Sensitivity of Lasiodiplodia theobromae from Brazilian papaya orchards to MBC and DMI fungicides

Stem rot caused by Lasiodiplodia theobromae is an important postharvest disease of papaya in Brazil, responsible for reducing the quality and quantity of fruits. Fungicide use is one of the main disease management measures. However, there are no estimates available of pathogen sensitivity to commonly employed fungicides. Therefore, the EC₅₀ from 120 isolates of L. theobromae from northeastern Brazil, representative of six populations of the pathogen, was estimated in vitro for fungicides of the methyl benzimidazole carbamates—MBC (benomyl and thiabendazole) and demethylation-inhibiting—DMI (imazalil, prochloraz, tebuconazole) groups. Mycelial growth on fungicide-free media and virulence on papaya fruits of the MBC-sensitive and non-sensitive isolates were compared. For MBCs, 8.4% of isolates were non-sensitive to fungicides. For the remaining 91.6%, the mean EC₅₀ ranged from 0.002 to 0.13 μg ml⁻¹ and 0.36 to 1.27 μg ml⁻¹ for benomyl and thiabendazole, respectively. For DMIs, the mean EC₅₀ range for imazalil was 0.001 to 2.27 μg ml⁻¹, 0.04 to 1.75 μg ml⁻¹ for prochloraz, and 0.14 to 4.05 μg ml⁻¹ for tebuconazole. The EC₅₀ values of non-sensitive isolates were significantly (P≤0.05) higher those for the sensitive isolates for each of the DMI fungicides. Differences (P≤0.05) were found in the levels of sensitivity to DMI fungicides among the isolate populations associated with orchards. The populations from two orchards were less sensitive to DMIs. No solid evidence was found for fitness costs relating to MBC non-sensitive isolates because mycelial growth in fungicide-free media and virulence on papaya fruits were similar to those of sensitive isolates.     

Analysis of Colletotrichum musae populations from Brazil reveals the presence of isolates with high competitive ability and reduced sensitivity to postharvest fungicides

In this study, the sensitivity of 218 isolates of Colletotrichum musae to imazalil and thiabendazole was evaluated, as well the fitness and competitive ability of less sensitive isolates. There was a positive correlation between the sensitivity to the two fungicides, but the isolates were more sensitive to imazalil. The estimated effective concentration of the fungicide able to inhibit mycelial growth by 50% (EC₅₀) was used to select four isolates with the lowest and the highest values for both fungicides, which were considered as sensitive (S) and less sensitive (LS), respectively. The level of sensitivity was maintained after 10 successive transfers on fungicide-free medium. Both fungicides were effective in controlling the disease caused by S isolates of C. musae in detached banana fruit when recommended doses were used. However, only imazalil was able to control the disease caused by LS isolates. For both fungicides, analysis of fitness-related variables (mycelial growth, sporulation, germination, and virulence) showed no difference between the groups of S and LS isolates, but a large variation was observed within the group. The LS isolates to thiabendazole that showed a mutation (F200Y) in the β-tubulin gene did not have fitness penalties. Our results allow a better understanding of the sensitivity and fitness of isolates of C. musae from Brazil, and demonstrate the importance of periodic monitoring to determine the frequency of LS isolates in populations, aiming at more effective management of anthracnose in banana orchards in Brazil.     

Decay control and fungicide residues in citrus fruits seal-packed in a high-density polyethylene film

The effects of a new packaging method of sealing individual fruits in film of highdensity polyethylene (HDPE), on decay control and the residue levels of various fungicides applied to the fruit, were investigated with four different citrus cultivars. HDPE seal-packaging by itself reduced the decay of Marsh grapefruit but slightly enhanced the decay of Valencia orange fruit in comparison with conventionally handled fruit. Seal-packaging of individual fruit resulted in much less decay than sealing a whole carton of fruit together. The fungicides imazalil, sec-butylamine, 2-phenylphenol, benomyl and thiabendazole markedly reduced the decay of sealed fruit in all cultivars of citrus fruits tested. Residue levels in treated fruit were below the tolerances permitted. The new method of packaging had no effect on the residue levels of benomyl, 2-phenyl-phenol and thiabendazole in the fruit; neither did it affect the extent of absorption of these fungicides into the fruit. Only the volatile fungicide sec-butylamine was found at a higher level (73% higher in the packaged fruit compared with conventionally treated fruit).     

