Effect of Environment on the Translocation and Toxicity of Acifluorfen to Showy Crotalaria (Crotalaria spectabilis)

Weed Science ◽  
1981 ◽  
Vol 29 (4) ◽  
pp. 397-401 ◽  
Author(s):  
Gene D. Wills ◽  
Chester G. McWhorter
Keyword(s):  
Relative Humidity ◽  
Growth Chamber ◽  
Nitrobenzoic Acid ◽  
Single Leaf ◽  
Air Temperatures ◽  
Over The Top ◽  
Crotalaria Spectabilis

Toxicity of non-radiolabeled and absorption and translocation of14C-activity of applied14C-acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} in showy crotalaria (Crotalaria spectabilisRoth) were evaluated in the growth chamber at air temperatures of 18, 27, or 35 C and 40 or 100% relative humidity (RH). Four days after treatment, acifluorfen applied over-the-top at 0.1 kg/ha resulted in 64 to 95% injury, but did not kill showy crotalaria. Acifluorfen was more toxic at 100% than at 40% RH. At either 40 or 100% RH, acifluorfen was more toxic at 27 and 35 C than at 18 C. Plants were placed in the greenhouse 4 days after treatment. At 6 weeks after treatment, there was extensive regrowth, and injury to all plants was less than 32%, except for those plants initially treated at 18 C and 40% RH for 4 days. These plants showed 76% injury. Acifluorfen applied to a single leaf midway up the stem caused 80 to 100% injury to the immature leaves near the apex, but less than 30% injury to lower leaves. Absorption of14C-activity from14C-acifluorfen applied to a single leaf midway up the shoot varied from 8 to 76% after 2 days. At either 40 or 100% RH, absorption was approximately four-fold greater at 27 and 35 C than at 18 C. At all temperatures tested, absorption was three- to four-fold greater at 100% than at 40% RH.

The Effect of Surfactant and Environment on the Toxicity of Metriflufen to Soybeans (Glycine max) and Johnsongrass (Sorghum halepense)

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 675-679 ◽  
Author(s):  
C. G. McWhorter
Keyword(s):  
Glycine Max ◽  
Methyl Ester ◽  
Relative Humidity ◽  
Air Temperature ◽  
Sorghum Halepense ◽  
Growth Chamber ◽  
Propanoic Acid ◽  
Herbicide Treatment ◽  
Over The Top

Metriflufen {2-[4-(4-trifluoromethylphenoxy)phenoxy] propanoic acid} was applied as the methyl ester at 0.28 and 0.56 kg/ha over-the-top to johnsongrass [Sorghum halepense(L.) Pers.] growing from rhizomes and to soybeans [Glycine max(L.) Merr. ‘Lee 68′]. After herbicide treatment, plants were grown in the growth chamber for 14 days at 16, 24, or 32 C with relative humidity (RH) at 40 or 100% at each air temperature. Johnsongrass was not controlled at 16 C regardless of metriflufen rate, RH, or the addition of nonoxynol [α-(p-nonylphenyl)-ω-hydroxypoly (oxyethylene)] (with 9.5 moles of polyoxyethylene) surfactant at 0.25 (g/100 ml) to spray solutions. Johnsongrass control at 24 C varied from 5 to 98%, with significantly better control at 100% than at 40% RH. The presence of surfactant increased johnsongrass control at 24 C and 40% RH but not at 24 C and 100% RH. Johnsongrass control at 32 C varied from 48 to 98%, and it was not increased by the presence of the surfactant, regardless of metriflufen rate or RH level. At 16 C metriflufen was more injurious to soybeans than to johnsongrass, but at 24 and 32 C johnsongrass control was significantly greater than soybean injury. The presence of surfactant in spray solutions generally did not increase soybean injury, regardless of temperature or RH level. These results suggest that metriflufen is most selective in controlling johnsongrass in soybeans at 24 C, especially under high RH.

