Effects of temperature and humidity on disease caused by Phoma medicaginis, resistance in some Medicago cultivars and the incidence of seed-borne inoculum

1987 ◽  
Vol 27 (6) ◽  
pp. 851 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Disease Severity ◽  
Post Inoculation ◽  
High Humidity ◽  
Symptom Development ◽  
Resistant Cultivars ◽  
Phoma Medicaginis ◽  
Temperature And Humidity ◽  
Effects Of Temperature ◽  
Moderate Resistance ◽  
Medicago Species

The effects of temperature and humidity on the development of Phoma blackstem disease (caused by Phoma medicagrnis) on Medicago spp. were investigated. Disease was greatest at 21/16� (12-h photoperiod), followed by 18/13�C, and least at 15/10�. Extending the period of post-inoculation high humidity increased disease severity and the rate of symptom development. Although no Medicago species or cultivars tested were highly resistant, there were large differences among both different species and cultivars of the same species, with several showing moderate resistance. Results show there is potential for control of Phoma blackstem through breeding and/or selecting resistant cultivars. Phoma medicaginis was associated with all but 1 of the 16 seed lines tested and the incidence of seed-borne contamination ranged from 0 to 38%.

scholarly journals Virulence Phenotypes on Chili Pepper for Phytophthora capsici Isolates from Michoacán, Mexico

HortScience ◽  
2019 ◽  
Vol 54 (9) ◽  
pp. 1526-1531
Author(s):  
Alfredo Reyes-Tena ◽  
Arturo Castro-Rocha ◽  
Gerardo Rodríguez-Alvarado ◽  
Gerardo Vázquez-Marrufo ◽  
Martha Elena Pedraza-Santos ◽  
...  
Keyword(s):  
New Mexico ◽  
Disease Severity ◽  
Recombinant Inbred ◽  
Recombinant Inbred Lines ◽  
Phytophthora Capsici ◽  
Inbred Lines ◽  
Chili Pepper ◽  
Economic Losses ◽  
Post Inoculation ◽  
Resistant Cultivars

Phytophthora blight of vegetables caused by Phytophthora capsici causes significant economic losses in production of Solanaceae and Cucurbitaceae crops in Mexico. The development of universal resistant chili pepper cultivars is challenging due to the diverse virulence phenotypes produced by P. capsici. The objective of the study was to characterize the diversity of phenotypic interactions for P. capsici isolates recovered from production fields in Michoacán, Mexico, to facilitate the development of resistant cultivars. Virulence phenotypes were characterized for 12 isolates of P. capsici using 26 Capsicum annuum New Mexico Recombinant Inbred Lines (NMRILs) in greenhouse conditions. Criollo de Morelos CM-334 and California Wonder were used as resistant and susceptible controls, respectively. Seedlings at the four to eight true leaf stage were inoculated with 10,000 zoospores per seedling and disease severity was evaluated at 20 days post-inoculation. Two of the P. capsici isolates did not infect any pepper host even though the isolate was less than a year old. The 10 virulent isolates were designated in 10 virulence phenotypes. The information generated by this study is of utmost importance for efforts of producing resistant cultivars specific for Michoacán producers.

Phoma medicaginis Isolate Differences Determine Disease Severity and Phytoestrogen Production in Annual Medicago spp.

Plant Disease ◽  
2021 ◽  
Author(s):  
Mahtab Omidvari ◽  
Gavin Flematti ◽  
Ming Pei You ◽  
Payman Payman Abbaszadeh-Dahaji ◽  
Martin John BARBETTI
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Severe Disease ◽  
Fold Increase ◽  
Leaf Spot Disease ◽  
Leaf Disease ◽  
Phoma Medicaginis ◽  
Annual Medicago ◽  
Relationship Of ◽  
Medicago Species

Phoma black stem and leaf spot disease of annual Medicago spp., caused by Phoma medicaginis, not only can devastate forage and seed yield, but also reduces herbage quality by inducing production of phytoestrogens, particularly coumestrol and 4'-O-methylcoumestrol, that can reduce ovulation rates of animals grazing infected forage. We determined the consequent phytoestrogen levels on three different annual Medicago species/cultivars (M. truncatula cv. Cyprus, M. polymorpha var. brevispina cv. Serena and M. murex cv. Zodiac), following inoculation with 35 isolates of P. medicaginis. Across the isolate x cultivar combinations, leaf disease incidence (%LDI), petiole disease incidence (%PDI), leaf disease severity (%LDS), petiole disease severity (%PDS), and leaf yellowing severity (%LYS) ranged up to 100, 89.4, 100, 58.1 and 61.2%, respectively. Cultivars Cyprus and Serena were most susceptible and cv. Zodiac the most resistant to P. medicaginis. Isolates WAC3653, WAC3658 and WAC4252 produced the most severe disease. Levels of phytoestrogens in stems ranged from 25 to 1995 mg/kg for coumestrol and from 0 to 418 mg/kg for 4'-O-methylcoumestrol. There was a significant positive relationship of disease incidence and severity parameters with both coumestrol and 4'-O-methylcoumestrol contents, as noted across individual cultivars, and as across the three cultivars overall where r=0.39 and 0.37 for coumestrol and 4'-O-methylcoumestrol, respectively (P<0.05). Although, cv. Serena was most susceptible to P. medicaginis and produced the highest levels of phytoestrogens in the presence of P. medicaginis, cv. Zodiac contained the highest levels of phytoestrogens in comparison with other cultivars in the absence of P. medicaginis. There was a 15-fold increase in coumestrol in cv. Serena but only a 7-fold increase in cv. Zodiac from infection of P. medicaginis. The study highlights that the intrinsic ability of a particular cultivar to produce phytoestrogens in the absence of the pathogen, and its comparative ability to produce phytoestrogens in the presence of the P. medicaginis, are both important and highly relevant to developing new annual Medicago spp. cultivars that offer improved disease resistance and better animal reproductive outcomes.

scholarly journals Quantitative light microscopic autoradiography. Emulsion sensitivity and latent image fading.

