Near‐field air concentrations of pesticides in potato agriculture in Prince Edward Island

BACKGROUND: Pesticides in air have become of increasing concern in recent years. This study examined downwind air concentrations of carbofuran, methamidophos, mancozeb and diquat dibromide resulting from spray drift within 24 h of application, within 100 m of potato fields. RESULTS: Concentrations ranged from less than 0.05 µg m^?3 in prespray samples to 6.37 µg m^?3 for methamidophos at 3 h post‐spray. For most applications, air concentrations decreased with distance from the field and with time after application. Methamidophos concentrations in the air downwind continued to increase up to 3 h after spray. Air concentrations during spray were positively correlated with application rate (r = 0.904), and air concentrations at 1 h and 3 h post‐spray were positively correlated with vapour pressure (r = 1.000 and r = 0.999 respectively). Carbofuran, methamidophos and diquat dibromide concentrations during spray were above some Canadian and international health protection guidelines. CONCLUSION: Although pesticide air concentrations measured in this study are generally consistent with other studies, maximum concentrations are greater than those that have been measured elsewhere, and some are above published air quality guidelines. An evaluation of the degree of risk posed by these and other pest control products to human and wildlife receptors is recommended. Copyright © 2009 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.     

Behaviour of metamitron and hydroxy-chlorothalonil in low-humic sandy soils

The behaviour of the herbicide metamitron and of the main transformation product, hydroxy-chlorothalonil (HTI), of the fungicide chlorothalonil was studied to assess the risk of leaching from low-humic sandy soil. The adsorption of metamitron corresponded to a K_om value of about 60 dm³ kg⁻¹ (moderate adsorption). The half-life of metamitron in soil at 15 °C was only three days, presumably due to adaptation of the micro-organisms. In the autumn, the residue of metamitron in the soil profiles corresponded to less than 1% of the cumulative dosage. The half-life of chlorothalonil at 15 °C was about 12 days and about 45% of it was transformed to HTI. The adsorption of HTI to the soils corresponded to a K_om value of 260 dm³ kg⁻¹. The incubation study (15 °C) showed the transformation of HTI in the soils to be very slow. The amounts of HTI remaining in the soil profiles in the autumn corresponded to 4 and 16% of the cumulative dosage of chlorothalonil. In winter, the HTI residue decreased by 40% relative to the autumn level. Occasionally, HTI could be detected in the upper ground-water level (at a depth of about 1 m), at an average concentration of 0.1 to 0.2 µg dm⁻³. © 1999 Society of Chemical Industry     

Methyl isothiocyanate volatilization from fields treated with metam‐sodium

Emission of methyl isothiocyanate (MITC) from fields treated with metam‐sodium (sodium N‐methyldithiocarbamate) is a potential environmental and human safety hazard. Concentrations of MITC at three heights above four arable fields were measured following the application of metam‐sodium at a rate of 480 litre ha⁻¹ (166 kg AI ha⁻¹). Two of these fields were treated by injection into a center‐pivot irrigation system (chemigation), while in the other two fields the fumigant was applied through injection directly into the soil. Generally, higher MITC air concentrations were observed above chemigated than above injected fields. Maximum MITC air concentrations were 11.2 and 7.4 µg m⁻³ recorded 10 cm above ground 6–8 h following application and the minimum concentrations were 0.7 and 0.2 µg m⁻³ observed at 200 cm 30–35 h after application above chemigated and injected fields, respectively. The estimated MITC respiratory exposure a worker might encounter during the re‐entry period ranged between 1.37 and 0.03 mg day⁻¹ in chemigated fields and between 0.35 and 0.02 mg day⁻¹ in the injected fields. These results suggest that application of the fumigant through injection reduced MITC volatilization losses in comparison with the chemigation method, thus posing a relatively lower risk of exposure to MITC emissions. © 2000 Society of Chemical Industry     

An appraisal of five methods for the measurement of the fungal population in soil treated with chlorothalonil

An experiment was carried out in a greenhouse with the aim of determining an acceptable method to quantify the fungal population in a soil treated with the fungicide chlorothalonil. Doses of the fungicide ranging from 12 to 96 µg AI g⁻¹ soil were applied and microbial biomass carbon (C), soil ergosterol content, living hyphal length, as well as counts of total and cellulolytic fungi colonies, were measured 1, 2, 3, 4 and 5 weeks after application. At the end of 16 weeks a new evaluation was done using the three first methods. The microbial biomass C was the least sensitive parameter and, on balance, the living hyphal length was the most sensitive parameter for demonstrating effects of chlorothalonil on the fungal population. Some problems related to the efficiency of the ergosterol content and living hyphal length measurements in the evaluation of the effect of the fungicide on the fungal microflora are discussed, as is the need to compare short‐term (0–5 weeks after treatment) with longer‐term (16 weeks) results. © 2000 Society of Chemical Industry     

