Abstract
North Dakota leads the United States in canola (Brassica napus L.) production (4). A canola field with a distinct patch of dead plants spreading over an area of approximately 0.4 ha was detected in Cavalier County, North Dakota, in early September 2013. Numerous spots within the patch had plant mortalities >80%. Dead plants pulled from the soil had roots with severe galling and clubbing. Clubbed roots were brittle and disintegrated easily when pressed between fingers. Root and soil samples collected at several locations within and outside the affected patch were pooled in separate groups. All plants collected in the patch were symptomatic but those collected outside were not. In the lab, total genomic DNA from three symptomatic and two healthy root samples was extracted using standard procedures and freehand slices were prepared for observation with a compound microscope. Also, DNA from pooled soil samples was extracted using FastDNA Spin Kit for Soil (MP Biomedicals, Solon, OH). Round resting structures ranging from 2.2 to 4.2 μm in diameter were observed by microscopic examination of symptomatic root tissues. These structures resembled those typically produced by Plasmodiophora brassicae Woronin. This initial identification was later confirmed through PCR analysis using the species specific primers TC1F/R and TC2F/R (1). PCR products of 548 bp (TC1F/R) and 519 bp (TC2F/R) were produced in the three symptomatic and two infested soil samples, confirming the presence of P. brassicae. PCR amplicons were not detected in healthy root and soil samples. Pathogenicity tests were conducted in greenhouse to fulfill Koch's postulates. Briefly, five square plastic pots (10 × 10 × 13 cm) were filled with a 10-cm layer of Sunshine Mix #1 potting mix (Fison Horticulture, Vancouver, BC, Canada) and then 1 g of ground root galls (approximately 5 × 10 5 resting spores) was spread evenly on its surface and covered with 2 cm of soilless mix. A similar number of pots were filled only with soilless mix and used as controls. All pots were planted with two seeds of canola cv. Westar and incubated in greenhouse conditions at 21°C and 16 h light daily. The experiment was conducted twice. Four weeks after planting, all plants in the inoculated pots had developed galls while plants in control pots were symptomless. Presence of P. brassicae resting spores in the newly developed galls was confirmed by microscopic observations and PCR. Based on the symptoms, morphology of resting spores, PCR reactions, and pathogenicity tests, we confirm the presence of P. brassicae on canola. While P. brassicae has been reported as widespread in North America (2), to our knowledge, this is the first report of clubroot on canola in North Dakota and the United States. Clubroot became the most important disease affecting canola production in central Alberta, Canada, within 5 years of its discovery in 2003 (3); since then, the disease has been detected in Saskatchewan and Manitoba (3), Canadian provinces that share borders with North Dakota. Considering the difficulties in management of clubroot, measures should be initiated to limit the spread of the disease before it could pose a threat to United States canola production. References: (1) T. Cao et al. Plant Dis. 91:80, 2007. (2) G. Dixon J. Plant Growth Regul. 28:194, 2009. (3) S. Strelkov and S. Hwang. Can. J. Plant Pathol. 36(S1):27, 2014. (4) USDA-NASS, Ag. Statistics No. 81, 2012.
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Claims 9
Claim · model-written summary
This is the first report of clubroot on canola in North Dakota and the United States.
- Taxon
- canola
.jpg?width=60)
Brassica napus var. napuse1 - Outcome
- first report of clubroote1
- Setting
- North Dakota and the United Statese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e1“this is the first report of clubroot on canola in North Dakota and the United States”
Claim · model-written summary
Numerous spots within the affected canola patch had plant mortalities above 80%.
- Taxon
- canolaBrassica napus var. napuse0
- Outcome
- plant mortalitiese1
- Value
- >80%e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“Numerous spots within the patch had plant mortalities >80%”
Claim · model-written summary
Dead canola plants had roots with severe galling and clubbing.
- Taxon
- canolaBrassica napus var. napuse0
- Organ / stage
- rootse1
- Outcome
- severe galling and clubbinge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“Dead plants pulled from the soil had roots with severe galling and clubbing”
Claim · model-written summary
Round resting structures 2.2 to 4.2 um in diameter, resembling those of Plasmodiophora brassicae, were observed in symptomatic root tissues.
- Taxon
- canolaBrassica napus var. napuse0
- Organ / stage
- symptomatic root tissuese1
- Outcome
- Round resting structurese1
- Value
- 2.2 to 4.2 μm in diametere1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“Round resting structures ranging from 2.2 to 4.2 μm in diameter were observed by microscopic examination of symptomatic root tissues”
Claim · model-written summary
Species-specific PCR produced products of 548 bp and 519 bp in the three symptomatic root and two infested soil samples, confirming the presence of P. brassicae.
- Taxon
- canolaBrassica napus var. napuse0
- Interactor
- P. brassicae
.jpg?width=60)
Plasmodiophora brassicaee1pathogen - Outcome
- PCR productse1
- Value
- 548 bp (TC1F/R) and 519 bp (TC2F/R)e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“canola (Brassica napus L.)”
e1“PCR products of 548 bp (TC1F/R) and 519 bp (TC2F/R) were produced in the three symptomatic and two infested soil samples, confirming the presence of P. brassicae”
Claim · model-written summary
PCR amplicons were not detected in healthy root and soil samples.
- Taxon
- canolaBrassica napus var. napuse0
- Organ / stage
- healthy roote1
- Outcome
- PCR ampliconse1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“PCR amplicons were not detected in healthy root and soil samples”
Claim · model-written summary
In the greenhouse pathogenicity test, all plants in inoculated pots developed galls four weeks after planting, while plants in control pots were symptomless.
- Taxon
- canolaBrassica napus var. napuse0
- Treatment
- inoculated potse1
- Outcome
- developed gallse1
- Comparator
- control potse1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“Four weeks after planting, all plants in the inoculated pots had developed galls while plants in control pots were symptomless”
Claim · model-written summary
P. brassicae resting spores were confirmed in the newly developed galls by microscopy and PCR.
- Taxon
- canolaBrassica napus var. napuse0
- Organ / stage
- newly developed gallse1
- Interactor
- P. brassicaePlasmodiophora brassicaee1pathogen
- Outcome
- P. brassicae resting sporese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“canola (Brassica napus L.)”
e1“Presence of P. brassicae resting spores in the newly developed galls was confirmed by microscopic observations and PCR”
Claim · model-written summary
The authors recommend that measures be initiated to limit the spread of clubroot before it threatens United States canola production.
- Taxon
- canolaBrassica napus var. napuse1
- Outcome
- limit the spread of the diseasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“measures should be initiated to limit the spread of the disease before it could pose a threat to United States canola production”
The same questions in other papers
inoculation · pest · Brassica napus (oilseed rape)Positive and negative results
1 paper in the same direction as this paper · 5 in the opposite direction
- negative
- negative
- negative
3 papers more in this group
See all 7 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.