N1‐aryl‐N2‐dichloroacetyl glycine and alanineamides as selective safeners for corn against chloroacetanilide herbicides

Abstract

Structurally new N¹aryl‐N²‐dichloroacetyl glycine and alaninamides were prepared. Greenhouse experiments were conducted to determine the effectiveness of the new compounds in protecting corn seedlings from chloroacetanilide (acetochlor, alachlor, dimethachlor, metazachlor, metolachlor) injury using dichlormid and BASF‐145138 as standard safeners. High rates of chloroacetanilides caused significant injury to sensitive corn hybrids. The most acive derivatives reduced injury to corn from dimethachlor and metolachlor and lesser extent from acetochlor and metazachlor. The most effective derivatives of the new compounds displayed better safening activity than the standards. Some of the new compounds were found to be selective safeners when formulated as a tank mixture with metolachlor in a 1:33–100 safener‐to‐herbicide ratio showing the same or better activity than the standard used.

Nomenclature: BASF‐145138, 1‐dichloroacetyl‐hexahydro‐3,3,8α‐trimethyl‐pyrrolo‐[1,2‐α]—pyrimidin‐6‐(2H)‐one; EPTC, S‐ethyl‐N,N‐dipropylcarbamothioate; dichlormid, 2,2‐dichloro‐N,N‐di‐2‐propenyl acetamide; corn, Zea Mays L. ‘Pannonia SC’.     

Effects of deltamethrin on hepatic microsomal cytochrome p450‐dependent monooxygenases in carp

Abstract The in vivo effects of sublethal concentrations of deltamethrin (DM), a pyrethroid insecticide, on the hepatic microsomal cytochrome P450 (Cyt P450) content and the Cyt P450‐dependent monooxygenase activities (para‐nitrophenetole‐O‐deethylase, pNPOD; aminopyrene‐N‐demethylase, APND; ethylmorphine‐N‐demethylase, EMND; 7‐ethoxycoumarin‐O‐deethylase, ECOD; and ethoxyresorufin‐O‐deethylase, EROD) were examined in adult carp (Cyprinus carpió L.).

0.2 μg/1 DM treatment resulted in significant increases in APND, EMND and ECOD activities, whereas 2 μg/1 DM resulted in significant inhibitions of all studied isoenzyme activities with the exceptions of pNPOD and APND after 72 h. EROD was the only enzyme for which a slight increase in activity was observed. On repeated treatment, Cyt P450 could not be detected after 48 h, but the Cyt P420 level increased. All tested isoenzyme activities were inhibited, with the exception ofthat of EROD, which was enhanced.

All these changes in enzyme activities and Cyt P450 content demonstrate the effects of DM on fish. DM treatment at low concentration is presumed to cause induction of the Cyt P450‐dependent monooxygenases which may lead to faster metabolization of the insecticide. In contrast, DM at higher concentration strongly inhibited the activities of the studied enzymes. This finding may be due to the damaging effect of DM on the xenobiotic metabolizing enzyme systems offish.     

Phytotoxicity of atrazine and alachlor in soil amended with sludge,manure and activated carbon

Abstract

Greenhouse studies were conducted to determine the influence of waste‐activated carbon (WAC), digested municipal sewage sludge (DMS), and animal manure on herbicidal activity of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐trazine] and alachlor [2‐chloro‐2’,6'‐diethyl‐N‐(methoxymethyl)acetanilide] in a Plainfield sandy soil. Amendments generally reduced bioactivity against oat (Avena sativa L.) and Japanese millet (E. crus‐galli frumentacea). The extent to which herbicide phytotoxicity was inhibited depended upon the application rate and the kind of soil amendment. WAC, applied at the loading rate of 2.1 mt C/ha, showed a significant inhibitory effect on both herbicides. In DMS‐ and manure‐amended soil, the reduction of atrazine activity was not significant at the rate of 8.4 mt C/ha, but reduction of alachlor activity was significant at the rate of 4.2 mt C/ha. Despite inhibition of herbicidal activity, the ED₅₀ of atrazine and alachlor was below 2 ppm in most of the amendment treatments. Before adopting carbon‐rich waste amendments as management practices for controlling pesticide leaching in coarse‐textured soils, further studies are needed to characterize how alterations in sorption, leaching and degradation may affect herbicidal activity.     

Toxic effects of 2,4‐D herbicide on fish

Abstract

Acute and subacute 2,4‐D toxicity to carp (Cyprinus carpio L.) were investigated. Acute toxicity (LC‐ 50) was investigated in semi‐static test during a 24, 48, and 96‐ hours exposition. Subacute toxicity was investigated by exposing fish to different 2,4,‐D concentrations (150, 200, and 250 mg/L) for 14 days. Biochemical and morphological changes in certain organs and tissues were investigated.

