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1.
MSMA-resistant (R) and -susceptible (S) biotypes of common cocklebur (Xanthium strumarium L.) were used to study PSI and PSII activities, and chlorophyll and carotenoid content of MSMA-treated and -untreated R and S biotypes. MSMA at 1, 10, and 100 mg/L did not inhibit either PSI or PSII activities. The R biotype had higher PSI and PSII activity than the S biotype with and without MSMA treatments. R biotype leaf discs had higher chlorophyll and carotenoid content than the S biotype after treatment with MSMA; the S biotype cotyldeons had higher levels of both pigments as compared to the R biotype cotyledons. MSMA induced a reduction in both pigments in S biotype cotyledons, and in young and mature leaf discs. Results indicate that photosynthetic capability might indirectly be involved in the resistance mechanism and carotenoids may protect against MSMA toxicity, possibly caused by an induced free radical mechanism.  相似文献   

2.
A. GUR  Y. GIL  B. BRAVDO 《Weed Research》1979,19(2):109-116
Application of several herbicides and a combination of herbicides in two vineyards resulted in a perfect control of Bermuda grass by glyphosate and mixed or alternate applications of MSMA and dalapon. Johnson grass was eliminated by MSM A with and without the addition of dalapon. Dalapon combined with MSMA reduced the yield of the grapevines and their growth, as measured by the weight of pruning. Yields were also significantly reduced by aminotriazole and in one vineyard also by simazine. Reduced vegetative growth was caused by MSMA and glyphosphate. MSMA and glyphosphate reduced the chlorophyll content of the grape leaves and the reducing sugar content of the canes in winter. Amino triazole reduced the reducing sugar content of both leaves and canes and the nitrogen content of the canes. In one vineyard simazine reduced the chlorophyll content of the leaves and increased the nitrogen content of the canes. MSMA alone and in combination with dalapon increased the arsenic content of leaves, canes and fruits of grapevines. Arsenic levels were the highest in the canes, but still did not exceed 0.6 ppm. Levels were lowest in fruits and did not exceed 0.1 ppm. Dalapon reduced the chlorophyll content of leaves in June and increased it in July. It also affected the reducing sugar content of leaves and canes without affecting yields or growth.  相似文献   

3.
MSMA (monosodium methylarsonate) was applied to rice (Oryza sativa L. cv. ‘Labelle’) plants at weekly intervals from the time the plants were 46 cm high until heading. Each application was to a different set of plants. The sprayed plant tops were analysed for MSMA immediately after spraying and at weekly intervals thereafter until heading. MSMA deposits became completely absorbed after one week and then the total residues declined exponentially to background levels with a half-life of about 15 days. Plant stunting effects depended on the amount of MSMA applied and the rate of growth at the time of application. Sterilisation effects depended on the amount of MSMA applied and the proximity in time of the application to panicle initiation. A mathematical model of the data showed that sterility symptoms were consistent with calculated MSMA concentration in tissue at the time of panicle initiation.  相似文献   

4.
MSMA (monosodium methylarsonate) is non-volatile and degrades in the environment to arsenic species which can be determined at the nanogram level. It is thus an excellent tracer for the study of the efficiency of deposition (defined as the fraction of material sprayed that deposits on target foliage) and subsequent fate of a water-soluble pesticide applied to foliage. MSMA was applied to rice (Oryza sativa L. cv. Labelle) foliage at two rates and at various stages of growth. After spraying the foliage was sampled and analysed for surface (removable by water-washing) and absorbed MSMA. Absorption of MSMA was so rapid that within the two hours between application and washing nearly one-half of the recovered MSMA became unavailable for wash-off. The total amounts of MSMA recovered were approximately proportional to plant size and application rate. When the rice foliage reached approximately 80 cm in height, the canopy closure (ground cover) was complete; nevertheless, only about 50% of the sprayed MSMA was found on and in the plants. As the rice canopy approached maturity, or approximately 130 cm high, complete interception of the spray occurred. These results indicate that canopy volume rather than ground cover was more important in determining the efficiency of spray deposition in this case, and that deposition efficiency may approach 100% with non-volatile active ingredients.  相似文献   

