scholarly journals Differences Between Ascospores and Conidia of Didymella rabiei in Spore Germination and Infection of Chickpea

2007 ◽  
Vol 97 (12) ◽  
pp. 1600-1607 ◽  
Author(s):  
Antonio Trapero-Casas ◽  
Walter J. Kaiser
Keyword(s):  
Disease Severity ◽  
Spore Germination ◽  
Opposite Effect ◽  
Disease Development ◽  
Optimum Temperature ◽  
Water Potentials ◽  
Wetness Period ◽  
Moisture Conditions ◽  
Germ Tubes ◽  
Plant Surfaces

Studies were performed to compare the germination and infection of ascospores and conidia of Didymella rabiei under different temperature and moisture conditions. Germination of ascospores and conidia on cover glasses coated with water agar began after 2 h, with maximum germination (>95%) occurring in 6 h at 20°C. No germination occurred at 0 and 35°C. Ascospores germinated more rapidly than conidia at all temperatures. Germination declined rapidly as the water potential varied from 0 to –4 MPa, although some germination occurred at –6 MPa at 20 and 25°C. Ascospores germinated over a wider range of water potentials than conidia and their germ tubes were longer than those of conidia at most water potentials and temperatures. The optimum temperature for infection and disease development by both ascospores and conidia was around 20°C. Disease severity was higher when ascospores were discharged directly onto plant surfaces from naturally infested chickpea debris compared with aqueous suspensions of ascospores and conidia sprayed onto plants Disease severity increased as the length of the wetness period increased. When dry periods of 6 to 48 h occurred immediately after inoculation, disease severity decreased, except for the shorter periods which had the opposite effect. Disease severity was higher with ascospore inoculum when no dry periods occurred after inoculation.

scholarly journals The Effects of Temperature and Wetness Period on the Development of Spinach White Rust

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 753-758 ◽  
Author(s):  
M. J. Sullivan ◽  
J. P. Damicone ◽  
M. E. Payton
Keyword(s):  
Disease Severity ◽  
Temperature Effects ◽  
Multiple Regression Model ◽  
Disease Development ◽  
Optimum Temperature ◽  
Influence Of Temperature ◽  
White Rust ◽  
Wetness Period ◽  
Controlled Environments ◽  
Effects Of Temperature

Experiments were conducted in controlled environments to determine the influence of temperature and duration of wetness on development of white rust of spinach. Plants of the susceptible cv. Kent were exposed to temperatures of 6 to 28°C and interrupted wetness periods that totaled 3 to 84 h following inoculation. Disease severity was assessed following further incubation in a greenhouse at 20 to 30°C. Disease was observed at all temperatures and increased with wetness duration. The optimum temperature for disease development ranged from 12 to 18°C. Only 3 h of wetness were required for disease development at 12 to 22°C. A minimum wetness period of 6 to 12 h was required for disease development at suboptimal temperatures. A multiple regression model describing the response surface of arcsine square root transformed disease severity was developed that had significant quadratic wetness effects, cubic temperature effects, and interaction between temperature and wetness. The resulting polynomial model provided a good fit to the observed data, accounting for 89% of the variation in transformed disease severity.

Efficacy of Different Level of Systemic Fungicides on Management of Rice Blast at Baitadi, Nepal

2020 ◽  
Vol 7 ◽  
pp. 33-42
Author(s):  
Ashok Acharya ◽  
Prabin Ghimire ◽  
Dhurba Raj Joshi ◽  
Kishor Shrestha ◽  
Govinda Sijapati ◽  
...  
Keyword(s):  
Disease Severity ◽  
Rice Blast ◽  
Fungal Pathogens ◽  
Block Design ◽  
Rice Variety ◽  
Disease Suppression ◽  
Systemic Fungicide ◽  
Disease Development ◽  
Systemic Fungicides ◽  
Different Levels