LC‐ 50 values at 24 hours exposure was 310.0 mg/L, 295.0 mg/L for 48 hours, and 270.0 mg/L for 96 hours exposure.

Subacute toxicity tests show that 2,4‐D induce changes in the enzyme activities (AP, GOT, GPT) and morphological changes in the gills, liver and kidneys, but changes are of limited biological importance.     

Fate of permethrin in model outdoor ponds

Abstract

In 1979 and 1980, outdoor artificial ponds were treated with ¹⁴C‐pennethrin (labelled at either the cyclopropyl or methylene position) at 0.028 kg/ha (15 ug/L). Uptake of permethrin by duckweed and hydrosoil was monitored by direct combustion, TLC‐autoradiography, HPLC, and liquid scintillation counting. Rapid loss of permethrin from the waiter coincided with the detection of five degradation products in the water at concentrations below 2.0 ug/L. The products were cis‐ and trans‐cyclopropyl acid, phenoxybenzoic acid, and phenoxybenzyl alcohol, and an unknown non‐cleaved product of permethrin. Permethrin was readily sorbed by duckweed but was not persistent. Permethrin residues in the hydrosoil, which was the major sink for permethrin added to the ponds, were persistent and were detected at 420 days post‐treatment. Cis‐permethrin was more persistent in the hydrosoil than the trans‐permethrin. The results indicated that permethrin in water was short‐lived at an application rate of 15 ug/L because of the rapid degradation of permethrin in the water and sorption of permethrin by the hydrosoil and vegetation. However, at one year post‐treatment, permethrin residues were still detected in the hydrosoil at 1.0 ug/kg.     

Excretion balance,metabolic fate and tissue residues following treatment of rats with amitraz and N‘‐ (2,4‐dimethylphenyl)‐N‐methylformamidine

Abstract

Amitraz and its metabolite N‘‐ (2,4‐dimethylphenyl)‐N‐methyl‐formamidine (BTS‐27271) were administered orally to white rats. Both compounds were rapidly metabolized and eliminated primarily via the urine. The cumulative percentage of the dose eliminated in the urine was 77.6 for amitraz and 88.7 for BTS‐27271 by 96 hr posttreatment. Amitraz degradation products present in urine included BTS‐27271, 2,4‐dimethylformanilide, 2,4‐dimethylaniline, 4‐formamido‐3‐methylbenzoic acid, 4‐amino‐3‐methylbenzoic acid, and several unknowns. BTS‐27271 degradation products in rat urine were similar to those found with amitraz. Tissue residues generally were low (<25 ppb) with the exception of those in liver.     

Accelerated degradation of carbofuran in standing water from carbofuran‐retreated Azolla plots

Abstract

Carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl N‐methylcarbamate) was mixed with standing water from six flooded Azolla (a fern harboring a nitrogen fixing alga, Anabaena azollae) plots that had been regularly treated with carbofuran before. The insecticide completely disappeared in 5 to 10 days when mixed with water from three of the six plots. The enrichment culture, prepared by further additions of carbofuran to the standing water from an Azolla plot, degraded bendiocarb (2, 2‐dimethyl‐l, 3‐benzidioxol‐4‐yl‐N‐methylcarbamate), carbofuran and carbosulfan [2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl (di‐n‐butyl‐aoinosulfenyl) methyl‐carbamate ] in that order. Enrichment culture, upon sterilization by autoclavlng, lost its ability to degrade carbofuran. Evidently, accelerated degradation of carbofuran in standing water from retreated Azolla plots was mediated by microorganisms.     

Herbicide safeners: Tools for improving the efficacy and selectivity of herbicides

Abstract

Safeners (also known as antidotes) are chemical or biological agents that reduce the toxicity of herbicides to crop plants by a physiological or molecular mechanism. Commercialized safeners are mainly chemical compounds that enhance the tolerance of selected grass crops such as maize (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], rice (Oryza sativa L.), and wheat (Triticum aestivum L.) to chloroacetanilide, thiocarbamate, sulfonylurea, imidazolinone, and aryloxyphenoxypropionate herbicides. In practice, safeners are applied either to the crop prior to planting (seed safeners) or to the soil together with the herbicide, formulated as a prepackaged mixture. Safeners act as "bioregulators”; controlling the amount of a given herbicide that reaches its target site in an active form. A safener‐induced enhancement of the metabolic detoxification of herbicides in protected plants is the most apparent mechanism for the action of all commercialized safeners. Herbicide‐detoxifying enzymes such as glutathione transferases (GST), cytochrome P‐450 monooxygenases (CytP450), esterases, and UDP‐glucosyltransferases are induced by herbicide safeners. At the molecular level, safeners appear to act by activating or amplifying genes coding for these enzymes (e.g., GST).     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.     

