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1.
Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha?1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha?1. MCPA + dicamba at 0·9+0·15 kg ha?1 was applied to half of each plot when the second node was detectable (Zadok 32). Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn. MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments. The grain yield of the barley increased from 2·91 t ha?1 when A. millefolium was not controlled to 4·23 t ha?1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes.  相似文献   

2.
Field experiments at Lacombe on a Ponoka loam soil (9·6% organic matter) during 1982 and 1983 investigated the tolerance of spring wheat (Triticum aestivum L.) cv. Neepawa in a weed free situation to trifluralin applied at 0·0–3·0 kg ai ha?1 in the autumn or spring and incorporated to a depth of 10 cm. Rates of trifluralin above 1·0 kg ai ha?1 applied in the autumn or spring reduced the percent stand of wheat compared to an untreated control. Two weeks after emergence the crop showed 37 or 47% injury indicated by delayed growth, following application at 1·0 kg ai ha?1 in the autumn or spring, respectively. The wheat recovered throughout the course of the growing season. At harvest, trifluralin applied in the autumn or spring at rates below 1·0 kg ai ha?1 caused a yield increase while higher rates caused a yield decrease compared to the untreated control. Spring application caused a greater yield loss than autumn application. The tolerance of spring wheat to trifluralin at rates required for weed control (1·1 kg ai ha?1 or higher) on this soil type is marginal.  相似文献   

3.
Problems with the establishment of autumn-reseeded ryegrass can be attributed to a number of causes, one of which is damage by pests, particularly larvae of shoot-boring flies such as the frit fly (Oscinella frit). In trials over a period of 2 years, bendiocarb has been tested as a seed treatment and as spray and granule formulations for the protection of ryegrass seedlings from pest attack. The trials have included both conventional broadcasting of seed following ploughing of the old sward, and direct drilling following the use of total herbicide. Seed treatments at rates of 10 g a.i. kg?1 of seed and above have given greatly improved plant stands, resulting in yield increases in some trials. Spray and granule applications at 0.5-1.0 kg a.i. ha?1 have significantly improved establishment at some sites. Bendiocarb has also been tested on spring reseeded leys and although results have been less dramatic than on autumn sowings, significant increases in plant stand were obtained. No evidence of phytotoxicity has been found with any variety of Italian or perennial ryegrass which has been tested, nor with timothy and cocksfoot which have been included in mixtures.  相似文献   

4.
A study was conducted in the semi-arid region of the Loess Plateau in China to identify an alternative material for use instead of plastic film under maize crops. Plastic film (PMW), straw (SMW), and biodegradable film (BMW) were used for mulching throughout the whole season (fallow and growth periods), in addition to straw for mulching (SMF) only during the fallow period. The results showed that PMW and BMW treatments retained 17 mm and 11 mm more water, respectively, than the mean value of both SMW and SMF treatments, and 53 mm and 38 mm more water than nonmulching (NM) treatment during the fallow period. PMW and BMW treatments increased the soil water and temperature during the early growth stage of maize and significantly improved the dry matter accumulation. Under PMW and BMW treatments, the yield improved by 4.6–6.4 Mg ha?1 and 2.3–2.8 Mg ha?1, and the net income increased by 1166 USD ha?1 and 372 USD ha?1 compared with NM treatment, respectively. SMW treatment led to poor growth and yield reductions of 3.7 Mg ha?1 due to the lower temperature, whereas SMF treatment had no significant effects on the yield (P > 0.05). High water consumption with PMW treatment reduced the water supply capacity at the end of the season, and resulted in soil water deficit during 2015, indicating that high yields might not be sustained in the long-term. Therefore, BMW treatment is recommended as an effective method for increasing the maize yield and maintaining the balance of soil water in semi-arid areas.  相似文献   

