Soybean cultivar reaction and row width effect on Sclerotinia stem rot

1993 ◽  
Vol 73 (4) ◽  
pp. 1169-1175 ◽  
Author(s):  
R. I. Buzzell ◽  
T. W. Welacky ◽  
T. R. Anderson

The response of soybean (Glycine max (L.) Merr.) cultivars to Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, was assessed in replicated field trials in 1985–1987 and 1990 to obtain information relating to control of the disease. In 1986 and 1987, there were differences (P = 0.01) in disease incidence among 19 indeterminate cultivars. Cultivar differences in disease incidence were partially related to maturity (R2 = 0.67 in 1986; R2 = 0.37 in 1987) with earlier-maturing cultivars having less disease. Cultivars differed (P = 0.01) in the number of sclerotia produced per diseased plant and per square meter in 1986 and 1987. In a test conducted in 1990 there were differences (P = 0.05) in disease incidence among 14 determinate lines. In three tests in 1985–1986, row spacings of 23, 45 and 69 cm had no significant effect on the incidence of white mold in the cultivars Maple Arrow, Evans, S1346 and Corsoy 79. Yield loss from stem rot may be reduced by planting cultivars that are more resistant, earlier maturing and more tolerant to lodging. This practice would also result in fewer sclerotia to serve as primary inoculum in future years. Key words: Glycine max, soybean, Sclerotinia stem rot, cultivar and row width effects

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 297-300 ◽  
Author(s):  
G. A. Danielson ◽  
B. D. Nelson ◽  
T. C. Helms

The effects of Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, on yield of soybean were evaluated in the field with two cultivars in maturity group 0. Plants were inoculated at two growth stages, R3 and R5, using two inoculation methods. Seed weight, seed and pod numbers, seed protein, and oil content were measured. The effects of disease on yield were variable. Disease resulted in significant seed weight loss, with reductions per diseased plant ranging from 18.8 to 38.6%. The estimated yield loss per 10% disease incidence ranged from 83.2 to 229.0 kg/ha, with an average loss of 136.6 kg/ha for four field experiments. A reduction in the number of seeds and pods per plant and seed oil content occurred in some, but not all, experiments. Seed protein was not affected. When disease reduced seed weight, seed and pod numbers, or oil content, there was no growth stage × treatment interaction in the experiments, indicating that inoculation at R5 compared with R3 had a similar effect on yield.


Plant Disease ◽  
2021 ◽  
Author(s):  
Richard Wade Webster ◽  
Mitchell Roth ◽  
Brian Mueller ◽  
Daren S. Mueller ◽  
Martin I Chilvers ◽  
...  

Soybean (Glycine max) farmers in the Upper Midwest region of the United States frequently experience severe yield losses due to Sclerotinia stem rot (SSR). Previous studies have revealed benefits of individual management practices on SSR. This study examined the integration of multiple control practices on the development of SSR, yield, and the economic implications of these practices. Combinations of row spacings, seeding rates, and fungicide applications were examined in multi-site field trials across the Upper Midwest from 2017-2019. These trials revealed that wide row spacing and low seeding rates individually reduced SSR levels but also reduced yields. Yields were similar across the three higher seeding rates examined. However, site-years where SSR developed showed the highest partial profits in the intermediate seeding rates. This indicates that partial profits in diseased fields were negatively impacted by high seeding rates, but this trend was not observed when SSR did not develop. Fungicides strongly reduced the development of SSR, while also increasing yields. However, there was a reduction in partial profits due to their use at a low soybean sale price, but at higher sale prices fungicide use was similar to not treating. Additionally, the production of new inoculum was predicted from disease incidence, serving as an indicator of increased risk for SSR development in future years. Overall, this study suggests the use of wide rows and low seeding rates could be useful in fields with a history of SSR, while reserving narrow rows and higher seeding rates for fields without a history of SSR.