Rice blast (Pyriculariaoryzae Cavara) is one of the most devastating diseases affecting the rice crop in across the world. Systemic fungicides are used for the suppression of blast diseases caused by fungal pathogens. Propiconazole and Carbendazim are commercial chemical control products available in markets for the control of the fungal pathogen. An experiment was conducted to examine the effectiveness of systemic fungicide on suppression of rice blast incidence in farmers' field during wet seasons in 2016. The treatments consisted of the use of different levels of propiconazole and Carbendazim on ‘Rato Basmati’ a landrace rice variety. The experiments were arranged in a randomized complete block design with three replications. The disease was scored according to the standard scale developed by the International Rice Research Institute (IRRI). Disease severity and Area under Disease Progressive curve (AUDPC) was computed based on that scale score. Propiconazole and Carbendazim at different levels reduce disease development than no treatment (control). But its efficacy was not consistent. The magnitude of disease suppression by Propiconazole was high as compared to Carbendazim. The application of propiconazole at the rate of 1.5 ml effectively reduced disease severity and AUDPC at different dates. So propiconazole at the rate of 1.5 ml thrice at weekly intervals is effective to reduce the disease development

scholarly journals Salicylic acid and jasmonic acid can suppress green and blue moulds of citrus fruit and induce the activity of polyphenol oxidase and peroxidase

2019 ◽  
Vol 31 (1) ◽  
pp. 195-204 ◽  
Author(s):  
Anam Moosa ◽  
Shahbaz Talib Sahi ◽  
Sajid Aleem Khan ◽  
Aman Ullah Malik
Keyword(s):  
Salicylic Acid ◽  
Jasmonic Acid ◽  
Disease Severity ◽  
Polyphenol Oxidase ◽  
Disease Incidence ◽  
Citrus Fruit ◽  
Disease Development ◽  
Post Harvest ◽  
Blue Mould ◽  
Green Mould

AbstractThe ability of salicylic acid and jasmonic acid to suppress post-harvest infection with green mould Penicillium digitatum and blue mould P. italicum on three citrus species Citrus reticulata ‘Kinnow’, C. limon ‘Meyer Lemon’, and C. limetta ‘Mosambi’ was evaluated in a dose-response study. Salicylic acid (SA) and jasmonic acid (JA) were applied to the fruits as a post-harvest dip treatment followed by wound inoculation with the pathogens. Both resistance inducers caused a significantly lower disease severity compared with the infected but non-treated control, whereas disease incidence was not significantly lower than in the control. The efficacy of both SA and JA in reducing disease severity was concentration-dependent; the use of higher concentrations resulted in a greater degree of suppression. All the Citrus species tested in this study showed different responses in terms of disease development. C. limon ‘Meyer Lemon’ showed the highest disease development, and C. limetta ‘Mosambi’ the lowest. To get an insight into the mechanisms underlying the increase in resistance, the activity of defence-related enzymes – peroxidase (POD) and polyphenol oxidase (PPO) – was recorded in SA- and JA-treated fruit peelings. The activity of both enzymes was directly proportional to the concentration of the SA and JA applications. The highest activity of PPO and POD was observed in C. reticulata ‘Kinnow’ and the lowest in C. limon ‘Meyer Lemon’ fruits. This study is the first to document an increase in the activity of PPO and POD in SA- and JA-treated Citrus species in the presence of blue mould and green mould pathogens.

The Incidence of Climatic Conditions Favourable to Coffee Berry Disease in Kenya

1971 ◽  
Vol 7 (4) ◽  
pp. 303-314 ◽  
Author(s):  
J. M. Waller
Keyword(s):  
Air Temperature ◽  
Spore Germination ◽  
Growing Season ◽  
Climatic Conditions ◽  
Tree Canopy ◽  
Disease Development ◽  
Spore Dispersal ◽  
Coffee Berry ◽  
Coffee Berry Disease ◽  
Air Temperatures

SUMMARYClimatic conditions affecting the development of CBD are assessed by measuring wetness within the tree canopy and air temperature. Saturation of the tree canopy, necessary for spore dispersal, occurs most frequently at the tops of trees and the duration of wetness permitting spore germination is most prolonged at night. Night air temperatures are closest to berry temperatures and are important in assessing infection periods. Disease development in 1968 and 1969 was related to the number of infection periods during the growing season. Polythene tree covers which kept trees sufficiently dry to stop disease development were used in determining infection at different times of the year.

scholarly journals Effect of Temperature and Moisture Period on Infection of Rhododendron ‘Cunningham's White’ by Phytophthora ramorum

2009 ◽  
Vol 99 (9) ◽  
pp. 1045-1052 ◽  
Author(s):  
Paul W. Tooley ◽  
Marsha Browning ◽  
Kerrie L. Kyde ◽  
Dana Berner
Keyword(s):  
The United States ◽  
Phytophthora Ramorum ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Detached Leaf ◽  
Wide Range ◽  
Effects Of Temperature ◽  
Gradient Plate ◽  
Whole Plants ◽  
Moisture Conditions

