Carrots (Daucus carota L.) are grown in all regions of Canada, and the province of Ontario is the... more Carrots (Daucus carota L.) are grown in all regions of Canada, and the province of Ontario is the largest producer. Heterodera carotae Jones, 1950 is a plant-parasitic nematode commonly known as the carrot cyst nematode. Its distribution is limited to a few countries in Europe, and the state of Michigan in the U.S.A. (CABI 2015; Jones 1950). It can cause serious damage to carrot crops, is only known to infect carrots and wild carrots, and is considered an exotic plant-parasitic nematode to Canada. In recent years, poor growth of carrots in the Holland Marsh region, Simcoe County, Ontario, an important carrot growing region of the province with histosol soil, has caught the attention of farmers and researchers. In 2011, 2014, and 2016, soil and root samples were collected from two carrot fields near the Muck Crops Research Station (44°2′29.69″N, 9°35′55.30″W), where stunted growth, smaller and forked carrots (apex roots) with a proliferation of secondary roots, in some cases with visible cysts, were observed. Nematodes were extracted using Baermann funnel for vermiform nematodes and Fenwick method for cysts from those samples. Second-stage juveniles (J2), males, and cysts were recovered. The J2 populations ranged from 200 to 300 individuals per kg soil, with fewer cysts and males. Steam-sterilized soil planted with a common carrot cultivar Cellobunch was infested with 100 J2 hand-picked from the soil extractions in 1 kg soil per pot with three replicates. After 80 days of growing in the greenhouse, averages of 814 J2, 15 cysts, and 15 males were recovered. Using morphological and molecular methods, the species was identified both at the University of Manitoba and Agriculture and Agri-Food Canada as H. carotae. The cysts were lemonshaped with a distinct neck and vulva cone, ambifenestrate, without bullae, and an underbridge was observed in one specimen. The key morphometric characters of the cysts
BACKGROUNDCarrot weevil is an important pest throughout carrot‐producing regions in Canada. Pesti... more BACKGROUNDCarrot weevil is an important pest throughout carrot‐producing regions in Canada. Pesticides to control carrot weevil adults require application when the majority of adults have emerged and often this occurs after oviposition has already commenced and damage will be realized. One alternative to conventional pesticides are entomopathogenic nematodes. We studied four commercially available entomopathogenic nematode products (Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora) for efficacy against carrot weevil in Nova Scotia and Ontario carrot fields in 2017 and 2018. The longevity and infectivity of the products in fine sandy loam soil (Ontario) and sandy loam soil (Nova Scotia) were evaluated using Galleria mellonella larvae.RESULTSIn Nova Scotia soils, only S. kraussei when applied twice, showed some efficacy to reduce damage from carrot weevil in 2017. In Ontario, an early application of H. bacteriophora and S. feltiae significantly reduce...
Onion lines were evaluated for resistance to Allium white rot (Sclerotium cepivorum Berk.) and on... more Onion lines were evaluated for resistance to Allium white rot (Sclerotium cepivorum Berk.) and onion maggot [Delia antigua (Meig.)] in field plots established on organic soil in the Bradford Marsh, Ontario. White rote valuations were conducted on 20 lines in 1992–1994, with follow-up laboratory trials in 1995. Onion maggot screening was conducted on these same lines in 1993 and 1994. Plots were arranged in a randomized complete-block design with four replications per line. Significant differences in susceptibility to white rot were found in 1992 and 1993, while differences in onion maggot resistance were identified in 1993 and 1994. Commercial cultivars Norstar and Fortress had relatively low levels of onion maggot damage and Fortress demonstrated some tolerance to white rot. Other lines with low levels of white rot infection were 1292-91, 1564-91, 124-93, 116-93, and 117-93, from the breeding program at the Univ. of Wisconsin. Line 1292-91 also had low levels of onion maggot damage...
