Impact of Sclerotinia Stem Rot on Yield of Canola

Sclerotinia sclerotiorum is the causal agent of Sclerotinia stem rot (SSR) of canola (Brassica napus). In North Dakota, the leading canola producer in the United States, SSR is an endemic disease. In order to estimate the impact of this disease on canola yield, field experiments were conducted from 2000 to 2004 at several locations in North Dakota and Minnesota. Experimental plots were either inoculated with laboratory-produced ascospores or infected by naturally occurring inoculum in commercial fields. Applying fungicides at different concentrations and timings during the flowering period created epiphytotics of diverse intensities. Disease incidence was measured once prior to harvesting the crop on 50 to 100 plants per plot. Results of the study indicated that 0.5% of the potential yield (equivalent to 12.75 kg/ha) was lost for every unit percentage of SSR incidence (range of 0.18 to 0.96%). Considering the current cost of fungicide applications and the market value of this commodity, a 17% SSR incidence could cause losses similar to the cost of a fungicide application. Additional efforts are required to improve current levels of tolerance of canola plants to this pathogen.

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Suppression of Soybean Yield Potential in the Continental United States by Plant Diseases from 2006 to 2009

Plant Health Progress ◽

10.1094/php-2010-1122-01-rs ◽

2010 ◽

Vol 11 (1) ◽

pp. 5 ◽

Cited By ~ 138

Author(s):

Stephen R. Koenning ◽

J. Allen Wrather

Keyword(s):

United States ◽

The United States ◽

Plant Diseases ◽

Soybean Rust ◽

Yield Potential ◽

Stem Rot ◽

Yield Losses ◽

Sclerotinia Stem Rot ◽

Soybean Yield ◽

The Impact

Research must focus on management of diseases that cause extensive losses, especially when funds for research are limited. Knowledge of the losses caused by various soybean diseases is essential when prioritizing research budgets. The objective of this project was to compile estimates of soybean yield potential losses caused by diseases for each soybean producing state in the United States from 2006 to 2009. This data is of special interest since the 4-year period summarized in this report, permits an examination of the impact of soybean rust that was first reported in the United States in 2004. Thus, in addition to the goal of providing this information to aid funding agencies and scientists in prioritizing research objectives and budgets, an examination of the impact of soybean rust on soybean yield losses relative to other diseases is warranted. Yield losses caused by individual diseases varied among states and years. Soybean cyst nematode caused more yield losses than any other disease during 2006 to 2009. Seedling diseases, Phytophthora root and stem rot, sudden death syndrome, Sclerotinia stem rot, and charcoal rot ranked in the top six of diseases that caused yield loss during these years. Soybean yield losses due to soybean rust and Sclerotinia stem rot varied greatly over years, especially when compared to other diseases. Accepted for publication 21 October 2010. Published 22 November 2010.

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First Report of Sclerotinia Stem Rot of Chickpea Caused by Sclerotinia sclerotiorum in North Dakota and Washington

Plant Disease ◽

10.1094/pd-90-0114a ◽

2006 ◽

Vol 90 (1) ◽

pp. 114-114 ◽

Cited By ~ 5

Author(s):

W. Chen ◽

B. Schatz ◽

B. Henson ◽

K. E. McPhee ◽

F. J. Muehlbauer

Keyword(s):

North Dakota ◽

Sclerotinia Sclerotiorum ◽

Disease Incidence ◽

Ascochyta Blight ◽

Growing Season ◽

Stem Rot ◽

Sclerotinia Stem Rot ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Stem Breakage

Chickpea (Cicer arietinum L.) is cultivated as a rotational crop in the cereal-based production system in the U.S. Pacific Northwest (PNW) and its production is expanding to other northern tier states. During July 2005, symptoms of Sclerotinia stem rot were observed on chickpea cv. Dwelley and Dylan in fields near Spangle, WA and Carrington, ND, respectively, with disease incidence of approximately ≤1% in affected areas at both locations. Symptoms included stem whitening, wilting, and stem breakage. Occasionally, white fluffy mycelium was observed; however, production of sclerotia on infected plants was rarely observed. Sclerotinia sclerotiorum was isolated from diseased stems collected from both states. The isolates produced a ring of sclerotia near the edge of potato dextrose agar (PDA) plates in 7 days and produced neither conidia nor other fruiting bodies in culture after 30 days. PCR amplification of the rDNA internal transcribed spacer region from two representative isolates and subsequent digestion with restriction enzymes, Mbo I and Taq I, produced identical banding patterns to previously identified isolates of S. sclerotiorum from pea from the PNW (2). Chickpea cvs. Dwelley and Spanish White (eight plants of each) were inoculated by fastening mycelial agar plugs from an actively growing colony on PDA onto the stems with Parafilm. Symptoms of stem whitening were observed as early as 2 days after inoculation, and the lesions extended upward and downward from the inoculation site. Wilting and stem breakage were also observed. Control inoculations of four plants of each cultivar with PDA plugs without mycelium produced no visible symptoms. S. sclerotiorum was consistently reisolated from inoculated plants but not from control plants. Chickpea had been grown in the PNW for more than 20 years without any reported incidence of Sclerotinia stem rot although the disease has been reported from Arizona (3) and Asian countries (1). This is likely because of the upright growth habit of the chickpea plant coupled with relatively dry conditions late in the growing season. Previous chickpea cultivars were very susceptible to Ascochyta blight, an early-season disease of chickpea in the PNW that reduced chickpea stands and canopy coverage. Current cultivars possess much improved resistance to Ascochyta blight, allowing greater vegetative growth to occur and creating microenvironmental conditions conducive to Sclerotinia stem rot. In North Dakota, where humid conditions prevail late in the growing season, symptoms of Sclerotinia stem rot had been observed in previous years but had not been documented because of a recent history of chickpea cultivation there. To our knowledge, this is the first report of confirmed Sclerotinia stem rot of chickpea in North Dakota and Washington. References: (1) G. J. Boland and R. Hall. Can. J. Plant Pathol. 16:93, 1994. (2) I. Jimenez-Hidalgo et al. Phytopathology (Abstr.) 94(suppl.):S47, 2004. (3) M. E. Matheron and M. Porchas. Plant Dis. 84:1250, 2000.

