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1.
BACKGROUND: Five formulated insecticides (lambda‐cyhalothrin at 10 mg m?2, bifenthrin at 50 mg m?2, fipronil at 10 mg m?2, fenitrothion at 50 mg m?2, imidacloprid at 5 mg m?2) and one active ingredient (DDT at 500 mg m?2) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda‐cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed. RESULTS: The order of susceptibility of different stages of bed bugs was as follows: early stage ? lambda‐cyhalothrin > bifenthrin = imidacloprid > fipronil > fenitrothion > DDT; late stage—lambda‐cyhalothrin > bifenthrin > fenitrothion > imidacloprid > fipronil > DDT; adult—lambda‐cyhalothrin > imidacloprid > bifenthrin > fenitrothion > fipronil > DDT. The late instars exhibited significantly higher LT50 among the life stages. The addition of PBO to fipronil increased the susceptibility of the insects. CONCLUSIONS: Lambda‐cyhalothrin, bifenthrin, fenitrothion and fipronil at the recommended application rates were effective against C. hemipterus. Although imidacloprid demonstrated good initial response against C. hemipterus, the insects showed substantial recovery 72 h post‐treatment. The late instars (fourth and fifth instars) should be used as the model for toxicological evaluation. Copyright © 2011 Society of Chemical Industry  相似文献   

2.
BACKGROUND: Most insecticides used to control rice water weevil (Lissorhoptrus oryzophilus Kuscel) infestations are pyrethroids. However, pyrethroids are highly toxic to non‐target crayfish associated with rice–crayfish crop rotations. One solution to the near‐exclusive reliance on pyrethroids in a rice–crayfish pest management program is to incorporate neonicotinoid insecticides, which are insect specific and effective against weevils but not extremely toxic to crayfish. This study aimed to take the first step to assess neonicotinoids as alternatives to pyrethroids in rice–crayfish crop rotations by measuring the acute toxicities of three candidate neonicotinoid insecticides, clothianidin, dinotefuran and thiamethoxam, to juvenile Procambarus clarkii (Girard) crayfish and comparing them with the acute toxicities of two currently used pyrethroid insecticides, lambda‐cyhalothrin and etofenprox. RESULTS: Neonicotinoid insecticides are at least 2–3 orders of magnitude less acutely toxic (96 h LC50) than pyrethroids to juvenile Procambarid crayfish: lambda‐cyhalothrin (0.16 µg AI L?1) = etofenprox (0.29 µg AI L?1) ? clothianidin (59 µg AI L?1) > thiamethoxam (967 µg AI L?1) > dinotefuran (2032 µg AI L?1). CONCLUSION: Neonicotinoid insecticides appear to be much less hazardous alternatives to pyrethroids in rice–crayfish crop rotations. Further field‐level neonicotinoid acute and chronic toxicity testing with crayfish is needed. Copyright © 2009 Society of Chemical Industry  相似文献   

3.
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   

4.
Field and glasshouse experiments were conducted from 1995 through 1996 to evaluate application timing of asulam (methyl sulfanilylcarbamate) for torpedograss (Panicum repens L.) control in relation to plant age in sugarcane. Above‐ground shoots of torpedograss were completely controlled with asulam at 2–4 kg active ingredient (a.i.) ha?1 applied 60 or 80 days after planting (DAP) in artificially infested pots. But some newly developed rhizome buds survived after asulam application resulting in 1–25 and 76–100% or more regrowth in 60 and 80 DAP‐applied pots, respectively. Whereas the herbicide at 2–4 kg a.i. ha?1 applied within 60 DAP completely controlled above‐ground shoots, applied 80 DAP at 2 kg a.i. ha?1 it did not completely control the weed in the artificially infested field. Regrowth levels were 1–25 and 76–100% or more in 60 and 80 DAP‐applied plots, respectively. Asulam at 2–3 kg a.i. ha?1 applied 20, 40, 60 or 80 DAP in a naturally infested field completely controlled above‐ground shoots and regrowth levels were 76–100 or more, 51–75, 1–25 and 26–50% in these same DAP applied plots, respectively. The herbicide applied at 4 kg a.i. ha?1 caused chlorosis on younger sugarcane leaves (one‐leaf stage), but when applied at 2–3 kg a.i. ha?1, no injury symptoms were shown. The herbicide at 2–4 kg a.i. ha?1 applied within 60 DAP resulted in remarkably higher yield and shoot biomass of sugarcane than that applied 80 DAP. This study suggested that asulam at 2–3 kg a.i. ha?1 should be applied 60 days after planting for the maximum control of torpedograss regrowth and better yield of sugarcane. This study also indicated that torpedograss cannot be completely controlled with a single application of asulam in a naturally infested field because of rhizome fragmentation by cross plowing and distribution of rhizomes into different soil layers that require different times to emerge. The shoots emerging after asulam application could not be controlled. Another study is required to determine the interval between sequential applications of asulam for better control of torpedograss in a naturally infested field.  相似文献   