5.
BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a cosmopolitan insect pest of citrus and vectors the bacterium Candidatus Liberibacter asiaticus, a suspected causal organism of citrus greening or ‘huanglongbing’ disease. Aldicarb 150 g kg?1 GR (Temik® 15 G) was evaluated at three rates, two placements and three timings for ACP control in orange trees. RESULTS: Application of aldicarb at 5.6, 2.8 and 1.4 kg AI ha?1 in March 2006 reduced adults by 58–66%, 45–46% and 25–37% respectively compared with untreated controls in two separate trials. No difference was observed in placement (one versus two sides of the tree) or tree size (8 years old versus 12 years old). Application at 5.6 kg ha?1 in January 2007 reduced adults by 86% and shoot infestation by 77% in spring, and was generally better than the November and especially February applications. Even more striking results were evident on adults caged on treated plants for 25 days in March. Spiders and ladybeetles were equally abundant in treated and untreated trees. CONCLUSION: Aldicarb application at 5.6 kg ha?1 to the bed side of mature citrus trees 2–3 months before spring growth can suppress ACP through spring without a direct effect on principal psyllid natural enemies. Copyright © 2008 Society of Chemical Industry  相似文献   

6.
Field experiments were conducted from 1989 to 1992 to determine the effects of pre-emergence herbicides in sunflower (Helianthus armuus L.) on: (1) the control of Orobanche cemua Loefl. (broomrape) and (2) crop damage and crop yield. Herbicides tested belong to the imidazolinone, sulfonylurea and substituted amide families. Imazethapy r (20–40 g ha?1), imazapy r (12.5–25 gha?1) and chlorsulfuron (4–6 gha?1) controlled broomrape efficiently without crop injury. With good O. cernua control and good crop tolerance, sunflower seed yield from these treatments were generally similar to the non-infested checks and higher than the infestedchecks. Imazaquin (20–40 gha?1), triasulfuron(4gha?1), pdmisulfuron(3g ha?1), acetochlor (4–4 kg ha?1) and metazachlor (2 kg ha?1) were less effective. Imazamethabenz (200–600 g ha?1) and metolachlor (3–3 kg ha?1) were ineffective. Wetconditions aftercropsowing considerably decreased O. cemua control with pre-emergence herbicides probably caused by enhanced degrädation. Des herbicides de prelevee pour la lutte contre Vorobanche (Orobanche cemua Loefl.) dans le toumesol (Helianthus annuus L.) Des expérimentations au champ ont été conduites de 1989 á 1992 pour determiner les effets d'herbicides de pré1evée du toumesol sun (a) la destruction de l'orobanche (Orobanche cernua Loefl.) et (b) la phytotoxcité sur la culture. Les herbicides testés appartenaient aux imidazolinones, aux sulfonylurdes et aux amides substituées. L'imazethapyr (20 á 40 gha?1), l'imazapyr (12,5 á25gha?1)et le chlorsulfuron (4 á 6 gha?1) détruisaient efficacement l'orobanche sans occasionner de phytotoxidt6 sur la culture. Dans ces conditions, les rendements étaient généralement semblables à ceux des témoins non infestés et supérieurs à ceux des témoins infestés. L'imazaquin (20 à 40 g ha?1), le triasulfuron (4 gha?1), le primisulfuron (3 g ha?1), lacétolachlor (4,4 kg ha?1) et le métazachlor (2 kg ha?1) étaient moins efficaces. L'imazaméthabenz (200 á 600 g ha?1) et le métolachlor (3,3 kg ha?1) etaient inefficaces. Des conditions humides aprfes le semis diminuaient considérablement la destruction de O. cemua par les herbicides de prélevée, probablement à cause d'une dégradation plus élevée. Vorauflaufherbigide zur Bekdmpfung der Sommerwurz Orobanche cemua Loefl. in Sonnenblume (Helianthus annuus L.) Zwischen 1989 und 1992 wurden in Sonnenblume Feldversuche zur Wirkung von Vorauflaufherbiziden aus den Gruppen der Imidazolinone, Sulfonylharnstoffe und substitutierten Amide auf die Sommerwurz Orobanche cernua und auf Kulturpflanzenschaden sowie den Ertrag durchgefuhrt. Mit Imazethapyr (20 bis 40 g ha?1), Imazapyr (12,5 bis 25 g ha?1) und Chlorsulfuron (4 bis 6 g ha?1) lieβ sich die Sommerwurz wirksam bekampfen, ohne daβ Schaden an der Sonnenblume auftraten, und die Ertrage waren allgemein ahnlich oder hoher als bei der nichtparasitierten Kontrolle. Imazaquin (20 bis 40 ha?1), Triasulfuron (4 g ha?1).Primisulfuron (3 g ha ?1). Acetochlor (4,4 kg ha ?1 und Metazachlor (2 kg ha ?1) waren weniger wirksam. Imazamethabenz (200 bis 600 g ha?1) und Metolachlor (3,3 kg ha?1) hatten keine Wirkung. Bei Niederschlagen nach der Saat der Sonnenblume war die Bekampfung der Sommerwurz mit Vorauflaufherbiziden vermutlich wegen verstärkten Abbaus erheblich schwächer.  相似文献   