5.
The influence of alkylphenol polyoxyethylene non-ionic surfactants on the distribution pattern of MSMA (sodium hydrogen methylarsonate) was studied using scanning electron microscopy and X-ray microanalysis elementmapping techniques. Surfactant concentrations and lipophilic–hydrophilic constitution influenced phytotoxicity and residue patterns. Surprisingly, the percentage of leaf surface covered bore little correlation to phytotoxicity.  相似文献   

6.
Abstract

Results are given of a trial in which trifluralin, incorporated in the soil, at rates of 0.5 and 0.75 kg/ha, was combined with fluometuron at 1.6 kg/ha, and with prometryne at 1.0 kg/ha, both incorporated, pre- and post-em. and with noruron + MSMA (1.0:2.2) at 1.7 kg/ha post-em.

Best results were given by incorporated treatments of trifluralin + fluometuron (0.5 + 1.6) kg/ha, or by trifluralin incorporated at 0.5 or 0.75 kg/ha + fluometuron applied pre-em. at 1.6 kg/ha, or by trifluralin incorported at 0.75 kg/ha + prometryne applied pre-em. at 1.0 kg/ha.

It is recommended that noruron + MSMA (1.0:2.2) at 1.7 kg/ha be applied post-em. as a complementary treatment to trifluralin at 0.5 kg/ha in fields where Cyperus spp. are a problem.  相似文献   

7.
A model aquatic ecosystem was used to measure the bioaccumulation and distribution of 74As-arsenate and 14C-methanearsonic acid in the following aquatic organisms: algae, Oedogonium cardiacum; daphnids, Daphnia magna; fish, Gambusia affins and catfish, Ictalurus punctatus; and crayfish, Procambarus clarkii, Procambarus sp. Bioaccumulation ratios (BR) for 74As ranged from 80 to 480 and 4 to 7, for crayfish, and catfish, respectively, in Experiment I. Bioaccumulation ratios were 5, 127, 34, and 5 for daphnids, Gambusia, algae, and crayfish in Experiment II. Values declined for both crayfish and catfish after they were removed to untreated water. Homogenates of all organisms were extracted sequentially with cold 5% trichloroacetic acid, 75% EtOH, and hot 5% TCA. Distribution of the two arsenicals differed with extractant and biological species. The cold acid extracts of algae, daphnids, and crayfish contained the highest levels of 74As. Generally, 14C was distributed more uniformly among the four fractions and was found at a higher percentage in the residue than was arsenate. By gel filtration chromatography, several compounds were separated from extracts of algae, daphnids, Gambusia, and crayfish treated with 74As. These compounds were not arsenate, MSMA, or cacodylic acid. Extracts of MSMA-exposed organisms had one major compound which had the same retention volume (about the same molecular weight) as authentic MSMA. High-molecular-weight material (> 5000) was formed in Gambusia and algae treated with MSMA.  相似文献   

8.
Formulations of Bacillus thuringiensis Berliner (Bt) with insecticidal activity against the sugarcane borer, Diatraea saccharalis Fabricius (Lepidoptera: Pyralidae), were developed and tested under laboratory and field conditions. The formulations were prepared using biodegradable polymers such as modified corn starch as an encapsulating agent, gelatin as an adherent, powdered sugarcane as a feeding stimulant and a Bt var. kurstaki GM-34 strain from a non-sugarcane region as the active ingredient. The spore-crystal complex of this strain was mixed at three different concentrations (30, 70 and 100 g kg(-1)) with the other ingredients. The blends were prepared as spray-dried and granular formulations, and then submitted to laboratory tests with two day old larvae of D. saccharalis and field tests in sugarcane crops with natural sugarcane borer infestation. Spray-dried formulations in laboratory bioassays caused mortality near 100% with all three concentrations, and granular formulations caused mortality around 84%. The field tests showed that spray-dried formulations at 70 and 100 g kg(-1) concentrations were as effective as a commercial bioinsectide (Lepinox), while granular formulations were ineffective.  相似文献   

