scholarly journals Integrated Management of Downy Mildew on Slicing Cucumber With Fungicides and Host Resistance But Not Trellising

Plant Disease ◽  
2019 ◽  
Vol 103 (10) ◽  
pp. 2592-2598
Author(s):  
Anthony P. Keinath
Keyword(s):  
Downy Mildew ◽  
Host Resistance ◽  
Management Practices ◽  
Integrated Management ◽  
Cultivar Resistance ◽  
Fall Season ◽  
Fungicide Treatment ◽  
Progress Curve ◽  
Management Techniques ◽  
The Mean

The objective of this study was to evaluate fungicide applications, host resistance, and trellising, alone and in combination, as management practices for downy mildew on slicing cucumber. A split-split plot experimental design was used with three and four replications in spring and fall 2017, respectively. The whole-plot treatment was fungicide, four applications of chlorothalonil (Bravo Weather Stik 6SC) alternated with three applications of cyazofamid (Ranman 400SC), or water. Split plots were nontrellised or trellised with four strings supported by stakes. Split-split plots were cultivar Bristol, which is intermediately resistant to downy mildew, or cultivar Speedway, which is susceptible to downy mildew with similar parentage as Bristol. In both seasons, area under the disease progress curve (AUDPC) values were lower with fungicides than water for both cultivars. In the spring, AUDPC for Bristol was lower than for Speedway regardless of fungicide treatment. In the fall, Bristol had a lower AUDPC than Speedway with fungicides, but the AUDPC did not differ between the two cultivars with water. The mean AUDPC for trellised plants (376.2) was lower than for nontrellised plants (434.0; P = 0.007). Fungicide applications increased marketable and total fruit weights in both seasons (P ≤ 0.0002). Marketable weight with fungicides was almost double (93% greater) the marketable weight with water. Marketable weight was 55% greater for Bristol than for Speedway in spring, but yields did not differ between cultivars in fall (season-by-cultivar interaction, P ≤ 0.0003). Because trellising had no effect on marketable yields (P = 0.11), trellising is not recommended for managing downy mildew on slicing cucumber. Of the three management techniques examined, fungicides had the largest effects on disease and yields, followed by cultivar resistance.

Temporal Dynamics and Severity of Cucurbit Downy Mildew Epidemics as Affected by Chemical Control and Cucurbit Host Type

Plant Disease ◽  
2021 ◽  
Author(s):  
Isaack Kikway ◽  
Anthony P. Keinath ◽  
Peter S. Ojiambo
Keyword(s):  
Downy Mildew ◽  
Disease Severity ◽  
Temporal Dynamics ◽  
Parameter Estimates ◽  
Spring Season ◽  
Fall Season ◽  
Fungicide Treatment ◽  
Cucurbit Downy Mildew ◽  
Disease Progress ◽  
Host Type

Cucurbit downy mildew caused by the oomycete Pseudoperonospora cubensis is an important disease that affects members of Cucurbitaceae family globally. However, temporal dynamics of the disease have not been characterized at the field scale to understand how control strategies influence disease epidemics. Disease severity was assessed visually on cucumber and summer squash treated with weekly alternation of chlorothalonil with either cymoxanil, fluopicolide or propamocarb, during the 2018 spring season and 2019 and 2020 fall seasons in North Carolina, and the 2018 and 2020 fall seasons in South Carolina. Disease onset was observed around mid-June during the spring season and early September during the fall season, followed by a rapid increase in severity until mid-July in the spring season and late September or mid-October in the fall season, typical of polycyclic epidemics. The Gompertz, logistic and monomolecular growth models were fitted to disease severity using linear regression and parameter estimates used to compare the effects of fungicide treatment and cucurbit host type on disease progress. The Gompertz and logistic models were more appropriate than the monomolecular model in describing temporal dynamics of cucurbit downy mildew, with the Gompertz model providing the best description for 34 of the 44 epidemics examined. Fungicide treatment and host type significantly (P < 0.0001) affected standardized area under disease progress curve (sAUDPC), final disease severity (Final DS) and weighted mean absolute rates of disease progress (ρ), with these variables, in most cases, being significantly (P < 0.05) lower in fungicide treated plots than in untreated control plots. Except in a few cases, sAUDPC, Final DS and ρ were lower in cases where chlorothalonil was alternated with fluopicolide or propamocarb than in cases where chlorothalonil alternated with cymoxanil or when chlorothalonil was applied alone. These results characterized the temporal progress of cucurbit downy mildew and provided an improved understanding of the dynamics of the disease at the field level. Parameters of disease progress obtained from this study could serve as inputs in simulation studies to assess the efficacy of fungicide alternation in managing fungicide resistance in this pathosystem.