百菌清和福美双在蘑菇上的残留研究

建立了杀菌剂30%菇丰(12%百菌清和18%福美双)可湿性粉剂在蘑菇中的残留分析方法,并用该方法研究了其在蘑菇中的消解动态和最终残留。样品分别经GC-ECD和HPLC-UV检测。方法的添加回收率分别为90.19%~99.11%和73.94%~86.47%;变异系数分别为0.9%~3.2%和2.6%~15.8%;最小检出量分别为1×10-12g和6×10-9g;最低检测浓度分别为0.01和0.3mg/kg。田间残留动态试验结果表明,百菌清和福美双在蘑菇中的半衰期分别为2.5d和4.2h。在最高推荐剂量(1 800g/hm2)和推荐剂量2倍的条件下,施药12次,施药后第5d,蘑菇中百菌清残留量高于我国规定的MRL值(1mg/kg);而施药后2d福美双残留量已低于MRL值(3mg/kg)。试验结果表明,百菌清不适于在蘑菇中使用,而福美双则可以使用。     

In vivo control and in vitro antifungal activity of rhamnolipid B,a glycolipid antibiotic,against Phytophthora capsici and Colletotrichum orbiculare

The glycolipid antibiotic rhamnolipid B isolated from Pseudomonas aeruginosa strain B5 was evaluated for in vitro antifungal activity and in vivo control against phytophthora blight and anthracnose under glasshouse conditions. Rhamnolipid B showed antifungal activity against Cercospora kikuchii, Cladosporium cucumerinum, Colletotrichum orbiculare, Cylindrocarpon destructans, Magnaporthe grisea and Phytophthora capsici. Microscopic observation revealed that the high level of antifungal activity (10 µg ml ⁻¹) against P capsici was mainly due to a lytic effect on zoospores. Zoospore lysis began in the presence of 10 µg ml ⁻¹ of rhamnolipid B and most of the zoospores were collapsed at 25 µg ml ⁻¹. Rhamnolipid B showed inhibitory activity against the germination of zoospores and hyphal growth of P capsici at concentrations of 50 µg ml ⁻¹. Spore germination of the anthracnose plant pathogen C orbiculare was also inhibited in the presence of 50 µg ml ⁻¹ of rhamnolipid B, although hyphal growth was not affected at this concentration. In the glasshouse, the efficacy of rhamnolipid B against phytophthora blight was similar to that of metalaxyl on pepper plants when treated just before inoculation with P capsici. Treatment with either at 500 µg ml ⁻¹ completely protected pepper plants from phytophthora blight. Rhamnolipid B also suppressed the development of C orbiculare infection on leaves of cucumber plants. © 2000 Society of Chemical Industry     

Ambient air concentrations of pesticides used in potato cultivation in Prince Edward Island, Canada

Ambient air concentrations of nine selected pesticides used in potato cultivation were investigated on Prince Edward Island by collecting samples during the summer of 1998 at three potato farm sites and one non-agricultural site. In 1999, air samples were collected at a single potato farm site during local application of pesticides. The fungicide chlorothalonil was the only pesticide detected in every sample in both years, even in samples with a duration as little as 5 h. In 1998, maximum (45-458 ng m(-3)) and mean (22-193 ng m(-3)) concentrations of chlorothalonil from composite 42 h samples were one to two orders of magnitude greater at agricultural sites than at the non-agricultural site (3.9 and 2.5 ng m(-3), respectively). Maximum and mean concentrations of chlorothalonil from combined 24 h samples at the farm site in 1999 were higher than those measured in 1998 (636 and 284 ng m(-3), respectively). The ubiquitous presence in air of relatively high concentrations of chlorothalonil in agricultural areas on Prince Edward Island is likely related to its repeated use on potato farms where fungicides account for 80-90% of pesticides applied. Eight of nine pesticides were detected at farm sites in 1998 and they are ranked by mean concentration from highest to lowest as follows: chlorothalonil, methamidophos, azinphos-methyl, alpha-endosulfan, beta-endosulfan, pirimicarb, metobromuron, metribuzin, metalaxyl and fluazifop-P-butyl. Concentrations of metalaxyl, pirimicarb, metobromuron and fluazifop-P-butyl in air are among the first reported values for these pesticides. Five pesticides were detected at the Summerside farm in 1999, but only two fungicides (chlorothalonil and metalaxyl) were used locally, while the presence of metribuzin, alpha-endosulfan and methamidophos in air was not associated with local application. Evidence of pesticide drift was observed for chlorothalonil, alpha-endosulfan and methamidophos, and these pesticides were identified as being of high concern in terms of potential wildlife exposure on the Island.     

