Rhizoctonia Solani Ag 8 Associated With Stunted Onion Patches in South Australia

Anstis, S.T.; Wicks, Trevor; Pederick, S.

doi:10.17660/actahortic.2012.969.33

Cited by 3 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 and 2, respectively). Disease severity caused by R. solani AG 8 was expressed as the degree of stunting (Anstis et al, 2012;Patzek et al, 2013), i.e., the reduction in height of onion plants inoculated with R. solani AG 8 vs. that of noninoculated plants of the same genotype.…”

Section: Resultsmentioning

confidence: 99%

“…The fact that a majority of the 35 onion genotypes screened in this study were susceptible to R. solani AG 8 corroborates empirical observations of onion growers in the Columbia Basin that all storage type cultivars grown under conditions conducive to onion stunting in this region can develop patches of stunted plants, as well as the yield loss study by Sharma-Poudyal et al (2015) which documented significant yield reductions caused by onion stunting for each of six cultivars commonly grown in the Columbia Basin. It may be necessary to screen more diverse Allium germplasm, e.g., wild Allium relatives, to identify resistance to onion stunting that can be incorporated into cultivars suitable for the Columbia Basin and other regions of the world where onion stunting occurs, such as Australia (Anstis et al, 2012;Wicks et al, 2011).…”

Section: Resultsmentioning

confidence: 99%

“…Although R. solani AG 8 infects onion plants during the seedling phase of growth, the infections do not affect plant stand (Patzek et al, 2013). Therefore, the numbers of bulbs harvested from stunted patches vs. healthy areas of the field do not differ (Sharma-Poudyal et al, 2013b;Sharma-Poudyal et al, 2015) but bulb size and marketable yield are affected adversely (Anstis et al, 2012;Sharma-Poudyal et al, 2013b;Sharma-Poudyal et al, 2015). In a yield loss survey in the Columbia Basin in 2012 and 2013, stunted patches in onion crops caused up to 78% reduction in bulb yield within the patches of stunted plants.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of Onion Genotypes for Resistance to Stunting Caused by Rhizoctonia solani AG 8

Sharma‐Poudyal¹,

Paulitz²,

Toit

2015

horts

View full text Add to dashboard Cite

Thirty-five onion genotypes were evaluated for resistance to stunting caused by Rhizoctonia solani anastomosis group 8 (AG 8) in a growth chamber set at 15 ± 1 8C. The trial was repeated. Resistance to R. solani AG 8 was defined as a lack of significant difference in plant height, root length, and/or total dry biomass between inoculated and noninoculated plants of the same genotype. Plant height was not reduced significantly by R. solani AG 8 for 14 and 7 of the 35 genotypes in Trials 1 and 2, respectively. In Trial 1, plant height reduction caused by R. solani ranged from 24% for the cv. Lasalle to 62% for the experimental line R14882, and in Trial 2 plant height reduction ranged from 22% for the experimental line PX07713218 to 53% for the cv. Montblanc. However, the extent of reduction in plant height caused by R. solani did not differ significantly among genotypes in either trial. Onion root length was not reduced by R. solani AG 8 for 26 and 18 of the 35 genotypes in Trials 1 and 2, respectively. The degree of reduction in root length ranged from 9% (R14889) to 76% (Sterling and SN232) in Trial 1, and 14% (SN325) to 74% (Sterling) in Trial 2. Onion dry biomass was not reduced by R. solani AG 8 for 19 and 7 of the 35 genotypes in Trials 1 and 2, respectively, and ranged from 18% (Elbrus) to 69% (Sterling) in Trial 1, and 29% (SN232) to 79% (Sterling) in Trial 2. The reduction in onion root length and total biomass did not differ significantly among onion genotypes in Trial 1, but differed among genotypes in Trial 2. Of the 35 genotypes evaluated, 3, 16, and 3 demonstrated partial resistance to R. solani AG 8 for plant height, root length, and total biomass, respectively, in both trials. Only four genotypes displayed partial resistance to R. solani AG 8 for at least two of the three growth parameters: plant height, root length, and biomass of PX07713218 were unaffected by the fungus in either trial; and R14885, R14888, and SN307 displayed partial resistance in both trials for two of the three parameters, and in one of the two trials for the third parameter. These four genotypes could be used in onion breeding programs to develop cultivars partially resistant to stunting caused by R. solani AG 8.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of Onion Genotypes for Resistance to Stunting Caused by Rhizoctonia solani AG 8

Sharma‐Poudyal¹,

Paulitz²,

Toit

2015

horts

View full text Add to dashboard Cite

show abstract

Stunted Patches in Onion Bulb Crops in Oregon and Washington: Etiology and Yield Loss