9.
The resolved isomer of metolachlor, S-metolachlor, was registered in 1997. New formulations based primarily on the S-metolachlor isomer are more active on a gram for gram metolachlor basis than formulations based on a racemic mixture of metolachlor containing a 50:50 ratio of the R and S isomers. The labelled use rates of S-metolachlor-based products were reduced by 35% to give equivalent weed control to metolachlor. However, several companies have recently registered new metolachlor formulations with the same recommended use rates for weed control as S-metolachlor. This research was done to compare the soil behaviour and the biological activity of metolachlor and S-metolachlor in different soils under greenhouse and field conditions. Although K(d) ranged from 1.6 to 6.9 across the five soils, there were no differences in the binding of metolachlor and S-metolachlor to soil or in the rate of soil solution dissipation in a given soil. However, both greenhouse and field studies showed that S-metolachlor was 1.4-3-fold more active than metolachlor against Echinochloa crus-galli (L.) Beauv. in five different soils and that S-metolachlor was more active than metolachlor in three Colorado field locations. When the rates of metolachlor and S-metolachlor were adjusted for S isomer concentrations in the formulations, there were no differences between the formulations in field, greenhouse or bioassay studies. Thus herbicidal activity is due to the S isomers, with the R isomers being largely inactive.  相似文献   

10.
A total of sixty-five samples of eighteen different commercial formulations containing malathion were examined in this study. Twelve formulations were found to have a malathion content which was in general agreement with that declared. However, one of these twelve formulations (an emulsifiable concentrate) contained a high level of isomalathion. Five formulations (all emulsifiable concentrates) had significantly lower malathion contents than those declared and were contaminated with malathion analogues, present at concentrations ranging from c.2 to over 100 % mass/mass of the malathion found. These analogues of malathion appear to have resulted from the transesterification of malathion with alcohols used as formulating agents. One formulation (a dustable powder) was found to contain no malathion above the detection limit. Many of the formulations failed tests of their physical properties.  相似文献   

11.
Experiments were conducted in a glasshouse to evaluate the phytotoxicity of dibutylurea (DBU), a breakdown product of benomyl, benomyl formulations and constitutive ingredients of ‘Benlate’ Dry Flowable (DF) on whole cucumber (Cucumis sativus. Poinsett 76) plants. Benlate Wettable Powder (WP) and DF formulations did not affect the phytotoxicity of DBU. When commercially purchased (samples obtained from growers) DF and WP formulations containing equivalent DBU concentrations were compared for phytotoxicity, no statistical interactions between formulations were observed. Benomyl, DBU and DF inert ingredients were tested alone and in combination to assess their phytotoxicity. Only DBU at rates greater than 94 mg litre-1 caused a reduction in root and shoot growth. Also DBU applied alone or as a component of either Benlate formulation was shown to reduce the peak-to-terminal chlorophyll a fluorescence ratio measured in vivo by a plant productivity fluorometer. © 1998 SCI.  相似文献   

12.
BACKGROUND: For an oil adjuvant to enhance uptake of a particulate active ingredient (AI), it is hypothesised that closer association between the two should result in higher uptake. Accordingly, factors important for the spray deposit size on grapevine leaves have been investigated for a series of model suspoemulsion formulations containing colloidal crystalline AI or fluorescent pigment particles and an emulsion of an oil adjuvant with different degrees of wetting and different spray volumes. RESULTS: Low spray volumes (<100 L ha(-1)) produced small deposits with high particle-adjuvant association. Complementary uptake studies showed increased uptake with decreasing deposit size, in agreement with the above hypothesis. Higher spray volumes produced larger deposits that consisted of annuli formed by pinning of the contact line by particles. Low surfactant concentrations favoured particles in the annulus and adjuvant separated in the centre. Intermediate surfactant concentrations produced annuli containing both particles and adjuvant, while with high surfactant concentrations the deposits were large with few annuli.CONCLUSIONS: Small deposits result in high AI-adjuvant association. With larger deposits, annulus structures allow for enhanced AI-adjuvant association (5-20 times greater). The formation of annuli appears to be important in enhancing the biodelivery of particulate AIs in adjuvant-containing suspoemulsion formulations at intermediate spray volumes.  相似文献   

