Effect of Application Rate, Weed Species, and Weed Stage of Growth on Imazethapyr Activity

Weed Science ◽  
1992 ◽  
Vol 40 (2) ◽  
pp. 227-232 ◽  
Author(s):  
Tracy E. Klingaman ◽  
Charles A. King ◽  
Lawrence R. Oliver
Keyword(s):  
Field Experiments ◽  
Leaf Growth ◽  
Application Rate ◽  
Leaf Number ◽  
Red Rice ◽  
Weed Species ◽  
Leaf Stage ◽  
Time Of Application ◽  
True Leaf ◽  
Application Rates

Field experiments were conducted in 1986, 1987, and 1988 to evaluate imazethapyr rate and time of application on postemergence control of 24 weed species. Contour graphs were developed that predicted imazethapyr rates required for various levels of weed control based upon weed leaf number at application. Rates below the labeled rate (70 g ha−1) provided 90% or greater control of common cocklebur, smallflower morningglory, and smooth pigweed if applied to 3 true-leaf or smaller weeds and of barnyardgrass, seedling johnsongrass, and Palmer amaranth if applied while weeds were in the cotyledon or 1 true-leaf stage. A rate of 70 g ha−1provided 90% control of large crabgrass in the 1 true-leaf stage. Entireleaf morningglory, red rice, pitted morningglory, and velvetleaf are not susceptible enough to imazethapyr for 90% or greater control to be obtained with rates lower than 70 g ha−1at the 1 true-leaf growth stage. These data demonstrate how control data can be used for developing effective reduced-rate herbicide recommendations based on weed leaf number.

A re-evaluation of chlormequat application to wheat in Western Australia

1986 ◽  
Vol 26 (3) ◽  
pp. 361
Author(s):  
MW Perry ◽  
DJ Miers
Keyword(s):  
Grain Yield ◽  
Western Australia ◽  
Field Experiments ◽  
Leaf Growth ◽  
Maximum Yield ◽  
Growth Stages ◽  
Time Of Application ◽  
Natural Rainfall ◽  
Application Rates ◽  
Yield Responses

The effect of chlormequat on the grain yield of wheat was investigated in 24 field experiments between 1981 and 1983. Two times of application (at the 3.5- and 6-leaf growth stages-Zadoks decimal score 13.5 and 16.0) and rates of application up to 0.75 kg/ha a.i. were tested with two chlormequat formulations, Cycocel 750 and Bettaquat. Chlormequat application reduced crop height in all trials, but crop lodging did not occur in any trial. Statistically significant yield responses to rate of application alone were obtained in only three of 24 trials, with maximum yield occurring at 0.19-0.37 kg/ha a.i. and with some indication of a yield depression at 0.75 kg/ha a.i. A significant effect of time of application was observed in only two trials, but the results conflicted. In one trial there was a significant interaction between rate and time, with a response to rate of chlormequat only at the 6-leaf stage. No differences were detected between chlormequat formulations. In individual trials, the mean grain yield from the chlormequat treatments ranged from 92.9 to 116.5% of the control. However, averaging over all trials in each year, chlormequat treatments yielded 102.5, 99.3 and 100.0% of the control, respectively, in the three years. Our results confirm that low application rates of chlormequat, applied early in crop development, can increase grain yield. However, over the 24 trials, the effects of chlormequat were too small and inconsistent to warrant its use to increase wheat grain yields under natural rainfall in south-western Australia.

Influence of four commonly used pesticides on the survival, growth, and reproduction of the earthworm Aporrectodea trapezoides (Lumbricidae)

1998 ◽  
Vol 49 (8) ◽  
pp. 1297 ◽  
Author(s):  
L. P. D. Choo ◽  
G. H. Baker ◽  
L. P. D. Choo ◽  
G. H. Baker
Keyword(s):  
Filter Paper ◽  
Field Experiments ◽  
Application Rate ◽  
Normal Rate ◽  
Cocoon Production ◽  
Application Rates ◽  
Aporrectodea Trapezoides ◽  
Growth And Reproduction ◽  
Significant Mortality

