scholarly journals Control of speckled leaf blotch of wheat with fungicides

2000 ◽  
Vol 53 ◽  
pp. 103-108
Author(s):  
M.G. Cromey ◽  
M. Braithwaite ◽  
B.J.R. Alexander ◽  
S. Ganev ◽  
T.R. Cookson
Keyword(s):  
Disease Severity ◽  
Total Yield ◽  
Field Trials ◽  
Growth Stages ◽  
The South ◽  
Leaf Blotch ◽  
Fungicide Application ◽  
Low Levels ◽  
Disease Pressure

Two field trials were conducted in autumnsown wheat cv Domino which is highly susceptible to speckled leaf blotch in Central and South Canterbury Eighteen fungicide treatments were applied at two growth stages (tillering and ear emergence) at the manufacturers recommended rates Severity of speckled leaf blotch and other diseases was assessed on several occasions Speckled leaf blotch was severe in the South Canterbury trial but only low levels of the disease were recorded in the central Canterbury trial Most fungicides reduced disease severity and increased yield especially in the South Canterbury trial where disease pressure was highest and yield increases greater than 30 were recorded The second fungicide application appeared to provide most of the increase in yield The increases in thousand grain weights following fungicide applications contributed approximately onethird of the total yield increases in the South Canterbury trial and half in the Central Canterbury trial

scholarly journals Effect of Maize Hybrid and Foliar Fungicides on Yield Under Low Foliar Disease Severity Conditions

2015 ◽  
Vol 105 (8) ◽  
pp. 1080-1089 ◽  
Author(s):  
Sally O. Mallowa ◽  
Paul D. Esker ◽  
Pierce A. Paul ◽  
Carl A. Bradley ◽  
Venkata R. Chapara ◽  
...  
Keyword(s):  
Disease Severity ◽  
Field Trials ◽  
Gray Leaf Spot ◽  
Growth Stages ◽  
Lower Yield ◽  
Fungicide Application ◽  
Cercospora Zeae Maydis ◽  
Physiological Benefits ◽  
Foliar Fungicide ◽  
Corn Leaf Blight

Foliar fungicide use in the U.S. Corn Belt increased in the last decade; however, questions persist pertaining to its value and sustainability. Multistate field trials were established from 2010 to 2012 in Illinois, Iowa, Ohio, and Wisconsin to examine how hybrid and foliar fungicide influenced disease intensity and yield. The experimental design was in a split-split plot with main plots consisting of hybrids varying in resistance to gray leaf spot (caused by Cercospora zeae-maydis) and northern corn leaf blight (caused by Setosphaera turcica), subplots corresponding to four application timings of the fungicide pyraclostrobin, and sub-subplots represented by inoculations with either C. zeae-maydis, S. turcica, or both at two vegetative growth stages. Fungicide application (VT/R1) significantly reduced total disease severity relative to the control in five of eight site-years (P < 0.05). Disease was reduced by approximately 30% at Wisconsin in 2011, 20% at Illinois in 2010, 29% at Iowa in 2010, and 32 and 30% at Ohio in 2010 and 2012, respectively. These disease severities ranged from 0.2 to 0.3% in Wisconsin in 2011 to 16.7 to 22.1% in Illinois in 2010. The untreated control had significantly lower yield (P < 0.05) than the fungicide-treated in three site-years. Fungicide application increased the yield by approximately 6% at Ohio in 2010, 5% at Wisconsin in 2010 and 6% in 2011. Yield differences ranged from 8,403 to 8,890 kg/ha in Wisconsin 2011 to 11,362 to 11,919 kg/ha in Wisconsin 2010. Results suggest susceptibility to disease and prevailing environment are important drivers of observed differences. Yield increases as a result of the physiological benefits of plant health benefits under low disease were not consistent.

