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.

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.

scholarly journals Susceptibility of Deciduous Azalea Cultivars to Powdery Mildew Disease

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 773A-773
Author(s):  
Michael C. Long* ◽  
Stephen L. Krebs ◽  
Stan C. Hokanson
Keyword(s):  
Powdery Mildew ◽  
Leaf Area ◽  
Disease Severity ◽  
Host Resistance ◽  
Resistance Mechanism ◽  
Disease Symptoms ◽  
Leaf Surfaces ◽  
The Mean ◽  
Commercial Sources ◽  
Symptom Rating

Forty deciduous azalea (Rhododendron sp.) cultivars from commercial sources were evaluated for powdery mildew (Microsphaera sp.) resistance. Plants were established in two duplicate field plantings in Ohio and Minnesota and evaluated in 2002 and 2003. Plants were scored using a disease symptom rating based on the percent of leaf area infected, evaluating both ab- and adaxial leaf surfaces. Highly significant differences were found for cultivar, location, year, cultivar × location and cultivar × year for disease severity. Calendulaceum × speciosum, `Fragrant Star', `Garden Party', `Late Lady', `Millennium', `Parade', and `Popsicle' showed no powdery mildew symptoms in both locations. Another group of plants with only minimal symptoms (<25% leaf area affected) included `Jane Abbott', `Magic', `Northern Hi-Lights' and `Snowbird'. The symptom-free cultivars exhibited glaucous foliage, suggesting a potential, common resistance mechanism. The mean scores for the abaxial and adaxial leaf surfaces were 2.34 and 1.64, respectively, although four cultivars had more disease symptoms on the adaxial surface. `Arneson Gem' showed nearly a two-point difference between abaxial and adaxial scores. Evaluations of azalea powdery mildew susceptibility should consider both leaf surfaces and use the highest score as the best estimate of host resistance.

scholarly journals Effects of UV Radiation on the Chlorophyte Micromonas polaris Host–Virus Interactions and MpoV-45T Virus Infectivity

2021 ◽  
Vol 9 (12) ◽  
pp. 2429
Author(s):  
Charlotte Eich ◽  
Sven B. E. H. Pont ◽  
Corina P. D. Brussaard
Keyword(s):  
Uv Radiation ◽  
Algal Growth ◽  
Virus Production ◽  
Virus Infectivity ◽  
Negative Effects ◽  
Algal Viruses ◽  
Host Virus Interactions ◽  
Virus Interactions ◽  
The Impact ◽  
Uv C

Polar seas are under threat of enhanced UV-radiation as well as increasing shipping activities. Considering the ecological importance of marine viruses, it is timely to study the impact of UV-AB on Arctic phytoplankton host–virus interactions and also test the efficacy of ballast water (BW) UV-C treatment on virus infectivity. This study examined the effects of: (i) ecologically relevant doses of UV-AB radiation on Micromonas polaris RCC2258 and its virus MpoV-45T, and (ii) UV-C radiation (doses 25–800 mJ cm−2) on MpoV-45T and other temperate algal viruses. Total UV-AB exposure was 6, 12, 28 and 48 h (during the light periods, over 72 h total). Strongest reduction in algal growth and photosynthetic efficiency occurred for 28 and 48 h UV-AB treatments, and consequently the virus production rates and burst sizes were reduced by more than half (compared with PAR-only controls). For the shorter UV-AB exposed cultures, negative effects by UV (especially Fv/Fm) were overcome without impacting virus proliferation. To obtain the BW desired log−4 reduction in virus infectivity, a UV-C dose of at least 400 mJ cm−2 was needed for MpoV-45T and the temperate algal viruses. This is higher than the commonly used dose of 300 mJ cm−2 in BW treatment.