Changes in pesticide availability require that new compounds be tested for their efficacy in cont... more Changes in pesticide availability require that new compounds be tested for their efficacy in control of pests and pathogens on important vegetable crops. A study was conducted to determine the effectiveness of combinations of the insecticides LORSBAN® 15G (chlorpyrifos), GOVERNOR® 75WP (cyromazine), AZTEC® 2/0.1G (phosetbupirin + cyfluthrin) and REGENT® 80WG (fipronil), and the fungicides PRO-GRO® 30/50D (carbathiin + thiram), DITHANE
... Evaluation of Vesicular Arbuscular Mycorrhizae (vam) as a Biological Control of White Rot Scl... more ... Evaluation of Vesicular Arbuscular Mycorrhizae (vam) as a Biological Control of White Rot Sclerotium cepivorum (Berk) on Onions, 2000. ... 93912-3037 USA Tel: (831) 751-3624 RZ Rijk Zwaan Export BV, PO Box 40,2678, 2G Delier, Holland Tel: 0174-532300 Sak Sakata Seed ...
Abstract Clubroot caused by Plasmodiophora brassicae has been reported at sites across North Amer... more Abstract Clubroot caused by Plasmodiophora brassicae has been reported at sites across North America on brassica vegetables for more than 50 years. However, it had not been reported on canola (Brassica napus) on the Canadian prairies until the initial discovery of a cluster of 12 infested fields near Edmonton AB in 2003. The purpose of this review is to consolidate and summarize the data on the spread of P. brassicae on canola in Canada since 2003, to compare this pattern of distribution with observations from an infested site in Ontario, and to draw inferences about the relative importance of short- and long-distance transmission of the pathogen on clubroot distribution in the prairie region. Over the last decade, P. brassicae has spread across central Alberta, with the leading edge of the epidemic moving at about 20 km per year, resulting in more than 1850 fields confirmed infested. DNA of the pathogen has also been detected from soil collected at sites across Saskatchewan and Manitoba, and very slight clubroot symptoms have been observed at isolated sites across the prairies. Transport of resting spores in soil carried on farm equipment has been shown to be an important mechanism of short-distance dissemination in this region. Dispersal of resting spores with wind-borne soil may also have an important role in both short- and long-distance dissemination. Dispersal on seed does not appear to be an important factor in clubroot spread. In contrast to the rapid spread observed in Alberta, P. brassicae is spreading very slowly, if at all, at the site in Ontario. This likely reflects the relatively small size and strength of the inoculum source and the absence of susceptible hosts nearby at the site in Ontario, relative to the thousands of hectares of heavily infested fields that provide a large, strong inoculum source in central Alberta.
Abstract A shift to larger farms, bigger equipment and reduced crop diversity has been occurring ... more Abstract A shift to larger farms, bigger equipment and reduced crop diversity has been occurring in North American agriculture for many years. This has resulted in an increased reliance on genetic resistance and pesticides because much of the pest reduction from natural biological control (ecosystem services) associated with crop rotation and biological diversity has been lost. This shift has contributed to erosion of cultivar resistance and loss of sensitivity to pesticides. However, the impending change to autonomous field equipment represents an opportunity to reverse the trend towards ever-larger farm equipment. Small autonomous units have the potential to make intercropping, deployment of multi-lines, precision agriculture and even crop rotation, easier and more cost-effective. Remote sensing using drones, combined with precision application of pesticides and improved weather forecasts to help select optimum conditions, could improve the efficacy of both biocontrol agents and synthetic pesticides. Similarly, technologies such as marker-assisted selection for complex traits, gene editing to provide novel sources of resistance, and RNAi (gene silencing) to manage target pest populations could reduce reliance on synthetic pesticides. Crop rotation and improved strategies for deploying genetic resistance, combined with smaller fields, improved scouting and optimized pesticide application, could shift the balance back towards biological diversity and natural biological control within fields. Adding improved genetics for resistance to this mix could further reduce the need for large-scale pesticide application, and minimize both the use and impact of synthetic pesticides in agricultural systems.