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.

scholarly journals Measuring and Modeling Crop Loss of Wheat Caused by Septoria Leaf Blotch in Seven Cultivars and Lines in Iran

2009 ◽  
Vol 49 (3) ◽  
pp. 257-262 ◽  
Author(s):  
Shideh Mojerlou ◽  
Naser Safaie ◽  
Azizollah Alizadeh ◽  
Fatemeh Khelghatibana
Keyword(s):  
Grain Yield ◽  
Disease Severity ◽  
Integral Model ◽  
Yield Reduction ◽  
Multiple Point ◽  
Growth Stages ◽  
Research Station ◽  
Crop Loss ◽  
Septoria Leaf Blotch ◽  
Leaf Blotch

Measuring and Modeling Crop Loss of Wheat Caused by Septoria Leaf Blotch in Seven Cultivars and Lines in IranSeptoria leaf blotch caused bySeptoria tritici, is one of the most important diseases of wheat worldwide including Iran. To determine yield reduction caused by this disease in Golestan province, field experiments were carried out in randomized complete block design with four replications and five wheat cvs. Tajan, Zagros, Shiroodi, Koohdasht, Shanghai and two lines N-80-6 and N-80-19 at Gorgan Research Station. Artificial inoculation was performed using spore suspension at three growth stages (Zadoks scale) including tillering (GS 37), stem elongation (GS 45) and flag leaf opening (GS 53). Control plots were sprayed with water. In this study, the 1 000 kernel weight (TKW), grain yield and area under disease progress curve (AUDPC) during growth season were measured. Statistical analysis showed that the levels of yield reduction was different in various studied wheat cultivars and lines and was reduced by 30 to 50%. The highest losses were observed for cvs. Zagros and Tajan with 48.86% and 47.41% of grain yield reduction, respectively. There was a positive correlation between grain yield reduction and AUDPC. The results of crop loss modelling using integral and multiple point regression models showed that the integral model (L = 1230.91+1.37AUDPC) in which AUDPC and crop loss percentages were independent and dependent variables, respectively, could explain more than 95% of AUDPC variations in relation to crop loss in all cultivars in two years. In the study of integral model for each cultivar, cv. Shiroodi showed the highest fitness. In multiple point models, disease severity at various dates was considered as independent variables and crop loss percentage as dependent variable. This model with the highest coefficient of determination had the best fitness for crop loss estimation. Besides, the results showed that the disease severity at GS37, GS53 and GS91 stages (Zadok's scale) was more important for crop loss prediction than that in other phenological stages.

scholarly journals Effect of Foliar Fungicides on Hail-damaged Corn

2016 ◽  
Vol 17 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Adam J. Sisson ◽  
Yuba R. Kandel ◽  
Alison E. Robertson ◽  
Chad E. Hart ◽  
Amy Asmus ◽  
...  
Keyword(s):  
Disease Severity ◽  
Cost Benefit Analysis ◽  
Cost Benefit ◽  
Growth Stages ◽  
Benefit Analysis ◽  
Economic Returns ◽  
Foliar Disease ◽  
Fungicide Application ◽  
Positive Economic ◽  
Hail Damage

To test if fungicide applied to hail-injured corn improves yield and reduces disease, we simulated hail at VT and R2 growth stages for three years at three Iowa locations for a total of five site years. Hail damage was simulated using a string trimmer or an ice-propelling machine and non-hail controls were included. Estimated defoliation ranged from 5 to 51%, along with ear and stalk injury. After hail events, Headline AMP fungicide (pyraclostrobin + metconazole) was applied at an “immediate” or “deferred” timing (averaging 3 and 8 days afterwards, respectively). A non-fungicide treated control was included in hailed and non-hail control plots. Hail injury reduced fungal foliar disease compared to plants without hail injury, although overall disease severity was low during this study. Hail events at VT or R2 decreased yield compared to control plots (P = 0.1). Fungicide application did not provide yield-increasing plant health benefits after VT and R2 hail, at either “immediate” or “deferred” timing. While yield differences were not statistically significant, a cost/benefit analysis showed deferred fungicide application after VT hail, and immediate and deferred applications after VT for non-hail plots did provide positive economic returns. Results will help inform decisions about fungicide use in hail-damaged corn when foliar diseases are not present at high levels. Accepted for publication 7 January 2016. Published 13 January 2016.

scholarly journals Influence of crop growth and weather conditions on speckled leaf blotch in winter wheat

2003 ◽  
Vol 56 ◽  
pp. 246-250 ◽  
Author(s):  
T. Armour ◽  
S.L.H. Viljanen-Rollinson ◽  
S.F. Chng ◽  
R.C. Butler ◽  
M.G. Cromey ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Disease Severity ◽  
Weather Conditions ◽  
Crop Growth ◽  
Septoria Tritici ◽  
Yield Response ◽  
Growth Stages ◽  
Leaf Blotch ◽  
Weather Events ◽  
Significant Yield