scholarly journals Effect of Silicon and Host Resistance on Sheath Blight Development in Rice

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 827-832 ◽  
Author(s):  
F. Á. Rodrigues Peters ◽  
L. E. Datnoff ◽  
G. H. Korndörfer ◽  
K. W. Seebold ◽  
M. C. Rush
Keyword(s):  
Host Resistance ◽  
Partial Resistance ◽  
Dry Matter ◽  
Sheath Blight ◽  
Dry Matter Accumulation ◽  
Silicate Slag ◽  
Progress Curve ◽  
Calcium Silicate Slag ◽  
Lesion Extension ◽  
The Mean

Rice cultivars high in partial resistance (Jasmine, LSBR-5), moderately susceptible (Drew and Kaybonnet), and susceptible (Lemont and Labelle) to sheath blight were grown in a silicon-deficient Histosol with and without calcium silicate slag. The treatment with silicon increased the concentration of this element in plant tissue by 80%over all experiments. Fertilization with silicon significantly reduced the severity of sheath blight, and the total area under the vertical lesion extension progress curve on moderately susceptible and susceptible cultivars compared to those cultivars high in partial resistance without silicon. The percentage of infected tillers was significantly reduced by 82, 42, 28, 41, 26, and 17%respectively for Jasmine, LSBR-5, Drew, Kaybonnet, Lemont, and Labelle, when silicon was applied, over all experiments. Dry matter accumulation was significantly greater with added silicon. In the absence of disease, silicon enhanced dry matter accumulation by 15%over the control, whereas silicon more than doubled the mean dry matter accumulation in infected plants. The application of silicon to complement host resistance to sheath blight appears to be an effective strategy for disease management in rice, especially when the soil is low or limiting in plant-available silicon.

scholarly journals Components of Quantitative Resistance to Philippine Downy Mildew In Maize

Zuriat ◽  
2015 ◽  
Vol 13 (1) ◽  
Author(s):  
D. Ruswandi ◽  
A. D. Raymundo ◽  
R. M. Lantican ◽  
D. M. Hautea ◽  
A. M. Salazar ◽  
...  
Keyword(s):  
Downy Mildew ◽  
Inbred Line ◽  
Host Resistance ◽  
Quantitative Resistance ◽  
Disease Incidence ◽  
Transgressive Segregation ◽  
Adult Plant ◽  
Progress Curve ◽  
Systemic Symptoms ◽  
Line P

Resistance to Philippine downy mildew (Peronosclerospora philippinensis) was observed in a BC1F2 population developed from a cross between the susceptible inbred line Pi 23 and the resistant inbred line P 345. Five components of resistance namely, disease incidence, disease severity, onset of systemic symptoms, the-area- underdisease-progress- curve (AUDPC), and rate of downy mildew development affected host resistance reactions. All components were significantly correlated. The adult plant resistant reaction was evident in resistant progenies showing prolonged onset of systemic symptoms. Transgressive segregation that exceeded the high and low parent values was also observed for all components of quantitative resistance to Philippine downy mildew.

scholarly journals Rhizobacteria induces resistance against Fusarium wilt of tomato by increasing the activity of defense enzymes