Deora, A., Gossen, B. D., Hwang, S. F., Pageau, D., Howard, R. J., Walley, F. and McDonald, M. R.... more Deora, A., Gossen, B. D., Hwang, S. F., Pageau, D., Howard, R. J., Walley, F. and McDonald, M. R. 2014. Effect of boron on clubroot of canola in organic and mineral soils and on residual toxicity to rotational crops. Can. J. Pant Sci. 94: 109–118. Application of boron (B) has been reported to reduce clubroot severity in various Brassica spp., but residual B can have phytotoxic effects on other crops in the rotation. The objective of this study was to test the efficacy of broadcast application of B for clubroot suppression in canola (B. napus) and the effect of residual B on wheat, barley, field pea and canola. Field trials to assess clubroot suppression by B at various rates (1 to 64 kg B ha−1) were conducted in organic (Ontario) and mineral soils (Alberta, Quebec) heavily infested with Plasmodiophora brassicae in 2011 and 2012. Phytotoxicity was not observed in canola until applications rates exceeded 48 kg B ha−1. Boron did not reduce clubroot incidence at any site, irrespective of rate, and only reduced severity at the organic soil site at 6 wk after seeding. There was a small increase in shoot weight and yield of canola with increasing B application rates at the organic soil site. The potential phytotoxicity of residual B (4 to 16 kg B ha−1) was assessed in mineral soils in Ontario and Saskatchewan in 2012. Toxicity symptoms were noted initially in most of the crops, but seedlings recovered quickly and there was no significant reduction in fresh weight at harvest or seed yield of most of the cultivars. The present study indicates that pre-plant broadcast application of B delays clubroot development and increases vegetative growth and yield compared with non-treated plants in organic soil. Also, even high residual rates (16 kg ha−1) of application are unlikely to have a negative effect on crops in rotation in mineral soil. However, the effect of B application on canola yield found in this study was not sufficient to justify application for commercial canola production, even where clubroot is prevalent.
Carrots (Daucus carota L.) are grown in all regions of Canada, and the province of Ontario is the... more Carrots (Daucus carota L.) are grown in all regions of Canada, and the province of Ontario is the largest producer. Heterodera carotae Jones, 1950 is a plant-parasitic nematode commonly known as the carrot cyst nematode. Its distribution is limited to a few countries in Europe, and the state of Michigan in the U.S.A. (CABI 2015; Jones 1950). It can cause serious damage to carrot crops, is only known to infect carrots and wild carrots, and is considered an exotic plant-parasitic nematode to Canada. In recent years, poor growth of carrots in the Holland Marsh region, Simcoe County, Ontario, an important carrot growing region of the province with histosol soil, has caught the attention of farmers and researchers. In 2011, 2014, and 2016, soil and root samples were collected from two carrot fields near the Muck Crops Research Station (44°2′29.69″N, 9°35′55.30″W), where stunted growth, smaller and forked carrots (apex roots) with a proliferation of secondary roots, in some cases with visible cysts, were observed. Nematodes were extracted using Baermann funnel for vermiform nematodes and Fenwick method for cysts from those samples. Second-stage juveniles (J2), males, and cysts were recovered. The J2 populations ranged from 200 to 300 individuals per kg soil, with fewer cysts and males. Steam-sterilized soil planted with a common carrot cultivar Cellobunch was infested with 100 J2 hand-picked from the soil extractions in 1 kg soil per pot with three replicates. After 80 days of growing in the greenhouse, averages of 814 J2, 15 cysts, and 15 males were recovered. Using morphological and molecular methods, the species was identified both at the University of Manitoba and Agriculture and Agri-Food Canada as H. carotae. The cysts were lemonshaped with a distinct neck and vulva cone, ambifenestrate, without bullae, and an underbridge was observed in one specimen. The key morphometric characters of the cysts
BACKGROUNDCarrot weevil is an important pest throughout carrot‐producing regions in Canada. Pesti... more BACKGROUNDCarrot weevil is an important pest throughout carrot‐producing regions in Canada. Pesticides to control carrot weevil adults require application when the majority of adults have emerged and often this occurs after oviposition has already commenced and damage will be realized. One alternative to conventional pesticides are entomopathogenic nematodes. We studied four commercially available entomopathogenic nematode products (Steinernema feltiae, S. carpocapsae, S. kraussei and Heterorhabditis bacteriophora) for efficacy against carrot weevil in Nova Scotia and Ontario carrot fields in 2017 and 2018. The longevity and infectivity of the products in fine sandy loam soil (Ontario) and sandy loam soil (Nova Scotia) were evaluated using Galleria mellonella larvae.RESULTSIn Nova Scotia soils, only S. kraussei when applied twice, showed some efficacy to reduce damage from carrot weevil in 2017. In Ontario, an early application of H. bacteriophora and S. feltiae significantly reduce...
