scholarly journals Effect of Variable Temperature on Infection Severity of Podosphaera macularis on Hops

2003 ◽  
Vol 93 (12) ◽  
pp. 1587-1592 ◽  
Author(s):  
Walter F. Mahaffee ◽  
William W. Turechek ◽  
Cynthia M. Ocamb
Keyword(s):  
Disease Risk ◽  
Variable Temperature ◽  
Optimal Conditions ◽  
Risk Assessment Models ◽  
Temperature Regimes ◽  
Uninoculated Control ◽  
Growth Chambers ◽  
Simulated Field ◽  
Favorable Conditions ◽  
Podosphaera Macularis

The effect of variable temperature on the infection severity of Podosphaera macularis was investigated. Potted ‘Symphony’ hop plants were inoculated and exposed to different temperature regimes that included supraconducive temperatures (30 to 42°C) for varying periods of time (2 to 9 h). Infection severity (lesions per cm2 of leaf area) was calculated 7 to 10 days after inoculation. Immediately exposing inoculated plants to 30°C for as little as 2 h significantly (P ≤ 0.05) reduced infection severity compared with exposure at a constant 18°C. However, exposure of inoculated plants to optimal conditions for 24 or 48 h prior to exposure to supraconducive conditions reduced this effect for plants exposed to 30, 33, or 36°C. Exposure to 39 or 42°C for 2 or more hours resulted in infection frequencies not significantly different from that of the uninoculated control regardless of prior exposure to favorable conditions. Exposure to simulated field temperatures programmed into growth chambers indicated that inoculation at 1700 or 2100 h resulted in significantly more disease than did inoculation at 0900 or 1300 h. Plants exposed to supraconducive or simulated field temperatures for 7 days prior to inoculation developed significantly lower disease severity than did plants maintained at 18°C for 7 days. The magnitude, length, and time of exposure to supraconducive temperatures in relation to time of inoculation plays an important role in the development of hop powdery mildew, and rules addressing these variables could be a useful addition to disease risk assessment models.

scholarly journals Long-term Effect of Temperature and Triadimefon on Proliferation of Uncinula necator: Implications for Fungicide Resistance and Disease Risk Assessment

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1187-1192 ◽  
Author(s):  
H. L. Ypema ◽  
W. D. Gubler
Keyword(s):  
Risk Assessment ◽  
Disease Risk ◽  
Resistant Isolate ◽  
Effect Of Temperature ◽  
Daily Maximum ◽  
Uncinula Necator ◽  
Risk Assessment Models ◽  
Temperature Regimes ◽  
Entire Duration ◽  
Maximum Temperatures

Triadimefon has been used in California to control Uncinula necator, causal agent of grape powdery mildew, since 1982. Instances of unsatisfactory control have occurred mainly in the cooler coastal areas of California. The effect of temperature and application of triadimefon was investigated over a 53-day-period on two U. necator isolates, sensitive and resistant to triadimefon. At 15°C, 25°C, or temperatures fluctuating between 15 and 25°C, in absence of triadimefon, the isolates continued to produce high numbers of conidia for the entire duration of the experiment. Sporulation declined at daily maximum temperatures of 32°C for 6 h, 36°C for 3 h, and 40°C for 1 h, but was detectable when the experiment was terminated. At these temperature regimes, sporulation of the triadimefon-treated sensitive isolate ceased after 23 days. When treated with triadimefon, sporulation of the resistant isolate was comparable to that of the water-treated control. At daily maximum temperatures of 32°C for 11 h, 36°C for 6 h, and 40°C for 3 h, sporulation of both isolates generally ceased after 23 days, regardless of triadimefon application. Triadimefon resistance is most likely to manifest itself under high disease pressure, which is in part a function of temperature. The duration of daily maximum temperatures may be a valuable addition to disease risk assessment models.

Temperature Influences on Powdery Mildew Susceptibility and Development in the Hop Cultivar Cascade

Plant Disease ◽  
2022 ◽  
Author(s):  
David H. Gent ◽  
Briana Claassen ◽  
Michele S. Wiseman ◽  
Sierra N Wolfenbarger
Keyword(s):  
Powdery Mildew ◽  
Partial Resistance ◽  
Disease Risk ◽  
Rapid Onset ◽  
Risk Assessments ◽  
Temperature Regimes ◽  
Moderate Disease ◽  
Ontogenic Resistance ◽  
Specific Temperature ◽  
Podosphaera Macularis