We investigated the temperature and moisture conditions that allow Phytophthora ramorum to infect Rhododendron ‘Cunningham's White’. Most experiments were performed with a single P. ramorum isolate from the NA1 clonal lineage. For whole plants incubated in dew chambers at 10 to 31°C, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5°C. Disease occurred over the entire range of temperatures tested, although amounts of disease were minor at the temperature extremes. For whole plants exposed to varying dew periods at 20°C and then incubated at 20°C for 7 days, a dew period as short as 1 h resulted in a small amount of disease; however, at least 4 h of dew were required for >10% of the leaves to become diseased. Moisture periods of 24 and 48 h resulted in the greatest number of diseased leaves. In detached-leaf, temperature-gradient-plate experiments, incubation at 22°C resulted in the greatest disease severity, followed by 18°C and then 14°C. In detached-leaf, moisture-tent experiments, a 1-h moisture period was sufficient to cause disease on 67 to 73% of leaves incubated for 7 days at 20°C. A statistical model for disease development that combined the effects of temperature and moisture period was generated using nonlinear regression. Our results define temperature and moisture conditions which allow infection by P. ramorum on Cunningham's White rhododendron, and show that P. ramorum is able to infect this host over a wide range of temperatures and moisture levels. The results indicate that P. ramorum has the potential to become established in parts of the United States that are outside its current range.

scholarly journals Effect of temperature, wetness duration and cultivar on the development of anthracnose in guava fruits

2014 ◽  
Vol 40 (4) ◽  
pp. 307-312 ◽  
Author(s):  
Ana Raquel Soares-Colletti ◽  
Silvia de Afonseca Lourenço
Keyword(s):  
Disease Severity ◽  
Warning System ◽  
Effect Of Temperature ◽  
White Pulp ◽  
Conidial Suspension ◽  
Postharvest Diseases ◽  
Wetness Period ◽  
The Mean ◽  
Ripening Rate ◽  
Favorable Temperature

The development of a large number of postharvest diseases is closely associated with fruit ripeness. Environmental conditions may affect both the pathogen development and the fruit ripening rate. The aim of this study was to determine the most favorable temperature and wetness duration to the development of anthracnose in guava fruits. Cultivars 'Kumagai' (white pulp) and 'Pedro Sato' (red pulp) were inoculated with a conidial suspension of Colletotrichum gloeosporioides and C. acutatum and incubated at constant temperature ranging from 10 to 35ºC and wetness duration of 6 and 24 hours. Disease severity and incidence were evaluated at every two days during 12 days. No infection occurred at 10 and 35ºC, regardless of the wetness duration. The optimum conditions for fruit infection were 26 and 27ºC for 'Kumagai' and 25 and 26ºC for 'Pedro Sato', adopting 24 hours of wetness. In general, the disease development in 'Kumagai' cultivar was more affected by the wetness period, compared to 'Pedro Sato'. Disease severity for 'Kumagai' fruits was maximal between 25 and 30ºC , depending on the Colletotrichum species. Regarding 'Pedro Sato', the mean diameter of lesions was greater in fruits stored at 20, 25 and 30ºC , compared to 'Kumagai' cultivar, depending on the wetness period and the species. The incubation period (between 6 and 7 days) and the latent period (between 8 and 10 days) were minimal at 30ºC. The data generated in this study will be useful either for the development of a disease warning system or for the increase in the shelf life of guavas in the postharvest.

Sensitivity of Ulocladium atrum, Coniothyrium minitans, and Sclerotinia sclerotiorum to benomyl and vinclozolin

2002 ◽  
Vol 80 (8) ◽  
pp. 892-898 ◽  
Author(s):  
G Q Li ◽  
H C Huang ◽  
S N Acharya
Keyword(s):  
Growth Inhibition ◽  
Sclerotinia Sclerotiorum ◽  
Spore Germination ◽  
Mycelial Growth ◽  
Germination Rate ◽  
Effective Concentration ◽  
Coniothyrium Minitans ◽  
Inhibition Concentration ◽  
Maximum Inhibition ◽  
Germ Tubes