Effects of Environment on the Toxicity of Glyphosate to Johnsongrass(Sorghum halepense)and Soybeans(Glycine max)

Weed Science ◽  
1978 ◽  
Vol 26 (6) ◽  
pp. 605-608 ◽  
Author(s):  
C. G. McWhorter ◽  
W. R. Azlin
Keyword(s):  
Soil Moisture ◽  
Glycine Max ◽  
Relative Humidity ◽  
Sorghum Halepense ◽  
Growth Chamber ◽  
Environmental Condition ◽  
Over The Top

Johnsongrass [Sorghum halepense(L.) Pers.] and soybeans [Glycine max(L.) Merr. ‘Lee 68’] were treated over-the-top with glyphosate [N-(phosphonomethyl)glycine] at 0.2 and 0.4 kg/ha with surfactant in spray solutions and 0.4 and 0.7 kg/ha without surfactant in spray solutions. Treated plants were maintained in the growth chamber for 2 weeks after treatment at 24, 29, and 35 C; 45 and 100% relative humidity (RH); and 12 and 20% soil moisture. Glyphosate at 0.4 kg/ha applied without surfactant controlled johnsongrass better at 100% than at 45% RH. Johnsongrass control was better with 20% than with 12% soil moisture. Averaged over all evironments, the order of glyphosate toxicity to johnsongrass at 0.4 and 0.7 kg/ha was 35 C > 29 C > 24 C. The environmental condition of 45% RH and 12% soil, moisture resulted in least johnsongrass control regardless of temperature. The order of glyphosate toxicity to soybeans when applied without surfactant was 24 C > 29 C > 35 C. Glyphosate applied without surfactant was more toxic to soybeans at 100% than at 45% RH and more toxic at 12% than at 20% soil moisture. Surfactant in spray solutions increased glyphosate toxicity to johnsongrass and soybeans.

scholarly journals Quantifying the Independent Influences of Land Cover and Humidity on Microscale Urban Air Temperature Variation in Hot Summer: Methods of Path Analysis and Genetic SVR

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1377
Author(s):  
Weifang Shi ◽  
Nan Wang ◽  
Aixuan Xin ◽  
Linglan Liu ◽  
Jiaqi Hou ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Land Cover ◽  
Path Analysis ◽  
Temperature Variation ◽  
Direct Effect ◽  
Air Temperature ◽  
Urban Areas ◽  
Support Vector ◽  
Urban Air ◽  
Air Temperatures

Mitigating high air temperatures and heat waves is vital for decreasing air pollution and protecting public health. To improve understanding of microscale urban air temperature variation, this paper performed measurements of air temperature and relative humidity in a field of Wuhan City in the afternoon of hot summer days, and used path analysis and genetic support vector regression (SVR) to quantify the independent influences of land cover and humidity on air temperature variation. The path analysis shows that most effect of the land cover is mediated through relative humidity difference, more than four times as much as the direct effect, and that the direct effect of relative humidity difference is nearly six times that of land cover, even larger than the total effect of the land cover. The SVR simulation illustrates that land cover and relative humidity independently contribute 16.3% and 83.7%, on average, to the rise of the air temperature over the land without vegetation in the study site. An alternative strategy of increasing the humidity artificially is proposed to reduce high air temperatures in urban areas. The study would provide scientific support for the regulation of the microclimate and the mitigation of the high air temperature in urban areas.

Root and Foliar Absorption of Atrazine Applied Postemergence to Broadleaf Weeds

Weed Science ◽  
1970 ◽  
Vol 18 (3) ◽  
pp. 349-351 ◽  
Author(s):  
Lafayette Thompson ◽  
F. W. Slife
Keyword(s):  
Relative Humidity ◽  
Field Experiments ◽  
Foliar Spray ◽  
High Relative Humidity ◽  
Growth Chamber ◽  
Foliar Absorption ◽  
Root Absorption

Results from both growth chamber and field experiments indicate that root absorption of 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine) applied postemergence to small broadleaf weeds is not a requisite for their control. Though broadleaf weeds absorb toxic quantities of atrazine from wet soil, they can be killed by foliar absorption alone because all of their meristems are exposed to a foliar spray. They are particularly sensitive when foliar penetration is enhanced by high relative humidity and wet foliage.