The effects of 4 commonly used pesticides, endosulfan (insecticide), fenamiphos (nematicide), methiocarb (molluscicide), and ridomil (fungicide) on the survival, growth, and reproduction of the earthworm Aporrectodea trapezoides (Lumbricidae) were measured in laboratory and field experiments. When the earthworms were exposed to the pesticides on moist filter paper for 48 h, fenamiphos and, to a lesser extent, endosulfan caused significant mortality. In contrast, the survival of A. trapezoides was rarely affected by the pesticides during exposure for 5 weeks in pots and cages containing soil (only noted under 10 × normal application rate of endosulfan against adult worms). However, endosulfan did significantly reduce the weight of juvenile A. trapezoides within 5 weeks when applied to soil at normal application rate in both the field and laboratory. Fenamiphos did so at normal application rate in the field only. Fenamiphos and methiocarb reduced earthworm weight in the laboratory when applied at 10 × normal rate. The clitella of adult earthworms regressed with exposure to endosulfan at normal rate and also exposure to fenamiphos at 10 × normal rate. Cocoon production was inhibited by endosulfan and fenamiphos at normal application rates and methiocarb at 10 × normal rate. The use of some pesticides, in particular endosulfan, could significantly reduce the establishment of abundant and beneficial populations of earthworms in Australian pastures.

scholarly journals Effect of Gypsum Application Rate, Soil Type, and Soil Calcium on Yield, Grade and Seed Quality of Runner Type Peanut Cultivars

2017 ◽  
Vol 44 (1) ◽  
pp. 13-18 ◽  
Author(s):  
J.A. Arnold III ◽  
J.P. Beasley ◽  
G.H. Harris ◽  
T.L. Grey ◽  
M. Cabrera
Keyword(s):  
Field Experiments ◽  
Seed Quality ◽  
Soil Depth ◽  
Application Rate ◽  
Seed Vigor ◽  
Application Rates ◽  
Peanut Cultivars ◽  
Research And Education ◽  
The University ◽  
Gypsum Application

ABSTRACT Calcium (Ca) availability in the 0 to 8 cm soil depth often limits peanut yield and influences grade in the southeastern United States. Field experiments were conducted in 2012 and 2013 at the University of Georgia's Coastal Plain Experiment Station, Tifton, GA (CPES) and the Southwest Georgia Research and Education Center, Plains, GA (SWREC) to determine large-seeded (Georgia-06G) and medium-seed sized (Georgia Greener) runner-type cultivar response to gypsum application rates of 0, 560, 1120, 1650 kg/ha. Peanut pod yield and grade (TSMK) were significantly different between locations with 7610 and 6540 kg/ha at CPES and SWREC, respectively. However, there were no differences between peanut cultivars or gypsum rates. Standard germination, seed vigor (cold germination), and seed Ca content analysis were also conducted on subsamples from each plot. Average peanut seed germination was 97% across all samples. No differences were observed for standard germination or vigor testing. Differences in locations were observed for yield, TSMK, percent jumbo, percent medium kernels, and seed Ca content. Peanut cultivar and gypsum application rate had effects on seed Ca concentration. Seed Ca concentration levels were 825 and 787 mg/kg for Georgia Greener and Georgia-06G, respectively. Seed Ca content increased as field gypsum application rate increased at both locations.

scholarly journals MANAGEMENT OF RED RICE (ORYZA SATIVA) AND BARNYARDGRASS (ECHINOCHLOA CRUS-GALLI) GROWN WITH SORGHUM WITH REDUCED RATE OF ATRAZINE AND MECHANICAL METHODS

2012 ◽  
Vol 48 (4) ◽  
pp. 587-596 ◽  
Author(s):  
ANDRÉ ANDRES ◽  
GERMANI CONCENÇO ◽  
GIOVANI THEISEN ◽  
LEANDRO GALON ◽  
FRANCO TESIO
Keyword(s):  
Oryza Sativa ◽  
Weed Control ◽  
Control Method ◽  
Application Rate ◽  
Soil Tillage ◽  
Weedy Rice ◽  
Red Rice ◽  
Weed Species ◽  
Mechanical Methods ◽  
Tillage System