Spread of phytophthora rot on stored citrus and its prevention by fungicide dips1

Oranges and lemons infected with Phytophthora citrophthora and P. syringae were placed among healthy fruits in boxes kept at 5, 10 and 14°C. The spread of the rot by contact infection was assessed after 3,6,12 and 18 days and again after 7 days' shelf-life at 17°C. P. citrophthora infected adjacent fruits after 12 days at 10°C and 3 days at 14°C. No infection occurred at 5°C. P. syringue infected the fruits at all the temperatures tested. On fruits kept for 6 days at 5°C, the rot developed after shelf-life. The presence of Phytophthora-infected fruits in orange and lemon packing boxes enhanced the development of penicillium rots. Post-harvest dips in metalaxyl at 0.05 and 0.1% concentrations and fosetyl-Al at 0.1,0.2 and 0.3% concentrations prevented the spread of P. citrophthora in packing boxes kept for 30,40 and 60 days at 11°C, but had no effect on penicillium rots. The mixture of the above fungicides with thiabendazole at 0.1%] or imazalil at 0.05%, concentrations gave best control against phytophthora and penicillium rots.     

Fungi in stored barley treated with systemic fungicides

Six fungicides (benomyl, carbendazim, fuberidazole, thiabendazole, thiophanate and thiophanate-methyl) were applied as dusts to barley in concentrations of 100, 1000 and 10 000 μg g^?1 and the barley then stored at 20°C and 90% relative humidity for 60, 105 and 150 days, respectively. Fungal development during storage was assessed by counting the visible patches of developing mould and by dilution plating. None of the fungicides completely prevented fungi developing but for the period up to 60 days, all provided a degree of control that was generally greatest for the highest concentration of fungicide. Benomyl was the most effective of the fungicides but no clear pattern was established for the others. Of the fungi that developed, species of Aspergillus and Penicillium accounted for 94% of the total count.     

The occurrence of thiabendazole-resistant isolates of Polyscytalum pustulans and Helminthosporium solani on seed potato tubers in relation to fungicide treatment and storage

Tubers infected with thiabendazole-sensitive isolates of Polyscytalum pustulans and Helminthosporium solani were treated annually for 4 years with benomyl, thiabendazole or a formulated mixture of thiabendazole and imazalil, and grown at three farms in Scotland. The proportion of thiabendazole-resistant isolates of H. solani increased, and isolates producing black colonies became more common with successive annual applications of thiabendazole or benomyl. Silver scurf was not reduced after three annual applications. When these fungicides were applied once to untreated seed the incidence of resistant isolates of H. solani was much less in 1988 than in 1991 when tubers had been grown on farms for 3 years from untreated seed.
The proportion of resistant isolates of P. pustulans increased with the number of successive applications of thiabendazole or benomyl but at differing rates on each farm. At one farm, skin spot was not reduced by three annual applications of these fungicides whereas at the other farms it was reduced by 90–100% by four annual applications.
A smaller proportion of resistant isolates of P. pustulans and H. solani was obtained after applying the mixture of thiabendazole and imazalil than after benomyl or thiabendazole alone. Their occurrence was not related to the number of fungicide applications. The mixture also reduced both diseases by more than 75% over the 4 years.
At one farm where resistant isolates of H. solani were present, tubers were infected when stored on trays but not when stored in bags.     