Off-target glyphosate from aerial silvicultural applications,and buffer zones required around sensitive areas

Off-target glyphosate deposits were measured downwind of aerial silvicultural applications which used D8-46 hollow-cone hydraulic nozzles, ‘Micronair’ AU 5000 rotary atomisers, and the ‘Thru Valve Boom’ (030), with volume application rates of 35, 20 and 20 litre ha^?1 respectively, and a glyphosate application rate of 2·1 kg ha^?1. Crosswind spray lines were released 10 m above ground level over a short forest canopy, from a fixed-wing aircraft flying at 45 m s ¹ in atmospheric boundary layers with average wind speeds and air temperatures of 2·2-3·7 m s^?1 and 8-23°C at release height. Ground sheets and artificial foliage clusters were exposed at downwind distances of between 50 and 300 m. Glyphosate deposit measurements at various downwind distances (x) were fitted with non-linear regression lines; deposits were attenuated at rates inversely proportional to x at powers of 1·3-2·3. For a particular trial, deposits on ground sheets and artificial foliage were generally similar, and ranged between 19 and 0·04 mg m^?2 over the sampling distances used. For 100-ha applications the estimated buffer-zone widths around water bodies were less than 50 m, whereas those around non-target vegetation ranged between 75 and 1200 m, depending on the application method and the meteorological conditions.     

A new aqueous suspension concentrate formulation of cis‐permethrin and its insecticidal activity

Isomers of pyrethroids usually have different insecticidal activities. Permethrin, a non‐cyano pyrethroid, is not an exception and cis‐permethrin is much more active than the trans‐isomer against Triatoma infestans, vector of Chagas' Disease in Argentina. The large‐scale separation of cis‐ and trans‐permethrin was performed by successive recrystallizations from ethanol‐water mixtures. An aqueous suspension concentrate (flowable) formulation of pure crystalline cis‐permethrin was prepared and assayed for its insecticidal activity on wood and ceramic surfaces against nymph V of T infestans. This formulation was at least three times more effective than deltamethrin, with LC₅₀ values on ceramic of 0.11 µg cm⁻² and 0.33 µg cm⁻² respectively. On wood surfaces, the LC₅₀ value was 0.57 µg cm⁻² compared with 3.20 µg cm⁻² for deltamethrin. Against other insect species such as Periplaneta americana, Aedes aegypti and Culex quinquefasciatus, the suspension concentrate formulation of cis‐permethrin was, however, less effective than similar formulations of deltamethrin or β‐cypermethrin. © 2000 Society of Chemical Industry     

Mechanism of action and fate of the fungicide chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in biological systems: I. Reactions with cells and subcellular components of Saccharomyces pastorianus

The mechanism and sequence of reaction of chlorothalonil in cells of Saccharomyces pastorianus was investigated by the use of either ¹⁴C-labeled fungicide or Na₂³⁵SO₄-labeled cells. The initial uptake of fungicide resulted in rapid formation of substituted chlorothalonil-reduced glutathione (GSH) derivatives. Chlorothalonil reacted with proteins during derivative formation but decreased cell viability did not occur until all the GSH was reacted and inhibition of specific NAD thiol-dependent glycolytic and respiratory enzymes occurred. It is postulated that enzyme activity and cell viability are controlled either directly or indirectly by the concentration of GSH. The loss of GSH through derivative formation with chlorothalonil and the lack of regeneration of the reduced thiol could be an important feature in the sequence of toxicity of the fungicide. The general mechanism of action of chlorothalonil resembles the trichloromethyl sulfenyl fungicides in that treated cells accumulate large concentrations of fungicide; reactions involve both low and high molecular-weight thiols, with the formation of glutathione-fungicide derivatives; and toxicity resides ultimately with the inhibition of thiol-dependent enzymes.     