Applying the Passivhaus standard to a terraced house in a hot and humid tropical climate – Evaluation of comfort and energy performance

2020 ◽  
Vol 41 (3) ◽  
pp. 247-260
Author(s):  
Roy Candra Sigalingging ◽  
David Chow ◽  
Steve Sharples
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Best Practice ◽  
Natural Ventilation ◽  
Tropical Climate ◽  
Energy Performance ◽  
Tropical Region ◽  
Humid Tropical Climate ◽  
Air Temperatures

In a hot and humid tropical climate, natural ventilation brings high levels of moisture into dwellings that, together with occupant activity, can result in very elevated internal relative humidity levels. Coupling these high relative humidities with high internal air temperatures creates occupant thermal discomfort, which is typically ameliorated in the tropics using energy-intensive air conditioning systems. This paper has investigated the potential benefits for thermal comfort and energy usage of applying the German Passivhaus standard to tropical dwellings. By creating a super insulated and air-tight envelope, the Passivhaus standard reduces fabric heat transfer, controls air infiltration and provides low-energy comfort. Applying this approach to a tropical terraced house might be effective but could, potentially, have an adverse impact on mechanical cooling demand. This study took an actual terraced property in Jakarta, Indonesia and thermally modelled its performance as insulation and airtightness levels were incrementally improved up to the Passivhaus standard. Field measurements in the dwelling of air temperature and relative humidity were used to validate the thermal model of the existing house. The validated model then tested the feasibility of meeting the Passivhaus energy standard for cooling in the modified tropical house. Simulation allowed the effects of air conditioning (AC) and dehumidifiers on thermal comfort and cooling loads to be investigated. The research develop the Passivhaus building model that had the floor insulation removed to let the ground floor act as a thermal sink and potentially provide radiant cooling. Analysis revealed that the building’s predicted air temperatures were affected in a beneficial way by having the Passivhaus without floor insulation. Practical application: Cooling in hot and humid tropical region is an energy-intensive approach. Design approaches that can bring comfort and save energy for the occupant are essential. The success of Passivhaus standard in mild climate might be transferable to bring comfort in tropical housing. Best practice can be developed by analysing the Passivhaus building performance in hot and humid tropical region.

Temperature and Relative Humidity Effects on Diphenylether Herbicides

1992 ◽  
Vol 6 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Rex A. Wichert ◽  
Robert Bozsa ◽  
Ronald E. Talbert ◽  
Lawrence R. Oliver
Keyword(s):  
Relative Humidity ◽  
Herbicidal Activity ◽  
High Relative Humidity ◽  
Growth Chamber ◽  
Similar Response ◽  
Application Timing ◽  
Influence Of Temperature ◽  
Humidity Effects ◽  
Lower Temperature ◽  
Prickly Sida

The influence of temperature and relative humidity on the activity of acifluorfen, fomesafen, lactofen, and acifluorfen plus bentazon on prickly sida, pitted and entireleaf morningglory, and common cocklebur was evaluated in a growth chamber. Reduced control of all species was observed at 50% relative humidity as compared to 85% relative humidity when temperatures were higher (32/55 C day/night). Similar response to relative humidity was observed at the lower temperature (25/15 C) when treatments were applied 14 days after emergence (DAE). Changes in temperature at the same relative humidity did not alter herbicidal activity. Delaying application timing from 7 to 14 DAE decreased control by all herbicides except lactofen applied at high relative humidity, which controlled prickly sida at both 7 and 14 DAE.

scholarly journals Evaluation of Microbial and Conventional Insecticides for Control of Larval European Corn Borer on Whorl Stage Corn, Clay Center, Ne, 1995

1996 ◽  
Vol 21 (1) ◽  
pp. 218-218
Author(s):  
Terry A. DeVries ◽  
Robert J. Wright
Keyword(s):  
Relative Humidity ◽  
Air Temperature ◽  
Environmental Conditions ◽  
Wind Direction ◽  
Growth Stage ◽  
Crop Growth ◽  
Larval Feeding ◽  
Egg Masses ◽  
Crop Growth Stage ◽  
Over The Top