SUMMARYThe weedy variety ofOryza sativaoccurs in several rice cultivation areas reducing both grain yield and quality. Prevention and crop rotation are considered the basic means to reduce its presence. Weed control in sorghum is generally attained with atrazine. In this study, the efficacy of both chemical and mechanical methods for control, under different soil tillage conditions, of weedy rice and barnyardgrass during sorghum cultivation was evaluated with the aim to reduce the application rate of atrazine. In the case of chemical control, the atrazine rate (1000, 1500, 2000, 2500 and 3000 ga.i.ha−1) and application timing (pre- and post-emergence) were assessed. With the mechanical control method, the number of interventions (inter-row hoeing with sorghum at 3, 4–5 and 6–8 leaves) to avoid weed competition was determined. The effect of the tillage system on weed population was investigated comparing conventional (ploughing), minimum-tillage (disc harrowing) and sod seeding (no-tillage) in combination with pre- and post-emergence herbicide treatments. The results showed that efficient control of weedy rice and barnyardgrass was achieved in lowlands with sorghum in rotation with rice. Both chemical and mechanical methods of weed control in sorghum gave a level of efficiency higher than 60%. The application of atrazine was more efficient in pre-emergence application, rather than in post-emergence treatments, in all soil tillage systems tested. On both weed species, the most suitable application rate was the pre-emergence treatment with 1500 ga.i.ha−1, and the adoption of higher rates did not significantly increase the herbicidal efficacy. The adoption of two or three mechanical interventions resulted in sorghum yield higher than the chemical post-emergence application, and similar to the application of atrazine in pre-emergence. Higher yield results were in accordance to greater weed control, being obtained in the conventional tillage system.

Ammonia volatilization following surface-applied pig and cattle slurry in France

1995 ◽  
Vol 125 (2) ◽  
pp. 245-252 ◽  
Author(s):  
J.-F. Moal ◽  
J. Martinez ◽  
F. Guiziou ◽  
C.-M. Coste
Keyword(s):  
Field Experiments ◽  
Arable Land ◽  
Matter Content ◽  
Total Loss ◽  
Dry Matter Content ◽  
Pig Slurry ◽  
Ammoniacal Nitrogen ◽  
Cattle Slurry ◽  
Time Of Application ◽  
Application Rates

SUMMARYField experiments were carried out in Brittany (Western France) in 1993 to measure ammonia losses from surface-applied pig and cattle slurry. Experiments were conducted on grass, stubble (wheat and maize) and arable land using a wind tunnel system. Ammonia losses were followed during periods ranging from 20 to 96 h after slurry application. Rates of slurry applied varied from 40 to 200 m3/ha. In two experiments, losses from cattle slurry were respectively 75 and 54% of the ammoniacal nitrogen applied in the slurry. Ammonia emissions from pig slurry applied at a rate of 40 m3/ha, during spring and summer experiments, were higher on grass (45–63% of the total ammoniacal nitrogen applied) than on wheat stubble (37–45%). On average, 75% of the total loss in all experiments occurred within the first 15 h after spreading. Significant correlations were found between ammonia losses (kg N/ha) and mean soil temperature and slurry dry matter content (%) using simple linear regressions and stepwise procedures. The time of application was also found to influence the magnitude of ammonia loss: 83% of the total loss occurred within 6 h when the slurry was applied at midday compared with 42% when it was applied in the evening.

Pronamide Effects on Physiology and Yield of Sugar Beet

Weed Science ◽  
2008 ◽  
Vol 56 (3) ◽  
pp. 457-463 ◽  
Author(s):  
Kalliopi Kadoglidou ◽  
Chrysovalantis Malkoyannidis ◽  
Kalliopi Radoglou ◽  
Ilias Eleftherohorinos ◽  
Helen-Isis A. Constantinidou
Keyword(s):  
Sugar Beet ◽  
Leaf Area ◽  
Field Experiments ◽  
Leaf Growth ◽  
Sugar Yield ◽  
Growth Stages ◽  
Area Index ◽  
Vegetative Period ◽  
Leaf Stage ◽  
Photosynthetic Yield