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

Plant Disease ◽

10.1094/pdis.2002.86.1.26 ◽

2002 ◽

Vol 86 (1) ◽

pp. 26-31 ◽

Cited By ~ 67

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%.

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Effects of Mowing, Seeding Rate, and Foliar Fungicide on Soybean Sclerotinia Stem Rot and Yield

Plant Health Progress ◽

10.1094/php-11-20-0097-rs ◽

2021 ◽

Author(s):

Kurt A. Carpenter ◽

Adam J. Sisson ◽

Yuba R. Kandel ◽

Viviana Ortiz ◽

Martin I. Chilvers ◽

...

Keyword(s):

Management Practices ◽

Management Practice ◽

The United States ◽

Field Trials ◽

Cultural Practice ◽

Stem Rot ◽

Yield Response ◽

Sclerotinia Stem Rot ◽

Seeding Rate ◽

Potential Yield

Sclerotinia stem rot (SSR or white mold), caused by Sclerotinia sclerotiorum (Lib.) DeBary, is an economically important fungal disease of soybean. SSR routinely causes yield loss in the upper Corn Belt of the United States due to wet, humid conditions that coincide with moderate temperatures. This study investigated the novel cultural practice of mechanical cutting, or mowing, as an SSR management practice across multiple seeding rates. Mowing soybean during early vegetative growth alters plant architecture and growth habit. This results in a microclimate within the canopy less suitable for disease development. Field trials were conducted in Iowa, Illinois, Michigan, and Wisconsin in 2017 and 2018. Experimental design was a randomized complete block with four replications. Treatments included mowing (mowing and no mowing), seeding rate (197,684, 271,816, and 345,947 seeds/ha), and fungicide application (boscalid, Endura, and no fungicide). Soybean was mowed at approximately the V4 (four unfolded trifoliate leaves) growth stage. Mowing reduced disease in multiple locations; however, it also reduced yield in most of the locations. In general, there was less SSR in plots with lower seeding rates. Fungicide significantly reduced SSR in two of the five site-years for which disease was observed. Significant yield response to fungicide was also observed in two of the nine total field trials. Results indicate cultural practices such as mowing and reduced seeding rate can decrease SSR severity but also can impact potential yield. Additionally, yield response to SSR management practices may not be observed if disease is absent or at low levels.

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Spread of Sclerotinia stem rot of soybean from area and point sources of apothecial inoculum

Canadian Journal of Plant Science ◽

10.4141/p99-015 ◽

2000 ◽

Vol 80 (2) ◽

pp. 389-402 ◽

Cited By ~ 17

Author(s):

S. N. Wegulo ◽

P. Sun ◽

C. A. Martinson ◽

X. B. Yang

Keyword(s):

Power Law ◽

Field Experiments ◽

Disease Incidence ◽

Exponential Model ◽

Point Sources ◽

Stem Rot ◽

Power Law Model ◽

Sclerotinia Stem Rot ◽

Soybean Field ◽

Area Source

Field experiments were conducted from 1995 to 1998 to quantify the spread of ascospores of Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot of soybean. Incidence of Sclerotinia stem rot measured in a soybean field adjacent to a corn field naturally infested with S. sclerotiorum (area source) was highest close to the area source and decreased with distance from the area source. Disease gradients in the soybean field were described nearly equally well by the exponential model, power law model, and logit-log model. Disease incidence in transects in non-infested areas of a soybean field increased with distance from the edges of soybean and corn area sources of inoculum, reached a maximum at 10–12 and 18–20 m, respectively, from the edges of the inoculum area sources, then decreased in a manner characteristic of the disease gradient curve between 10–12 and 32 m, and 18–20 and 44 m from the edges of the area sources. In soybean plots, disease incidence decreased with distance from point sources of apothecial inoculum. The results from these studies suggest 1) the potential for field to field dispersal of S. sclerotiorum, and 2) that the majority of ascospores of S. sclerotiorum are deposited close to the source (apothecia). Where a concentrated area or point source of S. sclerotiorum inoculum exists, the general exponential model may provide good fits to Sclerotinia stem rot gradient data. Key words: Apothecial inoculum, disease gradients, logit-log model, power law model, simple exponential model

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

Plant Disease ◽

10.1094/pdis.2004.88.3.297 ◽

2004 ◽

Vol 88 (3) ◽

pp. 297-300 ◽

Cited By ~ 23

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.