七种杀菌剂对蘑菇褐腐病菌的药效及对双孢蘑菇的安全性评价

采用菌丝生长速率法测定了7种杀菌剂对蘑菇褐腐病菌Mycogone perniciosa Magn.的室内毒力及其中5种杀菌剂对双孢蘑菇Agaricus bisporus的室内安全性,并通过田间小区试验评价了其中6种杀菌剂对蘑菇褐腐病的药效及对双孢蘑菇的安全性。室内测定结果表明:多菌灵、咪鲜胺、噻菌灵、百菌清、苯醚甲环唑及戊唑醇对蘑菇褐腐病菌的毒力均较强,EC50值分别为0.036 9、0.024 5、0.296、0.136、0.036 0和0.058 1 mg/L,福美双毒力较弱,EC50值为88.0 mg/L;多菌灵和百菌清对双孢蘑菇较安全,苯醚甲环唑、戊唑醇及福美双对其有药害风险。田间试验结果表明:按有效成分质量分数计,50%多菌灵可湿性粉剂（WP）250、500和1 000 mg/kg,50%咪鲜胺锰盐WP 333、266和200 mg/kg,75%百菌清WP 375 mg/kg对蘑菇褐腐病的防效较好,且对双孢蘑菇生长无显著影响;而采用43%戊唑醇悬浮剂（SC）143.3、86.0 mg/kg防治褐腐病时,双孢蘑菇的减产率分别为20.54%和13.19%,采用10%苯醚甲环唑可分散粒剂（WG）33.3 mg/kg时,减产率为4.73%,表明这2种杀菌剂对双孢蘑菇的安全性较差,不宜用于防治蘑菇褐腐病;50%福美双WP 1 000 和 500 mg/kg均会造成蘑菇出菇推迟,而166.7 mg/kg的防效较差,因此也不宜用于防治蘑菇褐腐病。     

改进的QuEChERS气相色谱-串联质谱法测定草莓中21种杀菌剂残留

采用改进的QuEChERS气相色谱-串联质谱法建立了检测草莓中21种杀菌剂（螺环菌胺、甲霜灵、四氟醚唑、酞菌酯、嘧菌环胺、戊菌唑、氟吡菌酰胺、氟菌唑、嘧菌胺、E-苯氧菌胺、抑霉唑、腈菌唑、醚菌酯、环氟菌胺、肟菌酯、丙环唑、环酰菌胺、氟环唑、咪唑菌酮、啶酰菌胺、嘧菌酯）残留的方法。样品经乙腈提取,采用N-丙基乙二胺（primary secondary amine,PSA）和石墨化碳黑（graphitized carbon blacks,GCB）作为分散固相萃取（dispersive solid phase extraction,DSPE）的吸附材料,净化液经氮气吹干、用V（正己烷）:V（丙酮）=9:1混合溶液定容,采用气相色谱-串联质谱（gas chromatography-tandem mass spectrometry,GC-MS/MS）测定。结果表明:在质量浓度0.005~0.2 mg/kg范围内,21种杀菌剂与对应的峰面积间呈良好的线性关系;在0.01、0.05和0.1 mg/kg 3个添加水平下,21种杀菌剂的平均回收率均在70%~122%之间,RSD < 20%。该方法适用于草莓中21种杀菌剂残留的快速、高效和准确分析。     

Sensitivity of Penicillium digitatum and P. italicum to Postharvest Citrus Fungicides in California

ABSTRACT Penicillium digitatum isolates (326), collected in California citrus groves and packinghouses, were assayed qualitatively for their sensitivity to imazalil, thiabendazole, and o-phenylphenol. Eighteen typical triple-resistant isolates, acquired in each of 3 years (1988, 1990, and 1994), were assayed quantitatively for their sensitivity to each of the three fungicides. No significant differences were found in the mean sensitivity of the isolates collected in different years. However, the proportion of isolates that were resistant to all three fungicides increased from 43% in 1988 to 77% in 1990 and 74% in 1994. Imazalil-resistant biotypes of P. digitatum were isolated frequently in California packinghouses, while resistant P. italicum was rare. No fungicide-resistant biotypes of either species were collected from citrus groves. Wild-type P. italicum was slightly less sensitive than wild-type P. digitatum to all three fungicides. The concentration of imazalil producing 50% growth inhibition (EC(50)) was three times greater when the age of the P. digitatum assay inoculum was increased from 12 to 24 h. Activity of imazalil increased with pH of the assay medium in the range pH 5.1 to 5.9, reflecting the greater concentration of dissociated imazalil at the higher pH value.     

The determination of thiabendazole (2-(4-thiazolyl)-benzimidazole) in citrus fruit dips

Methods for analysing the strength of thiabendazole (TBZ) dipping fluids are described. The methods which require only the minimum laboratory facilities and can be used in citrus packing houses, are based upon (i) a titration method utilising the complex formed by TBZ with silver ions, for accurate work, and (ii) a refractive index method after concentration for rapid checking by packing house employees. These methods are compared with a spectrophotometric method.     