Field experiments were conducted in northern Greece during 2001 and repeated in 2002 and 2004 to evaluate the effects of pronamide on sugar beet. Total leaf area, leaf area index (LAI), leaf and root dry weights, photosynthetic yield (quantum yield of photochemical energy conversion in photosystem II), chlorotic index, and yield components of sugar beet were monitored after pronamide application. Three sugar beet cultivars, ‘Avantage’, ‘Dorothea’, and ‘Bianca’, requiring short, intermediate, and long vegetative periods, respectively, were subjected to treatment. Pronamide was applied on sugar beet either as a double application of 0.63 kg ai ha−1at the two- to four-leaf and 0.63 kg ai ha−1at the four- to six-leaf stage or as a single application of 1.26 kg ai ha−1performed at the latter leaf stage. Both application procedures were combined with a split application of phenmedipham at 0.04 kg ai ha−1plus desmedipham at 0.04 kg ai ha−1plus metamitron at 0.70 kg ai ha−1plus ethofumesate at 0.10 kg ai ha−1plus mineral oil at 0.50 L ha−1applied POST at the cotyledon–to–two-leaf as well as at the four-leaf growth stages. Pronamide (both single and double application) initially caused chlorosis and reduction of sugar beet growth. LAI and photosynthetic yield were also significantly affected for a 2-mo period following the final application, after which the negative effects caused by pronamide were ameliorated. At harvest, sugar beet root and sugar yield, sucrose, K+, Na+, and N-amino acid concentrations were not affected by the herbicide treatments compared with those produced in weed-free and herbicide-free plots, indicating that all cultivars managed to overcome the transient pronamide stress. Regarding sugar beet cultivars, root and sugar yield of Avantage and Dorothea at harvest were higher than that of Bianca, whereas sucrose concentration of Avantage was the lowest. There was not an apparent relationship between the order of sugar yield per cultivar (Dorothea > Avantage > Bianca) and the length of the vegetative period (Avantage < Dorothea < Bianca).

scholarly journals Chemical control and herbicide resistance of hairy fleabane [Conyza bonariensis (L.) Cronquist] in Jordan

2022 ◽  
Author(s):  
Jamal R. Qasem
Keyword(s):  
Herbicide Resistance ◽  
Date Palm ◽  
Field Experiments ◽  
Weed Species ◽  
Jordan Valley ◽  
Application Rates ◽  
Conyza Bonariensis ◽  
Central Jordan ◽  
Nonchemical Weed Control ◽  
Hairy Fleabane

Two field experiments were conducted to evaluate the effectiveness of 12 herbicides in controlling hairy fleabane [ Conyza bonariensis (L.) Cronquist] in a date palm orchard located in the central Jordan valley during the spring of 2017. Results showed that C. bonariensis resists paraquat (2.5, 5 and 7.5kgha -1 ), oxadiazon (5kgha -1 ) and oxyflourfen (3.3kgha -1 ) herbicides applied at normal or higher than the recommended rates. None of the three herbicides was significantly effective against the weed and treated plants continued growing normally similar to those of untreated control. Higher rates (10-fold of the recommended rates) of the same herbicides failed to control the weed. The effect of other tested herbicides on the weed was varied with bromoxynil plus MCPA (buctril ® M), 2,4-D- iso-octyl ester, glyphosate, glyphosate trimesium and triclopyr were most effective and completely controlled the weed at recommended rates of application. Testing paraquat, oxadiazon and oxyflourfen using the normal recommended and 10-fold higher rates on two populations of C. bonariensis grown from seeds of the date palm and al-Twal (another site in the Jordan Valley) weed populations and grown in pots under glasshouse conditions showed that Date palm population was resistant to the three herbicides at both application rates while al-Twal site population was highly susceptible and completely controlled at normal and high rates of the three herbicides. It is concluded that certain populations of C . bonariensis developed resistance to paraquat, oxadiazon and oxyflourfen but control of this weed was possible using other herbicides of different mechanism of action. Herbicide rotation or other nonchemical weed control methods have been suggested to prevent or reduce the buildup and spread of resistant populations of this weed species. These results represent the first report on herbicide resistance of C. bonariensis in Jordan.

scholarly journals Morphology and Anatomy of the Fused Vein Trait in Cucurbita pepo L.

1996 ◽  
Vol 121 (1) ◽  
pp. 6-12
Author(s):  
R. Bruce Carle ◽  
J. Brent Loy
Keyword(s):  
Genetic Background ◽  
Leaf Blade ◽  
Cucurbita Pepo ◽  
Leaf Growth ◽  
Leaf Size ◽  
Leaf Number ◽  
Central Vein ◽  
Vascular Bundles ◽  
Leaf Production ◽  
Leaf Stage