7.
Biological characterization of sulfoxaflor, a novel insecticide   总被引：1，自引：0，他引：1  
BACKGROUND: The commercialization of new insecticides is important for ensuring that multiple effective product choices are available. In particular, new insecticides that exhibit high potency and lack insecticidal cross‐resistance are particularly useful in insecticide resistance management (IRM) programs. Sulfoxaflor possesses these characteristics and is the first compound under development from the novel sulfoxamine class of insecticides. RESULTS: In the laboratory, sulfoxaflor demonstrated high levels of insecticidal potency against a broad range of sap‐feeding insect species. The potency of sulfoxaflor was comparable with that of commercial products, including neonicotinoids, for the control of a wide range of aphids, whiteflies (Homoptera) and true bugs (Heteroptera). Sulfoxaflor performed equally well in the laboratory against both insecticide‐susceptible and insecticide‐resistant populations of sweetpotato whitefly, Bemisia tabaci Gennadius, and brown planthopper, Nilaparvata lugens (Stål), including populations resistant to the neonicotinoid insecticide imidacloprid. These laboratory efficacy trends were confirmed in field trials from multiple geographies and crops, and in populations of insects with histories of repeated exposure to insecticides. In particular, a sulfoxaflor use rate of 25 g ha?1 against cotton aphid (Aphis gossypii Glover) outperformed acetamiprid (25 g ha?1) and dicrotophos (560 g ha?1). Sulfoxaflor (50 g ha?1) provided a control of sweetpotato whitefly equivalent to that of acetamiprid (75 g ha?1) and imidacloprid (50 g ha?1) and better than that of thiamethoxam (50 g ha?1). CONCLUSION: The novel chemistry of sulfoxaflor, its unique biological spectrum of activity and its lack of cross‐resistance highlight the potential of sulfoxaflor as an important new tool for the control of sap‐feeding insect pests. Copyright © 2010 Society of Chemical Industry  相似文献   

8.
In a greenhouse metabolism study, sunflowers were seed‐treated with radiolabelled imidacloprid in a 700 g kg?1 WS formulation (Gaucho® WS 70) at 0.7 mg AI per seed, and the nature of the resulting residues in nectar and pollen was determined. Only the parent compound and no metabolites were detected in nectar and pollen of these seed‐treated sunflower plants (limit of detection <0.001 mg kg?1). In standard LD50 laboratory tests, imidacloprid showed high oral toxicity to honeybees (Apis mellifera), with LD50 values between 3.7 and 40.9 ng per bee, corresponding to a lethal food concentration between 0.14 and 1.57 mg kg?1. The residue level of imidacloprid in nectar and pollen of seed‐treated sunflower plants in the field was negligible. Under field‐growing conditions no residues were detected (limit of detection: 0.0015 mg kg?1) in either nectar or pollen. There were also no detectable residues in nectar and pollen of sunflowers planted as a succeeding crop in soils which previously had been cropped with imidacloprid seed‐treated plants. Chronic feeding experiments with sunflower honey fortified with 0.002, 0.005, 0.010 and 0.020 mg kg?1 imidacloprid were conducted to assess potential long‐term adverse effects on honeybee colonies. Testing end‐points in this 39‐day feeding study were mortality, feeding activity, wax/comb production, breeding performance and colony vitality. Even at the highest test concentration, imidacloprid showed no adverse effects on the development of the exposed bee colonies. This no‐adverse‐effect concentration of 0.020 mg kg?1 compares with a field residue level of less than 0.0015 mg kg?1 ( = limit of detection in the field residue studies) which clearly shows that a sunflower seed dressing with imidacloprid poses no risk to honeybees. This conclusion is confirmed by observations made in more than 10 field studies and several tunnel tests. © 2001 Society of Chemical Industry  相似文献   

