scholarly journals Oil Adjuvants Enhance the Efficacy of Pyraclostrobin in Managing Cucumber Powdery Mildew (Podosphaera xanthii) by Modifying the Affinity of Fungicide Droplets on Diseased Leaves

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1657-1664
Author(s):  
Lifei He ◽  
Xiaoxu Li ◽  
Yangyang Gao ◽  
Beixing Li ◽  
Wei Mu ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Powdery Mildew ◽  
Field Experiments ◽  
Plant Diseases ◽  
Work Of Adhesion ◽  
Podosphaera Xanthii ◽  
Effective Strategy ◽  
Cucumber Powdery Mildew ◽  
Fungicide Mixtures

Adding adjuvants improved the affinity of fungicide droplets to cucumber leaves infected with powdery mildew (Podosphaera xanthii) and subsequent efficacy of fungicide treatments in reducing the disease. The affinity of oil adjuvants was quantified by adhesional tension and “work of adhesion”. Oil adjuvant-fungicide mixtures were applied to plants in field experiments to evaluate their effectiveness in disease prevention. Both the adhesional tension and work of adhesion of the adjuvants at selected concentrations increased on powdery-mildew-infected cucumber leaves more than on healthy cucumber leaves. The adjuvant GY-Tmax (GYT) displayed the best surface activity or “surfactivity” in enhancing the affinity and adherence of droplets to powdery-mildew-infected cucumber leaves, while epoxidized soybean oil (ESO), methyl oleate, and biodiesel exhibited much lower effects in terms of the surface tension, contact angle, adhesional tension, and work of adhesion. Field experiments determined that the combination of GYT at 1,000 mg liter−1 and pyraclostrobin (150 g a.i. ha−1) was most effective (91.52%) in controlling cucumber powdery mildew. Pyraclostrobin with ESO was also highly effective (ranging from 77.54 to 89.65%). The addition of oil adjuvants, especially GYT and ESO, to fungicide applications can be an effective strategy to enhance the efficacy of pesticides in controlling plant diseases by modifying the affinity of fungicide droplets to symptomatic leaves.

scholarly journals Role of hydrogen peroxide and Pharmaplant-turbo against cucumber powdery mildew fungus under organic and inorganic production

2008 ◽  
Vol 14 (3) ◽  
Author(s):  
Y. M. Hafez ◽  
Y. A. Bayoumi ◽  
Z. Pap ◽  
N. Kappel
Keyword(s):  
Hydrogen Peroxide ◽  
Powdery Mildew ◽  
Disease Severity ◽  
Ascorbic Acid Content ◽  
Plant Diseases ◽  
Organic Fertilizers ◽  
Nitrate Content ◽  
Antifungal Compound ◽  
Powdery Mildew Fungus ◽  
Cucumber Powdery Mildew

Cucumber leaves have been sprayed with a solution of hydrogen peroxide (H202) or Pharmaplant-turbo combined with organic or inorganic fertilizers under plasic house. Under the influence of H202, leaves exhibited resistant against Podoshaera fusca fungus, the causal agent of cucumber powdery mildew. H202 (15 mM) was able to decrease the disease severity from 90.4% to 12% in two experiments conducted in two seasons. Pharmaplant-turbo (Turbo) is new chemical compound and used as an antifungal compound. Turbo in 1 ml/L was able to decrease the disease severity from 90.4% to 11.5% in the both experiments as well. Both of H202 and Turbo were combined with organic treatment (compost + compost tea + seaweed extracts) which showed significant effect against cucumber powdery mildew fungus and strongly suppressed it as compared to control leaves. Organic treatment produced higher vegetative growth characters and greater early and total yields as compared to inorganic treatment, also organic fruits produced the lower nitrate content and the higher ascorbic acid content as compared to inorganic fruits. Our study have indicated that, H202 and Turbo combined with organic fertilizers play a role in the resistance of cucumber against powdery mildew by decreasing the disease severity. We suggest to give more attention to the direct application of H202 in low concentration and Turbo against powdery mildew diseases and other plant diseases.

