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Lum G.B.,University of Guelph | DeEll J.R.,Ontario Ministry of Agriculture Food and Rural Affairs | Hoover G.J.,University of Guelph | Subedi S.,University of Guelph | And 2 more authors.
Postharvest Biology and Technology | Year: 2017

European pears (Pyrus communis L.) are stored under low temperatures to extend postharvest life. Unfortunately, senescent scald and internal breakdown are likely to occur with prolonged exposure to storage. Both disorders can be reduced by controlled atmosphere (CA) and/or the ripening inhibitor, 1-methylcylcopropene (1-MCP). The principal aim of this study was to investigate the effect of 1-MCP and CA on fruit quality, including physiological disorders, and oxidative stress metabolites in stored ‘Cold Snap’ and ‘Swiss Bartlett’ pears. Freshly harvested pears were treated with or without 1-MCP, and then stored at 0 °C under refrigerated air or CA (18 kPa or 2.5 kPa O2, and 2 kPa CO2) for at least 167 d. 1-MCP and CA delayed and/or reduced the rates of ethylene production in stored fruit of both cultivars. 1-MCP and CA delayed fruit softening and peel yellowing in ‘Swiss Bartlett’ pears, but had negligible to slight effects with ‘Cold Snap’. In both cultivars, high incidences of senescent scald and internal breakdown occurred in non-1-MCP-treated pears during refrigerated air storage. For the most part these symptoms were reduced by CA and 1-MCP, resulting in minimal to negligible incidence in 1-MCP-treated pears stored at 2.5 kPa O2. γ-Aminobutyrate accumulated in stored pears, although 1-MCP and CA slightly reduced the levels in ‘Cold Snap’ fruit and 1-MCP increased levels in ‘Swiss Bartlett’ fruit. Ascorbate (total and reduced) levels were rapidly depleted in ‘Cold Snap’ fruit, regardless of treatment; these levels were better maintained in 1-MCP-treated ‘Swiss Bartlett’ fruit than control fruit across all storage atmospheres. In both cultivars, glutathione (total and reduced) concentrations and redox status fluctuated during storage, although these levels were generally higher in 1-MCP-treated fruit. Moreover, glutathione depletion occurred in advance of the development of senescence disorders in stored pear fruit. © 2017 Elsevier B.V.


Balde H.,Agriculture and Agri Food Canada | VanderZaag A.C.,Agriculture and Agri Food Canada | Burtt S.D.,Agriculture and Agri Food Canada | Wagner-Riddle C.,University of Guelph | And 3 more authors.
Bioresource Technology | Year: 2016

Methane (CH4) emissions were measured over two years at an earthen storage containing digestate from a mesophilic biodigester in Ontario, Canada. The digester processed dairy manure and co-substrates from the food industry, and destroyed 62% of the influent volatile solids (VS). Annual average emissions were 19 g CH4 m-3 d-1 and 0.27 g CH4 kg-1 VS d-1. About 76% of annual emissions occurred from June to October. Annual cumulative emissions from digestate corresponded to 12% of the CH4 produced within the digester. A key contributor to CH4 emissions was the sludge layer in storage, which contained as much VS as the annual discharge from the digester. These findings suggest that digestate management provides an opportunity to further enhance the benefits of biogas (i.e. reducing CH4 emissions compared to undigested liquid manure, and producing renewable energy). Potential best practices for future study include complete storage emptying, solid-liquid separation, and storage covering. © 2016 Elsevier Ltd.


PubMed | Environment Canada, University of Guelph, Ontario Ministry of Agriculture Food and Rural Affairs and Agriculture and Agri Food Canada
Type: | Journal: Bioresource technology | Year: 2016

Methane (CH4) emissions were measured over two years at an earthen storage containing digestate from a mesophilic biodigester in Ontario, Canada. The digester processed dairy manure and co-substrates from the food industry, and destroyed 62% of the influent volatile solids (VS). Annual average emissions were 19gCH4m(-3)d(-1) and 0.27gCH4kg(-1)VSd(-1). About 76% of annual emissions occurred from June to October. Annual cumulative emissions from digestate corresponded to 12% of the CH4 produced within the digester. A key contributor to CH4 emissions was the sludge layer in storage, which contained as much VS as the annual discharge from the digester. These findings suggest that digestate management provides an opportunity to further enhance the benefits of biogas (i.e. reducing CH4 emissions compared to undigested liquid manure, and producing renewable energy). Potential best practices for future study include complete storage emptying, solid-liquid separation, and storage covering.