5.
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   

6.
BACKGROUND: Chlorantraniliprole, a novel anthranilic diamide insecticide, was recently introduced into the United States where rice–crayfish crop rotations are practiced to control rice water weevil (Lissorhoptrus oryzophilus Kuschel) infestations. Chlorantraniliprole has high margins of mammalian safety and excellent insecticidal efficacy, but its toxicity to non‐target crayfish is uncertain. In this study, the acute toxicity of chlorantraniliprole to the red swamp crayfish Procambarus clarkii Girard was determined using aquatic and feeding assays. RESULTS: The aquatic 96 h median lethal toxicity (LC50) data indicate that technical‐grade chlorantraniliprole is highly toxic (US EPA category) to crayfish with an LC50 of 951 µg L?1 (95% CL = 741–1118 µg L?1). A no observed effect concentration (NOEC) of 480 µg L?1 was recorded. Neither the 36 day chronic feeding study, where crayfish fed on chlorantraniliprole‐treated rice seed in aquaria, nor the 144 h acute feeding test, where crayfish fed on rice seeds treated with chlorantraniliprole, produced mortality or abnormal behavior. CONCLUSION: Chlorantraniliprole is three orders of magnitude less acutely toxic to P. clarkii than lambda‐cyhalothrin and etofenprox, two pyrethroid insecticides also used in rice, and is less likely to cause acute crayfish toxicity in rice pond ecosystems. Based on acute toxicity data, the use of chlorantraniliprole should be more compatible with rice–crayfish crop rotations than pyrethroids. Copyright © 2010 Society of Chemical Industry  相似文献   

7.
Wild barley (Hordeum spontaneum) is one of the most troublesome weed species in winter wheat (Triticum aestivum) in Iran. Two bioassay experiments were conducted in order to study the response of wild barley and wheat to different herbicides and to study the efficacy of pre‐emergence (PRE), postemergence (POST), and PRE followed by POST applications of sulfosulfuron on wild barely. Moreover, the degradation of sulfosulfuron was studied by liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS). The results showed that wild barley was highly tolerant to clodinafop‐propargyl and its dry weight was reduced by only 15%, compared to the control, at the recommended dose (64 g ai ha?1). Sulfosulfuron reduced the wild barley biomass by ≤50% at the highest dose (90 g ai ha?1) in the first bioassay but by not more than 20% and 12% at the recommended dose (22 g ai ha?1) in the first and second bioassay, respectively. Significant differences were found among the application methods of sulfosulfuron, with the POST application being the least effective method. In contrast to the POST application, wild barley was severely injured by the PRE application of sulfosulfuron, with an ED50 dose of 7.3 g ai ha?1. The degradation study showed that wild barley can metabolize sulfosulfuron that is applied POST, but at a lower rate than wheat. By 4 h after application, wild barley had metabolized 26% of the sulfosulfuron, compared to 46% by wheat. In conclusion, wild barley can metabolize the recommended dose of sulfosulfuron that is applied POST; thus, the PRE application of sulfosulfuron or other integrated methods should be considered for the effective control of wild barley in wheat.  相似文献   