百菌清在中药材浙贝上的残留动态研究

研究了百菌清在浙贝Frifillaria thuubergii上的残留动态,应用气相色谱电子捕获检测器63Ni和1.5% OV-17+2.8% OV-210 Chromosorb W/AW-DMCS(80-100目)色谱柱,测定百菌清在浙贝叶、块根和土壤中的残留量。该方法在浙贝叶、块根和土壤中的回收率分别为94.7%、101.6%、119.3%,百菌清在浙贝叶和土壤中的半衰期分别为4.8和4.7 d。     

Residues in apples and sweet cherries after methyl bromide fumigation

Methyl bromide fumigations are used to treat apples, Malus domestica Borkh, and sweet cherries, Prunus avium (L), before export to Japan. In order to expand existing markets, additional cultivars are being prepared for export to Japan. As part of the approval process, residue analyses must be conducted and residues must be at acceptable levels. Five apple cultivars (‘Braeburn,’ ‘Fuji,’ ‘Gala,’ ‘Jonagold,’ and ‘Granny Smith’) were fumigated at 40 g m⁻³ for 2 h at 10 °C, and six sweet cherry cultivars (‘Brooks,’ ‘Garnet,’ ‘Lapin,’ ‘Rainier,’ ‘Sweetheart,’ and ‘Tulare’) were fumigated for 2 h with 64 g m⁻³ at 6 °C, 48 g m⁻³ at 12 °C, 40 g m⁻³ at 17 °C, and 32 g m⁻³ at 22 °C. Three replicates of fruit from each fumigation were analyzed for methyl bromide and bromide ion residues periodically with time. Methyl bromide residues for both apples and cherries were the highest immediately after fumigation, but rapidly declined so that only ‘Braeburn’ had residues >8 µg kg⁻¹ after 13 days and, except for ‘Lapin,’ all cherries were <1 µg kg⁻¹ after seven days. Average bromide ion residues were between 3.3 and 4.9 mg kg⁻¹ among apple cultivars, and between 3.7 and 8.0 µg kg⁻¹ among cherry cultivars. Published in 2000 for SCI by John Wiley & Sons, Ltd     

百菌清、腈菌唑和吡唑醚菌酯在草莓中的残留及其风险评估

为明确在草莓采果期使用百菌清、腈菌唑和吡唑醚菌酯可能产生的膳食安全风险,进行了残留试验及不同人群的膳食暴露和风险评估。在保护地条件下用75%百菌清WP 400倍液 、 40%腈菌唑SC 4 000倍液(66.7 g/hm2)和25%吡唑醚菌酯EC 1 000 倍液(166.7 g/hm2)处理草莓,果实上的原始沉积量分别为39.2、3.4和3.8 mg/kg;半衰期分别为3.76、3.39和4.06 d。采用风险商方法进行评估,喷施百菌清后7 d内的草莓对2~4岁儿童以及1 d内对18~30岁女性的风险都是不可接受的(风险商为1.2~4.6);而喷施腈菌唑和吡唑醚菌酯后0~7 d内的草莓对2~4岁、18~30岁和60~70岁人群的风险都很低(风险商分别为0.003~0.07和0.02~0.36)。因此,建议草莓中腈菌唑和吡唑醚菌酯的最高残留限量值设定为2 mg/kg,安全间隔期均定为3 d;而百菌清则不宜在草莓采果期使用。     

Modellversuch zur Feinstaubbindung: extensive Dachbegrünung vs. Schotterdach

The increasing air pollution of urban areas caused by particulate matter poses a problem for human health. Plants are able to bind the fine dust particles on their surface and to remove them therefore from the air. Therefore, roof plantings can contribute to the reduction of fine particulate matter pollution in cities. To identify roof vegetation forms with high filter ability, suitable test procedures are missing up to now. Trials to identify the filtering potential of different roof top vegetation mats were conducted in a 1 m³ big Perspex chamber under controlled conditions. Geotextile mats with Sedum and moss vegetation were compared. Uncovered geotextile mats as well as crushed stones were used as controls. In the measuring chamber, artificial particulate matter (fire-fighting powder) was applied and the concentration of particle fractions of 0.3, 0.5 and 1 µm over the period of 90 min measured. During 5 min in the middle of the 90 minute measuring period, wind with a speed of 2 m/s in 10 cm height was generated by means of a ventilating fan. Particulate matter binding capacity of different greening mats was determined as difference between the particle concentration after application of the dust (concentration maximum) and the concentration at the end of the trial. After 90-minute dust exposition, significantly lower dust concentrations in the chamber were registered in the treatments with Sedum mats compared to the controls (reductions from: 11.3?% in the fraction of 0.3 µm, 30.9?% in the fraction of 0.5 µm and 33.4?% in the fraction of 1 µm particles). None of the mat variations could bind the particulate matter in the fraction of 0.3 µm under wind speed of 2 m/s. However, the moss as well as the Sedum mats reduced the particulate matter concentration of both, 0.5 and 1 µm fractions, under wind significantly compared to the controls. The high filter performance of Sedum can be explained due to the high surface of the plants. To what extent plants can bind or uptake particulate matter under outdoor conditions permanently cannot be cleared in this experiment. However, the system allows to measure differences in binding capacity for different rooftop greening sytems.     