The hop cultivar Cascade possesses partial resistance to powdery mildew (Podosphaera macularis) that can be overcome by recently emerged, virulent isolates of the fungus. Given that hop is a long-lived perennial and that brewers still demand Cascade, there is a need to better understand factors that influence the development of powdery mildew on this cultivar. Growth chamber experiments were conducted to quantify the effect of constant, transient, and fluctuating temperature on Cascade before, concurrent to, and after inoculation as contrasted with another powdery mildew susceptible cultivar, Symphony. Exposure of plants to supraoptimal temperature (26 and 32°C) prior to inoculation led to more rapid onset of ontogenic resistance in intermediately aged leaves in Cascade as compared to Symphony. Cascade was overall less susceptible to powdery mildew when exposed to constant temperature ranging from 18 to 32°C directly after inoculation. However, cultivar also interacted with temperature such that proportionately fewer and smaller colonies developed on Cascade than Symphony at supraoptimal yet permissive temperatures for disease. When plants were inoculated and then exposed to high temperature, colonies became progressively more tolerant to temperatures of 26 to 30°C with increasing time from inoculation to exposure, as moderated by cultivar, the specific temperature, and their interaction. Subjecting plants to simulated diurnal temperature regimes at the time of inoculation or 24 h later indicated Cascade and Symphony responded proportionately similar on days predicted to be marginally unfavorable or marginally favorable for powdery mildew, although Cascade was quantitatively less susceptible than Symphony. In sum, this research indicates that Cascade is overall less susceptible to powdery mildew than Symphony, and supraoptimal temperature before, concurrent to, or after infection may interact differentially to moderate disease risk in Cascade. Therefore, cultivar-specific risk assessments for powdery mildew appear warranted.

scholarly journals A comparison of cumulative-germination response of cheatgrass (Bromus tectorum L.) and five perennial bunchgrass species to simulated field-temperature regimes

2010 ◽  
Vol 69 (3) ◽  
pp. 320-327 ◽  
Author(s):  
Stuart P. Hardegree ◽  
Corey A. Moffet ◽  
Bruce A. Roundy ◽  
Thomas A. Jones ◽  
Stephen J. Novak ◽  
...  
Keyword(s):  
Bromus Tectorum ◽  
Germination Response ◽  
Temperature Regimes ◽  
Field Temperature ◽  
Simulated Field

Inter- and intra-varietal variation in aerobic methane emissions from environmentally stressed pea plants

Botany ◽  
2018 ◽  
Vol 96 (12) ◽  
pp. 837-850 ◽  
Author(s):  
Awatif M. Abdulmajeed ◽  
Mohammad I. Abo Gamar ◽  
Mirwais M. Qaderi
Keyword(s):  
Stress Factors ◽  
Interactive Effects ◽  
Controlled Environment ◽  
Uvb Radiation ◽  
Pisum Sativum L ◽  
Temperature Regimes ◽  
Varietal Variation ◽  
Growth Chambers ◽  
Effects Of Temperature ◽  
Two Temperature

Environmental stress factors can influence methane (CH4) emissions from plants. There are a few studies on the interactive effects of stress factors on plant aerobic CH4, but none on the comparative evaluation of CH4 emissions between and among plant varieties. We examined the effects of temperature, UVB radiation, and watering regime on CH4 emissions from 10 pea (Pisum sativum L.) varieties first and then selected two varieties with the highest (237J Sundance; var. 1) and lowest (422 Ho Lan Dow; var. 2) emissions for further studies. Plants were grown in controlled-environment growth chambers under two temperature regimes (22 °C / 18 °C and 28 °C / 24 °C, 16 h light / 8 h dark), two UVB levels (0 and 5 kJ·m−2·d−1), and two watering regimes (well-watered and water-stressed) for 14 days, after one week of growth under 22 °C / 18 °C. Higher temperatures and water stress increased CH4 emissions, and increased emission was associated with stress. Pea varieties varied in growth and CH4 emissions; var. 1 was more stressed and had higher emission than var. 2. In the stressed variety, the water-stressed plants grown under higher temperatures at UVB5 had the highest CH4 emission, whereas the well-watered plants grown under lower temperatures at UVB5 had the lowest emission. We conclude that climatic stress conditions increase CH4 emissions, which vary with plant varieties.

scholarly journals Proteomic Signatures of Corals from Thermodynamic Reefs

2020 ◽  
Vol 8 (8) ◽  
pp. 1171
Author(s):  
Anderson B. Mayfield
Keyword(s):  
Molecular Mechanisms ◽  
Elevated Temperatures ◽  
Variable Temperature ◽  
Deep South ◽  
Lipid Trafficking ◽  
Reef Corals ◽  
Temperature Conditions ◽  
Temperature Regimes ◽  
Unique Nature ◽  
Seriatopora Hystrix

