Application of thiophanate-methyl at different host growth stages for management of sclerotinia stem rot in soybean

2004 ◽  
Vol 23 (10) ◽  
pp. 983-988 ◽  
Author(s):  
D.S. Mueller ◽  
C.A. Bradley ◽  
C.R. Grau ◽  
J.M. Gaska ◽  
J.E. Kurle ◽  
...  
Keyword(s):  
Stem Rot ◽  
Growth Stages ◽  
Sclerotinia Stem Rot ◽  
Thiophanate Methyl ◽  
Host Growth

scholarly journals Suppression of Sclerotinia Stem Rot of Soybean by Lactofen Herbicide Treatment

1999 ◽  
Vol 89 (7) ◽  
pp. 598-602 ◽  
Author(s):  
E. K. Dann ◽  
B. W. Diers ◽  
R. Hammerschmidt
Keyword(s):  
Disease Severity ◽  
Field Experiments ◽  
Lesion Size ◽  
Stem Rot ◽  
Growth Stages ◽  
Sclerotinia Stem Rot ◽  
High Disease Severity ◽  
Disease Pressure ◽  
Seed Yields ◽  
Field Plots

Severity of Sclerotinia stem rot of soybean after treatment with lactofen (Cobra) and other herbicides was assessed in field experiments conducted in Michigan from 1995 to 1997. At sites where disease pressure was high, disease severity was reduced 40 to 60% compared with controls when lactofen was applied at the V3 (1995 and 1996) or R1 (1997) growth stages. Corresponding seed yields were unchanged or up to 20% greater when lactofen was applied at the R1 stage in 1997. Disease severity was not reduced by lactofen treatments in years and at sites where disease pressure was low to medium, and corresponding yields often were reduced by ≈10%. High levels of glyceollin accumulated in lactofen-injured leaves collected from field plots in 1996 and 1997. High glyceollin content in lactofen-treated leaves was associated with significant reductions in lesion size when leaves were challenge-inoculated with Sclerotinia sclerotiorum.

Relationship between sunflower development and the onset of stem rot induced by Sclerotinia minor

1996 ◽  
Vol 36 (1) ◽  
pp. 87
Author(s):  
DR Burgess ◽  
IJ Porter ◽  
DG Parbery
Keyword(s):  
Vegetative Growth ◽  
Lateral Roots ◽  
Disease Onset ◽  
Dry Weight ◽  
Stem Rot ◽  
Growth Stages ◽  
Sclerotinia Stem Rot ◽  
Sclerotinia Minor ◽  
Rate Of Increase ◽  
Direct Inoculation

Sclerotinia stem rot, caused by Sclerotinia minor, has not been reported in sunflower (Helianthus annuus) during vegetative growth. During an investigation of disease development in the highly susceptible inbred line, PacF2582, the disease was first observed in the field at bud development. In glasshouse studies with inoculated soil, onset of disease was delayed until late vegetative growth. Direct inoculation of roots with disks of mycelium or with pregerminated sclerotia confirmed that sunflowers are susceptible to infection during the vegetative growth stages. Root measurements found that the rate of increase in root dry weight was maximum between the early and midbud stages in field-grown plants (230%/week) and between the 6- and 10-leaf stages in glasshouse plants (240%/week). Synchronisation of disease onset with proliferation of lateral roots suggests that active root growth is required to initiate infection.

scholarly journals Validating Sclerotinia sclerotiorum Apothecial Models to Predict Sclerotinia Stem Rot in Soybean (Glycine max) Fields

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2592-2601 ◽  
Author(s):  
Jaime F. Willbur ◽  
Mamadou L. Fall ◽  
Adam M. Byrne ◽  
Scott A. Chapman ◽  
Megan M. McCaghey ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Disease Risk ◽  
Stem Rot ◽  
Weather Data ◽  
Growth Stages ◽  
Sclerotinia Stem Rot ◽  
Chemical Application ◽  
Information Platform ◽  
Logistic Regression Models ◽  
Ssr Development

In soybean, Sclerotinia sclerotiorum apothecia are the sources of primary inoculum (ascospores) critical for Sclerotinia stem rot (SSR) development. We recently developed logistic regression models to predict the presence of apothecia in irrigated and nonirrigated soybean fields. In 2017, small-plot trials were established to validate two weather-based models (one for irrigated fields and one for nonirrigated fields) to predict SSR development. Additionally, apothecial scouting and disease monitoring were conducted in 60 commercial fields in three states between 2016 and 2017 to evaluate model accuracy across the growing region. Site-specific air temperature, relative humidity, and wind speed data were obtained through the Integrated Pest Information Platform for Extension and Education (iPiPE) and Dark Sky weather networks. Across all locations, iPiPE-driven model predictions during the soybean flowering period (R1 to R4 growth stages) explained end-of-season disease observations with an accuracy of 81.8% using a probability action threshold of 35%. Dark Sky data, incorporating bias corrections for weather variables, explained end-of-season disease observations with 87.9% accuracy (in 2017 commercial locations in Wisconsin) using a 40% probability threshold. Overall, these validations indicate that these two weather-based apothecial models, using either weather data source, provide disease risk predictions that both reduce unnecessary chemical application and accurately advise applications at critical times.

