scholarly journals Carpogenic Germinability of Diverse Sclerotinia sclerotiorum Populations Within the Southwestern Australian Grain Belt

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2891-2897
Author(s):  
Pippa J. Michael ◽  
King Yin Lui ◽  
Linda L. Thomson ◽  
Katia Stefanova ◽  
Sarita J. Bennett
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Temperature Fluctuations ◽  
Sclerotinia Stem Rot ◽  
Dark Cycle ◽  
Diurnal Temperature ◽  
Population Responses ◽  
Carpogenic Germination ◽  
Southwestern Australia ◽  
Temperature Regimes ◽  
Mycelial Compatibility

Sclerotinia stem rot, caused by the necrotrophic plant pathogen Sclerotinia sclerotiorum (Lib.) de Bary, is a major disease of canola and pulses in Australia. Current disease management relies greatly on cultural and chemical means of control. Timing of fungicide applications remains a challenge, because efficacy is dependent on accurate prediction of ascospore release and presence on the plant. The aims of this study were to determine the optimal temperature for carpogenic germination of S. sclerotiorum populations sampled from canola and lupin fields in southwestern Australia and characterize diversity using mycelial compatibility groupings (MCGs). Sclerotia were collected from four diseased canola and one diseased lupin field from across southwestern Australia. Forty sclerotia from each population were incubated at four alternating temperatures of 30/15, 20/15, 20/4, and 15/4°C (12-h/12-h light/dark cycle) and assessed every 2 to 3 days for a 180-day period. MCG groupings for populations were characterized using 12 reference isolates. Results indicated the time to initial carpogenic germination decreased as diurnal temperature fluctuations decreased, with a fluctuation of 5°C (20/15°C) having the most rapid initial germination followed by 11°C (15/4°C) followed by 16°C (20/4°C). Optimal germination temperature for all five populations was 20/15°C; however, population responses to other diurnal temperature regimes varied considerably. No germination was observed at 30/15°C. MCG results indicate extensive diversity within and between populations, with at least 40% of sclerotia within each population unable to be characterized. We suggest that this diversity has enabled S. sclerotiorum populations to adapt to varying environmental conditions within southwestern Australia.

scholarly journals Favorable Bioactivity of the SDHI Fungicide Benzovindiflupyr Against Sclerotinia sclerotiorum Mycelial Growth, Sclerotial Production, and Myceliogenic and Carpogenic Germination of Sclerotia

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1613-1620 ◽  
Author(s):  
Xue-ping Huang ◽  
Jian Luo ◽  
Yu-fei Song ◽  
Bei-xing Li ◽  
Wei Mu ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Mycelial Growth ◽  
Disease Incidence ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Baseline Sensitivity ◽  
Carpogenic Germination ◽  
Alternative Product ◽  
Application Potential ◽  
New Generation

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.

scholarly journals Effect of some fungicides against the growth inhibition of Sclerotinia sclerotiorum mycelial compatibility groups

2015 ◽  
Vol 55 (4) ◽  
pp. 354-361 ◽  
Author(s):  
Alireza Dalili ◽  
Saeed Bakhtiari ◽  
Hossein Barari ◽  
Majid Aldaghi
Keyword(s):  
Growth Inhibition ◽  
Sclerotinia Sclerotiorum ◽  
Integrated Management ◽  
In Vitro Tests ◽  
Sclerotinia Stem Rot ◽  
Mazandaran Province ◽  
Brassica Napus L ◽  
Northern Iran ◽  
Mycelial Compatibility

Abstract Sclerotinia sclerotiorum (Lib.) de Bary, the causal agent of Sclerotinia stem rot, is one of the most important pathogens of Brassica napus L. in northern Iran. In this study, 13 mycelial compatibility groups (MCGs) of the fungus were identified among 31 isolates sampled from four regions of Mazandaran province, Iran. Effective fungicides are useful in the integrated management of the disease. So, the effect of tebuconazole, propiconazole, cyproconazole, and Rovral-TS at five doses (0.0001, 0.001, 0.01, 0.1, and 1 ppm) was studied on the growth inhibition of S. sclerotiorum as in vitro tests. Maximum inhibition (100%) of S. sclerotiorum mycelial growth was obtained by the highest dose (1 ppm) of all tested fungicides, as well as by the doses of 0.1 and 0.01 ppm of propiconazole, cyproconazole, and tebuconazole. In this investigation, the reaction of S. sclerotiorum isolates belonging to different MCGs was evaluated against tebuconazole, propiconazole, cyproconazole, and Rovral-TS at their EC50 ranges. The results revealed that there was high variation of S. sclerotiorum MCGs against different fungicides. The inhibition percentage varied between 4.29% and 71.72%.