Bragantia ◽  
2014 ◽  
Vol 73 (3) ◽  
pp. 274-283 ◽  
Author(s):  
Hélvio Gledson Maciel Ferraz ◽  
Renata Sousa Resende ◽  
Patrícia Ricardino Silveira ◽  
Camila Cristina Lage Andrade ◽  
Elisângela Aparecida Milagres ◽  
...  
Keyword(s):  
Jasmonic Acid ◽  
Fusarium Wilt ◽  
Host Resistance ◽  
Plasma Membranes ◽  
Integrated Management ◽  
Positive Control ◽  
Defense Enzymes ◽  
Tomato Plants ◽  
Tomato Yield ◽  
Progress Curve

Fusarium wilt, caused by Fusarium oxysporum f.sp. lycopersici (Fol), is one of the most important diseases that affect tomato yield worldwide. This study investigated the potential of three antagonists, Streptomyces setonii (UFV 618), Bacillus cereus (UFV 592) and Serratia marcescens (UFV 252), and as positive control the hormone jasmonic acid (JA), to reduce Fusarium wilt symptoms and to potentiate the defense enzymes in the stem tissues of tomato plants infected by Fol. The seeds were microbiolized with each antagonist, and the soil was also drenched with them. The plants were sprayed with JA 48 h before Fol inoculation. The area under the Fusarium wilt index progress curve was reduced by 54, 48, 47 and 45% for the UFV 618, JA, UFV 592 and UFV 252 treatments, respectively. The three antagonists, and even the JA spray, efficiently reduced the Fusarium wilt symptoms on the tomato plant stems, which can be explained by the lower malondialdehyde concentration (an indication of oxidative damage to lipids in the plasma membranes) and the greater activities of peroxidases, polyphenoloxidases, glucanases, chitinases, phenylalanine ammonia-lyases and lipoxygenases, which are commonly involved in host resistance against fungal diseases. These results present a novel alternative that can be used in the integrated management of Fusarium wilt on tomatoes.

Impression management and legitimacy strategies: The BP case

2013 ◽  
pp. 35-64 ◽  
Author(s):  
Giovanna Michelon
Keyword(s):  
Impression Management ◽  
Management Practices ◽  
Legitimacy Theory ◽  
British Petroleum ◽  
Wide Range ◽  
Management Techniques ◽  
Disclosure Tone ◽  
The Empirical Analysis ◽  
A Company ◽  
Texas City

The aim of this paper is to study if and how impression management varies during different phases of the legitimation process, in particular during the legitimacy building and legitimacy repairing phases (Suchman, 1995). We aim at understanding whether and how the disclosure tone adopted by a company in the two different moments is diverse and thus functional to the intrinsic objective of the each phase. The empirical analysis focuses on the case of British Petroleum Plc. We investigated the impression management practices undertaken by the company both during the preparation of the rebranding operation, i.e. a situation in which the company is trying to build legitimacy; and during the happenings of two legitimacy crises, like the explosion of the refinery in Texas City and the oil spill in the Gulf of Mexico. The evidence appears in line with the theoretical prediction of legitimacy theory. Results show that while the company tends to privilege image enhancement techniques during the legitimacy-building phase, it uses more obfuscation techniques when managing a legitimacy-repairing process. Moreover, the analysis suggests that the company makes more extensive use of impression management techniques in the disclosures addressed to shareholders, investors and other market operators than in the disclosures addressed to the wide range of other stakeholders.

scholarly journals Organic Farming and Cover-Crop Management Reduce Pest Predation in Austrian Vineyards

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 220
Author(s):  
Jo Marie Reiff ◽  
Sebastian Kolb ◽  
Martin H. Entling ◽  
Thomas Herndl ◽  
Stefan Möth ◽  
...  
Keyword(s):  
Organic Farming ◽  
Pest Control ◽  
Cover Crops ◽  
Cover Crop ◽  
Management Practices ◽  
Integrated Management ◽  
Lobesia Botrana ◽  
Management Options ◽  
Natural Pest Control ◽  
Predation Rates