8.
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   

9.
Petroleum spray oil (2, 4 and 6% in water) was applied to Valencia orange, Citrus sinensis (L.) Osbeck, for the control of Chinese wax scale, Ceroplastes sinensis del Guercio, using a low-volume ( <2000 litre ha?1)air-blast (LV AB) sprayer, a low- to high-volume (L-HV) (up to 7000 litre ha?1) sprayer with four fan-assisted rotary atomiser (FARA) spray heads mounted on a vertical tower, and a high-volume (>7000 litre ha?1) oscillating boom (HV OB) sprayer. The most effective sprayer was the L-HV FARA sprayer. The most cost-effective treatment was a 20 ml litre?1 (60 litre oil ha?1) spray applied at 3000 litre ha?1 by the L-HV FARA sprayer. It gave mortality equivalent to a standard 20 ml litre?1, 10 700 litre ha?1 spray (214 litre oil ha?1) applied by the HV OB sprayer but with 72% less spray and significantly less oil deposited per cm2 of leaf area. Equivalent or significantly (P = 0·05) higher mortality than that given by the 10 700 litre ha?1 HV OB spray was given by the 40 ml litre?1, 3000 (120 litre oil ha?1) and 60 ml litre?1, 2180 and 3000 litre ha?1 (130·8 and 180 litre oil ha?1) L-HV FARA sprays, but the 60 ml litre?1 sprays deposited more oil per cm2 than the 20 ml litre?1 HV OB spray and were considered to be potentially phytotoxic. The least effective sprayer was the LV AB sprayer, which applied a 60 ml litre?1 spray (57·6 litre oil ha?1) at 960 litre ha?1. Linear relationships were established for Chinese wax scale mortality, transformed using an angular transformation (arcsin proportion), versus log10 spray volume for the 20, 40 and 60 ml litre?1 sprays applied by L-HV FARA at 1260,2180 and 3000 litre ha?1, mortality versus log10 μg oil cm?2 and log10 μg oil versus log10 volume of oil sprayed.  相似文献   

10.
Hyaliodes vitripennis (Say) is a univoltine indigenous predacious mirid. It has been reported in several orchards where IPM programmes are used. It is a generalist, and feeds on phytophagous mites in addition to other arthropods. In Quebec, a foliar application of imidacloprid, deltamethrin or lambda‐cyhalothrin is used at least once per season to manage arthropod pests such as leafhoppers and leaf‐eating caterpillars. Meanwhile, several applications of metiram, flusilazole, myclobutanil and mancozeb are made to control apple scab [Venturia inaequalis (Cooke) Winter]. In laboratory trials, comparison of lethal concentrations of the three insecticides against H vitripennis nymphs and adults showed no significant difference. However, when lethal concentrations were compared between two growth stages for each insecticide, a significant difference was noted between adults and nymphs treated with lambda‐cyhalothrin, adults being more susceptible than nymphs. No such difference could be detected for imidacloprid or deltamethrin. When LC50 values were compared with the manufacturer's label rates, deltamethrin and imidacloprid were toxic to the nymphs and adults, and lambda‐cyhalothrin was slightly toxic to the nymphs and moderately toxic to the adults. Among the fungicides evaluated in the laboratory, myclobutanil showed moderate toxicity to adults at the manufacturer's label rate. The remaining fungicides had no toxic effects to adults or nymphs, even at four times the manufacturer's label rate. © 2001 Society of Chemical Industry  相似文献   

11.
BACKGROUND: Soybean aphid, a serious economic pest of soybean in North America, is currently managed by applying non‐selective foliar insecticides during outbreaks according to decision thresholds and crop maturity. Natural enemies, such as the parasitoid Aphelinus certus Yasnosh, potentially play an important role in suppressing soybean aphid. Using selective insecticides that preserve A. certus may enhance the biological control service they provide and thus prevent or reduce the severity of soybean aphid outbreaks. The toxicity of five insecticides (λ‐cyhalothrin, dimethoate, flonicamid, mineral oil, spirotetramat) and the biopesticide Beauveria bassiana to A. certus was assessed. RESULTS: The LD50 values of λ‐cyhalothrin and dimethoate were similar; however, the hazard quotient of dimethoate was greater than that of λ‐cyhalothrin. In a screening bioassay, the descending order of toxicity for the recommended rates 48 h after application was dimethoate > λ‐cyhalothrin > flonicamid > mineral oil > Beauveria bassiana > spirotetramat. CONCLUSIONS: Overall, λ‐cyhalothrin and dimethoate were both harmful to A. certus. The other insecticides tested were harmless to A. certus and are potential candidates for inclusion in soybean aphid management programs. Copyright © 2011 Society of Chemical Industry  相似文献   