Fate of metolachlor under subirrigation in a sandy soil: A lysimeter study

Abstract

A three‐year field lysimeter study was conducted to investigate the role of subirrigation systems in reducing the risk of water pollution from metolachlor (2‐chloro‐N‐(2‐ethyl‐6‐methlphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide). Nine large PVC lysimeters, 1 m long x 0.45 m diameter, were packed with a sandy soil. Three water table management treatments, i.e. two subirrigation treatments with constant water table depths of 0.4 and 0.8 m, respectively, and a free drainage treatment in a completely randomized design with three replicates were used. Corn (Zea mays L.) was grown in each lysimeter, and at the beginning of summer of each year metolachlor was applied, at the locally recommended rate of 2.75 kg a.i./ha. Soil and water samples were collected at different time intervals after each natural or simulated rainfall event. Metolachlor was extracted from these samples and analyzed using Gas Chromatography.

Results obtained in this three year study, (1993–1995), lead to the conclusion that metolachlor is quite mobile since it leached to a depth of 0.85 m below the soil surface quite early in the growing season. Metolachlor concentrations decreased with depth as well as with time. The shallower water table in the 0.4 m subirrigation treatment showed less residues in the soil solution than that of other treatments. However, a mass balance study, supported by an independent laboratory investigation, shows that water table management, statistically, has no significant effect on the reduction of metolachlor residues in sandy soils.     

Evaluation of chlordimeform and degradation products for mutagenic and DNA‐damaging activity in salmonella typhimurium and escherichia coli

Abstract

The mutagenic activity of chlordimeform and two of its breakdown products, 4‐chloro‐o‐toludine and 4‐chloro‐N‐formyl‐o‐toluidine were determined with five histidine dependent strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA98, TA100) and five tryptophan dependent strains of E. coli WP₂. (WP₂, WP₂uvrA, WP67, CM611, CM571) with and without rat liver microsomal enzymes. 4‐chloro‐o‐toluidine increased the number of the reversions of the S. typhimurium strain TA1535 more than two fold over spontaneous at the concentration of 400 μg/plate.

The results of the DNA repair tests in the Salmonella TA1538/TA1978 and E. coli multirepair deficient systems showed that both breakdown products were active in inducing damage not repaired in at least one repair deficient strain while chlordimeform itself was inactive.     

Behaviour of pendimethalin in tropical and mediterranean plain field condition

Abstract

Behaviour of the herbicide pendimethalin [N‐(l‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] was evaluated in plain field under wet tropical conditions (Martinique, FWI) and in the Mediterranean area (Languedoc, South of France). Simultaneously, adsorption parameters were discussed with Freundlich equation, and desorption evaluated using a model with two compartments corresponding to two different energy levels. Pendimethalin showed a strong adsorption in all three soils and was very difficult to desorb. Higher clay content in tropical vertisol and ferrisol involved adsorption parameters (Kfa) higher than the one found in the Mediterranean fluvisol. Although heavy rainfalls in the tropics intervene on migration, pendimethalin propensity to leaching is levelled by its strong adsorption potential and appears very limited under the conditions chosen during this work. Half‐life of the compound (in the 0–25 cm soil layer) varied from 13 to 17 days. Pendimethalin was also classified as a “non‐leacher” compound using the “Gustafson model”.     

Release of soil bound (nonextractable) residues by various physiological groups of microorganisms∗

Abstract

Soil bound ¹⁴C‐labeled residues were released by four different physiological groups of microorganisms from an organic soil treated with ¹⁴C‐ring‐labeled prometryn [2‐(methylthio) ‐4,6‐bis(isopropylamino)‐s‐triazine]. The extent to which the different microbial populations released bound ¹⁴C residues (25–30% of the total bound ¹⁴C) from the Y‐irradiated soil after 28 days incubation did not differ considerably. Analysis of the extractable material from the incubated soil showed the presence of small amounts of the parent compound, and its hydroxy and mono‐N‐dealkylated analogues. Low level of ¹⁴CO₂ (1.5–3.0% of the total bound ¹⁴C) was evolved from the microbial systems indicating ring cleavage of the released material as being a very minor reaction.     