scholarly journals Efficacy of Fungicides on Sclerotinia sclerotiorum and Their Potential for Control of Sclerotinia Stem Rot on Soybean

Plant Disease ◽  
2002 ◽  
Vol 86 (1) ◽  
pp. 26-31 ◽  
Author(s):  
D. S. Mueller ◽  
A. E. Dorrance ◽  
R. C. Derksen ◽  
E. Ozkan ◽  
J. E. Kurle ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Radial Growth ◽  
Disease Incidence ◽  
Leaf Tissue ◽  
The United States ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Thiophanate Methyl ◽  
Application Systems

Sclerotinia stem rot of soybean, caused by Sclerotinia sclerotiorum, is a major disease in the north central region of the United States. One approach to managing Sclerotinia stem rot on soybean is the use of fungicides. S. sclerotiorum was assayed for sensitivity to benomyl, tebuconazole, thiophanate methyl, and vinclozolin in pure cultures on agar medium, inoculated soybean seedlings, detached inoculated leaves, and in experimental field plots. To evaluate the inhibitory effect of four fungicides on growth of S. sclerotiorum in vitro, potato dextrose agar (PDA) was amended with the fungicides at six concentrations. Based on measurements of fungal radial growth, vinclozolin was the most effective in inhibiting S. sclerotiorum mycelial growth at 1.0 μg a.i./ml of PDA. Ranges of reduction of radial growth of 91 isolates of S. sclerotiorum on PDA amended with thiophanate methyl and vinclozolin were 18 to 93% and 93 to 99%, respectively, when compared with the nonamended agar control. Benomyl, thiophanate methyl, and vinclozolin applied to greenhouse-grown seedlings prevented S. sclerotiorum from expressing symptoms or signs on leaf tissue. Detached leaves sprayed with thiophanate methyl and then inoculated with mycelial plugs of S. sclerotiorum did not express symptoms or signs. Of 13 different environments in Illinois, Indiana, Ohio, and Wisconsin from 1995 through 2000, six had low Sclerotinia stem rot incidence (<1%), three environments had low to moderate Sclerotinia stem rot incidence (5 to 25%), and four environments had high Sclerotinia stem rot incidence (>25%). When disease incidence was high, no consistent control of Sclerotinia stem rot was observed with benomyl or thiophanate methyl using different application systems. However, under low disease incidence, spray systems that were able to penetrate the canopy reduced the incidence of Sclerotinia stem rot an average of 50%.

scholarly journals Timing Fungicide Applications for Managing Sclerotinia Stem Rot of Potato

Plant Disease ◽  
2006 ◽  
Vol 90 (6) ◽  
pp. 755-758 ◽  
Author(s):  
Dennis A. Johnson ◽  
Zahi K. Atallah
Keyword(s):  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Full Bloom ◽  
Thiophanate Methyl ◽  
Potato Foliage

Fungicides were applied to potato foliage at row closure (between rows) and at full bloom of primary inflorescences to control Sclerotinia stem rot during replicated trials in 2003, 2004, and 2005. Application at row closure followed labeled recommendations from manufacturers. Incidence of Sclerotinia stem rot did not vary significantly among fungicides when full labeled rates of thiophanate-methyl, fluazinam, and boscalid were applied at full bloom of primary inflorescences. Incidence of Sclerotinia stem rot was significantly less when fungicides thiophanatemethyl, fluazinam, or boscalid were applied to potato foliage at full bloom of primary inflorescences than at row closure or when fungicides were not applied in 2004 and 2005, and when thiophanate-methyl or fluazinam was applied to potato foliage at full bloom of primary inflorescences than at row closure or when fungicides were not applied in 2003. Mean percentage of control for the fungicides combined, relative to the nontreated control, was 43, 48, and 20% in 2003, 2004, and 2005, respectively, when application was made at row closure; whereas, it was 77, 83, and 80% in 2003, 2004, and 2005, respectively, when application was at full bloom of primary inflorescences. Mean disease incidences of infected stem were significantly less when fluazinam was applied at 100% bloom of primary inflorescences than at 20% drop of blossoms from primary inflorescences in 2004 and 2005. In summary, control of Sclerotinia stem rot was significantly better when fungicides were applied at full bloom of primary inflorescences than at row closure during all 3 years of the study.