Impact of preconditioning temperature and duration period on carpogenic germination of diverse Sclerotinia sclerotorium (Lib.) de Bary populations in south-western Australia

Plant Disease ◽  
2020 ◽  
Author(s):  
Pippa J Michael ◽  
King Yin Lui ◽  
Linda Thomson ◽  
Ashmita Lamichhane ◽  
Sarita J Bennett
Keyword(s):  
Severe Disease ◽  
Population Diversity ◽  
Sclerotinia Stem Rot ◽  
Carpogenic Germination ◽  
Time Period ◽  
Broad Leaf ◽  
Mycelial Compatibility ◽  
Conditioning Temperature ◽  
Significant Yield ◽  
C 50

The soil-borne pathogen Sclerotinia sclerotorium is the causal agent of sclerotinia stem rot, a severe disease of broad-leaf crops including canola/rapeseed Brassica napus that can result in significant yield losses. Sclerotia, the hard melanized resting structure of the pathogen, requires preconditioning before carpogenic germination can occur. We investigated the effect of pre-conditioning temperature (4°C, 20°C, 35°C, 50°C and field conditions) and duration (0, 30, 60, 120, 179, 240, 301 days) on germination of S. sclerotorium sclerotia collected from five canola fields in the south-western Australian grain-belt. The ecological diversity of each population was characterised using mycelial compatibility groups (MCGs) typing. No response was observed for isolates conditioned at 4°C at any time period indicating chilling is not a preconditioning requirement for these isolates. Sclerotia required preconditioning for a minimum of 60 days before any significant increase in germination occurred, with no further increases in germination recorded in response to longer conditioning after 60 days. The highest germination was observed in sclerotia conditioned at 50°C. The MCG results indicated significant within and between population diversity suggesting local adaptation to different environments as well as ensuring the ability to respond to seasonal variation between years.

scholarly journals Mycelial Compatibility Grouping and Aggressiveness of Sclerotinia sclerotiorum

Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 325-332 ◽  
Author(s):  
L. S. Kull ◽  
W. L. Pedersen ◽  
D. Palmquist ◽  
G. L. Hartman
Keyword(s):  
Population Structure ◽  
Disease Management ◽  
Sclerotinia Sclerotiorum ◽  
Stem Rot ◽  
Management Systems ◽  
Sclerotinia Stem Rot ◽  
Pathogen Population ◽  
Causal Organism ◽  
Soybean Field ◽  
Mycelial Compatibility

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.

The effect of light and number of diurnal temperature fluctuations on germination of Phragmites australis

1999 ◽  
Vol 9 (2) ◽  
pp. 165-170 ◽  
Author(s):  
B. Ekstam ◽  
R. Johannesson ◽  
P. Milberg
Keyword(s):  
Phragmites Australis ◽  
Soil Seed Bank ◽  
Temperature Fluctuations ◽  
Diurnal Temperature ◽  
Temperature Cycles ◽  
Temperature Regimes ◽  
Persistent Soil Seed Bank ◽  
Germination Timing ◽  
Germination Experiment ◽  
Positive Effect

AbstractSeed germination of the wetland emergent perennial Phragmites australis is stimulated by diurnally fluctuating temperatures. A germination experiment in darkness and light at different temperature regimes showed that P. australis germinated as well in darkness as in light over most of the temperature regimes tested. The germination requirements could partly explain why this species, despite a large annual production of small seeds, does not accumulate a persistent soil seed bank. A second experiment examined the effect of one to four diurnal temperature cycles with amplitude of fluctuations ranging from 0 to 30°C; diurnal mean temperature of 15°C. Germination in the absence of fluctuations was low, and logistic model estimates showed a positive effect of number of temperature cycles which was strongly influenced by amplitude size. For seeds that have fallen on moist ground during the winter, these laboratory results predict that a few large diurnal temperature fluctuations could be sufficient for onset of germination in the subsequently warmer spring period. Seeds that are located under water, however, are predicted to remain ungerminated until the water level falls. Hence, we suggest that the requirement for fluctuating temperature, in addition to being a sensor for ‘exposed’ seed sites, is also effectively acting as a germination timing mechanism.

scholarly journals Population Structure and Aggressiveness of Sclerotinia sclerotiorum From Rapeseed (Brassica napus) in Chongqing City

Plant Disease ◽  
2020 ◽  
Vol 104 (4) ◽  
pp. 1201-1206
Author(s):  
Yang Yu ◽  
Junsong Cai ◽  
Linhao Ma ◽  
Zhiqiang Huang ◽  
Yabo Wang ◽  
...  
Keyword(s):  
Population Structure ◽  
Sclerotinia Sclerotiorum ◽  
Plant Pathogens ◽  
Gene Diversity ◽  
Sclerotinia Stem Rot ◽  
Pair Group ◽  
Fungal Plant Pathogens ◽  
Chongqing City ◽  
Mycelial Compatibility ◽  
Rapeseed Production