Speckled leaf blotch (SLB) a foliar disease of winter wheat caused by Septoria tritici (teleomorph Mycosphaerella graminicola) can cause significant yield losses Wheat crops are at greatest risk during stem extension when the final three leaves emerge in close proximity to infected leaves lower in the canopy Winter wheat cv Consort was sown in May 2002 to test a model that links development of SLB in the field to weather events and to compare disease severity between plots treated with fungicide applied at three different crop growth stages Generally quite low disease levels were experienced associated with a small number of likely infection events This meant that the top three leaves were infected after they were fully emerged and SLB severity was low as there was little time for secondary cycles to occur before the leaves senesced Despite low disease severity there was a significant yield response to applied fungicide increasing with the number of applications The model requires some improvement

scholarly journals Comparing Disease Predictors and Fungicide Programs for Late Blight Management in Celery

Plant Disease ◽  
2007 ◽  
Vol 91 (5) ◽  
pp. 532-538 ◽  
Author(s):  
R. S. Bounds ◽  
M. K. Hausbeck
Keyword(s):  
Late Blight ◽  
Disease Control ◽  
Disease Severity ◽  
Environmental Conditions ◽  
Disease Development ◽  
Foliar Disease ◽  
Fungicide Application ◽  
Disease Pressure ◽  
Late Blight Management ◽  
Reduced Risk

Late blight, incited by the fungus Septoria apiicola, is the most important foliar disease of celery in Michigan and results in necrotic lesions on leaves and petioles that can reduce yield up to 80%. Most celery growers apply the fungicide chlorothalonil as frequently as every 7 days to protect the crop; however, some of these applications may not be needed when environmental conditions do not favor disease development. The purpose of this study was to evaluate disease predictors using a standard (chlorothalonil) and a reduced-risk (azoxystrobin alternated with chlorothalonil) fungicide program for managing late blight on ‘Dutchess’ celery in 2003 to 2005. Fungicides were initiated 1 week after transplanting and reapplied every 7 days or according to the Septoria, Cercospora, or TOM-CAST predictors. The TOM-CAST predictor was tested using 10, 15, and 20 disease severity values (DSV) as thresholds for fungicide application. In each year of this study, timing sprays according to the TOM-CAST 10-DSV predictor resulted in disease control comparable with the 7-day interval, but required up to five fewer sprays and reduced fungicide costs up to $215/ha. The Septoria, Cercospora, and TOM-CAST 15-DSV predictors often provided control similar to the 7-day interval, but these predictors were somewhat inconsistent compared with TOM-CAST 10-DSV. The TOM-CAST 20-DSV predictor required the fewest number of sprays but unacceptable levels of disease resulted. The standard and reduced-risk fungicide programs frequently provided similar control; however, azoxystrobin alternated with chlorothalonil was more effective than chlorothalonil alone when disease pressure was high.

scholarly journals Epidemiology and management of bacterial leaf spot on watermelon caused byPseudomonas syringae

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1222-1229 ◽  
Author(s):  
E. A. Newberry ◽  
L. Ritchie ◽  
B. Babu ◽  
T. Sanchez ◽  
K. A. Beckham ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Negative Relationship ◽  
Disease Outbreaks ◽  
Field Trials ◽  
Multiple Regression Model ◽  
Bacterial Leaf Spot ◽  
Progress Curve ◽  
Cool Conditions

Bacterial leaf spot of watermelon caused by Pseudomonas syringae has been an emerging disease in the southeastern United States in recent years. Disease outbreaks in Florida were widespread from 2013 to 2014 and resulted in foliar blighting at the early stages of the crop and transplant losses. We conducted a series of field trials at two locations over the course of two years to examine the chemical control options that may be effective in management of this disease, and to investigate the environmental conditions conducive for bacterial leaf spot development. Weekly applications of acibenzolar-S-methyl (ASM) foliar, ASM drip, or copper hydroxide mixed with ethylene bis-dithiocarbamate were effective in reducing the standardized area under the disease progress curve (P < 0.05). Pearson’s correlation test demonstrated a negative relationship between the average weekly temperature and disease severity (–0.77, P = 0.0002). When incorporated into a multiple regression model with the square root transformed average weekly rainfall, these two variables accounted for 71% of the variability observed in the weekly disease severity (P < 0.0001). This information should be considered when choosing the planting date for watermelon seedlings as the cool conditions often encountered early in the spring season are conducive for bacterial leaf spot development.