scholarly journals Soybean Stem Lignin Concentration Relates to Resistance to Sclerotinia sclerotiorum

Plant Disease ◽  
2009 ◽  
Vol 93 (2) ◽  
pp. 149-154 ◽  
Author(s):  
A. J. Peltier ◽  
R. D. Hatfield ◽  
C. R. Grau
Keyword(s):  
Disease Resistance ◽  
Sclerotinia Sclerotiorum ◽  
Field Experiments ◽  
Lignin Content ◽  
Stem Rot ◽  
Growth Stages ◽  
Soybean Plant ◽  
Sclerotinia Stem Rot ◽  
Lignin Concentration ◽  
Stem Lignin

Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, is an economically important disease of soybean (Glycine max) in the north-central United States and other temperate regions throughout the world. The occurrence and severity of Sclerotinia stem rot in the field is highly dependent upon prevailing environmental conditions, which can prove problematic when evaluating soybean accessions for resistance. The identification of an environmentally stable plant trait associated with resistance to S. sclerotiorum could be used to indirectly screen for resistance and would prove useful in the identification and development of resistant germplasm. Observations of the soybean–S. sclerotiorum interaction suggest a role for preformed stem lignin content in disease resistance. Although S. sclerotiorum produces numerous enzymes that degrade plant cell wall components, no lignin-degrading enzymes have been reported. Despite a hypothesized direct relationship between preformed lignin content and disease resistance, previous studies on soybean have correlated lignin content to nutritional value and not to disease resistance. We hypothesized that plants with low stem lignin are more susceptible and exhibit greater Sclerotinia stem rot severity than plants with high lignin concentrations. Six soybean accessions that varied in response to S. sclerotiorum were selected for study in a series of field experiments. Soybean stems were sampled at reproductive developmental stages that correspond to specific events in both soybean plant development and the Sclerotinia stem rot disease cycle. The lignin concentration of stem component samples was quantified. Soybean accessions expressed statistically different disease phenotypes in both 2004 and 2006. Lignin concentrations differed among accessions, growth stages, and plant parts. Results were contrary to our hypothesis, with positively ranked correlations observed between accession Sclerotinia stem rot severity and lignin concentration for all nodes and internodes assayed. For the R3 growth stage, lignin concentration of the internode between the fourth and fifth trifoliate leaves correlated best with disease severity data from each year (P = 0.005). These results indicate that resistance is related to low stem lignin concentration and that soybean stem lignin concentration can be used as a biological marker to select for resistance to S. sclerotiorum.

Effect of Sclerotinia Stem Rot on Yield of Soybean Inoculated at Different Growth Stages

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 297-300 ◽  
Author(s):  
G. A. Danielson ◽  
B. D. Nelson ◽  
T. C. Helms
Keyword(s):  
Seed Weight ◽  
Oil Content ◽  
Field Experiments ◽  
Seed Protein ◽  
Disease Incidence ◽  
Stem Rot ◽  
Growth Stages ◽  
Diseased Plant ◽  
Sclerotinia Stem Rot ◽  
Effect On Yield

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.

scholarly journals Efficacy of Fungicides for Control of Sclerotinia Stem Rot of Canola

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1129-1134 ◽  
Author(s):  
C. A. Bradley ◽  
H. A. Lamey ◽  
G. J. Endres ◽  
R. A. Henson ◽  
B. K. Hanson ◽  
...  
Keyword(s):  
Brassica Napus ◽  
North Dakota ◽  
Sclerotinia Sclerotiorum ◽  
Untreated Control ◽  
Field Trials ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
Application Timing ◽  
Thiophanate Methyl

Sclerotinia stem rot (SSR), incited by Sclerotinia sclerotiorum, causes yield reductions to canola (Brassica napus) grown in North Dakota and Minnesota. Field trials were conducted in North Dakota and Minnesota from 2000 to 2004 to evaluate the effect of foliar fungicides on SSR and canola yield. Levels of SSR varied among years and location. In general, fungicides that consistently reduced SSR incidence compared with an untreated control were azoxystrobin, benomyl, boscalid, iprodione, prothioconazole, tebuconazole, thiophanate-methyl, trifloxystrobin, and vinclozolin. Significant reductions in SSR incidence with fungicides did not always translate into differences in canola yield, however. Inconsistent results were observed with different timings of applications based on percent bloom. This indicates that application timing should be based on factors in addition to percent bloom.

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