Nighttime Application of UV-C to Control Cucumber Powdery Mildew

2020 ◽  
Vol 21 (1) ◽  
pp. 40-46 ◽  
Author(s):  
Jaimin S. Patel ◽  
Leora C. Radetsky ◽  
Rohan Nagare ◽  
Mark S. Rea
Keyword(s):  
Powdery Mildew ◽  
Leaf Area ◽  
Disease Severity ◽  
Uv Radiation ◽  
Podosphaera Xanthii ◽  
Laboratory Studies ◽  
Time Of Application ◽  
Cucumber Powdery Mildew ◽  
The Impact ◽  
Uv C

Nonionizing, ultraviolet (UV) radiation is effective for mitigating powdery mildew associated with a variety of crops including strawberry, grapes, rosemary, tomato, rose, and cucumber. The effectiveness of UV radiation depends upon the dose (irradiance × duration), the frequency of dosing, the time of application, and the sensitivity of the crop to UV radiation. Reported here are the results of two laboratory studies examining the impact of UV-C (254 nm) on cucumber and its obligate powdery-mildew-causing pathogen Podosphaera xanthii. In the first study, doses of UV-C (72 and 144 J m–2) applied every night were more effective at reducing disease severity than dosing every day. However, leaf area was reduced more following nighttime applications than daytime applications, suggesting that both day and night applications of UV-C could compromise yield without necessarily eliminating the disease. The second study showed that a dose of UV-C (7.2 J m–2) applied every night or a higher dose (70 J m–2) applied every fourth night were both effective for eliminating powdery mildew without significantly reducing leaf area. These findings, if confirmed in the field, could provide cucumber growers with additional options for controlling powdery mildew without compromising yield.

The effects of different biological control agents (BCAs) and plant defence elicitors on cucumber powdery mildew (Podosphaera xanthii)

2012 ◽  
Vol 2 (2) ◽  
pp. 89-101 ◽  
Author(s):  
Charilaos Giotis ◽  
Emilia Markellou ◽  
Aphroditi Theodoropoulou ◽  
George Kostoulas ◽  
Stephen Wilcockson ◽  
...  
Keyword(s):  
Biological Control ◽  
Powdery Mildew ◽  
Plant Defence ◽  
Podosphaera Xanthii ◽  
Biological Control Agents ◽  
Cucumber Powdery Mildew

Ring distraction technique for measuring surface tension of sputum: relationship to sputum clearability

1996 ◽  
Vol 81 (6) ◽  
pp. 2690-2695 ◽  
Author(s):  
G. M. Albers ◽  
R. P. Tomkiewicz ◽  
M. K. May ◽  
O. E. Ramirez ◽  
B. K. Rubin
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Work Of Adhesion ◽  
Small Samples ◽  
Low Surface Energy ◽  
Measuring Surface ◽  
Significant Difference ◽  
Ring Method ◽  
Young Equation ◽  
Made In

Albers, G. M., R. P. Tomkiewicz, M. K. May, O. E. Ramirez, and B. K. Rubin. Ring distraction technique for measuring surface tension of sputum: relationship to sputum clearability. J. Appl. Physiol. 81(6): 2690–2695, 1996.—Poor sputum clearance has been related to sputum adhesion tension. In this study, we describe a modified du Noüy ring method for measuring the surface tension (γ) of small samples of sputum and for comparinge the calculated work of adhesion (Wad) for sputum specimens with the measured mucociliary transportability (MCTR) and cough transportability (CTR). The γ, as measured by this method, correlates with γ measured by sputum contact angle on a low-surface-energy solid ( R 2= 0.368, P = 0.03). There is a small but significant difference in measurements made by these two methods ( P = 0.03). Wad calculated from the surface tension ring method is inversely correlated with CTR ( R 2= 0.181, P = 0.004) but has no correlation with MCTR in this study. The miniaturized ring method gives accurate and reproducible measurements of the surface tension of small amounts of respiratory secretions. Because sputum behaves enough like a liquid that the assumptions made in using the Young equation to calculate Wad appear valid, we also showed that the Neumann equation can be used to determine the surface tension of sputum by its contact angle on tetrafluoroethylene (Teflon).

scholarly journals Activity, Translocation, and Persistence of Isopyrazam for Controlling Cucumber Powdery Mildew