9.
During sowing of pesticide-treated seeds, pesticide-laden dust and abraded seed particles may be emitted to the environment, possibly leading to environmental contamination and posing health risks. In many countries there is currently no legislation concerning the acceptable amount of dust of treated seeds. This study aimed to gain insight in the abrasion potential of available pesticide-treated seeds and its associated factors. The abrasion potential of 45 seed samples of 7 different species (viz. sugar beet, oat, barley, wheat, spelt, pea, and maize) was determined using the Heubach test and amounts of dust were expressed as g 100 kgseeds?1, g 100,000 seeds?1, and g ha?1. The abrasion potential fell generally within the boundaries of maximum permissible values adopted by different countries. Species, seed treatment company, number of active ingredient (AIs) and combination of AIs had significant effects on the abrasion potential, whereas little or no effect of agitation and conservation was found. However, species were situated differently with respect to each other depending on the unit in which the abrasion potential was expressed. A standard unit that takes into account the species’ seed rate is suggested to give the fairest assessment of dust drift risk and would allow international comparison.  相似文献   

10.
BACKGROUND: Cashew (Anacardium occidentale L.) has become a very important non‐traditional tree crop in Ghana. The crop is, however, attacked by sap‐sucking insects, particularly the mosquito bug, Helopeltis schoutedeni Reuter, the leaf‐footed bug, Pseudotheraptus devastans (Dist.), and the coreid bug, Anoplocnemis curvipes (F.), which feed on shoots, panicles and fruits. Their damage is characterised by withering of the latter. In Ghana, Oecophylla longinoda Latr. occurs in large numbers on cashew and other native plants, but little is known about its relationship with insect pests. The relationship between O. longinoda and shoot and panicle damage by sap‐sucking bugs and the effectiveness of O. longinoda as a biocontrol agent in the protection of cashew as compared with two chemical insecticides, lambda‐cyhalothrin (Karate®) and cypermethrin + dimethoate (Cyperdim®), were therefore investigated at Bole in the northern region of Ghana. RESULTS: There was a negative correlation between numbers of O. longinoda nests and pest damage. Trees treated with cypermethrin + dimethoate (969 mg AI mL?1 tree?1) and lambda‐cyhalothrin (100 mg AI mL?1 tree?1) recorded the smallest bug numbers, followed by O. longinoda. Trees infested by Oecophylla longinoda and trees treated with cypermethrin + dimethoate and with lambda‐cyhalothrin had less than 6% pest damage to shoots, panicles and fruits, while water‐sprayed trees recorded damage as high as 36.8% (shoots) in February, 32.9% (panicles) in February and 37.8% (fruits) in March. Cypermethrin + dimethoate again recorded the highest (485.0 kg ha?1) nut yield, followed by O. longinoda (431.0 kg ha?1), with water recording the lowest (93.0 kg ha?1) nut yield. CONCLUSION: The results indicate that O. longinoda can be used to control some sucking bugs as effectively as some insecticides. Copyright © 2008 Society of Chemical Industry  相似文献   