Sharma‐Poudyal

Paulitz²,

Toit

2015

Plant Disease

View full text Add to dashboard Cite

Onion stunting caused by Rhizoctonia spp. is an important soilborne disease on very sandy soils in the Columbia Basin of Oregon and Washington. From 2010 to 2013, 251 isolates of Rhizoctonia or Rhizoctonia-like spp. were obtained from soil and onion plant samples collected from inside and outside patches of stunted plants in 29 onion fields in the Columbia Basin. Sequence analysis of the internal transcribed spacer (ITS) region was used to identify the isolates, with 13 anastomosis groups (AGs) or subspecies detected. The most frequent was Waitea circinata var. circinata (25%), followed by Rhizoctonia solani AG 3 (17%), R. solani AG 4 (14%), Ceratobasidium sp. AG A (10%), R. solani AG 8 (7%), Ceratobasidium sp. AG K (6%), R. solani AG 2-1 (6%), W. circinata var. zeae (6%), R. solani AG 5 (4%), Ceratobasidium sp. AG G (2%), R. solani AG 11 (2%), and R. solani AG 1-1B and AG 10 (each <1%). However, the distribution of AGs and subspecies varied depending on whether soil or onion plants samples were collected within or adjacent to patches of stunted onion plants. In an attempt to predict the risk of onion stunting for a field prior to planting, DNA concentrations of AG 2-1, AG 3, AG 4, and AG 8 were quantified from bulk soil samples collected from each of nine growers’ fields approximately 1 month before onion sowing in 2012. The preplant DNA concentrations did not show a significant association with the amount of stunting observed in the fields during the growing season. In contrast, the frequency of isolation and DNA concentration of R. solani AG 8 detected in soil samples collected during the growing season were greater from inside patches of stunted onion plants than from adjacent healthy areas of an onion crop sampled in 2012, but not for soil samples collected similarly from an onion crop in 2013. AG 2-1, AG 3, and AG 4 DNA concentrations did not differ significantly in soil sampled inside versus outside stunted patches in the fields sampled in 2012 and 2013. Relationships between the number of bulbs harvested or bulb weight versus severity of stunting were defined using correlation and regression analyses for six onion cultivars grown in seven fields surveyed in 2012 and 2013. Onion stunting reduced the average marketable bulb yield by 25 to 60% within stunted patches of the six cultivars. Stunting did not reduce onion plant stand but consistently reduced the size of bulbs, and yield reduction increased with increasing disease severity.

show abstract

Timing of Glyphosate Applications to Wheat Cover Crops to Reduce Onion Stunting Caused by Rhizoctonia solani

2016

View full text Add to dashboard Cite

Stunting caused by Rhizoctonia spp. is economically important in irrigated onion bulb crops in the semiarid Columbia Basin of Oregon and Washington, where cereal winter cover crops commonly are planted the previous fall to prevent wind erosion of soil. The cover crop is killed with herbicide application just before or shortly after onion seeding, so that the dead rows of cereal plants provide a physical barrier tall enough to protect onion seedlings against wind and sand blasting but not tall enough to shade onion seedlings. However, the cover crop also serves as a green bridge for Rhizoctonia spp. on cereal roots to colonize the onion roots, potentially resulting in severe stunting of onion seedlings. To determine the effect of timing of application of the herbicide glyphosate to reduce this green bridge effect and, subsequently, onion stunting, three herbicide application intervals preceding onion planting were evaluated in a grower’s onion field in each of 2012 and 2014 in the Columbia Basin. The wheat cover crop was killed with a glyphosate application 27, 17, and 3 days before onion seeding in 2012 and 19, 10, and 3 days before seeding in 2014. As the interval between herbicide application and onion planting increased from 3 days to 19 and 27 days, the number of patches of stunted onion plants decreased by ≥55%, total area of stunted patches decreased by 54 to 63%, and patch severity index decreased by 59 to 65%. Similarly, the Rhizoctonia solani AG 8 DNA concentration in soil sampled from the dead cover crop rows declined as the interval between glyphosate application and onion seeding increased in the 2012 trial but not in the 2014 trial. R. solani AG 3 and AG 8 DNA concentrations in soil sampled from the cover crop rows were significantly positively correlated with the number of patches of stunted onion plants (r = 0.490 and 0.607 at P = 0.039 and 0.008, respectively), total area of stunted patches (r = 0.496 and 0.659 at P = 0.035 and 0.003, respectively), and patch severity index (r = 0.492 and 0.635 at P = 0.038 and 0.005, respectively) in the 2012 trial; however, these variables were only correlated significantly with R. solani AG 3 DNA concentration in the 2014 trial. Increasing the interval between herbicide application to the cover crop and onion planting provides a practical management tool for stunting in onion bulb crops.

show abstract

Rhizoctonia Solani Ag 8 Associated With Stunted Onion Patches in South Australia

Cited by 3 publications

References 0 publications

Evaluation of Onion Genotypes for Resistance to Stunting Caused by Rhizoctonia solani AG 8

Evaluation of Onion Genotypes for Resistance to Stunting Caused by Rhizoctonia solani AG 8

Stunted Patches in Onion Bulb Crops in Oregon and Washington: Etiology and Yield Loss

Timing of Glyphosate Applications to Wheat Cover Crops to Reduce Onion Stunting Caused by Rhizoctonia solani

Contact Info

Product

Resources

About