Habitat simplification and intensive use of pesticides are main drivers of global arthropod declines and are, thus, decreasing natural pest control. Organic farming, complex landscapes, and local vineyard management practices such as implementation of flower-rich cover-crop mixtures may be a promising approach to enhance predator abundance and, therefore, natural pest control. We examined the effect of organic versus integrated management, cover-crop diversity in the vineyard inter-rows, and landscape composition on the natural pest control of Lobesia botrana eggs and pupae. Predation of L. botrana pupae was reduced by organic farming and species-poor cover-crops by about 10%. Predation rates of L. botrana eggs did not differ significantly in any of the studied management options. Dominant predators were earwigs (Forficulidae), bush crickets (Tettigoniidae), and ants (Formicidae). Negative effects of organic viticulture are most likely related to the negative nontarget effects on arthropods related to the frequent sulfur and copper applications in combination with the avoidance of strongly damaging insecticides by integrated winegrowers. While a 10% difference in predation rates on a single pest stage is unlikely to have strong practical implications, our results show that the assumed effectiveness of environmentally friendly agriculture needs to be evaluated for specific crops and regions.

scholarly journals Effectiveness of Home-Based Occupational Therapy on COPM Performance and Satisfaction Scores in Patients with COPD

2020 ◽  
pp. 000841742097112
Author(s):  
Eleonore H. Koolen ◽  
Martijn A. Spruit ◽  
Marianne de Man ◽  
Jeanine C. Antons ◽  
Elieke Nijhuis ◽  
...  
Keyword(s):  
Occupational Therapy ◽  
Integrated Management ◽  
Performance Measure ◽  
Occupational Performance ◽  
Post Intervention ◽  
Canadian Occupational Performance Measure ◽  
Home Based ◽  
Copd Patients ◽  
The Mean ◽  
Mean Differences

Background. Occupational therapy (OT) may be an important intervention in patients with COPD, but studies show conflicting results. Purpose. To evaluate the effectiveness of home-based monodisciplinary OT in COPD patients Method. We conducted an observational clinical study. Main outcomes were the mean differences in the Canadian Occupational Performance Measure (COPM) performance and satisfaction scores, pre and post intervention. Findings. Pre- and postintervention data were obtained from 41 patients. Statistically significant increases were observed in COPM performance (5.0 ± 1.1 versus 6.9 ± 0.9; P<0.001) and satisfaction (4.6 ± 1.3 versus 6.9 ± 1.0; P<0.001). The most frequently reported occupational performance problems were found in the domains of productivity (47%) and mobility (40%), fewer in self-care (10%) and the least in leisure (3%). Implications. Home-based monodisciplinary OT can contribute significantly to the improvement of daily functioning of patients with COPD. OT should therefore be considered more often as part of the integrated management of these patients.

scholarly journals The impact of cultivar resistance and fungicide treatment on mycotoxin content in grain and yield losses caused by Fusarium head blight in wheat

2010 ◽  
Vol 46 (No. 1) ◽  
pp. 21-26 ◽  
Author(s):  
V. Šíp ◽  
J. Chrpová ◽  
O. Veškrna ◽  
L. Bobková
Keyword(s):  
Grain Yield ◽  
Fusarium Head Blight ◽  
Field Experiments ◽  
Yield Loss ◽  
Joint Effect ◽  
Yield Losses ◽  
Cultivar Resistance ◽  
Head Blight ◽  
Fungicide Treatment ◽  
The Impact

Reactions to artificial infection with Fusarium graminearum isolates and a new fungicide Swing Top were studied in nine winter wheat cultivars evaluated in field experiments at two sites for three years for expression of symptoms, deoxynivalenol (DON) content in grain and grain yield. The results demonstrate a pronounced and relatively stable effect of cultivar resistance on reducing head blight, grain yield losses and contamination of grain by the mycotoxin DON. It is advantageous that the moderate level of resistance to Fusarium head blight (FHB) was detected also in two commonly grown Czech cultivars Sakura and Simila. Average fungicide efficacy for DON was 49.5% and 63.9% for a reduction in yield loss, however, it was found highly variable in different years and sites. The joint effect of cultivar resistance and fungicide treatment was 86.5% for DON and even 95.4% for reducing the yield loss. A very high risk was documented for susceptible cultivars and also the effects of medium responsive cultivars were found to be highly variable in different environments and therefore not guaranteeing sufficient protection against FHB under different conditions.