Unlike most parts of the world, coral reefs of Taiwan’s deep south have generally been spared from climate change-induced degradation. This has been linked to the oceanographically unique nature of Nanwan Bay, where intense upwelling occurs. Specifically, large-amplitude internal waves cause shifts in temperature of 6–9 °C over the course of several hours, and the resident corals not only thrive under such conditions, but they have also been shown to withstand multi-month laboratory incubations at experimentally elevated temperatures. To gain insight into the sub-cellular basis of acclimation to upwelling, proteins isolated from reef corals (Seriatopora hystrix) featured in laboratory-based reciprocal transplant studies in which corals from upwelling and non-upwelling control reefs (<20 km away) were exposed to stable or variable temperature regimes were analyzed via label-based proteomics (iTRAQ). Corals exposed to their “native” temperature conditions for seven days (1) demonstrated highest growth rates and (2) were most distinct from one another with respect to their protein signatures. The latter observation was driven by the fact that two Symbiodiniaceae lipid trafficking proteins, sec1a and sec34, were marginally up-regulated in corals exposed to their native temperature conditions. Alongside the marked degree of proteomic “site fidelity” documented, this dataset sheds light on the molecular mechanisms underlying acclimatization to thermodynamically extreme conditions in situ.

SIMULATION OF TEMPERATURE-DEPENDENT DEVELOPMENT IN POPULATION DYNAMICS MODELS

1975 ◽  
Vol 107 (11) ◽  
pp. 1167-1174 ◽  
Author(s):  
R. E. Stinner ◽  
G. D. Butler ◽  
J. S. Bacheler ◽  
C. Tuttle
Keyword(s):  
Population Dynamics ◽  
Trichoplusia Ni ◽  
Variable Temperature ◽  
Heliothis Zea ◽  
Anthonomus Grandis ◽  
Temperature Dependent ◽  
Dependent Development ◽  
Temperature Regimes ◽  
Population Dynamics Models ◽  
Dynamics Models

AbstractThe simulation of variability in temperature-dependent development is discussed. An algorithm for simulation of this variability is developed and validated under constant and variable temperature regimes for Anthonomus grandis, Trichoplusia ni, and Heliothis zea.

Inoculation of Euphorbia lathyris with cotton strings infested with Macrophomina phaseolina, causal agent of charcoal rot disease

1991 ◽  
Vol 69 (3) ◽  
pp. 682-685
Author(s):  
Phyllis T. Himmel
Keyword(s):  
Key Words ◽  
Macrophomina Phaseolina ◽  
Causal Agent ◽  
Silica Sand ◽  
Optimal Conditions ◽  
Lesion Development ◽  
Charcoal Rot ◽  
Temperature Regimes ◽  
Rot Disease ◽  
Euphorbia Lathyris

Root infections caused by Macrophomina phaseolina were initiated under optimal conditions for the host, Euphorbia lathyris. Two-week-old Euphorbia lathyris seedlings were inoculated by tying roots with cotton strings infested with Macrophomina phaseolina. Ninety-three per cent of the inoculated roots developed infections after 2 weeks incubation in silica sand at 25 °C. By using infested strings, differences in the incidence of lesion development were detected when infected roots were subjected to differing temperature regimes. After approximately 6 weeks, there was a significantly [Formula: see text] greater incidence of lesion development at 34 °C than at 25 °C, whereas there was no difference in the incidence of infection. Aerial symptoms indicative of charcoal rot were not observed during the course of these studies. Key words: infested strings, charcoal rot.

scholarly journals EFFECT OF PHOTOPERIOD AND TEMPERATURE REGIMES ON YIELD OF SWEET POTATOES GROWN USING THE NUTRIENT FILM TECHNIQUE (NFT)

HortScience ◽  
1990 ◽  
Vol 25 (8) ◽  
pp. 858g-858
Author(s):  
Desmond Mortley ◽  
Conrad Bonsi ◽  
Philip Loretan ◽  
Walter Hill ◽  
Edwin Martinez
Keyword(s):  
Sweet Potato ◽  
Constant Temperature ◽  
Continuous Light ◽  
Storage Root ◽  
Sweet Potatoes ◽  
Root Numbers ◽  
Temperature Regimes ◽  
Nutrient Film Technique ◽  
Growth Chambers ◽  
Hoagland Nutrient Solution

Hydroponic experiments using the nutrient film technique (NFT) were conducted in environmental growth chambers to evaluate the response of two sweet potato cultivars, `Georgia Jet' and `TI-155', to two photoperiod and temperature regimes. Vine cuttings of these cultivars were planted in growth channels supplied with modified half-Hoagland nutrient solution using NFT. Plants were subjected to a 24 h photoperiod or a 12:12 h light:dark photoperiod, a constant temperature of 28C or light:dark temperature of 28/22C. Plants were exposed to irradiance levels of 400 umol m-2 s-1 at canopy level and 70% RH. Storage root fresh and dry weights were increased for both cultivars under the 24 h photoperiod at the 28C constant temperature. `Georgia Jet' storage root numbers were not affected by any treatment while those for `TI-155' were reduced under continuous light for both temperature regimes. Foliage fresh and dry weights were not affected by any treatment.

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