12.
Chinese violet (Asystasia gangetica (L.) T. Anderson) is a perennial invasive weed belonging to Acanthaceae. Leaves of this weed have been suggested to possess phytotoxic activity. However, phytotoxic substances in this weed have not yet been reported. Therefore, the present study investigated phytotoxic activity of Chinese violet extracts and phytotoxic substances. The extracts of Chinese violet leaves inhibited the root and shoot growth of cress, lettuce, alfalfa, barnyard grass, ryegrass, and timothy, where the level of inhibition increased with increasing extract concentrations. Bioassay‐guided separations of the extracts led to isolation of two phytotoxic substances, indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol. Indole‐3‐carboxaldehyde significantly inhibited the root and shoot growth of cress at concentrations ≥100 and 30 μmol L?1, respectively, and concentrations of the substance required for 50% growth inhibition were 210 and 127 μmol L?1 for cress roots and shoots, respectively. The other substance, (6R,9S)‐3‐oxo‐α‐ionol, was reported to have strongly inhibited cress roots and shoots. The present results suggest that Chinese violet contains two phytotoxic substances indole‐3‐carboxaldehyde and (6R,9S)‐3‐oxo‐α‐ionol, and those substances may play an important role in the phytotoxic activity of Chinese violet.  相似文献   

13.
The sap-sucking rates of the white-backed planthopper (WBPH) Sogatella furcifera (Horv.) (Homoptera, Delphacidae) were examined under a series of experimental conditions in the laboratory. The sucking rate increased with the age of the planthopper. The relative sucking rate of nymphs at the 1st, 2nd, 3rd, 4th, and 5th instars and macropterous male adult was 0.19, 0.27, 0.37, 0.49, 0.59, 0.69, and 1 of that of macropterous female adult (set as standard insect [SI]), respectively. The SI sucked at a maximum rate from rice plants at tillering stage. In indica rice varieties, the SI had higher sucking rate than in japonica varieties. The effect of temperature on sucking rate could be described by an exponential quadratic equation. A power equation (W=0.0001S1.8107) could be used to transfer the relative sucking rate in area (S, mm2) of honeydew excreted by WBPH into absolute dry mass weight (W, mg). The relationship between injury to rice by WBPH in cage and yield loss assessment showed that yield loss was mainly caused by decreased filling percentage of kernels and kernel weights rather than the number of panicles and spikelets per panicle. Finally, experimental results were integrated to a formula that links percentage of yield loss and sucking equivalence of WBPH.  相似文献   

14.
The sap-sucking rates of the white-backed planthopper (WBPH) Sogatella furcifera (Horv.) (Homoptera, Delphacidae) were examined under a series of experimental conditions in the laboratory. The sucking rate increased with the age of the planthopper. The relative sucking rate of nymphs at the 1st, 2nd, 3rd, 4th, and 5th instars and macropterous male adult was 0.19, 0.27, 0.37, 0.49, 0.59, 0.69, and 1 of that of macropterous female adult (set as standard insect [SI]), respectively. The SI sucked at a maximum rate from rice plants at tillering stage. In indica rice varieties, the SI had higher sucking rate than in japonica varieties. The effect of temperature on sucking rate could be described by an exponential quadratic equation. A power equation (W=0.0001S1.8107) could be used to transfer the relative sucking rate in area (S, mm2) of honeydew excreted by WBPH into absolute dry mass weight (W, mg). The relationship between injury to rice by WBPH in cage and yield loss assessment showed that yield loss was mainly caused by decreased filling percentage of kernels and kernel weights rather than the number of panicles and spikelets per panicle. Finally, experimental results were integrated to a formula that links percentage of yield loss and sucking equivalence of WBPH.  相似文献   

15.
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   

16.
The dimpling bug, Campylomma austrina Malipatil, has been recognised since 2002 as a serious mango pest in the Northern Territory, Australia. To fully understand the damage the bug causes and its relationship with ants, field experiments were conducted in five mango orchards in the Darwin area from 2001 to 2003 along with laboratory rearing trials. The latter revealed that the dimpling bug sucked sap mainly from the ovary of the flowers. As the ovary ripened, each puncture resulted in a black pimple on the skin of the marble-sized fruit (<5 mm in diameter). All of the most heavily damaged marble-sized fruits (>10 pimples/fruitlet) dropped from the trees. A field survey and field experiments showed that marble-sized fruit damage levels on trees bearing abundant weaver ants, Oecophylla smaragdina Fabricius, were similar to those protected by chemical insecticides, however both suffered less damage than trees bearing fewer or no weaver ants or black ants, Iridomyrmex sp. We propose that the weaver ant is an efficient bio-control agent of the dimpling bug, and to limit the bug damage, high levels of weaver ant populations are required in mango orchards.  相似文献   