Compatible Biological and Chemical Control Systems for Rhizoctonia solani in Potato

A series of chemical and biological control agents were tested for compatibility with the Rhizoctonia-specific biocontrol fungus Verticillium biguttatum aimed at designing novel control strategies for black scurf (Rhizoctonia solani) and other tuber diseases in potato. The efficacy of chemicals, alone and in combination with V. biguttatum was tested in in vitro assays on nutrient agar plates, in bio-assays with minitubers and in the field. Generally, there were both antagonistic, neutral and additive interactions with V. biguttatum among the combinations tested; there were no indications for synergistic interactions. Broad-spectrum fungicides (azoxystrobin, chlorothalonil, thiabendazole) were fungitoxic to V. biguttatum as shown in in vitro assays, and hampered black scurf control by V. biguttatum in bio-assays. Oomycete-specific chemicals (cymoxanil and propamocarb) and various biocontrol strains (Gliocladium spp., Pseudomonas spp. and Trichoderma spp.) did not interfere with the growth of V. biguttatum on agar nutrient plates and did not affect black scurf control by V. biguttatum in co-applied treatments in the minituber bio-assay. Rhizoctonia-specific (pencycuron, flutalonil) fungicides co-applied with V. biguttatum showed additive effects on black scurf control. When combinations of V. biguttatum and cymoxanil or propamocarb were applied to immature potato tubers at green crop lifting, a reduction of both black scurf and Pythium- or Phytophthora-incited tuber rot was observed at harvest. In conclusion, the biocontrol fungus V. biguttatum is compatible with selected chemical control systems and may improve control efficacy in combination with Rhizoctonia-specific fungicides or may extend control spectrum in combination with Oomycete-specific fungicides.     

Fenpropimorph: a promising fungicide for postharvest diseases in citrus fruits

Sour rot, green mold and blue mold are postharvest diseases of citrus fruit. Benzimidazole and imidazole fungicides control molds, and guazatine controls sour rot, but strains ofPenicillium spp. resistant to these chemicals have been reported. Aqueous formulations of fenpropimorph, a morpholine fungicide, are very active in controlling fungi attacking postharvest citrus fruits. The fungicidal effect of the chemical in the coating wax was investigated in combined treatments with guazatine in dip or spray applications on various citrus fruit varieties. Fenpropimorph alone was as good as or a better curative and protective treatment than the current commercial treatments applied in packinghouses in Israel for decay control.     

桃蛀螟对青霉菌侵染苹果的产卵选择与行为趋向反应

为探明桃蛀螟Conogethes punctiferalis偏好于在青霉菌Penicillium侵染的苹果上产卵的特点与机理,从苹果、玉米和柑橘上分离、纯化获得15株青霉菌,通过形态学和rDNA-ITS序列分析鉴定后,以健康苹果为对照,测试不同青霉菌菌株侵染的苹果对桃蛀螟产卵选择的影响,并利用四臂嗅觉仪测试桃蛀螟对青霉菌诱导的苹果挥发物的行为趋向反应。结果表明,15株青霉菌分别属于皮落青霉P. crustosum、橘青霉P. citrinum、苏门答腊青霉P. sumatrense和指状青霉P. digitatum的不同株型;桃蛀螟对其中的12株青霉菌侵染的苹果的产卵选择率均极显著高于健康苹果,尤其对皮落青霉CO5菌株、苏门答腊青霉OR3菌株和指状青霉OR5菌株侵染的苹果的产卵选择率最高,分别达到67.73%、61.50%和68.39%;桃蛀螟对感染皮落青霉CO5菌株和指状青霉OR5菌株的苹果挥发物的选择率分别为31.37%和29.19%,均显著高于对感染橘青霉OR1菌株和苏门答腊青霉OR3菌株的苹果挥发物的选择率18.14%和21.31%,且前二者之间、后二者之间均无显著差异。表明青霉菌可通过影响寄主植物挥发物释放,从而影响桃蛀螟对寄主植物的产卵选择和行为趋向反应。     

Characterization of Fusarium spp. responsible for causing dry rot of potato in Great Britain