Abstract Bacillus thuringiensis formulations and conventional insecticides were evaluated for efficacy against larval ECB in whorl stage field corn. All plots were planted without soil insecticide on 16 May. The experimental design was a RCB with 4 replicates. Each plot consisted of a single row, 40 ft long with a 30-inch row spacing. Plots were artificially infested with black-head stage ECB egg masses. The egg masses were deposited on wax paper discs, precounted in the laboratory and placed in the whorl of the infested plants on 30 Jun and 9 Jul. Crop growth stage was 37 and 57 inches extended leaf height, respectively. The same 5 plants in each treatment replicate were infested with 10 egg masses per infestation date. All granular insecticides were applied on 13 Jul. Environmental conditions were: air temperature, 81°F; wind direction and speed, west (250°) at 7 mph; relative humidity, 53%; and crop growth stage, 63 inches extended leaf height. A 10-inch Almaco smooth belt cone rear mounted on a Hahn Hi-Boy was used to apply preweighed amounts of the granular insecticides over the top of the plant whorls (G). Liquid insecticides were applied on 15 Jul. Environmental conditions were: air temperature, 74°F; wind direction and speed, east (80°) at 5 mph; relative humidity, 76%; and crop growth stage, 67 inches extended leaf height. A CO2 pressurized backpack sprayer at 30 psi was used to apply a band application over the top of the whorl (total spray volume = 1050 ml/plot) of premeasured amounts of the liquid insecticides (L). All infested plants were evaluated for ECB larval feeding damage on 14-15 Aug. The stalks of the infested plants were split lengthwise and the accumulated length and number of cavities in the 5 plants per treatment replicate were used to evaluate ECB larval damage. The percent infestation at evaluation was determined by the plants with a minimum of 1 cavity per treatment replicate. Data were analyzed by ANOVA for RCB with mean separation using DMRT.

Factors that Influence Germination and Mycoherbicidal Activity ofAlternaria cassiae

1991 ◽  
Vol 5 (1) ◽  
pp. 82-86 ◽  
Author(s):  
Donald J. Daigle ◽  
Peter J. Cotty
Keyword(s):  
Relative Humidity ◽  
Phosphate Buffer ◽  
Potassium Phosphate ◽  
Tween 80 ◽  
Growth Chamber ◽  
Potassium Phosphate Buffer ◽  
Potato Dextrose Broth ◽  
Leaf Stage ◽  
True Leaf

The influences of pH, surfactants, and nutrients on germination were investigated to develop a basis for improvement ofAlternaria cassiaemycoherbicide formulations. In vitro results indicated that a formulation with a pH of approximately 6.5 containing 0.1 to 1% Tween 80, 0.02 M potassium phosphate buffer, and 1% dehydrated potato dextrose broth best promoted germination. Sicklepod plants at the 2 to 3 true-leaf stage were sprayed with test solutions, incubated in the dark at 100% relative humidity (28 C) for 6 h, and placed in a growth chamber maintained at 30 C. Assessment of the plants after 2 d indicated that the ability of the formulation components to induce germination ofAlternaria cassiaein vitro corresponded well with their ability to improve infection of sicklepod seedlings.

INFLUENCE OF TEMPERATURE AND HUMIDITY ON THE EMERGENCE BEHAVIOUR OF ANAX JUNIUS (ODONATA: AESHNIDAE)

1973 ◽  
Vol 105 (7) ◽  
pp. 975-984 ◽  
Author(s):  
Robert Trottier
Keyword(s):  
Relative Humidity ◽  
Water Temperature ◽  
Air Temperature ◽  
Water Surface ◽  
Average Speed ◽  
Anax Junius ◽  
Air Temperatures ◽  
Stage 4 ◽  
Temperature And Humidity ◽  
Three Stages

AbstractEmergence from the water of Anax junius Drury normally occurred after sunset. The onset was affected independently by water temperature and air temperature; low water temperature and high air temperature delayed the onset of emergence. In the field, the net vrtical distance travelled above the water, before ecdysis, was positively correlated with air temperature. In the laboratory, the vertical distance travelled above the water was greatest when air and water temperatures were approximately the same. The average speed of climbing to the first resting position above the water surface was faster at high than low water temperature, but the average speed of climbing from there to the final position, where ecdysis occurred, was reduced due to the effects of air temperature and humidity. Air temperatures below 12.6 °C were found to retard ecdysis and larvae returned to the water and emerged early the following day making the final process of emergence and ecdysis diurnal instead of nocturnal. The duration of ecdysis was shorter at high than low air temperatures and only the first three stages, as arbitrarily defined, were longer at low than high relative humidity; stage 4, shortened with low relative humidity. This study shows that A. Junius, emerging from the water is affected at first by the temperature experienced when submerged, but it becomes gradually and cumulatively affected by air temperature and humidity while climbing to the ecdysial position and moulting.

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