Assays on mycelial growth and spore germination were carried out to determine the sensitivity of the biocontrol agents Ulocladium atrum and Coniothyrium minitans and the plant pathogen Sclerotinia sclerotiorum to benomyl and vinclozolin. Ulocladium atrum was more tolerant to these fungicides than C. minitans and S. sclerotiorum. The 50% effective concentration (EC50) of U. atrum based on the mycelial growth inhibition was 1467.3 µg active ingredient (a.i.)/mL for benomyl and 12.6 µg a.i./mL for vinclozolin, and the maximum inhibition concentration was higher than 4000 µg a.i./mL for both fungicides. For C. minitans and S. sclerotiorum, however, the EC50 based on mycelial growth inhibition was lower than 1 µg a.i./mL. After incubation for 24 h at 20°C, the germination rate of U. atrum conidia was 90–99% on potato dextrose agar (PDA) amended with benomyl at 100–500 µg a.i./mL or vinclozolin at 10–500 µg a.i./mL. At these concentrations, germ tubes of U. atrum developed into long, branched hyphae in benomyl treatments, but they remained short and clustered in vinclozolin treatments. Pycnidiospores of C. minitans and ascospores of S. sclerotiorum germinated on PDA amended with benomyl at 100–500 µg a.i./mL, but the germ tubes did not grow further. Spore germination of C. minitans and S. sclerotiorum was less than 3.2% on PDA amended with vinclozolin at 10–500 µg a.i./mL after 24 h. This is the first report on the sensitivity of U. atrum and C. minitans to benomyl and vinclozolin. The results suggest that it is possible to control S. sclerotiorum using a combination of U. atrum and benomyl or vinclozolin.Key words: fungicides, mycelial growth, spore germination, integrated pest management.

scholarly journals Influence of Temperature and Wetness Periods on the Development of Stemphylium Blight on Lentil

Plant Disease ◽  
2010 ◽  
Vol 94 (10) ◽  
pp. 1219-1224 ◽  
Author(s):  
E. Mwakutuya ◽  
S. Banniza
Keyword(s):  
Leaf Wetness ◽  
Linear Quadratic ◽  
Canadian Prairies ◽  
Linear Temperature ◽  
Glass Slides ◽  
Wetness Period ◽  
Stemphylium Blight ◽  
Simple Logistic ◽  
Germ Tubes ◽  
Leaf Wetness Period

Stemphylium blight of lentil (Lens culinaris subsp. culinaris) caused by Stemphylium botryosum has become more prevalent in the Canadian prairies. Germination of conidia, appressorium formation, and infection of lentil plants were evaluated under controlled conditions at temperatures from 5 to 30°C and increasing incubation periods under wet conditions to elucidate the epidemiology of this disease. On glass slides, conidial germination increased steadily with temperature up to 25 and 30°C, and reached more than 80% after 20 h at these temperatures, compared with around 30% at 5°C. The response of germination on glass slides to temperature was nonlinear, as evident in significant linear, quadratic single factor, and linear, quadratic, and cubic cross factor temperature effects in the model. On lentil leaves, 18% of conidia had germinated after 2 h of incubation at 25°C, and a few germ tubes penetrated into the tissue through stomata. Germination reached 89% after 12 h, and 12% of germ tubes had penetrated into the leaves. Stemphylium blight severity reached more than 80% at 25 and 30°C with leaf wetness periods of 48 h. A simple logistic model with linear temperature, leaf wetness period, and cross factor effects described disease development on lentil plants.

scholarly journals Spore Germination, Infection Structure Formation, and Colony Development of Erysiphe pulchra on Dogwood Leaves and Glass Slides

Plant Disease ◽  
2005 ◽  
Vol 89 (12) ◽  
pp. 1301-1304 ◽  
Author(s):  
Y. H. Li ◽  
M. T. Windham ◽  
R. N. Trigiano ◽  
D. C. Fare ◽  
J. M. Spiers ◽  
...  
Keyword(s):  
Structure Formation ◽  
Spore Germination ◽  
Colony Development ◽  
Infection Structure ◽  
Flowering Dogwood ◽  
Glass Slides ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Germ Tubes ◽  
Leaf Disks

Spore germination, infection structure formation, and colony development of Erysiphe pulchra on glass slides and leaf disks of a susceptible flowering dogwood line were examined using light and scanning electron microscopes. On both glass slides and leaf disks, germination of conidia started within 2 h after inoculation (hai). One to four germ tubes grew from two poles of a conidium, one or two of the germ tubes formed initial appressoria, and only one of the germ tubes with initial appressoria formed secondary appressoria. However, formation of initial and secondary appressoria was delayed on glass slides (48 and 72 hai, respectively) compared with that on dogwood leaf disks (3 and 24 hai, respectively). Branching hyphae did not grow from germinated conidia on glass slides. However, on dogwood leaf disks, branched hyphae were observed 48 hai. In epidermal cells, the fungus formed compact and globose haustoria. Conidia formation on conidiophores started on leaf disks 7 days after inoculation.

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