Controlling Cabbage Black Leaf Spot Disease

In this study, we discovered that an ethanol (EtOH) extract of Solanum nigrum inhibited spore germination of Alternaria brassicicola, the causative agent of cabbage black leaf spot disease. At a concentration of 500 mg/L, this ethanol extract also caused the germ tubes to become completely swollen. Detached cabbage leaves were then used to evaluate the effects of the extract in controlling the disease. It was observed that the extract-induced swelling of A. brassicicola germ-tube spores did not cause the symptoms of black spot disease on cabbage leaves. Furthermore, an n-butanol fraction of the EtOH extract exhibited strong antifungal activity; at a concentration of 25 mg/L, a derived subfraction (Bu-11-13) showed complete inhibition of spore germination. A white powder was collected from fraction Bu-11-13, and its minimum inhibitory concentration was determined to be 8 mg/L. Using NMR and LC-MS/MS analysis, this white powder compound was identified as degalactotigonin.

The mixture of tertiary and quaternary alkaloids isolated from Argemone ochroleuca inhibits spore germination of some fungi

The mixture of tertiary and quaternary alkaloids isolated from Argemone ochroleuca was separately assessed against spore germination of some plant pathogenic fungi, e.g. Alternaria alternata, Alternaria brassicae, Alternaria cajani, Bipolaris sp., Curvularia lunata, Curvularia sp., Colletotrichum musae, Fusarium udum, Helminthosporium sp., Helminthosporium pennisetti and Helminthosporium speciferum. Spore germination of Fusarium udum and Helminthosporium sp. was completely inhibited at very low concentration (200 ppm). A similar effect was observed on A. alternata, C. musae and H. pennisetti at 600, 800 and 1000 ppm. With quaternary alkaloids, Curvularia sp. and Colletotrichum musae were most sensitive as complete inhibition of spore germination was observed at 400, 600, 800 and 1000 ppm and a similar effect was observed with A. brassicae and A. cajani at 600, 800 and 1000 ppm. The remaining fungi were also highly sensitive to the mixture at different concentrations.

Effect of acetic acid fumigation on soil-borne fungi and cucumber root rot disease under greenhouse conditions

The effect of acetic acid vapour on soil-borne fungi and root rot disease of cucumber plants under greenhouse conditions was studied. Acetic acid vapour at four concentrations was tested against linear growth and spore germination of some soil-borne fungi, in vitro. The most sensitive fungus to acetic acid vapours was Rhizoctonia solani which inhibited at 4 µl l−1, while Fusarium solani, Fusarium oxysporium f. sp. cucumerinum, Scleroitium rolfsii and Didymella melonis inhibited at 6 µl l−1. Complete inhibition of spore germination was obtained with acetic acid vapours at 4 µl l−1 with all tested fungi. Acetic acid vapours significantly reduced germination of resting stage of all tested fungi. Complete inhibition of chlamedospores of F. solani and F. oxysporum f. sp. cucumerinum was obtained with acetic acid vapour at 10 µl l−1, meanwhile, sclerotia of S. rolfsii was killed at 20 µl l−1 of acetic acid vapour. Four types of soil: sandy, loamy, clay and peat-moss were fumigated with acetic acid vapour for 60 minutes. A higher response was recorded with peat-moss and sandy soil in which soil-borne fungi were inhibited at 75 and 100 µl l−1 respectively, while in loamy and clay soil fungi were inhibited at 125 µl l−1. Peat-moss soils were artificially infested with individual cucumber root rot fungi and fumigated with acetic acid vapour for 60 minutes. A population count of pathogenic fungi and cucumber root rot disease was carried out. Results indicated that acetic acid vapour at 75 µl l−1 caused a complete reduction in the population of cucumber root rot fungi and under greenhouse conditions it reduced the cucumber root rot disease more than 93.3 and 95.4% for pre- and post-emergence respectively. It could be suggested that acetic acid vapours might be safely used for controlling cucumber root rot disease under greenhouse conditions.

Antifungal Activity of Securinine against Some Plant Pathogenic Fungi

The alkaloid securinine was assessed against spore germination of some plant pathogenic and saprophytic fungi (Alternaria alternata, Alternaria brassicae, Alternaria brassicicola, Curvularia lunata, Curvularia maculans, Curvularia pallenscens, Colletotrichum musae, Colletotrichum sp., Erysiphe pisi, Helminthosporium echinoclova, Helminthosporium spiciferum, Heterosporium sp.). Spore germinations of all the tested fungi were inhibited. Alternaria brassicicola, C. lunata, C. pallenscens and H. spiciferum were highly sensitive as complete inhibition of spore germination was observed at very low concentrations (200 ppm).