Sclerotinia sclerotiorum is one of the most devastating fungal plant pathogens of oilseed Brassica and is distributed worldwide. In particular, Sclerotinia stem rot has always been a serious threat to rapeseed production in Chongqing City, China. In this study, simple sequence repeat (SSR) markers and mycelial compatibility groups (MCGs) were used to characterize the population structure of 90 geographic isolates of S. sclerotiorum collected from rapeseed in nine counties of Chongqing. A total of 52 microsatellite haplotypes were identified, and a few haplotypes were found with high frequency. Gene diversity ranged from 0.1570 to 0.4700 in nine populations. A constructed unweighted pair group with arithmetic mean dendrogram based on Nei genetic distance and a STRUCTURE analysis revealed that the genetic composition of the isolates collected in the five counties located in western Chongqing are different from those collected in the two eastern counties, suggesting that breed lines should be cultivated in both the western and eastern regions to effectively evaluate resistance levels. A total of 47 MCGs were identified, and 72% of the MCGs was represented by single isolates. Seven of 13 MCGs that included at least two isolates contained isolates from only one county. SSR haplotypes were not correlated with MCGs. A subset of 34 isolates were inoculated on rapeseed stems, and the aggressiveness showed variation. This research revealed the population genetic structure and aggressiveness of this pathogen in Chongqing, and the results will help to develop disease management and resistance screening strategies.

scholarly journals Scarification and Environmental Factors that Enhance Carpogenic Germination of Sclerotia of Sclerotinia sclerotiorum

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1041-1047 ◽  
Author(s):  
Harsh Garg ◽  
Krishnapillai Sivasithamparam ◽  
Martin J. Barbetti
Keyword(s):  
Environmental Factors ◽  
Sclerotinia Sclerotiorum ◽  
Tap Water ◽  
Primary Source ◽  
Sclerotinia Stem Rot ◽  
River Sand ◽  
Carpogenic Germination ◽  
Cropping Season ◽  
Disease Epidemics ◽  
Selection Of

Ascospores of Sclerotinia sclerotiorum are the primary source of inoculum for disease epidemics in many economically important crops. Mass production of ascospores under laboratory conditions is required to prepare inoculum for use in selection of genotypes with resistance against Sclerotinia diseases. A study was undertaken, first, to investigate the effect on carpogenic germination of scarifying sclerotia from two S. sclerotiorum isolates taken from canola (Brassica napus) and, second, to identify environmental factors that enhance carpogenic germination. Seven different environmental treatments were applied to scarified and unscarified sclerotia: (i) sterilized distilled water for 4 months at 15°C, (ii) aerated water for 4 months at 4°C, (iii) constant rinsing with tap water for 8 weeks at 4°C, (iv) cold-conditioning for 4 weeks at 4°C and subsequent transfer into moist unsterilized compost at 15°C, (v) incubation in sterilized river sand at 15°C, (vi) air drying for 2 weeks followed by subsequent transfer into sterilized moist river sand at 15°C, or (vii) placed into 0.5% water agar and incubated at 15°C. Carpogenic germination of scarified sclerotia was significantly greater (P < 0.05) than for unscarified sclerotia. There was significant interaction (P < 0.001) between scarification and the different environmental treatments in relation to the carpogenic germination. Carpogenic germination of scarified sclerotia was enhanced by incubation of sclerotia in compost or in sterilized river sand. Further, overall carpogenic germination of both scarified and unscarified sclerotia occurred to the greatest extent when sclerotia of either of the two isolates were subjected to constant rinsing with tap water. We believe this to be the first report of both the enhanced carpogenic germination by scarification in S. sclerotiorum and the environmental factors we report that enhance carpogenic germination of scarified sclerotia. The progression of carpogenic germination in all the environmental treatments was also monitored as a part of this study across the two consecutive years for the same two isolates. The majority of sclerotia of both isolates germinated between the months of June and September in both years, a period which coincides with the main part of the cropping season when Sclerotinia stem rot is normally observed in rainfed canola in Western Australia. These data suggested the existence of a seasonal rhythm-like pattern in relation to the carpogenic germination of this pathogen.

Prevalence of sclerotinia stem rot of canola in New South Wales

2003 ◽  
Vol 43 (2) ◽  
pp. 163 ◽  
Author(s):  
T. L. Hind ◽  
G. J. Ash ◽  
G. M. Murray
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
New South ◽  
New South Wales ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Mean Values ◽  
Stem Infection ◽  
South Wales

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.

Sign in / Sign up

Export Citation Format

Share Document