DeEll J.R.,Ontario Ministry of Agriculture Food and Rural Affairs | Ehsani-Moghaddam B.,Ontario Ministry of Agriculture Food and Rural Affairs | Bowen A.J.,Vineland Research and Innovation Center | Lesschaeve I.,Vineland Research and Innovation Center
Acta Horticulturae | Year: 2015

The objective of this study was to investigate the effects of 1- methylcyclopropene (1-MCP) and controlled atmosphere (CA) storage on the physical and sensory quality of 'Honeycrisp' apples during storage. Fruit were harvested from a commercial orchard, treated with or without 1-MCP (1 μlL-1) for 24 h at 8-10°C, held for 5 days at 10°C, and then stored at 3°C in air or CA (3.0 kPa O2 + 1.5 kPa CO2) for 8 months. Physical and sensory attributes were evaluated during subsequent holding at room temperature (~22°C) within 1 week. 'Honeycrisp' stored in CA or treated with 1-MCP had lower IEC and higher SSC. Fruit held in CA also had less peel greasiness, while those treated with 1-MCP had higher titratable acidity. The interaction of 1-MCP×CA resulted in inconsistent differences in fruit firmness. Internal CO2 injury was the most prevalent disorder, with the highest incidence in apples treated with 1-MCP and stored in CA. Sensory evaluations revealed that 'Honeycrisp' treated with 1-MCP had lower perceived intensities of oxidized red apple, earthy flavours, skin thickness and chewy textures than their counterparts without 1-MCP. In addition, apples treated with 1-MCP were rated overall as higher in lemony, fresh green apple flavours and acid taste. Fruit not treated with 1-MCP and stored in air were rated higher for oxidized red apple, earthy flavours compared to all other fruit, while CA-stored apples with 1-MCP were rated the highest for fresh green apple flavour and acid taste.


Dorea F.C.,University of Prince Edward Island | Revie C.W.,University of Prince Edward Island | McEwen B.J.,University of Guelph | McNab W.B.,Ontario Ministry of Agriculture Food and Rural Affairs | And 2 more authors.
Preventive Veterinary Medicine | Year: 2013

The practice of disease surveillance has shifted in the last two decades towards the introduction of systems capable of early detection of disease. Modern biosurveillance systems explore different sources of pre-diagnostic data, such as patient's chief complaint upon emergency visit or laboratory test orders. These sources of data can provide more rapid detection than traditional surveillance based on case confirmation, but are less specific, and therefore their use poses challenges related to the presence of background noise and unlabelled temporal aberrations in historical data. The overall goal of this study was to carry out retrospective analysis using three years of laboratory test submissions to the Animal Health Laboratory in the province of Ontario, Canada, in order to prepare the data for use in syndromic surveillance. Daily cases were grouped into syndromes and counts for each syndrome were monitored on a daily basis when medians were higher than one case per day, and weekly otherwise. Poisson regression accounting for day-of-week and month was able to capture the day-of-week effect with minimal influence from temporal aberrations. Applying Poisson regression in an iterative manner, that removed data points above the predicted 95th percentile of daily counts, allowed for the removal of these aberrations in the absence of labelled outbreaks, while maintaining the day-of-week effect that was present in the original data. This resulted in the construction of time series that represent the baseline patterns over the past three years, free of temporal aberrations. The final method was thus able to remove temporal aberrations while keeping the original explainable effects in the data, did not need a training period free of aberrations, had minimal adjustment to the aberrations present in the raw data, and did not require labelled outbreaks. Moreover, it was readily applicable to the weekly data by substituting Poisson regression with moving 95th percentiles. © 2012 Elsevier B.V.


