Development of a new field inoculation technique to assess partial resistance in soybean to Sclerotinia sclerotiorum

2004 ◽  
Vol 84 (1) ◽  
pp. 57-64 ◽  
Author(s):  
J. Auclair ◽  
G. J. Boland ◽  
E. Cober ◽  
G. L. Graef ◽  
J. R. Steadman ◽  
...  

The use of appropriate techniques to assess disease resistance is crucial to understanding the genetic control of host resistance to pathogens to develop resistant plant varieties. The objective of this study was to develop and evaluate a novel field-based inoculation technique for sclerotinia stem rot in soybean [Glycine max (L.) Merr.], caused by Sclerotinia sclerotiorum (Lib.) de Bary. The barley kernel inoculation technique involves stem inoculation using an infected barley kernel inserted into a wound made in the soybean stem. The damage on soybean plants is measured by the length of the lesion on inoculated stem and expressed as inoculation severity index (ISI). Soybean varieties were evaluated for 2 yr at different sites using the barley kernel inoculation technique, and compared with other controlled environment and natural infection-based techniques. The ISIs obtained at Elora, ON, were significantly correlated (r = 0.21, P = 0.021) between the 2 test years (1998 and 1999), and in 1998 with natural infection [as measured by the disease severity index, DSI] at the same location (r = 0.31; P = 0.0005). Using a small set of lines that were specifically selected over several years to respond to DSI, the correlation between the DSI from some locations and years and the ISI in 1999 was negative. The significant positive correlations obtained using soybean lines that were not previously selected for DSI suggest the potential of this technique for pre-screening the breeding material for partial resistance to sclerotinia stem rot prior to confirmation with natural infection levels as measured by DSI. This may be of value to soybean breeders trying to develop soybean lines partially resistant to sclerotinia stem rot because of the difficulty in obtaining consistent and reliable DSI scores across locations and over years. Key words: Sclerotinia stem rot, white mould, inoculation, resistance, soybean

2012 ◽  
Vol 92 (2) ◽  
pp. 279-288 ◽  
Author(s):  
Maxime Bastien ◽  
Tung Thanh Huynh ◽  
Geneviève Giroux ◽  
Elmer Iquira ◽  
Sylvie Rioux ◽  
...  

Bastien, M., Huynh, T. T., Giroux, G., Iquira, E., Rioux, S. and Belzile, F. 2012. A reproducible assay for measuring partial resistance to Sclerotinia sclerotiorum in soybean. Can. J. Plant Sci. 92: 279–288. In eastern Canada, Sclerotinia stem rot in soybean is an important disease, and resistance is systematically assessed in cultivar performance trials. The reference method used in these trials closely mimics the natural infection process, but is very demanding, and its success is highly subject to environmental conditions. Here we describe a simple, quick and reproducible inoculation method to measure resistance to pathogen progression on the main stem. Importantly, this method is the first to reproducibly identify quantitative trait loci (QTLs) conferring partial resistance to Sclerotinia stem rot in soybean. In this method, a cotton pad saturated with a mycelial suspension is applied to a floral bud and resistance is estimated by measuring lesion length on the main stem. The method was found to discriminate clearly between known resistant and susceptible checks in both the field and greenhouse. Clear discrimination between 26 recombinant inbred lines (RILs) contrasted for QTLs controlling resistance to Sclerotinia stem rot was also achieved in four independent trials, and lesion length was significantly correlated among all trials. When tested on 38, 42 and 40 lines in registration trials, the results of this method were significantly correlated with those of the reference method in 2 of 3 yr.


2011 ◽  
Vol 12 (1) ◽  
pp. 15 ◽  
Author(s):  
S. D. Khot ◽  
V. N. Bilgi ◽  
L. E. del Río ◽  
C. A. Bradley

A collection of Brassica napus plant introduction (PI) lines was evaluated in a series of research trials to identify lines with resistance to Sclerotinia sclerotiorum, causal agent of Sclerotinia stem rot of canola. Five PI lines (169080, 286418, 436554, 458940, and 633119) were identified that consistently had SSR resistance levels equal to or greater than the partially resistant check cultivar Hyola 357. In addition, two of these lines (436554 and 458940) were found to exhibit SSR field resistance levels similar to Hyola 357. The PI lines identified from our research studies could be used in canola breeding programs to develop cultivars with improved resistance to S. sclerotiorum. Accepted for publication 21 February 2011. Published 22 April 2011.


2020 ◽  
Vol 175 ◽  
pp. 105983
Author(s):  
Navin Chandra Gupta ◽  
Pankaj Sharma ◽  
Mahesh Rao ◽  
Pramod Kumar Rai ◽  
Ashish Kumar Gupta

2003 ◽  
Vol 43 (2) ◽  
pp. 163 ◽  
Author(s):  
T. L. Hind ◽  
G. J. Ash ◽  
G. M. Murray

Surveys of petal infestation and stem infection conducted in 1998, 1999 and 2000 indicated that Sclerotinia sclerotiorum poses a threat to the Australian canola industry. Inoculum was present throughout all canola-growing regions of New South Wales and the stem disease was widespread throughout southern New South Wales. Percentage petal infestation increased over the 3 years surveyed with values ranging from 0 to 99.4%. The highest petal infestation values were observed in 2000 (maximum of 99.4%, mean of 82.2%), with lower mean values in 1998 (38.4%) and 1999 (49.6%). Stem infection ranged from 0 to 37.5% and most fields had less than 10% stem infection. Stem rot incidence before harvest did not relate to percentage petal infestation determined during flowering. This indicated that factors other than percentage petal infestation were important in influencing stem rot incidence. While there was no relationship between percentage petal infestation and stem rot incidence, stem infection never occurred without prior petal infestation.


Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1613-1620 ◽  
Author(s):  
Xue-ping Huang ◽  
Jian Luo ◽  
Yu-fei Song ◽  
Bei-xing Li ◽  
Wei Mu ◽  
...  

Sclerotinia sclerotiorum, which can cause Sclerotinia stem rot, is a prevalent plant pathogen. This study aims to evaluate the application potential of benzovindiflupyr, a new generation of succinate dehydrogenase inhibitor (SDHI), against S. sclerotiorum. In our study, 181 isolates collected from different crops (including eggplant [n = 34], cucumber [n = 27], tomato [n = 29], pepper [n = 35], pumpkin [n = 32], and kidney bean [n = 25]) in China were used to establish baseline sensitivity to benzovindiflupyr. The frequency distribution of the 50% effective concentration (EC50) values of benzovindiflupyr was a unimodal curve, with mean EC50 values of 0.0260 ± 0.011 μg/ml, and no significant differences in mean EC50 existed among the various crops (P > 0.99). Benzovindiflupyr can effectively inhibit mycelial growth, sclerotial production, sclerotial shape, and myceliogenic and carpogenic germination of the sclerotia of S. sclerotiorum. In addition, benzovindiflupyr showed good systemic translocation in eggplant. Using benzovindiflupyr at 100 μg/ml yielded efficacies of 71.3 and 80.5% for transverse activity and cross-layer activity, respectively, which were higher than those of acropetal and basipetal treatments (43.6 and 44.7%, respectively). Greenhouse experiments were then carried out at two experimental sites for verification. Applying benzovindiflupyr at 200 g a.i. ha−1 significantly reduced the disease incidence and severity of Sclerotinia stem rot. Overall, the results demonstrated that benzovindiflupyr is a potential alternative product to control Sclerotinia stem rot.


2018 ◽  
Vol 108 (4) ◽  
pp. 469-478 ◽  
Author(s):  
Mamadou L. Fall ◽  
John F. Boyse ◽  
Dechun Wang ◽  
Jaime F. Willbur ◽  
Damon L. Smith ◽  
...  

Sclerotinia sclerotiorum is a significant threat to soybean production worldwide. In this study, an epidemiological approach was used to examine 11 years of historical data from a soybean management performance trial in order to advance our understanding of Sclerotinia stem rot (SSR) development and to identify environmental predictors of SSR epidemics and associated yield losses. Recursive partitioning analysis suggested that average air temperature and total precipitation in July were the most significant variables associated with disease severity. High levels of SSR disease severity index were observed when the average temperature in July was below 19.5°C and total precipitation in July was moderate, between 20 and 108.5 mm. A biphasic sigmoidal curve accurately described the relationship between SSR disease severity index (DSI) and yield, with a DSI threshold of 22, below which minimal yield loss was observed. A 10% increase in the DSI, from 22.0 to 24.2, led to an 11% decrease in yield, from 3,308.14 to 2,951.29 kg/ha. Also, a yield threshold (3,353 kg/ha) that was higher than the annual U.S. average soybean yield (3,039.7 kg/ha) was suggested as an expected yield under low or no SSR pressure in the U.S. Midwest. These thresholds can allow soybean stakeholders to assess the value of disease control and establish an SSR baseline for cost-effective management to protect yields. Because S. sclerotiorum has more than 400 plant host species, and because having quantitative information concerning crop losses is crucial for decision making, this study shows the usefulness of historical data on SSR and, hence, can serve as a model in other SSR pathosystems (canola, dry bean, potato, pea, and so on).


Plant Disease ◽  
2015 ◽  
Vol 99 (7) ◽  
pp. 969-975 ◽  
Author(s):  
Congying Xu ◽  
Xiaoyu Liang ◽  
Yiping Hou ◽  
Mingguo Zhou

We determined the effects and efficacy of benzothiostrobin, a new strobilurin-derived fungicide, against the plant-pathogenic fungus Sclerotinia sclerotiorum (the causal agent of Sclerotinia stem rot). Mycelial growth and sclerotial germination in vitro were strongly inhibited by benzothiostrobin in the presence of salicylhydroxamic acid. On detached rapeseed leaves, benzothiostrobin at 40 μg/ml reduced lesion development by 87%. No cross-resistance was detected between benzothiostrobin and carbendazim, iprodione, fludioxonil, or boscalid. A formulated mixture of benzothiostrobin and fluazinam at 1:1 had synergistic activity against S. sclerotiorum in vitro. In field trials, benzothiostrobin alone or formulated with fluazinam at 1:1 (150 g a.i. ha−1) was significantly (P < 0.05) superior to iprodione in controlling Sclerotinia stem rot of rapeseed. These results suggest that benzothiostrobin has substantial potential for the control of Sclerotinia stem rot.


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