Evaluation of Harvest-Aid Herbicides as Desiccants in Lentil Production

2016 ◽  
Vol 30 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Ti Zhang ◽  
Eric N. Johnson ◽  
Christian J. Willenborg
Keyword(s):  
Adverse Effects ◽  
Crop Yield ◽  
Seed Yield ◽  
Yield Loss ◽  
Field Trials ◽  
Growth Stages ◽  
Yield And Quality ◽  
Seed Field ◽  
Dry Down ◽  
General Reduction

Desiccants are currently used to improve lentil dry-down prior to harvest. Applying desiccants at growth stages prior to maturity may result in reduced crop yield and quality, and leave unacceptable herbicide residues in seeds. There is little information on whether various herbicides applied alone or as a tank-mix with glyphosate have an effect on glyphosate residues in harvested seed. Field trials were conducted at Saskatoon and Scott, Saskatchewan, Canada, from 2012 to 2014 to determine whether additional desiccants applied alone or tank mixed with glyphosate improve crop desiccation and reduce the potential for unacceptable glyphosate residue in seed. Glufosinate and diquat tank mixed with glyphosate were the most consistent desiccants, providing optimal crop dry-down and a general reduction in glyphosate seed residues without adverse effects on seed yield and weight. Saflufenacil provided good crop desiccation without yield loss, but failed to reduce glyphosate seed residues consistently. Pyraflufen-ethyl and flumioxazin applied alone or tank mixed with glyphosate were found to be inferior options for growers as they exhibited slow and incomplete crop desiccation, and did not decrease glyphosate seed residues. Based on results from this study, growers should apply glufosinate or diquat with preharvest glyphosate to maximize crop and weed desiccation, and minimize glyphosate seed residues.

CONTRIBUTION OF STEMS AND LEAVES TO THE YIELD AND NUTRIENT LEVEL OF IRRIGATED ALFALFA AT DIFFERENT STAGES OF DEVELOPMENT

1974 ◽  
Vol 54 (4) ◽  
pp. 739-742 ◽  
Author(s):  
M. R. KILCHER ◽  
D. H. HEINRICHS
Keyword(s):  
Nutritive Value ◽  
Total Yield ◽  
Nutrient Level ◽  
Growth Stages ◽  
Stages Of Development ◽  
Digestible Energy ◽  
Stems And Leaves

In Roamer alfalfa (Medicago media Pers.) the nutritive value in leaves deteriorated much more slowly than that in stems. The percentage of N declined 29% in leaves and 49% in stems; percentage P declined 4% in leaves and 34% in stems, and percentage digestible energy declined 3% in leaves and 34% in stems between early leaf and late bloom growth stages. The total yield of nutrient increased rapidly to the early bloom stage, but quite slowly thereafter. Because of possible leaf loss, delayed harvesting of an alfalfa crop beyond the mid-bloom stage would not be warranted to gain yield even when only one cutting is taken.

Management strategies to reduce losses caused by fusarium seedling blight of field pea

2013 ◽  
Vol 93 (4) ◽  
pp. 619-625 ◽  
Author(s):  
K. F. Chang ◽  
S. F. Hwang ◽  
H. U. Ahmed ◽  
B. D. Gossen ◽  
G. D. Turnbull ◽  
...  
Keyword(s):  
Root Rot ◽  
Field Experiments ◽  
Management Strategies ◽  
Stand Density ◽  
Field Trials ◽  
Field Pea ◽  
Seedling Blight ◽  
Inoculum Level ◽  
Fusarium Seedling Blight ◽  
Disease Pressure

Chang, K. F., Hwang, S. F., Ahmed, H. U., Gossen, B. D., Turnbull, G. D. and Strelkov, S. E. 2013. Management strategies to reduce losses caused by fusarium seedling blight of field pea. Can. J. Plant Sci. 93: 619–625. Fusarium seedling blight can cause substantial reductions in the stand density of field pea in western Canada. In greenhouse experiments, emergence decreased and root rot severity rose with increasing inoculum density. In field trials in 2007 and 2008 near Edmonton, AB, seeding at different depths and seeding dates did not consistently affect emergence or yield in Fusarium-infested soils. In field experiments, emergence declined significantly with each increase in inoculum level. Also, seed yield were reduced at high levels of disease pressure. Treatment of seed with Apron Maxx improved emergence, nodulation and yield of treatments challenged with inoculum of F. avenaceum in both greenhouse and field experiments. This research demonstrates the need to prevent seedling blight and root rot through proper seed treatment.

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