scholarly journals Effectiveness of Azoxystrobin in the Control of Erysiphe Cichoracearum and Pseudoperonospora Cubensis on Cucumber

2008 ◽  
Vol 48 (2) ◽  
pp. 147-159 ◽  
Author(s):  
Theerthagiri Anand ◽  
Angannan Chandrasekaran ◽  
Sasthamoorthy Kuttalam ◽  
Govindasamy Senthilraja ◽  
Thiruvengadam Raguchander ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Field Trial ◽  
Field Studies ◽  
Field Trials ◽  
Optimum Dose ◽  
Pseudoperonospora Cubensis ◽  
Erysiphe Cichoracearum ◽  
Cucumber Downy Mildew ◽  
Phytotoxic Effect

Effectiveness of Azoxystrobin in the Control ofErysiphe CichoracearumandPseudoperonospora Cubensison CucumberThe bioefficacy of azoxystrobin (Amistar 25 SC) was tested against cucumber downy mildew and powdery mildew diseases. The two season trials of field studies revealed that the disease progression of cucumber downy mildew and powdery mildew was successfully arrested by azoxystrobin. Spraying of azoxystrobin at various doses (31.25, 62.50 and 125g a.s./ha) revealed that 125 g a.s./ha (500 ml/ha) was considered as the optimum dose for the control of these diseases of cucumber. The treatment also recorded the highest yield of 13.23 and 14.46 tonnes/ha in the first and second season, respectively. No phytotoxic effect of azoxystrobin was observed in the both field trials even at four times of the recommended dose 125 g a.s./ha. The persistence of azoxystrobin at 250 and 500 g a.s./ha was observed up to seven days after last spraying. However, the persistence of azoxystrobin at 31.25, 62.50 and 125 a.s./ha was observed up to three to five days after last spraying. The safe waiting period for the harvest of cucumber fruits was 1.53 days in the first field trial and 2.37 days in the second field trial, respectively at azoxystrobin 125 g a.s./ha. The residues of azoxystrobin were at below detectable level (BDL) in the harvested cucumber fruits.

scholarly journals Distribution of Baseline Sensitivities to Natural Product Physcion Among Isolates of Sphaerotheca fuliginea and Pseudoperonospora cubensis

Plant Disease ◽  
2008 ◽  
Vol 92 (10) ◽  
pp. 1451-1455 ◽  
Author(s):  
X. J. Yang ◽  
L. J. Yang ◽  
F. S. Zeng ◽  
L. B. Xiang ◽  
S. N. Wang ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Selection Pressure ◽  
Ethanol Extract ◽  
Pseudoperonospora Cubensis ◽  
Sphaerotheca Fuliginea ◽  
Baseline Sensitivity ◽  
Cucumber Powdery Mildew ◽  
Significant Difference ◽  
Cucumber Downy Mildew

The ethanol extract from rhubarb was commercialized in China (Veguard, Physcion, 5 g/liter AS) for control of cucumber powdery mildew (Sphaerotheca fuliginea) and cucumber downy mildew (Pseudoperonospora cubensis). To provide the basic data for the risk assessment of resistance to this product, physcion was selected to represent the active ingredients to establish baseline sensitivity of powdery mildew and downy mildew populations. For powdery mildew, 262 isolates of S. fuliginea from nine regions and, for downy mildew populations, 116 isolates of P. cubensis from six regions were collected in China during 2004 and 2005 and tested for sensitivity. In addition, the sensitivity of a powdery mildew isolate was monitored for 15 asexual generations under selection pressure with physcion. The results showed that there was no significant difference among regions in the frequency distribution of baseline sensitivity to this ingredient for either cucumber powdery mildew isolates or cucumber downy mildew isolates. Baseline sensitivity was distributed as a normal unimodal curve with a mean median (50%) effective concentration (EC50) of 0.304 μg/ml for powdery mildew population and mean EC50 of 0.501 μg/ml for downy mildew population. The variation of sensitivity to physcion was low because the range factor (maximum EC50/minimum EC50 of isolates within population) varied from 1.63 to 3.42 among powdery mildew populations and from 1.70 to 2.38 among downy mildew populations. The powdery mildew isolate XZ4 did not decrease sensitivity under the selection pressure of physcion at the dose of EC70 for 15 generations.

scholarly journals Influence of soil pH, rainfall, dosage, and application timing of herbicide Merlin 750 WG (isoxaflutole) on phytotoxicity level in maize (Zea mays L.)