Guo X.,Agriculture and Agri Food Canada | Hao X.,Agriculture and Agri Food Canada | Zheng J.M.,Agriculture and Agri Food Canada | Little C.,Agriculture and Agri Food Canada | Khosla S.,Ontario Ministry of Agriculture Food and Rural Affairs
Acta Horticulturae | Year: 2016

High pressure sodium (HPS) lamps have traditionally been the main light source for supplemental lighting in greenhouse crop production because of high reliability and efficiency in producing photosynthetically active radiation (PAR). The light spectrum of HPS has reduced blue light in comparison to sunlight. Therefore, plant growth and development could be benefited from an alternative light source with a spectrum similar to sunlight and containing more blue light, such as the recently developed plasma lamps. Some growth chamber studies reveal that plant growth and development was indeed better under plasma light in comparison to HPS, when plasma light was used as the sole overhead light source. Plant responses to plasma in greenhouse conditions could be different because the plant is also exposed to natural solar radiation. Therefore, this study investigated the impacts of plasma light on greenhouse-grown mini cucumber (Cucumis sativus L. 'Picowell') growth, fruit yield and quality, in comparison to HPS light over two winter seasons (October 2012 to March 2013 and October 2014 to April 2015) in a 200-m2 greenhouse. The greenhouse was divided into 4 sections (50 m2 in each section); two sections were fitted with plasma light while the other two sections had HPS (2 replications). Both lighting types provided the same amount of PAR (165 μmol m-2 s-1). For both seasons, the total fruit yield was not affected by lamp type. However, in the first season (October 2012 to March 2013), the cumulative marketable fruit yield under plasma was significantly greater than that under HPS light. Due to the different impacts of light type on marketable fruit yield during the two winter season, future research should focus on the effect of solar radiation on choosing the proper light source in year-round greenhouse vegetable production with supplemental light.


Schaafsma A.,University of Guelph | Limay-Rios V.,University of Guelph | Baute T.,Ontario Ministry of Agriculture Food and Rural Affairs | Smith J.,University of Guelph | Xue Y.,University of Guelph
PLoS ONE | Year: 2015

Neonicotinoid insecticides have come under scrutiny for their potential unintended effects on non-target organisms, particularly pollinators in agro-ecosystems. As part of a larger study of neonicotinoid residues associated with maize (corn) production, 76 water samples within or around the perimeter of 18 commercial maize fields and neighbouring apiaries were collected in 5 maize-producing counties of southwestern Ontario. Residues of clothianidin (mean = 2.28, max. = 43.60 ng/mL) and thiamethoxam (mean = 1.12, max. = 16.50 ng/mL) were detected in 100 and 98.7%of the water samples tested, respectively. The concentration of total neonicotinoid residues in water within maize fields increased six-fold during the first five weeks after planting, and returned to pre-plant levels seven weeks after planting. However, concentrations in water sampled from outside the fields were similar throughout the sampling period. Soil samples from the top 5 cm of the soil profile were also collected in these fields before and immediately following planting. The mean total neonicotinoid residue was 4.02 (range 0.07 to 20.30) ng/g, for samples taken before planting, and 9.94 (range 0.53 to 38.98) ng/g, for those taken immediately after planting. Two soil samples collected from within an conservation area contained detectable (0.03 and 0.11 ng/g) concentrations of clothianidin. Of three drifted snow samples taken, the drift stratum containing the most wind-scoured soil had 0.16 and 0.20 ng/mL mainly clothianidin in the melted snow. The concentration was at the limit of detection (0.02 ng/mL) taken across the entire vertical profile. With the exception of one sample, water samples tested had concentrations below those reported to have acute, chronic or sublethal effects to honey bees. Our results suggest that neonicotinoids may move off-target by wind erosion of contaminated soil. These results are informative to risk assessment models for other non-target species in maize agro-ecosytems. © 2015 Schaafsma et al.


Medhanie G.A.,University of Guelph | McEwen S.A.,University of Guelph | Weber L.,Lloyd Weber Consulting Services | Sanei B.,Ontario Ministry of Agriculture Food and Rural Affairs | And 5 more authors.
Preventive Veterinary Medicine | Year: 2013