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Demonstrating Nutrient Cost Gradients: A Brooklyn Case Study

International Journal for Vitamin and Nutrition Research ◽

10.1024/0300-9831/a000210 ◽

2014 ◽

Vol 84 (5-6) ◽

pp. 244-251 ◽

Cited By ~ 2

Author(s):

Robert J. Karp ◽

Gary Wong ◽

Marguerite Orsi

Keyword(s):

Low Income ◽

Energy Content ◽

Food Selection ◽

The United States ◽

United States Department ◽

Micronutrient Deficiencies ◽

Caloric Density ◽

Low Income Families ◽

The Cost ◽

The Impact

Abstract. Introduction: Foods dense in micronutrients are generally more expensive than those with higher energy content. These cost-differentials may put low-income families at risk of diminished micronutrient intake. Objectives: We sought to determine differences in the cost for iron, folate, and choline in foods available for purchase in a low-income community when assessed for energy content and serving size. Methods: Sixty-nine foods listed in the menu plans provided by the United States Department of Agriculture (USDA) for low-income families were considered, in 10 domains. The cost and micronutrient content for-energy and per-serving of these foods were determined for the three micronutrients. Exact Kruskal-Wallis tests were used for comparisons of energy costs; Spearman rho tests for comparisons of micronutrient content. Ninety families were interviewed in a pediatric clinic to assess the impact of food cost on food selection. Results: Significant differences between domains were shown for energy density with both cost-for-energy (p < 0.001) and cost-per-serving (p < 0.05) comparisons. All three micronutrient contents were significantly correlated with cost-for-energy (p < 0.01). Both iron and choline contents were significantly correlated with cost-per-serving (p < 0.05). Of the 90 families, 38 (42 %) worried about food costs; 40 (44 %) had chosen foods of high caloric density in response to that fear, and 29 of 40 families experiencing both worry and making such food selection. Conclusion: Adjustments to USDA meal plans using cost-for-energy analysis showed differentials for both energy and micronutrients. These differentials were reduced using cost-per-serving analysis, but were not eliminated. A substantial proportion of low-income families are vulnerable to micronutrient deficiencies.

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Autism Tsunami: the Impact of Rising Prevalence on the Societal Cost of Autism in the United States

Journal of Autism and Developmental Disorders ◽

10.1007/s10803-021-05120-7 ◽

2021 ◽

Author(s):

Mark Blaxill ◽

Toby Rogers ◽

Cynthia Nevison

Keyword(s):

Forecast Model ◽

The United States ◽

Population Projections ◽

Base Case ◽

Prevention Strategies ◽

Total Base ◽

Cost Categories ◽

The Cost ◽

The Impact ◽

First Time

AbstractThe cost of ASD in the U.S. is estimated using a forecast model that for the first time accounts for the true historical increase in ASD. Model inputs include ASD prevalence, census population projections, six cost categories, ten age brackets, inflation projections, and three future prevalence scenarios. Future ASD costs increase dramatically: total base-case costs of $223 (175–271) billion/year are estimated in 2020; $589 billion/year in 2030, $1.36 trillion/year in 2040, and $5.54 (4.29–6.78) trillion/year by 2060, with substantial potential savings through ASD prevention. Rising prevalence, the shift from child to adult-dominated costs, the transfer of costs from parents onto government, and the soaring total costs raise pressing policy questions and demand an urgent focus on prevention strategies.

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Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Insects ◽

10.3390/insects12040321 ◽

2021 ◽

Vol 12 (4) ◽

pp. 321

Author(s):

Stefan Cristian Prazaru ◽

Giulia Zanettin ◽

Alberto Pozzebon ◽

Paola Tirello ◽

Francesco Toffoletto ◽

...

Keyword(s):

Field Experiments ◽

Field Studies ◽

Generalist Predators ◽

Predator Species ◽

Potted Plants ◽

Naturally Occurring ◽

Orius Majusculus ◽

Limited Effectiveness ◽

Pest Outbreaks ◽

The Impact

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

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Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽

10.1094/pdis-06-10-0454 ◽

2011 ◽

Vol 95 (3) ◽

pp. 263-268 ◽

Cited By ~ 4

Author(s):

S. K. Gremillion ◽

A. K. Culbreath ◽

D. W. Gorbet ◽

B. G. Mullinix ◽

R. N. Pittman ◽

...

Keyword(s):

United States ◽

Disease Resistance ◽

Leaf Spot ◽

Field Experiments ◽

Disease Incidence ◽

The United States ◽

Yield Potential ◽

Cercospora Arachidicola ◽

Breeding Lines ◽

Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

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