17.
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   

18.
BACKGROUND: The spotted bollworm Earias vittella (Fab.) is a serious pest of cotton and okra in Pakistan. Owing to persistent use of insecticides, this pest has developed resistance, especially to pyrethroids. The present studies aimed at determining the extent of resistance to pyrethroid, organophosphorus and new chemical insecticides in Pakistani populations of E. vittella. RESULTS: Field populations of E. vittella were monitored at Multan, Pakistan, from 1999 to 2007 for their resistance against six pyrethroid, four organophosphorus and six new chemical insecticides using a leaf‐dip bioassay. Of the pyrethroids, resistance was generally low to zeta‐cypermethrin and moderate to high or very high to cypermethrin, deltamethrin, esfenvalerate, bifenthrin and lambda‐cyhalothrin. Resistance to organophosphates chlorpyrifos, profenofos, triazophos and phoxim was recorded at very low to low levels. Among new chemicals, E. vittella had no or a very low resistance to spinosad, emamectin benzoate and methoxyfenozide, a very low to low resistance to abamectin, a very low to moderate resistance to indoxacarb and a moderate resistance to chlorfenapyr. CONCLUSION: The results indicate a lack of cross‐resistance between pyrethroid and organophosphorus insecticides in E. vittella. Rotation of insecticides showing no, very low or low resistance, but belonging to different insecticide classes with unrelated modes of action, may prevent or mitigate insecticide resistance in E. vittella. Copyright © 2009 Society of Chemical Industry  相似文献   

19.
Influence of picloram on Cirsium arvense (L.) Scop, control with glyphosate   总被引：1，自引：0，他引：1  
Low rates of picloram in mixture with glyphosate provided a rapid enhancement of the onset of injury to the shoots of Cirsium arvense (Canada thistle or creeping thistle) under field (0.07+1.0 and 0.07+1.5 kg ha?1) and greenhouse (0.035+0.42 and 0.07+0.84 kg ha?1) conditions. Picloram slightly reduced the amount of 14C-glyphosate absorbed at 24 and 48 but not 72 h after treatment. Movement of 14C-glyphosate from the treated leaves to the shoot apex, remainder of the shoot and roots was reduced in the presence of picloram. Necrosis of the treated leaves above the treated spots was evident, presumably indicating acropetal movement of either or both herbicides. With the picloram + glyphosate mixtures there was increased shoot regrowth over glyphosate alone at 1 year after treatment under field, and with certain mixtures at 18 days and 4 weeks after treatment under greenhouse conditions. Following application of the mixtures, accumulation of glyphosate in the shoots may be responsible for the enhanced onset of shoot injury while failure of enough glyphosate to translocate to, and cause death of, the roots may be responsible for the increased shoot regrowth over glyphosate alone.  相似文献   

20.
In this paper, we report the sowing date and intensity of chemical control on presence of the cereal leaf beetles (CLB) on spring wheat. The CLB monitoring (Oulema melanopus L. and Oulema gallaeciana Voet.) was conducted in May–June of each year, following the announcement of the IOR-PiB in Poznań (Institute of Plant Protection, National Research Institute), that economic threshold levels in Poland of this pest is observed. For the spring sowing dates between (20 March–20 April) and late autumn sowings (21 November–7 December) larger amounts of CLB adults (1.6–1.1) in comparison to early autumn sowings (25 October–02 November) were noticed (0.4). Following the insecticidal seed treatment with imidacloprid, the occurrence of adults was 0.2–0.7 individual per stem, while the use of fungicidal treatment with triadimenol–imazalil–fuberidazol resulted in average 1.1–2.2 individual per stem. The reduction in the number of larvae per stem was 7–10 fold larger following the foliar application (pirimicarb + dimethoate + cypermethrin) compared to the seed treatment with imidacloprid. The lowest grain yield (3.83 t ha?1) from the spring crop without any insecticide was obtained. Foliar application with blend of pirimicarb + dimethoate + cypermethrin increased the yield crop by 0.41 t ha?1 (10.7%) and additionally by 0.78 t ha?1 (20.4%) to compare to the fungicidal control when imidacloprid was used. Wheat seed treatment with imidacloprid and sowing date in autumn showed to be suitable and economically efficient preventive strategies for controlling the pest population.  相似文献   

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