Onion lines were evaluated for resistance to Allium white rot (Sclerotium cepivorum Berk.) and on... more Onion lines were evaluated for resistance to Allium white rot (Sclerotium cepivorum Berk.) and onion maggot [Delia antigua (Meig.)] in field plots established on organic soil in the Bradford Marsh, Ontario. White rote valuations were conducted on 20 lines in 1992–1994, with follow-up laboratory trials in 1995. Onion maggot screening was conducted on these same lines in 1993 and 1994. Plots were arranged in a randomized complete-block design with four replications per line. Significant differences in susceptibility to white rot were found in 1992 and 1993, while differences in onion maggot resistance were identified in 1993 and 1994. Commercial cultivars Norstar and Fortress had relatively low levels of onion maggot damage and Fortress demonstrated some tolerance to white rot. Other lines with low levels of white rot infection were 1292-91, 1564-91, 124-93, 116-93, and 117-93, from the breeding program at the Univ. of Wisconsin. Line 1292-91 also had low levels of onion maggot damage...
Changes in pesticide availability require that new compounds be tested for their efficacy in cont... more Changes in pesticide availability require that new compounds be tested for their efficacy in control of pests and pathogens on important vegetable crops. A study was conducted to determine the effectiveness of combinations of the insecticides LORSBAN® 15G (chlorpyrifos), GOVERNOR® 75WP (cyromazine), AZTEC® 2/0.1G (phosetbupirin + cyfluthrin) and REGENT® 80WG (fipronil), and the fungicides PRO-GRO® 30/50D (carbathiin + thiram), DITHANE
... Evaluation of Vesicular Arbuscular Mycorrhizae (vam) as a Biological Control of White Rot Scl... more ... Evaluation of Vesicular Arbuscular Mycorrhizae (vam) as a Biological Control of White Rot Sclerotium cepivorum (Berk) on Onions, 2000. ... 93912-3037 USA Tel: (831) 751-3624 RZ Rijk Zwaan Export BV, PO Box 40,2678, 2G Delier, Holland Tel: 0174-532300 Sak Sakata Seed ...
Abstract Clubroot caused by Plasmodiophora brassicae has been reported at sites across North Amer... more Abstract Clubroot caused by Plasmodiophora brassicae has been reported at sites across North America on brassica vegetables for more than 50 years. However, it had not been reported on canola (Brassica napus) on the Canadian prairies until the initial discovery of a cluster of 12 infested fields near Edmonton AB in 2003. The purpose of this review is to consolidate and summarize the data on the spread of P. brassicae on canola in Canada since 2003, to compare this pattern of distribution with observations from an infested site in Ontario, and to draw inferences about the relative importance of short- and long-distance transmission of the pathogen on clubroot distribution in the prairie region. Over the last decade, P. brassicae has spread across central Alberta, with the leading edge of the epidemic moving at about 20 km per year, resulting in more than 1850 fields confirmed infested. DNA of the pathogen has also been detected from soil collected at sites across Saskatchewan and Manitoba, and very slight clubroot symptoms have been observed at isolated sites across the prairies. Transport of resting spores in soil carried on farm equipment has been shown to be an important mechanism of short-distance dissemination in this region. Dispersal of resting spores with wind-borne soil may also have an important role in both short- and long-distance dissemination. Dispersal on seed does not appear to be an important factor in clubroot spread. In contrast to the rapid spread observed in Alberta, P. brassicae is spreading very slowly, if at all, at the site in Ontario. This likely reflects the relatively small size and strength of the inoculum source and the absence of susceptible hosts nearby at the site in Ontario, relative to the thousands of hectares of heavily infested fields that provide a large, strong inoculum source in central Alberta.
