Impact of time between field application of Bacillus subtilis strains SB01 and SB24 and inoculation with Sclerotinia sclerotiorum on the suppression of Sclerotinia stem rot in soybean

2011 ◽  
Vol 131 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Jinxiu Zhang ◽  
Allen G. Xue ◽  
Malcolm J. Morrison ◽  
Yao Meng
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.


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.


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.


Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 325-332 ◽  
Author(s):  
L. S. Kull ◽  
W. L. Pedersen ◽  
D. Palmquist ◽  
G. L. Hartman

Population variability of Sclerotinia sclerotiorum, the causal organism of Sclerotinia stem rot of soybean, was determined by mycelial compatibility grouping (MCG) and isolate aggressiveness comparisons. MCG and aggressiveness of S. sclerotiorum isolates from diverse hosts and geographic locations (Diverse Set, 24 isolates), from a soybean field in Argentina (Argentine Set, 21 isolates), and from soybean fields in DeKalb and Watseka, Illinois (DeKalb Set, 124 isolates, and Watseka Set, 130 isolates) were assessed. Among 299 isolates tested, 42 MCGs were identified, and 61% were represented by single isolates observed at single locations. Within the Diverse Set, 17 MCGs were identified; 1 MCG consisted of six isolates, and 16 MCGs consisted of one isolate each. Nine MCGs were identified within the Argentine field with two MCGs composed of either five or six isolates, two MCGs composed of two isolates, and the remaining composed of one isolate each. Each Illinois field was a mosaic of MCGs, but MCG frequencies differed between the two fields. Common MCGs were identified among the Diverse, DeKalb, and Watseka Sets, but no MCGs within the Argentine Set were observed with other sets. MCG 8 was the most frequently sampled and widely dispersed MCG and occurred at a frequency of 29, 36, and 62% in the Diverse, DeKalb, and Watseka Sets, respectively. Variation in isolate aggressiveness was assessed using a limited-term, plug inoculation technique. Isolate aggressiveness varied (P = 0.001) within the Diverse, Argentine, DeKalb, and Watseka Sets. Within widely dispersed MCGs, isolate aggressiveness varied (P ≤ 0.10); however, within locally observed MCGs detected only in single fields, isolate aggressiveness did not vary. Additionally, individual MCGs within the DeKalb and Watseka Sets differed in isolate aggressiveness. Using six soybean cultivars and six S. sclerotiorum isolates, no cultivar-isolate interaction was detected, but resistant and susceptible cultivars performed similarly when inoculated with either less or highly aggressive isolates. Pathogen population structure and variability in isolate aggressiveness may be important considerations in disease management systems.


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


Plant Disease ◽  
2016 ◽  
Vol 100 (1) ◽  
pp. 223-223 ◽  
Author(s):  
I. Y. Choi ◽  
J. H. Kim ◽  
B. S. Kim ◽  
M. J. Park ◽  
H. D. Shin

Plant Disease ◽  
1997 ◽  
Vol 81 (9) ◽  
pp. 1093-1093 ◽  
Author(s):  
K. F. Chang ◽  
R. J. Howard ◽  
R. G. Gaudiel ◽  
S. F. Hwang

Purple coneflower (Echinacea purpurea (L.) Moench; Asteraceae), a perennial herb originating from North America, is used as a garden ornamental and is grown commercially for use in medicinal preparations as an immunostimulant. In October 1996, a previously undescribed stem rot disease was observed in a research plot of 6-month-old echinacea plants at Brooks. Seedlings had been raised in small rockwool cubes (2 × 2 × 5 cm3) in a greenhouse, then transplanted into the field in early June. By late August, dead and dying plants were observed throughout the stand. They had dark brown to black stem lesions above and at the soil level and dead leaves with bleached petiole lesions that extended ca. 15 cm above the axil. Diseased stems and petioles often disintegrated, leaving only fibrous tissues intact. Roots were rotted and black. Superficial white mycelium developed over the basal part of affected stems. Black, oblong to irregular-shaped sclerotia, 5.1 to 17.6 mm in size, formed externally on the crown areas after plant death. Sclerotinia sclerotiorum (Lib.) de Bary (1) was isolated from the diseased plants. Five isolates were selected to fulfill Koch's postulates with 3-month-old echinacea seedlings grown in 12-cm pots of soilless mix. Sclerotia from wilted, field-grown echinacea plants were transferred onto potato dextrose agar medium for 2 days at 20°C. Agar disks were cut with a 1-cm cork borer and two plugs containing sclerotial and mycelial tissues were inserted into the soilless mix 0.5 cm deep and 0.5 cm from the opposite sides of stems of test plants. Inoculated plants were enclosed in transparent plastic bags for 5 days and incubated in a growth chamber at 15/18°C (night/day) with a 12-h photoperiod. One to four lower leaves per plant wilted within 1 week after inoculation and aerial mycelia appeared on the petioles. Infected leaves quickly withered, dried, and dropped off the plant after the bags were removed. Plants often died 3 weeks after inoculation and S. sclerotiorum was reisolated from infected crown tissues. This disease was also found on 3-year-old plants of E. pallida (Nutt.) Nutt. var. angustifolia (DC.) Cronq. in Vernon, British Columbia, Canada, in May 1997. This is the first report of sclerotinia stem rot on Echinacea spp., a disease that could have a significant impact on the longevity and productivity of this crop in the field and greenhouse. Reference: (1) L. H. Purdy. Phytopathology 69:875, 1979.


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