1975 ◽  
Vol 23 (12) ◽  
pp. 901-909 ◽  
Author(s):  
H G Boren ◽  
E C Wright ◽  
C C Harris
Keyword(s):  
Radiation Dose ◽  
Direct Measurement ◽  
Exposure Time ◽  
Quantitative Methods ◽  
Internal Standard ◽  
High Humidity ◽  
Latent Image ◽  
Temperature And Humidity ◽  
Effects Of Temperature

Emulsion sensitivity, latent image fading, and the effects of temperature, humidity, radiation dose and chemography on them were measured for NTB2 autoradiographic emulsion using quantitative methods. Sensitivity of NTB2 emulsion increased as the temperature during exposure increased, with the greatest increase per degree occurring between -20 degrees C. At 4 degrees C, emulsion sensitivity remained constant with time and radiation dose. Direct measurement of latent image fading showed no latent image fading for 60 weeks on slides exposed at 4 degrees C with Drierite. Slides exposed at 27 degrees C showed significant latent image fading and great variation between samples. High humidity decreased emulsion sensitivity and increased latent image fading. No evidence of either positive or negative chemography was found. The practical use of autoradiography requires an internal standard on each slide to correct for fluctuations in temperature and humidity during exposure time.

Behavioural aspects of microhabitat segregation of different age stages in the wetland land snail Vertigo moulinsiana (Eupulmonata: Vertiginidae) in the laboratory

2020 ◽  
Vol 86 (3) ◽  
pp. 228-232
Author(s):  
Zofia Książkiewicz-Parulska
Keyword(s):  
High Temperature ◽  
Land Snail ◽  
Snail Species ◽  
High Humidity ◽  
Short Period ◽  
Temperature And Humidity ◽  
In The Wild ◽  
Different Response ◽  
Behavioural Aspects ◽  
Microhabitat Segregation

ABSTRACT This laboratory study investigated behavioural differences between adults and juveniles of the wetland land snail species Vertigo moulinsiana with respect to temperature and humidity. Juveniles of V. moulinsiana, for example, tend to remain within the shaded, humid and cool layer of the litter, while adults usually climb above wet vegetation to a height of over 2 m. Adults are thus exposed to greater variation in temperature and humidity than juveniles. My experiments showed that adults of V. moulinsiana remain active longer than juveniles when subject to high temperature (36 °C) and low relative humidity (RH 30%). Conversely, juveniles stay active longer than adults in high humidity (22 °C, RH 100%). A short period of starvation lengthened the time needed for the juveniles to become active after dormancy, possibly indicating a different response between adults and juveniles to lack of nutritional reserves. These behavioural differences to food availability and the risk of water loss correspond to the microhabitat differences observed between adults and juveniles in the wild.

Observations on the free-living stages of the stomach worm Haemonchus contortus

Parasitology ◽  
1963 ◽  
Vol 53 (3-4) ◽  
pp. 469-481 ◽  
Author(s):  
J. H. Rose
Keyword(s):  
Haemonchus Contortus ◽  
Free Living ◽  
Rate Of Development ◽  
Temperature And Humidity ◽  
Survival And Development ◽  
Effects Of Temperature ◽  
Eggs And Larvae ◽  
Heavy Mortality

Outdoor observations were made on the rate of development of the free-living stages of H. contortus at different times of the year, and on the migratory activities and longevity of the larvae in faeces, on herbage and in soil.The effects of temperature and humidity on the survival and development of eggs and larvae, both in faeces and when separated from the faeces, were studied in the laboratory.The results of these observations are discussed in relation to the heavy mortality of the free-living stages of H. contortus and to the transmission of infection in the field.

scholarly journals The Effect of Temperature and Humidity May Reduce the Growth Rate of the Coronavirus Disease 2019 Epidemic

2020 ◽  
Author(s):  
Lei Qin ◽  
Qiang Sun ◽  
Jiani Shao ◽  
Yang Chen ◽  
Xiaomei Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Effect Of Temperature ◽  
Average Temperature ◽  
Temperature And Humidity ◽  
Scatter Plots ◽  
Low Humidity ◽  
Average Relative Humidity ◽  
Effects Of Temperature ◽  
The Relationship

Abstract Background: The effects of temperature and humidity on the epidemic growth of coronavirus disease 2019 (COVID-19)remains unclear.Methods: Daily scatter plots between the epidemic growth rate (GR) and average temperature (AT) or average relative humidity (ARH) were presented with curve fitting through the “loess” method. The heterogeneity across days and provinces were calculated to assess the necessity of using a longitudinal model. Fixed effect models with polynomial terms were developed to quantify the relationship between variations in the GR and AT or ARH.Results: An increased AT dramatically reduced the GR when the AT was lower than −5°C, the GR was moderately reduced when the AT ranged from −5°C to 15°C, and the GR increased when the AT exceeded 15°C. An increasedARH increased theGR when the ARH was lower than 72% and reduced theGR when the ARH exceeded 72%.Conclusions: High temperatures and low humidity may reduce the GR of the COVID-19 epidemic. The temperature and humidity curves were not linearly associated with the COVID-19 GR.

Sign in / Sign up

Export Citation Format

Share Document