scholarly journals The differential transmissibility of myxoma virus strains of differing virulence grades by the rabbit flea Spilopsyllus cuniculi (Dale)

1975 ◽  
Vol 75 (2) ◽  
pp. 237-247 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan
Keyword(s):  
Host Resistance ◽  
Oryctolagus Cuniculus ◽  
Selective Advantage ◽  
Myxoma Virus ◽  
Laboratory Studies ◽  
Natural Conditions ◽  
Male And Female ◽  
The Mean ◽  
Virus Strains ◽  
Sampling Times

SUMMARYLaboratory studies showed that few rabbit fleas (Spilopsyllus cuniculi (Dale)) transmitted myxomatosis after removal from wild rabbits (Oryctolagus cuniculus (L)) that had been infected for fewer than 10–12 days, irrespective of the virulence of the myxoma virus strain involved. Rabbits infected with fully virulent (Grade I) strains died within 10–15 days and few fleas from these hosts became infective; averaging all the samples taken, 12% of the fleas were infective. Also, few fleas acquired infectivity on individual rabbits which recovered from infection with attenuated strains; the mean was 8% infective. Rabbits which died between 17 and 44 days after infection had higher proportions of infective fleas at all sampling times; the mean was 42% infective. Male and female fleas transmitted virus with equal efficiency.For rabbits infected with any of the attenuated virus strains the mean percentage of infective fleas was inversely related to the survival time of the host. Rabbits infected with moderately attenuated strains (Grades IIIA and IIIB) had, on average, the highest proportion of infective fleas; hence such strains have a selective advantage and have become predominant under natural conditions in Britain. The changes that might occur if there is an increase in host resistance to myxomatosis are discussed.

scholarly journals Climate change and the occurrence of downy mildew in Brazilian grapevines

2017 ◽  
Vol 52 (6) ◽  
pp. 426-434 ◽  
Author(s):  
Francislene Angelotti ◽  
Emília Hamada ◽  
Edineide Elisa Magalhães ◽  
Raquel Ghini ◽  
Lucas da Ressureição Garrido ◽  
...  
Keyword(s):  
Climate Change ◽  
Latent Period ◽  
Downy Mildew ◽  
Temporal Distribution ◽  
Gas Emission ◽  
Grapevine Downy Mildew ◽  
Diseased Leaf Area ◽  
The Mean ◽  
Potential Impact ◽  
Logic Functions

Abstract: The objective of this work was to evaluate the potential impact of climate change on the occurrence of grapevine downy mildew in Brazil. Seedlings containing four to six leaves were sprayed with a sporangia suspension containing 105 sporangia per milliliter. After spraying, the seedlings were subjected to temperatures of 26, 28, 29.1, 30.4, and 31.8°C for 24 hours. The percentage of diseased leaf area and the latent period were evaluated. Maps of the geographic and temporal distribution of the disease were made considering the monthly average of the mean air temperature and leaf wetness duration for the reference climate or climate normal (1961-1990) and the future climates (2011-2040, 2041-2070, and 2071-2100), considering the A2 and B1 gas emission scenarios, designed by the Intergovernamental Panel on Climate Change (IPCC). Favorability ranges were set and used in logic functions of the geografical information system (GIS) to generate monthly maps for grapevine downy mildew. Rising temperatures interfered with the grapevine downy mildew infections, reduced the disease severity, and increased the latent period. Future climate scenarios indicate a reduction of favorability of downy mildew in Brazil, with variability in the different grape producing regions.

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