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1139-1144 ◽  
Author(s):  
Lei-ming He ◽  
Kai-di Cui ◽  
Di-cheng Ma ◽  
Rui-ping Shen ◽  
Xue-ping Huang ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Causal Agent ◽  
Podosphaera Xanthii ◽  
Systemic Movement ◽  
Cucumber Powdery Mildew ◽  
Long Duration ◽  
Duration Of Efficacy

A cotyledon bioassay was conducted to assess the activity of isopyrazam against Podosphaera xanthii (Castagne) U. Braun & N. Shishkoff, causal agent of cucumber powdery mildew. Results showed that isopyrazam has protective and curative activity against P. xanthii, with EC50 values of 0.04 and 0.05 mg liter–1, respectively. These activities are higher than those for hexaconazole, difenoconazole, pyraclostrobin, kresoxim-methyl, and azoxystrobin, fungicides currently used against cucumber powdery mildew. Isopyrazam at 0.5 mg liter–1 damaged conidiophores. Results of inoculation tests in greenhouse pots indicate that isopyrazam demonstrates a level of systemic movement in cucumber plants, especially regarding translaminar and transverse translocation. Efficacy following translaminar and transverse translocations on cotyledons and leaves treated with 60 mg liter–1 was 94.40% and 88.96%, and 95.26% and 82.83%, respectively. In addition, isopyrazam at 60 mg liter–1 exhibited a long duration of efficacy against cucumber powdery mildew, almost 2 to 3 weeks longer than that of triazoles and strobilurins. Similar trends in residual durations were observed during 2014 and 2015 greenhouse trials. Isopyrazam at 30 and 60 a.i. g ha–1 provided efficacy ranging from 83.27 to 90.83% 20 days following treatment. In conclusion, isopyrazam has translaminar and transverse translocation in cucumber leaves, and long duration of activity against cucumber powdery mildew.

Simple, Fast, and Accurate In silico Estimations of Contact Angle, Surface Tension, and Work of Adhesion of Water and Oil Nanodroplets on Amorphous Polypropylene Surfaces

2012 ◽  
Vol 4 (6) ◽  
pp. 2855-2859 ◽  
Author(s):  
Daniel Romero Nieto ◽  
Francesca Santese ◽  
Radovan Toth ◽  
Paola Posocco ◽  
Sabrina Pricl ◽  
...  
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
In Silico ◽  
Work Of Adhesion

Isolation, purification and identification of the active compound of turmeric and its potential application to control cucumber powdery mildew

2018 ◽  
Vol 156 (3) ◽  
pp. 358-366 ◽  
Author(s):  
W. J. Fu ◽  
J. Liu ◽  
M. Zhang ◽  
J. Q. Li ◽  
J. F. Hu ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Crude Extract ◽  
Active Compound ◽  
High Performance ◽  
Curcuma Longa ◽  
Control Plant ◽  
Plant Diseases ◽  
Cucumber Powdery Mildew ◽  
Fungicidal Effect ◽  
Ability To Act

AbstractCucumber powdery mildew is a destructive foliar disease caused by Podosphaera xanthii (formerly known as Sphaerotheca fuliginea) that substantially damages the yield and quality of crops. The control of this disease primarily involves the use of chemical pesticides that cause serious environmental problems. Currently, numerous studies have indicated that some plant extracts or products potentially have the ability to act as natural pesticides to control plant diseases. It has been reported that turmeric (Curcuma longa L.) and its extract can be used in agriculture due to their insecticidal and fungicidal properties. However, the most effective fungicidal component of this plant is still unknown. In the current study, the crude extract of C. longa L. was found to have a fungicidal effect against P. xanthii. Afterwards, eight fractions (Fr.1–Fr.8) were gradually separated from the crude extract by column chromatography. Fraction 1 had the highest fungicidal effect against this pathogen among the eight fractions. The active compound, (+)-(S)-ar-turmerone, was separated from Fr 1 by semi-preparative high-performance liquid chromatography and identified based on its 1H nuclear magnetic resonance (NMR) and 13C NMR spectrum data. The EC50 value of (+)-(S)-ar-turmerone was found to be 28.7 µg/ml. The compound also proved to have a curative effect. This is the first study to report that the compound (+)-(S)-ar-turmerone has an effect on controlling this disease. These results provide a basis for developing a new phytochemical fungicide from C. longa L. extract.

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