Author(s):  
Rawnaq Chowdhury ◽  
Connie Tande ◽  
Emmanuel Z Byamukama

Phytophthora root and stem rot, caused by Phytophthora sojae, is an important disease of soybean (Glycine max L.) in South Dakota. Because P. sojae populations are highly diverse and resistance genes deployed in commercial soybean varieties often fail to manage the disease, this study was initiated to determine P. sojae pathotype distribution in South Dakota. A total of 216 P. sojae isolates were baited from soil collected from 422 soybean fields in South Dakota in 2013-2015 and 2017. The pathotype of each isolate was determined by inoculating 10 seedlings of 13 standard soybean P. sojae differential lines using the hypocotyl inoculation technique. Of the 216 pathotyped isolates, 48 unique pathotypes were identified. The virulence complexity of isolates ranged from virulence on one Rps gene (Rps7) to virulence on 13 Rps genes and mean complexity was 5.2. Harosoy (Rps7), Harlon (Rps1a), Williams 79 (Rps 1c), William 82 (Rps1k), Harosoy 13XX (Rps1b), were susceptible to 98, 80, 78, 73, 72% of the isolates, respectively. These results highlight the highly diverse P. sojae pathotypes in South Dakota and the likely Rps genes to fail in commercial soybean varieties


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 19 (1) ◽  
pp. 46-53 ◽  
Author(s):  
David A. Marburger ◽  
Jaime F. Willbur ◽  
Maria E. Weber ◽  
Jean-Michel Ané ◽  
Medhi Kabbage ◽  
...  

Lipo-chitooligosaccharides (LCOs) are signal molecules produced by plant root endosymbionts and have been identified, formulated, and marketed as growth-promoting adjuvants for soybean (Glycine max [L.] Merr.). Experiments were conducted under controlled environmental conditions to characterize the effects of foliar LCO applications on early symptom development of sudden death syndrome (SDS), caused by Fusarium virguliforme, and Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum. Treatment factors for the SDS experiment included two soybean cultivars (Sloan and CH2105R2), two inoculation levels (noninoculated control and inoculated), and two LCO applications (control and foliar LCO application), whereas two experimental soybean lines (91-38 and 91-44) and two LCO applications (water control and foliar LCO application) were used in the SSR experiment. The LCO application did not significantly influence SDS root symptom severity or early-season growth characteristics. However, on the susceptible line (P = 0.01) and with LCO application (P = 0.03), significantly larger SSR lesions developed compared with the nontreated control and resistant line. These results suggest foliar-applied LCOs have a limited effect on early root symptom development caused by F. virguliforme but increase stem symptom development caused by S. sclerotiorum.


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.


2000 ◽  
Vol 80 (4) ◽  
pp. 889-898 ◽  
Author(s):  
M. Bom ◽  
G. J. Boland

Selected environmental, crop and pathogen variables were sampled weekly from winter and spring canola crops before and during flowering and evaluated for the ability to predict sclerotinia stem rot, caused by Sclertinia sclerotirum. Linear and nonlinear relationships were examined among variables but, because no strong correlations were observed between final disease incidence and any of the variables tested, a categorical approach (e.g., disease severity) was used instead. Disease severity in individual crops was categorized as low (< 20% diseased plants) or high (> 20% disease), and differences in weekly rainfall, soil moisture, crop height, percentage of petal infestation, and number of apothecia m−2 and clumps of apothecia m−2 were significantly associated with differences in disease severity within or between years. Two disease prediction models were compared for the ability to predict low or high disease severities using petal infestation alone, or petal infestation in combination with soil moisture. The model that included petal infestation and soil moisture predicted more fields correctly than the model using petal infestation alone, but the accuracy of both was affected by the timing of soil moisture measurements in relation to petal infestation, and threshold values used in discriminating categories of soil moisture and petal infestation. Key words: Brassica rapa, Brassica napus, Sclerotinia sclerotiorum, disease prediction


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