Sub‐lethal effects of imidacloprid on bumblebees,Bombus terrestris (Hymenoptera: Apidae), during a laboratory feeding test

A laboratory feeding test was conducted on queenless micro‐colonies of three bumblebee workers (Bombus terrestris L) to study the effects of low doses of imidacloprid on pollen and syrup consumption, worker survival, brood size and larval development. Two doses were used: D1 = 10 µg AI kg⁻¹ in syrup and 6 µg AI kg⁻¹ in pollen; D2 was 2.5 times higher in syrup and 2.7 higher in pollen. During 85 days 27, 30 and 29 micro‐colonies were reared for control, D1 and D2 treatments respectively. Food consumption was not affected by either dose. During the 5‐day pre‐oviposition period the mean insecticide intake was 4.8 ng per day per worker in treatment D2. Both doses slightly but significantly affected worker survival rate by 10% during the first month, without any dose‐effect relationship. Brood production was significantly reduced in D1 treatment and larval ejection by workers was significantly lower in D1 and D2 than in control. No significant effect of D1 and D2 treatments on the duration of larval development was revealed. No residue could be detected in workers still alive after 85 days. It was concluded that the survival rate and reproductive capacity of B terrestris was not likely to be affected by prolonged ingestion of nectar produced by sunflower after seed‐dressing treatment with imidacloprid (Gaucho), since honey or pollen collected by honeybees foraging treated sunflower never revealed concentrations of imidacloprid higher than 10 µg kg⁻¹. © 2000 Society of Chemical Industry     

Laboratory and field evaluation of spinosad against the gypsy moth,Lymantria dispar

The toxicity of the naturally derived insecticide spinosad was tested against the gypsy moth, Lymantria dispar. Bioassays using red oak leaf disks, treated with spinosad in a Potter spray tower, yielded an LC₅₀ value of 0.0015 µg AI cm⁻² (3‐day exposure; 13‐day evaluation; 2nd instar larvae). Applied to foliage to run‐off in the laboratory (potted red oak seedlings) and the field (4 m‐tall birch trees), spinosad effectively controlled 2nd instar larvae at concentrations ranging from 3 to 50 mg litre⁻¹. Toxicity in the laboratory, and efficacy and persistence in the field, were comparable to those achieved with the insecticide permethrin. Laboratory studies supported field observations that control was achieved in part by knockdown due to paralysis. In addition, laboratory results demonstrated that crawling contact activity may play an important role in field efficacy; 50% of treated larvae were paralyzed 16 h after a 2‐min crawling exposure to glass coated with a 4 mg litre⁻¹ spinosad solution. © 2000 Society of Chemical Industry     

The mode of action of RH‐1965: a new phenylpyrimidinone bleaching herbicide

RH‐1965 is a new bleaching herbicide which causes newly developing leaf tissue to emerge devoid of photosynthetic pigments. Mode‐of‐action studies revealed that RH‐1965 inhibited the accumulation of both total chlorophyll and β‐carotene. Concomitantly, it induced the accumulation of the β‐carotene precursors, phytoene, phytofluene and, in particular, ξ‐carotene. Inhibition of chlorophyll accumulation by RH‐1965 is attributed to the photo‐oxidative destruction of chlorophyll in the absence of β‐carotene because RH‐1965 blocked chlorophyll accumulation to a greater extent under high light (50–330 µE m⁻² s⁻¹) than under low light (0.8 µE m⁻² s⁻¹) conditions. Radish (Raphanus sativus L) and barnyardgrass (Echinochloa crus‐galli (L) Beauv) were very senstive to RH‐1965. Under high light (330 µE m⁻² s⁻¹), the I₅₀ values for inhibition of chlorophyll accumulation were 0.10 and 0.15 µM , respectively. Wheat (Triticum aestivus L), on the other hand, was much less sensitive to RH‐1965 (I₅₀ = 1.4 µM ). It is concluded that the mode of action of RH‐1965 involves the inhibition of ξ‐carotene desaturation. © 2000 Society of Chemical Industry     