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

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.

scholarly journals Powdery Mildew and Nutritional Qualities of Cashew Apple and Kernels

2017 ◽  
Vol 5 (2) ◽  
pp. 116
Author(s):  
Uaciquete, Americo ◽  
Manjate, Cicilia ◽  
Muidingui, Lucas
Keyword(s):  
Powdery Mildew ◽  
Vitamin C ◽  
Disease Severity ◽  
Soluble Solids ◽  
Ph Values ◽  
Randomized Design ◽  
Nutritional Qualities ◽  
Completely Randomized Design ◽  
The Impact

In this study we quantitatively evaluated the impact of cashew’s powdery mildew on nutritional quality of both apples and nut products. Specifically we assessed pH, Brix, Vitamin C and the concentration of alcohol on juice, fermented juice and distilled spirit. In addition, kernels from diseased nuts were assessed for moisture, ash, lipids, proteins and carbohydrates content. A completely randomized design with at least three replications was followed in each trial and analysis of variance (ANOVA) performed to check the disease severity categories effect, on nutritional qualities of apples drinkables and kernels. Treatment means were separated by Tukey’s test (P<0.01). Apple disease severity significantly increased pH values of apple juice from 5.22 to 5.34 and 5.47 respectively from healthy, infected and severely infected fruits. Similarly, the amount of Vitamin C increased statistically from 158.92 to 169.02 and 182.15 mg/ml. Finally, Juice Total Soluble Solids (TSS) significantly increased from 13.9 to and 15.1 and 18.9 O Brix. In the wine from healthy, infected and severely infected fruits, pH values varied from 4.66 to 4.79 and 5.47 respectively. Similar trends were observed in fermented wine and distilled spirit. However, the effect of powdery mildew nut scarification on kernels content in moisture, ash, lipids, proteins and carbohydrates was not statistically significant (P>0.01). In conclusion, powdery mildew disease improved the nutritional qualities of cashew apples derived drinks but caused no effect on nutritional components of the kernels. Therefore in disease endemic regions apple selection is highly recommended for fresh consumption or preparation of cashew drinkables.

scholarly journals Powdery Mildew Resistant Rootstocks that Impart Tolerance to Grafted Susceptible Watermelon Scion Seedlings

Plant Disease ◽  
2018 ◽  
Vol 102 (7) ◽  
pp. 1290-1298 ◽  
Author(s):  
Chandrasekar S. Kousik ◽  
Mihir Mandal ◽  
Richard Hassell
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Disease Severity ◽  
Citrullus Lanatus ◽  
The United States ◽  
Bottle Gourd ◽  
Economic Losses ◽  
Podosphaera Xanthii ◽  
Lagenaria Siceraria ◽  
True Leaf

Powdery mildew (PM) is a major foliar disease causing serious economic losses of cucurbit crops grown in the United States. The pathogen Podosphaera xanthii, which causes PM, is known to infect seedlings, stems, foliage, petioles, and fruit of cucurbit crops. In recent years, grafting watermelon on resistant rootstocks for managing soilborne diseases has been gaining popularity in the U.S.A. However, grafting for managing foliar diseases has not yet received adequate attention. Three greenhouse experiments were conducted during the summer months of 2012, 2013, and 2014 to determine if PM-resistant rootstocks could impart resistance to a susceptible watermelon scion. Susceptible watermelon scion ‘Mickey Lee’ seedlings were grafted onto 25 watermelon (Citrullus lanatus, C. amarus, C. mucosospermus) and four bottle gourd (Lagenaria siceraria) rootstocks. Grafted plants were inoculated with a 2 × 104 conidia ml−1 suspension of P. xanthii conidia and disease severity was rated 14 days after inoculation. Mickey Lee grafted on six PM-resistant watermelon rootstocks had significantly (P ≤ 0.05) lower PM severity on cotyledons, 2nd true leaf, and upper leaves (rating for 3rd to 7th or 8th true leaf) compared with Mickey Lee grafted on susceptible watermelon USVL677-PMS or bottle gourd USVL848-PMS rootstocks. However, some of the resistant watermelon rootstocks did not impart significant resistance to the scion. The resistant bottle gourd rootstocks USVL482-PMR and USVL351-PMR provided significantly greater levels of resistance, compared with many of the resistant watermelon rootstocks. Grafting watermelon on resistant rootstocks may help mitigate the effects of PM on susceptible scion seedlings.

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