Abstract A shift to larger farms, bigger equipment and reduced crop diversity has been occurring ... more Abstract A shift to larger farms, bigger equipment and reduced crop diversity has been occurring in North American agriculture for many years. This has resulted in an increased reliance on genetic resistance and pesticides because much of the pest reduction from natural biological control (ecosystem services) associated with crop rotation and biological diversity has been lost. This shift has contributed to erosion of cultivar resistance and loss of sensitivity to pesticides. However, the impending change to autonomous field equipment represents an opportunity to reverse the trend towards ever-larger farm equipment. Small autonomous units have the potential to make intercropping, deployment of multi-lines, precision agriculture and even crop rotation, easier and more cost-effective. Remote sensing using drones, combined with precision application of pesticides and improved weather forecasts to help select optimum conditions, could improve the efficacy of both biocontrol agents and synthetic pesticides. Similarly, technologies such as marker-assisted selection for complex traits, gene editing to provide novel sources of resistance, and RNAi (gene silencing) to manage target pest populations could reduce reliance on synthetic pesticides. Crop rotation and improved strategies for deploying genetic resistance, combined with smaller fields, improved scouting and optimized pesticide application, could shift the balance back towards biological diversity and natural biological control within fields. Adding improved genetics for resistance to this mix could further reduce the need for large-scale pesticide application, and minimize both the use and impact of synthetic pesticides in agricultural systems.
Deora, A., Gossen, B. D., Hwang, S. F., Pageau, D., Howard, R. J., Walley, F. and McDonald, M. R.... more Deora, A., Gossen, B. D., Hwang, S. F., Pageau, D., Howard, R. J., Walley, F. and McDonald, M. R. 2014. Effect of boron on clubroot of canola in organic and mineral soils and on residual toxicity to rotational crops. Can. J. Pant Sci. 94: 109–118. Application of boron (B) has been reported to reduce clubroot severity in various Brassica spp., but residual B can have phytotoxic effects on other crops in the rotation. The objective of this study was to test the efficacy of broadcast application of B for clubroot suppression in canola (B. napus) and the effect of residual B on wheat, barley, field pea and canola. Field trials to assess clubroot suppression by B at various rates (1 to 64 kg B ha−1) were conducted in organic (Ontario) and mineral soils (Alberta, Quebec) heavily infested with Plasmodiophora brassicae in 2011 and 2012. Phytotoxicity was not observed in canola until applications rates exceeded 48 kg B ha−1. Boron did not reduce clubroot incidence at any site, irrespective of rate, and only reduced severity at the organic soil site at 6 wk after seeding. There was a small increase in shoot weight and yield of canola with increasing B application rates at the organic soil site. The potential phytotoxicity of residual B (4 to 16 kg B ha−1) was assessed in mineral soils in Ontario and Saskatchewan in 2012. Toxicity symptoms were noted initially in most of the crops, but seedlings recovered quickly and there was no significant reduction in fresh weight at harvest or seed yield of most of the cultivars. The present study indicates that pre-plant broadcast application of B delays clubroot development and increases vegetative growth and yield compared with non-treated plants in organic soil. Also, even high residual rates (16 kg ha−1) of application are unlikely to have a negative effect on crops in rotation in mineral soil. However, the effect of B application on canola yield found in this study was not sufficient to justify application for commercial canola production, even where clubroot is prevalent.
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