A 3-year survey was undertaken to establish the relative frequency of different Fusarium spp. present as inoculum on potato tubers collected from four regions of Great Britain. A total of 219 samples (comprising 10 950 tubers) were collected from the 2000, 2001 and 2002 crops and processed to recover dry rot-producing isolates. In total, 228 isolates of Fusarium spp. were recovered. Most (94·7%) of these isolates were attributed to one of four Fusarium species: F. coeruleum, F. avenaceum, F. culmorum and F. sambucinum (formerly F. sulphureum) . The incidence of the combined Fusarium spp. increased the further south the crops had been grown. Fusarium coeruleum was the most commonly isolated species in each survey year, comprising 37 to 52% of the total Fusarium species. Selected isolates of each species were evaluated for their ability to produce rots in potato tubers. Fusarium sambucinum was a more aggressive pathogen than the other Fusarium species in eight out of 10 cultivars. Fusarium avenaceum and F. culmorum were relatively weaker pathogens. However, these species were aggressive on some cultivars, notably Hermes. The selected isolates were also assessed for their sensitivity to the fungicides thiabendazole and imazalil. Using in vitro tests, 65% of F. sambucinum isolates were resistant to thiabendazole and 7% of F. avenaceum isolates were resistant to imazalil. Tubers treated with imazalil yielded a higher proportion of isolates of F. avenaceum than those that were untreated. Similarly, a higher proportion of F. sambucinum isolates were recovered from tubers treated with thiabendazole than from those that were not treated.     

A during-infection spray strategy using sulphur compounds,copper, silicon and a new formulation of potassium bicarbonate for primary scab control in organic apple production

In a field experiment conducted over two growing seasons, the effectiveness and phytotoxicity of inorganic fungicides such as sulphur, lime sulphur, copper, silicon and Armicarb (a new formulation of potassium bicarbonate) was compared with water for the control of primary apple scab infections in Belgium on high, medium and low scab-susceptible cultivars (cvs ‘Pinova’, ‘Pirouette’ and ‘Reinette des Capucins’, respectively). In order to drastically reduce the amount of fungicide applied in the orchard, two approaches were used: (1) a strategy involving spraying during the infection process, before fungal penetration and (2) a tunnel sprayer machine for treatment applications. Under field conditions highly favourable for disease, low rates of elemental sulphur (31.8 and 38.6 kg ha⁻¹ year⁻¹ in 2005 and 2006, respectively) combined with low rates of copper (2.1 kg ha⁻¹ year⁻¹ in both years) provided the best scab control and reduced scab severity on the fruits of cv. ‘Pinova’ by 97 and 98% compared with water control in 2005 and 2006, respectively. Lime sulphur was much more effective than wettable sulphur and appeared to be efficient at temperatures below 10°C, but its effectiveness against apple scab decreased if the treatments were applied 12–24 h later than in the ‘during-infection’ spray strategy. Armicarb used alone significantly reduced apple scab severity on the leaves and fruits of the three cultivars compared with the water control. Its effectiveness was as good as wettable sulphur applied using the same timing and dosage. Silicon reduced apple scab on fruits very slightly, but not on leaves. The amounts of wettable sulphur, lime sulphur, copper, silicon and potassium bicarbonate used in this experiment to control apple scab were not phytotoxic, did not increase fruit russet, did increase the yield of each cultivar and did not affect summer density of the beneficial Typhlodromus pyri. The potential and limitations of ‘during-infection’ spraying as a protection strategy against apple scab in organic farming are discussed.     

Fate of vinclozolin,thiabendazole and dimethomorph during storage,handling and forcing of chicory

BACKGROUND: As part of ongoing research for a sustainable production of Belgian endives, the fate of three fungicides during storage, handling and forcing of witloof chicory roots was investigated. Storage roots are protected against Sclerotinia sp. Fuckel and Phoma exigua var. exigua Desm. by means of vinclozolin and thiabendazole respectively. During hydroponic forcing, the most imminent pathogen is Phytophthora cryptogea Pethybr. & Laff., which is controlled by the use of dimethomorph. RESULTS: Vinclozolin and thiabendazole concentrations on roots remained constant during storage at ?1 °C. Dermal exposure of the workers in hydroponics was exceeded. Vinclozolin and thiabendazole residues were not detected 2 weeks after hydroponic forcing; dimethomorph was still detected at harvest. At harvest, the vinclozolin concentration in the chicory heads was below the maximum residue limit, but the chicory roots contained residues much above the thiabendazole and dimethomorph maximum residue level. CONCLUSION: Vinclozolin and thiabendazole residues applied before storage are still present on the roots at the start of the forcing cycle. During the set‐up of chicory roots, preventive measures are recommended, as effects of repeated human exposure to low doses of applied fungicides cannot be excluded. Dimethomorph applied at the start of the hydroponic forcing is the only pesticide detected in the drainage water at harvest. The chicory heads were safe for human consumption. However, more attention should be paid to the residues of fungicides in the roots used for cattle feeding. Copyright © 2009 Society of Chemical Industry     