The morphology, growth rate and anatomy of the fused vein trait were characterized in Cucurbita pepo using the inbreds NH2405 (fused vein), NH7210 (moderately fused vein), and NH614 (normal). Morphological analysis showed that the trait is characterized by a partial fusion of the five primary leaf veins. Fusion begins at the distal point of the petiole and extends along the central vein. Branching of the veins is delayed and there is a reduction of the interveinal leaf blade. Consequently, the upper leaf surface appears puckered or wrinkled. Depending on genetic background, the onset of fused vein leaf production starts at the fourth to tenth leaf stage and continues throughout vegetative growth. The extent of fusion increases with leaf number but stabilizes by the twentieth leaf stage maximum extent of vein fusion also varies with genetic background (5-20 cm). Though fused vein and normal inbreds differed in the rate and pattern of leaf growth, examination of F2 and BC populations revealed no significant effect of the fused vein trait on leaf number, leaf size, and rate of leaf initiation. Anatomical examination revealed different vascular patterns in the transition zone between petiole and leaf blade for normal and fused vein leaves. In normal leaves, the vascular bundles of the petiole enlarge and coalesce to form a vascular crescent. The crescent reorganizes and diverges as large vascular columns and pairs of smaller flanking vascular bundles into each vein. In contrast, two cycles of enlargement, coalescence, and dispersal occur in fused vein leaves.

scholarly journals COMPARISON OF JUVENILITY IN TWO GENERA OF THE ASTERACEAE

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 718F-718
Author(s):  
Peggy Damann ◽  
Robert E. Lyons
Keyword(s):  
The Other ◽  
Leaf Number ◽  
Leaf Stage ◽  
Perennial Plants ◽  
True Leaf

Chrysanthemum × superbum, Coreopsis lanceolata, and Coreopsis grandiflora are LD flowering perennial plants. The end of juvenility could be defined as the minimum expanded leaf number required for fastest flowering once placed in LD. This research was conducted to compare juvenility and flowering requirements in dwarf and standard cultivars of these species. Plants were maintained under SD and transferred to LD upon reaching true leaf stages beginning with 0 (cotyledons only) and progressing at 2 or 3 leaf intervals to the 24 leaf stage. Coreopsis `Sunray' and Chrysanthemum `G. Marconi' were relatively unresponsive to LD whereas LD induced flowering in 70-100% of the plants in each leaf number treatment in Coreopsis `Early Sunrise'. Plants transferred at the 15 leaf stage required the least number of LD to reach anthesis. LD promoted complete flowering in Chrysanthemum × superbum `Snow Lady' plants and 90% of the SD control plants flowered as well. SD control plants from the other 3 cultivars remained vegetative. Effects of vernalization will also be presented.

Comparison of Glyphosate Salts (Isopropylamine, Diammonium, and Potassium) and Calcium and Magnesium Concentrations on the Control of Various Weeds

2006 ◽  
Vol 20 (1) ◽  
pp. 164-171 ◽  
Author(s):  
Thomas C. Mueller ◽  
Christopher L. Main ◽  
M. Angela Thompson ◽  
Lawrence E. Steckel
Keyword(s):  
Field Experiments ◽  
Water Source ◽  
Weed Species ◽  
Yellow Nutsedge ◽  
Application Rates ◽  
Pitted Morningglory ◽  
Calcium And Magnesium ◽  
Diammonium Sulfate ◽  
And Control ◽  
Glyphosate Formulations

Greenhouse and field experiments were conducted near Knoxville, TN, during 2002 and 2003 to investigate the effects of calcium and magnesium ions on the performance of three glyphosate formulations with and without diammonium sulfate (AMS). Weed species investigated in the greenhouse were broadleaf signalgrass, pitted morningglory, Palmer amaranth, and yellow nutsedge. Three glyphosate formulations (isopropylamine salt, diammonium salt, and potassium salt) and two glyphosate application rates (0.42 and 0.84 kg ae/ha) were applied to weeds in water fortified with either calcium or magnesium at concentrations of 0, 250, 500, 750, and 1,000 ppm. In all comparisons, there were no differences in the three glyphosate formulations. Glyphosate activity was reduced only when cation concentration was >250 ppm, and this antagonism was not observed when 2% w/ w AMS was added to the spray solution. A chemical analysis of the calcium and magnesium concentrations in water collected from farmers indicated that water samples from eight different producers contained relatively low amounts of cations, with calcium at <40 ppm and magnesium at <8 ppm. In the field results using these and other waters as the herbicide carrier, broadleaf signalgrass control was greater with the 0.84 kg ae/ha than 0.42 kg ae/ha glyphosate rate regardless of water source or addition of AMS. Pitted morningglory responded similarly to glyphosate with water from all farms and with AMS added, and the addition of AMS gave similar results for both glyphosate rates. In 2003, common cocklebur was evaluated and control was >93% regardless of glyphosate rate, water source, or AMS addition. Based on these results, the addition of AMS-based adjuvants to many glyphosate applications may not be warranted.

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