Antifungal Activity of an Alkaloid Allosecurinine against Some Fungi

An allosecurinine alkaloid was assayed against spore germination of some saprophytic and pathogenic fungi e.g., Alternaria alternala, A. solani, A. brassieieola, A. brassieae, Curvularia lunata, C. palleseens, C. maeulans, Cumularia species, Colletotrichum species, C. musae, C. glaeaspariaides, Erysiphe pisi, Fusarium udum, Helmintltosporium ecltinoelova, H. pennisetti, H. spiciferum, and Heterosporium sp. It inhibited mild spore germination of all the fungi tested. Cumularia lunata, Cumularia sp., Collectotrichum sp., C. musae and Heterosporium sp. were most sensitive as complete inhibition of spore germination was observed at very low concentrations.

Tulbaghia violacea L. II: In vivo antifungal properties towards plant pathogens

In vitro antifungal activity of crude extracts from Tulbaghia violacea against 6 economically important plant pathogenic fungi was previously reported. The in vivo control of Mycosphaerella pinodes, causative of Ascochyta blight, by different concentrations of a crude aerial part extract of T. violacea was subsequently followed qualitatively and quantitatively in terms of lesions that developed over a 6-day period at 20°C on detached pea (Pisum sativum) leaves. Infection by M. pinodes spores was prevented when the extract was applied both before and after inoculation, confirming complete inhibition of spore germination, whereas no phytotoxic effect was observed on the leaves. Additionally, the control of sorghum covered (Sporisorium sorghi) and loose (S. cruentum) kernel smuts by seed treatment with the crude extract was tested under field conditions. Before planting, different sorghum seed lots were inoculated separately with spores from the 2 pathogens at a rate of 0.5% per kg (w/w), followed by treatment with the crude extract, at a concentration of 2.0 mg/mL, 24 h later. A standard fungicide, Thiram (65 W), was applied as a positive control at a rate of 0.25% per kg (v/w). Disease incidence was quantified during harvest and expressed as percentage infected plants. Seed treatment with the extract significantly (P &lt; 0.05) reduced the incidence of both sorghum loose and covered smut diseases, compared favourably with the standard fungicide, and resulted in significant yield increases compared to the untreated control.

Biological activity and physical modes of action of the Qo inhibitor fungicides trifloxystrobin and pyraclostrobin against Cercospora beticola

The effect of trifloxystrobin and pyraclostrobin on spore germination and mycelial growth of Cercospora beticola, were determined in vitro. In addition, the protective, curative, translaminar and post-symptom activity against the pathogen was determined on sugar beet plants in growth chambers with difenoconazole and chlorothalonil as standard fungicide treatments. Both pyraclostrobin and trifloxystrobin were highly active causing complete inhibition of spore germination at concentrations of 0.01 and 0.1μgml−1, respectively, although higher concentrations were required for complete inhibition of fungal growth. Both fungicides were protective against C. beticola when applied 96h and 24h before inoculation of plants. Both fungicides, applied at 20μgml−1 , were superior to difenoconazole applied at 10μgml−1 and to chlorothalonil applied at 100μgml−1. Effective control was obtained when strobilurin fungicides were applied 24h after inoculation, but were less effective at 96h after inoculation. Pyraclostrobin at 20μgml−1 applied 96h after inoculation, was more effective than difenoconazole while control with trifloxystrobin at 20μgml−1 applied 96h after inoculation was similar to that obtained with difenoconazole. Chlorothalonil showed little activity against C. beticola in curative treatments. Tests to evaluate translaminar activity showed that disease severity on leaves treated with strobilurin fungicides on the upper leaf surface and inoculated on the opposite surface was similar to that obtained on leaves treated and inoculated on the same surface. Anti-sporulant activity was good with both strobilurin fungicides applied at concentrations of 10 or 20μgml−1 when applied after the appearance of the symptoms. The anti-sporulant activity of difenoconazole was similar to that of pyraclostrobin and trifloxystrobin applied at 5μgml−1, while chlorothalonil did not provide significant antisporulant activity. Such results encourage the evaluation of trifloxystrobin and pyraclostrobin under field conditions to select optimal partner fungicides for use in mixtures.