Brachyspira species are frequent colonizers of the gastrointestinal tract in a variety of domestic animals, including birds. In chickens, Brachyspira species are associated with a clinical condition known as avian intestinal spirochetosis (AIS), a disease characterized by chronic diarrhoea, weight loss, low egg production, and faecal-stained eggs. The purpose of this study was to identify risk factors associated with the presence of Brachyspira species in Ontario layer chicken flocks. Pooled faecal samples were collected from 89 flocks from 58 farms between August 2010 and February 2011; 52 flocks were classified as dirty flocks (history of downgrades for dirty eggs) and 37 were classified as clean flocks (no history of downgrades for dirty eggs). A questionnaire related to management, biosecurity practices, and antimicrobial use was administered prior to sample collection. Using real-time polymerase chain reaction; 63.5% of the dirty flocks and 24.3% of the clean flocks were positive for Brachyspira species.A logistic regression model with a random effect for farm showed that the odds of Brachyspira species for flocks≥60 weeks of age were higher than for flocks≤34 weeks (OR=9.3; P=0.014). The odds of Brachyspira species in flocks housed in A-frame cages with manure curtains (OR=20.0; P=0.002) and flocks from multi-age farms (OR=8.5; P=0.001) were higher than for flocks in cage-stacked houses and from single-age farms, respectively. The odds of Brachyspira species for flocks housed in barns≥30 years old was lower than for flocks housed in barns≤14 years old (OR=0.1; P=0.002). The calculated intra-class correlation coefficient was 5.6×10-14; the notably low proportion of variation among farms after the fixed effects were included in the model suggests that the farm-level variable (multi-age farm) included in the final model accounted for most of the farm-to-farm variation in Brachyspira presence. Therefore, it is recommended that strict biosecurity, and between-flock decontamination efforts to reduce the infection pressure, be followed on farms with multiple flocks of different ages to avoid transmission of the bacteria between flocks. © 2012 Elsevier B.V.


Dorea F.C.,University of Prince Edward Island | McEwen B.J.,University of Guelph | McNab W.B.,Ontario Ministry of Agriculture Food and Rural Affairs | Revie C.W.,University of Prince Edward Island | Sanchez J.,University of Prince Edward Island
Journal of the Royal Society Interface | Year: 2013

Diagnostic test orders to an animal laboratory were explored as a data source for monitoring trends in the incidence of clinical syndromes in cattle. Four years of real data and over 200 simulated outbreak signals were used to compare pre-processing methods that could remove temporal effects in the data, as well as temporal aberration detection algorithms that provided high sensitivity and specificity. Weekly differencing demonstrated solid performance in removing day-of-week effects, even in series with low daily counts. For aberration detection, the results indicated that no single algorithm showed performance superior to all others across the range of outbreak scenarios simulated. Exponentially weighted moving average charts and Holt-Winters exponential smoothing demonstrated complementary performance, with the latter offering an automated method to adjust to changes in the time series that will likely occur in the future. Shewhart charts provided lower sensitivity but earlier detection in some scenarios. Cumulative sum charts did not appear to add value to the system; however, the poor performance of this algorithm was attributed to characteristics of the data monitored. These findings indicate that automated monitoring aimed at early detection of temporal aberrations will likely be most effective when a range of algorithms are implemented in parallel. © 2013 The Author(s) Published by the Royal Society. All rights reserved.


PubMed | University of Guelph and Ontario Ministry of Agriculture Food and Rural Affairs
Type: Journal Article | Journal: PloS one | Year: 2015

Neonicotinoid insecticides have come under scrutiny for their potential unintended effects on non-target organisms, particularly pollinators in agro-ecosystems. As part of a larger study of neonicotinoid residues associated with maize (corn) production, 76 water samples within or around the perimeter of 18 commercial maize fields and neighbouring apiaries were collected in 5 maize-producing counties of southwestern Ontario. Residues of clothianidin (mean = 2.28, max. = 43.60 ng/mL) and thiamethoxam (mean = 1.12, max. = 16.50 ng/mL) were detected in 100 and 98.7% of the water samples tested, respectively. The concentration of total neonicotinoid residues in water within maize fields increased six-fold during the first five weeks after planting, and returned to pre-plant levels seven weeks after planting. However, concentrations in water sampled from outside the fields were similar throughout the sampling period. Soil samples from the top 5 cm of the soil profile were also collected in these fields before and immediately following planting. The mean total neonicotinoid residue was 4.02 (range 0.07 to 20.30) ng/g, for samples taken before planting, and 9.94 (range 0.53 to 38.98) ng/g, for those taken immediately after planting. Two soil samples collected from within an conservation area contained detectable (0.03 and 0.11 ng/g) concentrations of clothianidin. Of three drifted snow samples taken, the drift stratum containing the most wind-scoured soil had 0.16 and 0.20 ng/mL mainly clothianidin in the melted snow. The concentration was at the limit of detection (0.02 ng/mL) taken across the entire vertical profile. With the exception of one sample, water samples tested had concentrations below those reported to have acute, chronic or sublethal effects to honey bees. Our results suggest that neonicotinoids may move off-target by wind erosion of contaminated soil. These results are informative to risk assessment models for other non-target species in maize agro-ecosytems.

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