11.
Disposition kinetics of cypermethrin and fenvalerate were investigated in lactating black Bengal goats following single dose intravenous administration at 57 and 45 mg kg?1 respectively. The maximum and minimum blood concentrations of cypermethrin were 18.49 (±3.17) and 0.06 (±0.002) μg ml?1, while the corresponding values for fenvalerate were 14.58 (±2.37) and 0.04 (±0.005) μg ml?1 respectively. Both cypermethrin and fenvalerate remained present in blood for 36 h. The mean t1/2β) and Vdarea values were 5.56 (±0.28) h and 10.38 (±2.20) litre kg?1 for cypermethrin and 5.66 (±0.35) h and 11.31 (±2.20) litre kg?1 respectively for fenvalerate. Both cypermethrin and fenvalerate persisted in goat milk for 36 h. The t1/2β) and AUC values of fenvalerate were 7.37 (±1.84) h and 122.38 (±11.65) μg h ml?1 whilst the corresponding values for cypermethrin were 6.66 (±1.54) h and 99.48 (±7.81) μg h ml?1 in milk respectively.  相似文献   

12.
Weed suppression in sugar beets (Beta vulgaris.) is commonly achieved with two to three post-emergent herbicide applications across the entire field. Field studies were performed, in order to investigate the weed suppressing ability of Medicago lupulina, Trifolium subterraneum and a mixture of Lolium perenne and Festuca pratensis as living mulches in sugar beet at four locations in South Germany during 2014 and 2015. Living mulches were sown 2 and 30 days after sowing (DAS) of sugar beet. Weed densities ranged from 0 to 143 plants m?2 with Chenopodium album, Polygonum convolvulus and Polygonum aviculare being the most abundant weed species. It has been found that living mulches could reduce herbicide input up to 65?%. Weed suppression of living mulch was highest with Trifolium subterraneum (71?%). The early sown living mulches (2 DAS) revealed a 28 g m?2 higher biomass compared to late sowing (30 DAS). However, no any linear correlation was found between living mulch biomass and weed suppression. White sugar yield (WSY) was highest in the herbicide treatments (12.6 t ha?1). Trifolium subterraneum yielded the highest WSY of the living mulches with 11.1 t ha?1 across all locations. Our work reveals that living mulch can play a major role in integrated plant protection by reducing herbicides in sugar beet production.  相似文献   

13.
W. W. DONALD 《Weed Research》1992,32(4):259-266
Three herbicide treatments were applied each year over a period of 4 years to Cirsium arvense (L.) Scop, infestations in no-till spring wheat (Triticum aestivum L.) in North Dakota, USA. Both chlorsulfuron at 30 g ai ha?1+a non-ionic surfactant and a mixture of clopyralid+2,4-D at 70+280 g ai ha?1 gradually reduced Cirsium arvense shoot density, root biomass, and adventitious root buds over the 4-year treatment period in two trials. These two treatments did not merely induce adventitious root buds to become dormant. They virtually eliminated roots to a depth of 50 cm by year 4. Tribenuron methyl at 10 g ai ha?1+ a non-ionic surfactant was less effective in reducing shoot density and root biomass. Lutte herbicide contre les racines et les tiges de Cirsium arvense (L.) Scop, dans du bli de printemps non laboure (Triticum aestivum L.) Trois traitements herbicides ont été appliqués chaque année pendant 4 ans, contre des infestations de Cirsium arvense (L.) Scop, dans du blé de printemps (Triticum aestivum L.) non labouré dans le Dakota Nord, USA. Tant le chlorsulfuron à 30 g m.a. ha?+un surfactant nonionique qu'un mélange de clopyralide+2,4-D à 70+280 g m.a. h? ont reduit progres-sivement la densité des pieds de Cirsium arvense, la biomasse racinaire, et les bourgeons racinaires adventices pendant les 4 années de traitements dans les 2 essais. Ces traitements ont à peu près éliminé les racines sur une profondeur de 50 cm en 4 ans. Ces deux traitements n'ont pas induit de dormance des bourgeons racinaires adventices. Le tribenuron methyl à 10 g m.a. ha?+un surfactant non ionique a été moins efficace dans la réduction de la densité de plante et de la biomasse racinaire. Chemische Bekämpfung von Cirsium arvense (L.) Scop, in direktgesätem Sommerweizen (Triticum aestivum L.) In direktgesäter Sommerweizen (Triticum aestivum L.) wurdel in North Dakota. USA, Bestände von Cirsium arvense (L.) Scop, über 4 Jahre jährlich 3 Herbizidbehandlungen unterzogen. Sowohl Chlorsulfuron mit 30 g AS ha?1 nichtionischem Netzmittel als auch eine Mischung von Clopyralid+2,4D mit 70+280 g AS ha?1 verringerten die Sproßdichte der Acker-Kratzdistel, die Wurzelbiomasse und die Adventivknospen an den Wurzeln in 2 Ver-suchen graduell. Durch diese beiden Behand-lungen wurden nicht nur die Adventivknospen dormant, sondem auch die Wurzeln bis zu einer Tiefe von 50 cm bis zum 4. Jahr fast ganz elimi-niert. Tribenuron-methyl mit 10 g AS ha?1 nichtionischem Netzmittel war hinsichtlich der Reduktion von Sproßdichte und Wurzelbiomasse weniger wirksam.  相似文献   