2011 ◽  
Vol 50 (No. 2) ◽  
pp. 88-94 ◽  
Author(s):  
J. Soukup ◽  
M. Jursík ◽  
P. Hamouz ◽  
J. Holec ◽  
J. Krupka
Keyword(s):  
Soil Ph ◽  
Weight Reduction ◽  
Zea Mays L ◽  
Field Studies ◽  
Field Trials ◽  
Early Growth ◽  
Application Timing ◽  
Pot Trials ◽  
Phytotoxic Effect ◽  
Shoot Weight

Pot trials and field studies were carried out to describe the influence of soil pH and rainfall on the phytotoxic effect of the herbicide Merlin 750 WG (isoxaflutole) in maize. Symptoms as bleaching, and root and shoot weight reduction in early growth of maize were found. In pot trials, a statistically significant crop injury in early growth of maize was found only at the herbicide dose of 100 and 130 g/ha followed by 30 mm precipitation directly after herbicide application in soils with pH 6.5 and 7.2. Bleaching and significant weight reduction of maize up to growth stage BBCH 13 were observed in field trials at treatments with early post-emergence application of Merlin and 20 mm precipitations. Bleaching symptoms recovered up to BBCH 19. Significant differences were found in maize shoot weight and cob yield between treatments with and without watering (20 mm irrigation), and between pre- and post-emergence application of Merlin under field conditions. No significant differences were found between herbicide doses tested.

scholarly journals Fungicides for Control of Downy Mildew on Pickling Cucumber in Michigan

2019 ◽  
Vol 20 (3) ◽  
pp. 165-169 ◽  
Author(s):  
Katelyn E. Goldenhar ◽  
Mary K. Hausbeck
Keyword(s):  
Downy Mildew ◽  
Untreated Control ◽  
Field Studies ◽  
Pseudoperonospora Cubensis ◽  
Relative Area ◽  
Disease Progress Curve ◽  
Cucurbit Downy Mildew ◽  
Disease Progress ◽  
Pickling Cucumber ◽  
Progress Curve

Michigan growers rely on fungicides to limit cucurbit downy mildew (CDM), incited by Pseudoperonospora cubensis; resistance of the pathogen to fungicides is a concern. We evaluated fungicides against CDM in Michigan field studies from 2015 to 2017. According to the relative area under the disease progress curve (rAUDPC), in 2015, mandipropamid, propamocarb, fluxapyroxad/pyraclostrobin, copper octanoate, and dimethomorph resulted in disease levels similar to the control. These treatments, along with cymoxanil, were similar to the control in 2016. Fungicides that were ineffective during 2015 and 2016 did not limit CDM in 2017. Famoxadone/cymoxanil and fluopicolide did not limit CDM in 2017. Each year, the following treatments were similar for disease based on rAUDPC data: oxathiapiprolin applied alone or premixed with chlorothalonil or mandipropamid, ametoctradin/dimethomorph, fluazinam, mancozeb/zoxamide, cyazofamid, and ethaboxam. An exception occurred in 2017, when ethaboxam was less effective than fluazinam, oxathiapiprolin/chlorothalonil, and oxathiapiprolin/mandipropamid. Mancozeb and chlorothalonil treatments were similar in 2015 and 2017, according to rAUDPC data. In 2017, yields were increased for oxathiapiprolin/chlorothalonil, oxathiapiprolin/mandipropamid, mancozeb, ametoctradin/dimethomorph, mancozeb/zoxamide, ethaboxam, cyazofamid, chlorothalonil, and fluazinam compared with the untreated control.

scholarly journals Relationship Between Loci Conferring Downy Mildew and Powdery Mildew Resistance in Melon Assessed by Quantitative Trait Loci Mapping

2005 ◽  
Vol 95 (5) ◽  
pp. 556-565 ◽  
Author(s):  
L. Perchepied ◽  
M. Bardin ◽  
C. Dogimont ◽  
M. Pitrat
Keyword(s):  
Quantitative Trait Loci ◽  
Powdery Mildew ◽  
Downy Mildew ◽  
Resistance Genes ◽  
Quantitative Trait ◽  
Pseudoperonospora Cubensis ◽  
Podosphaera Xanthii ◽  
Resistance Qtl ◽  
Trait Loci ◽  
Artificial Inoculations

Partial resistance to downy mildew (Pseudoperonospora cubensis) and complete resistance to powdery mildew (Podosphaera xanthii races 1, 2, 3, and 5 and Golovinomyces cichoracearum race 1) were studied using a recombinant inbred line population between ‘PI 124112’ (resistant to both diseases) and ‘Védrantais’ (susceptible line). A genetic map of melon was constructed to tag these resistances with DNA markers. Natural and artificial inoculations of Pseudoperonospora cubensis were performed and replicated in several locations. One major quantitative trait loci (QTL), pcXII.1, was consistently detected among the locations and explained between 12 to 38% of the phenotypic variation for Pseudoperonospora cubensis resistance. Eight other Pseudoperonospora cubensis resistance QTL were identified. Artificial inoculations were performed with several strains of four races of Podosphaera xanthii and one race of G. cichoracearum. Two independent major genes, PmV.1 and PmXII.1, were identified and shown to be involved in the simple resistance to powdery mildew. Three digenic epistatic interactions involving four loci were detected for two races of Podosphaera xanthii and one race of G. cichoracearum. Co-localization between PmV.1, resistance genes, and resistance genes homologues was observed. Linkage between the major resistance QTL to Pseudoperonospora cubensis, pcXII.1, and one of the two resistance genes to powdery mildew, PmXII.1, was demonstrated.