Resistance to <Emphasis Type="Italic">Penicillium</Emphasis><Emphasis Type="Italic">hirsutum</Emphasis> Dierckx in garlic accessions

Among the factors affecting the quality and yield of garlic production, blue mold caused by -- Penicillium spp. -- is responsible for economical losses in many countries. Allicin, present in garlic bulbs, has been suggested as having antifungal activity against some Penicillium species. This study was conducted to evaluate the response of garlic accessions against Penicillium hirsutum infection and to compare this response with bulb allicin content. Twelve garlic accessions were inoculated with P. hirsutum, and assayed in greenhouse and growth chamber experiments. Plant growth parameters and the fungal production of conidia were evaluated. Significant differences were found among the accessions. Accessions Castaño and Morado were most resistant whereas AR-I-125 and Fuego were always severely affected by the disease. A low correlation was found (r = 0.17) between allicin content and tolerance, indicating that allicin is not the main factor involved in the resistance against P. hirsutum.     

小麦白粉病菌对喹氧灵和苯菌酮的敏感基线及药剂的生物活性

采用离体叶段法,分别测定了从河北、河南、湖北、陕西和四川5省分离的53个小麦白粉病菌单孢菌株对苯菌酮和喹氧灵的敏感性,并分析了白粉病菌对三唑酮和苯菌酮以及喹氧灵之间的 交互抗性。结果表明:小麦白粉病菌群体对苯菌酮和喹氧灵的平均EC50值分别为(0.001 9±0.000 6) 和(0.013 1±0.002 0) mg/L,苯菌酮比喹氧灵具有更高的抑菌活性;小麦白粉病菌对三唑酮和苯菌酮与喹氧灵之间均不存在交互抗性(R2值分别为0.102 6和0.491 9);室内盆栽试验结果显示:接种前1 d和接种后1d施药,苯菌酮和喹氧灵对小麦白粉病的保护与治疗作用防效分别为92.21%、84.25%和82.43%、70.25%,表明这2种药剂不仅具有优异的保护作用,同时还具有较好的治疗作用。     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Assessment of <Emphasis Type="Italic">Pichia anomala</Emphasis> (strain K) efficacy against blue mould of apples when applied pre- or post-harvest under laboratory conditions and in orchard trials

The yeast Pichia anomala strain K was selected in Belgium from the apple surface for its antagonistic activity against post-harvest diseases of apples. The efficacy of this strain against P. expansum was evaluated in the laboratory in three scenarios designed to mimic practical conditions, with different periods of incubation between biological treatment, wounding of fruit surface, and pathogen inoculation. Higher protection levels and higher final yeast densities were obtained when the applied initial concentration was 1 × 10⁸ cfu ml⁻¹ than when it was only 1 × 10⁵ cfu ml⁻¹. The protection level correlated positively with the yeast density determined in wounds and was influenced by apple surface wetness. In orchard trials spanning two successive years, biological treatment against P. expansum, based on a powder of P. anomala strain K (1 × 10⁷ cfu ml⁻¹), β-1,3-glucans (YGT 2 g l⁻¹), and CaCl₂.2H₂0 (20 g l⁻¹), was applied to apples pre- or post-harvest under practical conditions and its effect compared with standard chemical treatments. The first year, the highest reduction (95.2%) against blue decay was obtained by means of four successive fungicide treatments and the next-highest level (87.6%) with pre-harvest high-volume spraying of the three-component mixture 12 days before harvest. The second year, the best results were obtained with post-harvest Sumico (carbendazim 25% and diethofencarb 25%) treatment and post-harvest biological treatment, both by dipping the apples, 88.3 and 56.3% respectively. A density threshold of 1 × 10⁴ cfu cm⁻² of strain K on the apple surface seemed to be required just after harvest for high protective activity, whatever the method and time of application. In the case of pre-harvest biological treatments, variations in meteorological conditions between the 2 years may have considerably affected strain K population density and its efficacies.