14.
BACKGROUND: A major problem of crop protection in Crete, Greece, is the control of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) with chemical insecticides owing to the rapid development of resistance. The aim of this study was to investigate the establishment of resistance and the underlying mechanisms to major insecticide classes with classical bioassays and known biochemical resistance markers. RESULTS: During a 2005–2007 survey, 53 Q biotype populations were collected. Application history records showed extensive use of neonicotinoids, organophosphates, carbamates and pyrethroids. High resistance levels were identified in the majority of populations (>80%) for imidacloprid (RF: 38–1958×) and α‐cypermethrin (RF: 30–600×). Low resistance levels (RF < 12) were observed for pirimiphos‐methyl. A strong correlation between resistance to imidacloprid and the number of applications with neonicotinoids was observed. Significant correlations were observed between COE and P450‐dependent monoxygenase activity with resistance to α‐cypermethrin and imidacloprid respectively. A propoxur‐based AChE diagnostic test indicated that iAChE was widespread in most populations. Resistance levels for α‐cypermethrin were increased when compared with a previous survey (2002–2003). Differentiation of LC50 values between localities was observed for imidacloprid only. CONCLUSION: Bemisia tabaci resistance evolved differently in each of the three insecticides studied. Imidacloprid resistance seems less established and less persistent than α‐cypermethrin resistance. The low resistance levels for pirimiphos‐methyl suggest absence of cross‐resistance with other organophosphates or carbamates used. Copyright © 2008 Society of Chemical Industry  相似文献   