Toxicity of formic acid to red imported fire ants, Solenopsis invicta Buren

BACKGROUND: Ants often compete with other ants for resources. Although formic acid is a common defensive chemical of formicine ants, it does not occur in any other subfamilies in Formicidae. No information on toxicity of formic acid to red imported fire ants, Solenopsis invicta, is available. This study examined its contact and fumigation toxicity to S. invicta in the laboratory. RESULTS: In a contact toxicity bioassay, 24 h LD₅₀ values of formic acid for workers ranged from 124.54 to 197.71 µg ant⁻¹. Female alates and queens were much less sensitive to formic acid than workers. At a concentration of 271.72 µg ant⁻¹, which killed 81.09 ± 16.04% of workers, the 24 h mortality was up to 39.64% for female alates and 38.89% for queens. In fumigation bioassays, 24 h LC₅₀ values ranged from 0.26 to 0.50 µg mL⁻¹ for workers, 0.32 µg mL⁻¹ for male alates and 0.70 µg mL⁻¹ for female alates. Complete mortality (100%) in queens occurred 24 h after they had been exposed to 1.57 µg mL⁻¹ of formic acid. At a concentration of 2.09 µg mL⁻¹, KT₅₀ values ranged from 23.03 to 43.85 min for workers, from 37.84 to 58.37 min for male alates, from 86.06 to 121.05 min for female alates and from 68.00 to 85.92 min for queens. CONCLUSION: When applied topically, formic acid was significantly less toxic than bifenthrin to red imported fire ants. Although its fumigation toxicity was lower than that of dichlorvos, formic acid had about an order of magnitude higher toxicity to S. invicta than to other insects studied so far. It may be worth investigating the use of formic acid for managing imported fire ants. Published 2012 by John Wiley & Sons, Ltd.     

Photodecomposition of chlorothalonil in benzene

Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) in benzene was photodecomposed by sunlight or low energy ultraviolet irradiation to a monophenyl adduct identified as 3,5,6-trichlorobiphenyl-2,4-dicarbonitrile. However, irradiation with a 100-W high-energy ultraviolet lamp yielded an additional compound identified as 2′, 5′ -dichloro-m-terphenyl-4′, 6′-dicarbonitrile. Photolysis was followed by a steady decrease in the chlorothalonil and monophenyl adduct concentrations, with a concomitant increase in the diphenyl adduct.     

Diversity and population dynamics of Penicillium spp. on apples in pre- and postharvest environments: consequences for decay development

Isolates of Penicillium spp. were collected regularly from 2001 to 2003 from the surfaces of apple fruit pre- and postharvest, and from the atmosphere of orchards and storage rooms in France. Penicillium spp. were not detected from the atmosphere of conventional orchards, while their density did not exceed 50 spores m⁻³ in the atmosphere of organically managed orchards. Penicillium spp. were seldom detected on apple surfaces in the orchard. The density of Penicillium on apples increased from 10 to 50 spores cm⁻² after 1 month in storage to 300–400 spores cm⁻² after 6 months. The level of airborne Penicillium increased by up to 2 × 10⁴ and 2·5 × 10³ spores m⁻³ within nondisinfected and previously disinfected warehouses, respectively. Penicillium expansum (30–62%) and P. solitum (6–45%) were the most prevalent species on apple or in storage rooms. Other species of Penicillium isolated included P. commune, P. verrucosum, P. chrysogenum, P. rugulosum and P. digitatum. Apple fruit were also surveyed for wounds and the number of open lenticels using the sulphur dioxide test. The incidence of wounding at harvest varied from 12 to 36%, depending on cultivar and locality. When apples were inoculated at harvest by either aqueous or aerial inoculum of P. expansum, the decay incidence was constantly higher than the incidence of wounding. The number of open lenticels per cm² of apple surface varied from 0·5 on cv. Boskoop to 4·4 on cv. Golden Delicious. An average of 13 and 2·1% of lenticels, respectively, were infected when they were inoculated by P. expansum and P. verrucosum. Cultivars of apple fruit that showed a greater number of open lenticels, combined with a large diameter varying from 100 to 200 µm, were more susceptible to P. expansum.