Microbial degradation op tripluralin by aspergillus carneus,fusarium oxysporum and trichoderma viride ∗

Abstract

³H‐Trifluralin was synthesized by condensation of ³H‐4‐chloro‐3,5‐dinitro‐α, α, α‐trifluorotoluene with di‐n‐propylamine.

After incubation of trifluralin with Aspergillus carneus, Fusarium oxysporum and Trichoderma viride for 10 days, a small percentage (less than 10%) of unchanged herbicide was recovered in the extractable fraction. This indicates a fairly rapid degradation of the herbicide by the fungal species. Other than trifluralin, the culture medium contained at least five labelled products: 2, 6‐dinitro‐N‐n‐propyl‐α, α, α‐tri‐fluoro‐p‐toluidine; 2, 6‐dinitro‐α, α, α‐trifluoro‐p‐toluidine; 2‐amino‐6‐nitro‐α, α,‐trifluoro‐p‐toluidine, 2, 6‐dinitro‐4‐trifluoromethyl phenol and a major polar product which constituted more than 50% of the total extractable transformation products. A pathway, which similates that of aerobic degradation of the herbicide in soil, is suggested for the microbiological degradation of trifluralin.     

Pesticide concentration variations correlated with well bore volume removal in shallow coastal plain ground water

Abstract

The effects of well bore volume removal (V_n) on the concentration of alachlor [2‐chloro‐N‐(2,6‐diethylphenyl)‐N‐(methoxy methyl) acetamide] and prometon (6‐methoxy‐N,N'‐bis(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] in ground water obtained from three monitoring wells installed in the Coastal Plain region of North Carolina was investigated. Seasonal effects were also investigated by conducting the exercise in February and May. In the majority of cases, the lowest pesticide concentrations occurred in the initial well bore volume (V₁ = stagnant water). Removal of additional well bore volumes (V₂ to V₁₀) from two of the wells resulted in pesticide concentrations that did not vary substantially. This indicates that a representative aquifer sample was obtainable, in most cases from these wells, after removal of the initial well bore volume. In contrast, a third well required the purging of two well bore volumes before a stable alachlor concentration was achieved. Seasonal effects of bore volume removal vs. pesticide concentrations for the three wells were not significant (P > 0.05). It was concluded that a protocol for improved accuracy in pesticide analyses of ground water can be obtained by establishing a pesticide concentration‐purging (well bore volume) relationship for each well.     

1‐Aminobenzotriazole increases glutathione‐s‐transferase activity of maize

Abstract

Glutathione‐S‐transferase (GST) activity of maize (Zea mays L.) seedlings treated with 1‐aminobenzotriazole (ABT) derivatives and/or EPTC were measured using EPTC‐sulfoxide as substrate. Both safeners and ABT derivatives significantly elevated the GST activity in the concentrations needed for effective safening action. ABT is considered as an inhibitor of plant cytochrome P‐450 monooxygenases (P‐450) and, because of this, used to study herbicide mode of action. Our data indicate that ABT has multiple effects on plants influencing not only P‐450 but GST as well. Thus the role of ABT in herbicide metabolism needs reconsideration.     

Influx,transport, and accumulation of cadmium in plant species grown at different Cd2+ activities

Abstract

Cadmium (Cd) has no known essential biological function, but it is toxic to plants, animals, and humans. A promising approach to prevent Cd from entering the food chain would be to select and/or create Cd‐accumulating plants to remediate contaminated soils or to develop Cd‐excluding plants to reduce Cd flow from soils into foods. The present study was undertaken to examine the differences in Cd influx, transport, and accumulation among five plant species in relation to plant tolerance to Cd toxicity. Ryegrass (Lolium perenne L.) had the least reduction in dry matter which may be due to its lowest Cd transport rate (TR) to shoots at all Cd levels among the plant species tested. White‐clover (Trifolium repens L.) was the most sensitive species to Cd toxicity, likely because of its highest Cd influx rate (IR) and high TR when plants were grown at low Cd²⁺ activity (≤8 μM). The high tolerance of cabbage (Brassica oleracea var. capitata L.) to moderate Cd toxicity (≤14 μM) appeared to be mainly due to the detoxification of Cd inside plant tissue since it recorded the highest TR and relatively high IR for Cd among the tested species. At Cd²⁺ activities up to 28 uM, the Cd uptake ratios of shoot/root for ryegrass were, on average, about 50‐fold and 27‐fold lower than that for cabbage and maize (Zea mays L.), respectively. These results showed that Cd could be easily transported into shoots of cabbage and maize, but was mainly confined to roots of ryegrass. We suggest that influx and transport rates, especially transport rate, could be used as plant physiological parameters for screening Cd‐excluding genotypes among monocotyledonous plants.     