13.
Multiple seeded cocklebur has been found in the last decade in Texas, and described as a biotype of Xanthium strumarium L with up to 25 seeds per bur instead of the usual two. The multiple seeded bur typically produces up to nine seedlings, causing concern that it may be harder to control than normal seeded common cocklebur. The efficacies of a series of fungal and conventional commercial herbicides have been compared in the greenhouse on seedlings of multiple seeded cocklebur from Texas (MSC-TX) and normal common cockleburs from Texas (NCC-TX), Arkansas (NCC-AR), Illinois (NCC-ILL) and two from Mississippi (NCC-MS#1, NCC-MS#2). Three measures of herbicidal activity (reductions in plant height and dry weight, and mortality) were used. The fungal herbicide Alternaria helianthi (Hansf) Tubaki & Nishihara at 1 x 10(5) conidia ml(-1) + 2 g liter(-1) Silwet L-77 with an 8-h dew period was an effective herbicide with all biotypes, as were the commercial chemical herbicides chlorimuron (14.8 g ha(-1)), imazaquin (29.6 g ha(-1)), sodium hydrogen methylarsonate (MSMA; 279.1 g ha(-1)) and imazethapyr (39.5 g ha(-1)). The membrane-disrupting organic arsenical MSMA was effective with all biotypes, whereas commercial chemical herbicides which act by inhibiting branched-chain amino acid synthesis (chlorimuron, imazaquin and imazethapyr) were less effective against normal seeded common cocklebur biotypes with short stature. These studies showed that multiple seeded cocklebur was at least as susceptible to the biological agent A helianthi and to the conventional commercial herbicides studied as were normal seeded cockleburs, suggesting that existing methods should be adequate to control this novel biotype.  相似文献   

14.
STORK 《Weed Research》1998,38(6):433-441
Conventional formulations of atrazine and simazine were compared with controlled-release formulations of these two herbicides for bioefficacy, leaching and crop safety in laboratory and field experiments. Three light-textured soils with a pH range of 5.8–8.5 were used for this work. An oat bioassay (Avena sativa L.) was used to quantify soil concentrations of the herbicides. Comparison of the initial bioefficacy of controlled-release formulations of atrazine and simazine showed their respective relative potencies to conventional formulations to be 0.51–0.85. The results indicated that the controlled-release formulations maintained an entrapped reserve of active ingredient after delivery with a conventional boomsprayer. In laboratory trials, the controlled-release formulations showed a reduction in leaching compared with conventional formulations. A controlled-release formulation and a conventional formulation of atrazine were tested further in a field trial. A higher concentration of atrazine in topsoil from the controlled-release formulation was observed 11 weeks after application after 107 mm of rainfall. It was deduced that this was caused by reduced leaching of the controlled-release formulation, as observed in laboratory trials. EWRC scores for the control of a range of grass and broad-leaved weeds were identical for both formulations. This indicated that, while the controlled-release formulation could inhibit leaching of the active ingredient, it did not hinder the level of potency necessary for early weed control. EWRC crop safety ratings of chickpeas (Cicer arietinum L.) sown at application were higher for the controlled-release formulation 10 weeks after sowing, and subsequent harvest yields were 50% higher. It was inferred that this resulted from a favourable interaction between crop growth and the timing of the release of the active ingredient from the controlled-release formulation. Altogether, the controlled-release formulations displayed the necessary prerequisites for their further development for large-scale use under arable regimes.  相似文献   

15.
以Morwet D-425和Witconol NP-100代替20%福·克和30%多·福·克 悬浮种衣剂配方中的乳化剂,结果表明:Morwet D-425和Witconol NP-100在20%福·克 种衣剂中质量分数分别为3.0%和1.0%、在30%多·福·克种衣剂中质量分数分别为4.0%和1.0%时,出料1 d后制剂粘度分别为390和510 mPa·s;经过30 d室温或14 d、(54±2)℃贮藏后,制剂的颗粒聚结数低于10%,并且无不可逆沉淀形成;热贮析水体积分别为5%和9%,较原配方种衣剂降低了20%以上,室温贮藏析水体积不足1%。用激光粒度分析仪分别检测添加Morwet D-425、Witconol NP-100或原配方乳化剂的种衣剂经过0.5、1.0、1.5、2.0 h研磨后的粒度分布,新配方种衣剂经过1.5 h研磨平均粒径分别达到1.85和1.91 μm,而原配方种衣剂经2.0 h研磨平均粒径仍大于2 μm。  相似文献   