15.
Unrestricted weed growth reduced the yield of transplanted onions (Allium cepa L.) by 26–48%. Hand-weeding once, 42 days after transplanting reduced the yield loss to 15%. Application of oxadiazon (1.1–1.3 kg ai ha?1), pendimethalin (1.2–1.8 kg ai ha?1), oxyfluorfen (0.14–0.43 kg ai ha?1) and chlorthal-dimethyl (8.3–13.1 kg ai ha?1) resulted in yields comparable to the hand-weeded control (82–126%). When sprayed at transplanting these herbicides gave excellent and persistent control of grasses (86–100%). However, they were less effective on broad-leaved weeds (38–94% control). Désherbage chimique de l'oignon repiqué (Allium cepa L.) dans la Gezireh soudanaise La croissance incontrôlée des mauvaises herbes réduit le rendement des oignons repiqués de 26–48%. Un désherbage manuel, 42 jours après le repiquage, ramène la baisse de rendement à 15%. L'application d'oxadiazon (1,1–1,3 kg ma ha?1), de pendiméthalin (1,2–1,8 ka ma ha1), d'oxyfluorfen (0,14–0,43 ka ma ha?1) et de chlortal-diméthyle (8,3–13,1 kg ma ha?1), a permis d'atteindre des rendements comparables aux témoins désherbés manuellement (82–126%). Lorsqu'ils ont été administrés au moment du repiquage, ces herbicides ont permis un contrôle efficace et persistant des monocotylédones (86–100%). Toutefois, ils se sont montrés moins efficaces à l'égard des dicotylédones (38–94% du témoin). Chemische Unkrautbekämpfung in verpflanzten Zwiebeln (Allium cepa L.) in der Region Gezira (Sudan) Ungehinderte Unkrautentwicklung in verpflanzten Zwiebeln (Allium cepa L.) verringerte die Ernte um 26–48%. Eine Handjätung, 42 Tage nach dem Auspflanzen, reduzierte den Ernteverlust auf 15%. Die Applikation von Oxadiazon (1,1–1,3 kg ai ha?1), Pendimethalin (1,2–1,8 kg ai ha?1), Oxyfluorfen (0,14–0,43 kg ai ha?1) und Chlorthal- dimethyl (8,3–13,1 kg ai ha?1) erbrachte Ernten, die mit denjenigen, der von Hand gejäteten Kontrollparzellen vergleichbar waren (82–126%). Diese Herbizide, zur Ausflanzzeit ausgebracht, ergaben eine ausgezeichnete und andauernde Kontrolle von Gräsern (86–100%), während die Wirkung gegen breitblättrige Unkräuter geringer ausfiel (38–94%).  相似文献   

16.
An emulsion concentrate formulation of cypermethrin (‘Ripcord’) was applied at seven different dose rates (between 5 and 500 g a. i. ha?1) to the water surface of 1-m3 stainless steel enclosures, located in a small outdoor pond, to which were introduced small rainbow trout and common carp. A range of water quality parameters were monitored frequently in all of the enclosures and in the open pond. At daily intervals, the concentration of cypermethrin was determined in water samples, collected from the enclosures treated with 5, 50 and 500 g a. i. ha-?1. Two further water samples were collected from these enclosures, and their toxicity was assessed by bioassay, using Gammarus pulex as the test organism. The experiment was terminated 96 h after application, when all the fish were removed and examined for mortality or adverse toxic effects. Throughout the study, the water quality parameters in all the enclosures remained similar to those recorded in the open pond. Cypermethrin residues, in the enclosures treated with 5 and 50 g a. i. ha?1, attained peak concentrations 24 h after application, and thereafter declined to about 50% of this level. Maximum cypermethrin concentrations were not attained until about 72 h after application in the enclosure treated with 500 g a. i. ha?1. Highly consistent responses, closely correlated with the applied dose rates, were obtained with G. pulex and both species of fish. Rainbow trout appeared to be about three times more susceptible to cyper-methrin than common carp, with calculated LD50 values of 92 and 300 g a. i. ha?1, respectively. It is therefore most unlikely that fish mortality would result from the use of cypermethrin in normal agricultural practice.  相似文献   

17.
The field life for contact activity of cypermethrin and permethrin, applied to pasture, was similar for all of five application rates between 0.25 and 1.5 kg ha?1. Laboratory bioassays with grass grub beetles, Costelytra zealandica (White), showed that the insecticides lost their activity after about 4–9 days on pasture. Microencapsulation significantly increased the active field life of permethrin.  相似文献   