scholarly journals Effects of Temperature and Moisture on Sporulation and Infection by Pseudoperonospora cubensis

Plant Disease ◽  
2017 ◽  
Vol 101 (4) ◽  
pp. 562-567 ◽  
Author(s):  
Shiling Sun ◽  
Sen Lian ◽  
Shulian Feng ◽  
Xiangli Dong ◽  
Caixian Wang ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Downy Mildew ◽  
Weibull Model ◽  
Infection Process ◽  
Effect Of Temperature ◽  
Effective Control ◽  
Pseudoperonospora Cubensis ◽  
Cucumber Downy Mildew ◽  
Effects Of Temperature ◽  
Modified Weibull

Cucumber downy mildew, caused by Pseudoperonospora cubensis, is a worldwide disease that causes severe damage to cucumber production. The effects of temperature and moisture on sporulation and infection by P. cubensis were investigated by inoculating cucumber (‘85F12’) cotyledons with sporangia and examining the sporangia produced on the inoculated cotyledons under artificially controlled environments. The result showed that the temperature required for sporangium infection by P. cubensis and sporulation of the downy mildew lesions occurred at 5 to 30°C. The optimal temperature estimated by the fitted model was 18.8°C for sporangium infection and 16.2°C for downy mildew lesion sporulation. The pathogen formed plenty of sporangia when disease cotyledons were wetted or in the environment with relative humidity = 100%. The downy mildew lesions produced only a few sporangia when placed in the environment with relative humidity = 90%. The inoculated cotyledons, which incubated for 5 days at about 20°C in a dry greenhouse, began to form sporangia 4 h after being wetted when incubated in darkness. The quantity of sporangia produced on the downy mildew lesions increased with extension of incubating period (within 12 h), and the relationship between produced sporangia and the incubation period at 15, 20, and 25°C can be described by three exponential models. The observed minimum wetness durations (MWD) required for sporangia to complete the infection process and cause downy mildew were 12, 4, 2.5, 1, 1, and 6 h for 5, 10, 15, 20, 25, and 30°C, respectively. The effect of temperature and wetness duration on infection by sporangia of P. cubensis can be described by the modified Weibull model. The shortest MWD was 0.45 h, about 27 min, estimated by model. The experimental data and models will be helpful in the development of forecasting models and effective control systems for cucumber downy mildew.

scholarly journals Testing of paraffin oil efficiency against grape powdery mildew in Eger wine region

2016 ◽  
pp. 73-80
Author(s):  
Xénia Pálfi ◽  
Dénes Bisztray ◽  
Szabolcs Villangó ◽  
Zita Pálfi ◽  
Tamás Deák ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Downy Mildew ◽  
Plasmopara Viticola ◽  
Field Trials ◽  
Intensity Of Infection ◽  
Erysiphe Necator ◽  
Regular Treatment ◽  
Paraffin Oil ◽  
Wine Region ◽  
Grape Varieties

The aim of the present study was to examine the efficiency of paraffin oil against powdery mildew in Eger wine region. The experiment has been carried out in 2013 and 2014 with Chardonnay and Kékfrankos grape varieties, which have different resistance against powdery mildew. The effectiveness of the oil was examined on leaves and clusters (frequency and intensity). This oil was effective against Erysiphe necator infection on field trials in Chile and Brazil. The spread of downy mildew (Plasmopara viticola) was also inhibited by this material in some experiments conducted in Spain and France. The differences between oil treatments represented the sensitivity of the grape varieties in accordance with the applied dosages. The oil was effective against powdery mildew with different extent as a result of the so called ”vintage effect”. In 2013, the treatment of the highest dosage (D3) didn’t differed significantly in frequency and intensity of infection from the regular treatment (clusters of Kékfrankos, leaves of Chardonnay). In 2014, the oil was not so effective against powdery mildew compared to 2013. No remarkable differences were detected between the treatments due to the strong pressure of powdery mildew. Furthermore, no any effect of the lowest dosage (D1) was detected in the case of the sensitive clusters of Chardonnay and leaves of Kékfrankos in both experimental years. In summary, the oil treatment has an effect against powdery mildew, however this efficiency largely depends on the vintage characteristics and the pressure of powdery mildew. Further investigations are neccessary, for example field trials with combinations of other sprays. The oil can be useable as fungicide with proper care in eco-friendly integrated and bio (ecological) viticulture.

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