Metabolism of gamma‐hexachlorocyclohexah (HCH) in vivo. Metabolism of orally administered gamma‐2,3,4,5,6‐pentachlorocyclohexen (PCCH)

Abstract

Mexacarbate (4‐dimethylamino‐3,5‐xylyl N‐methylcarbamate) insecticide has potential for use in spruce budworm (Choristoneura fumiferana Clem.) control operations in Canada. Its persistence and fate in balsam fir (Abies balsamea (L.) Mill.), litter and soil samples were studied by spraying aerially oil‐based and water‐based formulations, each at 70 g A.I./ha over a coniferous forest near Bathurst, New Brunswick. The oil‐based formulation gave the maximum concentration of the chemical in the substrates studied. In fir needles, the highest concentrations observed were 0.51 ppm and 0.19 ppm (fresh weight) for the oil‐based and emulsion formulations respectively, 1 h after application. The residue levels decreased very rapidly with a half‐life of approximately 5 h. Three and eight days after the spray application of the emulsion and oil formulations respectively, the concentrations of mexacarbate in foliage decreased to trace levels ( 0.008 ppm). Only very low levels of residue were detected in litter and soil. The peak concentrations for the two formulations ranged from 0.02 to 0.11 ppm (fresh weight) in litter and from 0.01 to 0.06 ppm (fresh weight) in soil. The residue levels in both litter and soil decreased to below the detection limit (0.005 ppm) within 1 d. The ground deposit levels found on glass plates and the droplet density and size spectra measured on Kromekote® cards reflected the variations in concentrations found in fir needles, litter and soil samples and correlated with the observed maximum concentrations in them. Under the stipulated use pattern, mexacarbate concentrations found in the terrestrial components studied were low and are not likely to have any undue adverse effects on non‐target species.     

Evaluation of a Daphnia magna renewal life‐cycle test method with diazinon

Abstract

Acute and chronic toxicity tests with diazinon (diethyl 2‐isopropyl‐6‐methyl‐4‐pyrimidinyl phosphorothionate) were conducted on Daphnia magna. The 24‐hr static LC50 was 0.86 μL.L^‐1. The sublethal effects of 0.05, 0.1, 0.5, 0.75 and 1.0 ngL^‐1 of diazinon concentrations on the survival, reproduction and growth of D. magna were monitored for 21 days. The algae Nannochloris oculata (5 x 10⁵ cellsmL^‐1) was used to feed the daphnids. The parameters used to determined the effect of the pesticide on D. magna were: mean total young per female; mean brood size; days to first brood; intrinsic rate of natural increase (r); growth; and survival. Reproduction as well as survival was significantly reduced at diazinon concentrations of 0.10 ngL^‐1 and higher. The intrinsic rate of natural increase (r) decreased with increasing concentrations of diazinon. Growth, as measured by body length, was depressed significantly at 0.05 ngL^‐1 of diazinon and higher concentrations. The maximum acceptable toxicant concentration (MATC) was calculated. The chronic data was used to formulate an acute/chronic ratio.     

Influence of additives in the end‐use mixes of tebufenozide on deposition,adhesion and persistence in spruce foliage

Abstract

A commercial flowable formulation of tebufenozide, RH‐5992 2F [N'‐t‐butyl‐N'‐(3,5‐dimethylbenzoyl)‐N‐(4‐ethylbenzoyl) hydrazine], was diluted with water, water and canola oil, and water and the methyl ester of canola oil, to provide six end‐use mixes with concentrations of 35 and 70 g of active ingredient (Al) litre^‐1. The mixes were applied at 70 and 140 g Al ha^‐1 over white spruce [Picea glauca (Moench) Voss] seedlings in a laboratory spray chamber and foliar concentrations of tebufenozide were determined over a 60‐d period. At intervals of time post‐spray, seedlings were sprayed with monosized droplets of Sunspray®11N as rainfall, and the amount of tebufenozide knocked off from foliage was determined. The potential energy of adhesion (PEA) of the Al particles on the foliage increased with time and varied according to the type of end‐use mix, its viscosity and the dosage sprayed.

The end‐use mixes were applied over white spruce trees under field conditions and persistence of tebufenozide was investigated. DT₅₀ values were influenced by the type of mix and dosage sprayed. Oil‐containing mixes and higher dosages increased the PEA of tebufenozide particles.