18.
Two field experiments were carried out a year apart on the alkaloid poppy (Papaver somniferum) in 2012 and 2013 in north-west Hungary, to assess the efficacy of mesotrione and tembotrione herbicides for post-emergence weed control. Our experiments tested (1) a single application of mesotrione at 144 g active ingredient (a.i.) ha–1, (2) two separate applications of mesotrione at 144 g a.i. ha–1, (3) a single application of tembotrione at 88 g a.i. ha–1, (4) two separate applications of mesotrione at 88 g a.i. ha–1, and (5) the combination of a single application of mesotrione at 144 g a.i. ha–1 followed by a single application of tembotrione at 88 g a.i. ha–1. Both non-treated and hand-weeded plots were used as controls. Among the most important weeds, Chenopodium album was most successfully controlled in the majority of the test treatments, but Fallopia convolvulus and Polygonum aviculare tolerated each herbicide application in 2012, likely due to the dry weather conditions. Because of the botanical similarity to the crop, none of the treatments proved to be significant against Papaver rhoeas. One dosage of tembotrione alone never reduced the dry weights of the target weed species or weed numbers significantly. The cuticular wax layer of the opium poppy can provide a natural defence against these herbicides, but some temporary phytotoxic yellowish discoloration occurred after tembotrione treatments. Our results show that mesotrione in combination with tembotrione is the most effective treatment and should be employed in poppy cultivation.  相似文献   

19.
T K Das  D K Das 《Weed Research》2018,58(3):188-199
Variable dormancies result in periodicity in the germination of weeds and make weed control a repetitive practice. Under some conditions, repeated applications of selective herbicides can lead to the dominance of perennial weeds like Cyperus rotundus . Our hypothesis was that applying a chemical dormancy breaker (DB ) plus herbicide mixture would better control a mixture of weed species. Three experiments were designed to develop a cost‐effective DB treatment and to evaluate its dose with herbicides tank‐mixtures for effective weed management. KNO 3 and gibberellic acid GA 3 as dormancy breakers offered comparable effects, but KNO 3 was more economical than GA 3. KNO 3 at a 6% concentration was more effective in promoting weed germination than a 3% concentration in soyabean. A combination of KNO 3 (6%) and pre‐emergence pendimethalin 0.75 kg a.i. ha?1 + imazethapyr 0.10 kg a.i. ha?1 controlled annual weeds by 99% and reduced C. rotundus growth by 83%. This treatment gave significantly higher soyabean yield and net returns. Similarly, a tank‐mixture comprising of clodinafop 0.06 kg a.i. ha?1 + metsulfuron 0.006 kga.i. ha?1 was more effective against weeds than pre‐emergence tank‐mix application of pendimethalin 0.75 kg a.i. ha?1 + carfentrazone‐ethyl 0.02 kg a.i. ha?1 and isoproturon 0.75 kg a.i. ha?1. The use of pre‐emergence tank‐mixture of pendimethalin 0.75 kg a.i. ha?1 + imazethapyr 0.10 kg a.i. ha?1 should exhaust seed/tuber bank if repeated and reduce the application cost of herbicides by 50% and the dose, residue and cost of pendimethalin by 25%.  相似文献   

20.
Herbicide resistance in Alopecurus myosuroides causes severe problems in Western European cropping systems. Costs of herbicide resistance were investigated in this study by analysing variable production costs and sales revenues. Three farms were selected for this study, with winter wheat as the dominating crop in all farms. Resistance in A. myosuroides populations was verified at all locations. Four farming approaches were simulated over a period of 20 years: (i) continuing the actual cropping system without increase of resistance, (ii) continuing the actual cropping system with increase of resistance, (iii) changing cropping practice to overcome resistance and (iv) changing cropping practice to prevent resistance. Contribution margins representing the proportion of sales revenue that is not consumed by variable costs were calculated for all approaches. Comparative static simulations showed that average contribution margins in a cropping system with more than 60% winter cereals and reduced tillage practice dropped from 807 € ha?1 a?1 without herbicide resistance to 307 € ha?1 a?1 with herbicide resistance. Alopecurus myosuroides population densities increased to more than 1000 plants m?2. Diverse crop rotations, including spring crops, clover–grass leys and intensive tillage, suppressed A. myosuroides populations, and average contribution margin was 630 € ha?1 a?1. Preventive methods with rotations of winter cereals and spring crops with less clover–grass leys resulted in an average contribution margin of 691 € ha?1 a?1. In conclusion, rotations of winter cereals and spring crops combined with inversion tillage and herbicides provide stable yields and can prevent weed population increase.  相似文献   

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