16.
A method is described for the analysis of small amounts of hydrazine in maleic hydrazide formulations. Following derivative formation with pentafluorobenz-aldehyde, the pentafluorobenzaldehyde azine was extracted with hexane and determined by gas-liquid chromatography with electron-capture detection. Recoveries of 72-80% were obtained from samples fortified with 1 and 10 μg of hydrazine. The limit of detection was 0.05 mg kg?1. Fourteen commercial formulations with maleic hydrazide concentrations ranging from 180-360 g litre?1 were investigated. The hydrazine content of the maleic hydrazide used in these formulations ranged from less than 0.05 to 53 mg kg?1. During the storage of two samples at 50°C for 10 weeks, the hydrazine contents increased from 2.2 to 124 and 0.4 to 54 mg litre?1, respectively.  相似文献   

17.
The susceptibility ofThaumetopoea wilkinsoni larvae toBacillus thuringiensis (Bt) formulations was screened in 2003 and 2004. Eggs and larvae were collected from pine forests in 11 geographical locations in Israel. Larval mortality bioassays were conducted with commercial formulations (Delfin WG, Dipel DF and Foray 48B) at concentrations ranging from 0.001% to 0.1%. Significant differences in susceptibility toBt were recorded among populations that were treated withBt intensively, frequently, or never. The mortality recorded in a population that was never treated withBt was twice that in an intensivelyBt-treated population. The correlation between susceptibility toBt and the possible resistance to the microbe is discussed. http://www.phytoparasitica.org posting Jan. 31, 2007.  相似文献   

18.
Wettable powder formulations of simazine, metribuzin and linuron and a suspension concentrate of simazine were sprayed on to soil particles which were either at a water content equivalent to pF 2·5 or air dry. Air dry samples were then wetted to pF 2·5 immediately or after 24 h. Soil solutions were removed using a pressure membrane apparatus at intervals up to 96 h after wetting. In each case the concentration in soil solutions expressed after 96 h following application to wet soil, or dry soil wetted immediately, were close to those predicted on the basis of Freundlich adsorption isotherm data obtained in slurry equilibrium conditions. There were, however, some differences after shorter periods. Concentrations were always lower in solutions obtained from air dry soil that was not wetted for 24 h. After 96 h simazine and metribuzin concentrations were about 50% of those obtained following application to wet soil, while that of linuron was about 25%. Differences of this size may be large enough to affect mass transfer phenomena and phytotoxicity. It seems likely that suspension of these herbicides sprayed in formulations on to wet soil dissolved in soil water at least as fast as would be predicted theoretically.  相似文献   

19.
Using an iodometric method for the determination of malathion in emulsifiable concentrates, values of active ingredient in four commercial formulations and one primary reference standard were within ±0.7% weight/volume (w/v) of the stated concentrations. A standard deviation of 0.42% w/v and 95% confidence limits of ±0.9% w/v for a single determination were calculated for the method. Added moisture and elevated temperature were found to accelerate malathion breakdown in the commercial formulations. The greatest breakdown rate of 5.2% w/v per 100 days occurred with a formulation stored at 27 °C containing 0.5% v/v added moisture.  相似文献   

20.
A range of formulations of deltamethrin were prepared, some containing an ultraviolet (UV) absorber compound or a combination of the UV absorber and an oil, and applied to blue cotton tsetse fly target samples which were then exposed to the effect of simulated sunlight and water in the laboratory. The residue of insecticide remaining on the targets and the activity of the latter against tsetse flies was determined. Formulations containing the UV absorber and coconut oil or silicone oil remained the most effective against tsetse flies. A coconut oil formulation of the insecticide was selected for field evaluation in comparison with a commercial deltamethrin formulation, Glossinex 200′ S.C., which contains 10% UV absorber. Target samples treated with these formulations were exposed to natural tsetse fly habitat in Ghana for a period of five months and evaluated for deltamethrin residues and activity against four species of tsetse fly. After five months, 4–13 times more deltamethrin remained on the targets treated with the coconut oil formulation than on those treated with ‘Glossinex’, and consequently the former were more active against tsetse flies than the latter. Target samples sequentially dipped in the coconut oil formulation resulted in uniform insecticide concentration on the targets, whereas those dipped in ‘Glossinex’ contained gradually decreasing deltamethrin concentrations.  相似文献   

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