摘要:

AbstractEleven different commercial wettable powder formulations containing copper have been examined using standard CIPAC recommended techniques to determine the best chemical and physico‐chemical criteria for quality. This approach has allowed the setting‐up of a specification that retains only the essential criteria of quality control required for the official approval of a product of this type in Belg

ISSN:0031-613X    

DOI:10.1002/ps.2780290102

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractUptake of [14C‐phenyl]2,4‐D‐butyl by 4‐ to 6‐week‐old tomato plants was measured for vapour concentrations in the range 0.3–19 ng litre−1, for an exposure period of 4 h. Calculation of boundary layer thicknesses at the surface of the leaves, and depletion of the vapour concentration due to uptake by the plants, suggested that the plants experienced concentrations very close to the nominal values. Relationships between external vapour concentration and plant uptake, expressed in terms of fresh weight, leaf area, or on a whole plant basis, were linear in all cases. Twenty‐four hours after the commencement of exposure, leaves contained 63–93% of the total herbicide in the plant; the proportion retained by the leaves was greater at low vapour concentrations. The largest amount of herbicide was present in leaves from the mid‐position on the stem, but in terms of leaf area, the amount was greatest in leaves at the apex and decreased basipetally. It is not known whether this was due to a greater uptake rate per leaf area at the apex, or to translocation. As visible symptoms of phytotoxicity usually develop at the apex, both of these processes, together with the preferential retention of herbicide in leaves at low vapour concentrations, may all contribute to the develop

ISSN:0031-613X    

DOI:10.1002/ps.2780290103

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA method is presented for estimating the persistence and concentration of residual free methyl bromide (MB) present in apples during the aeration period following fumigation. The method is based on determining the rate of decline in concentration of methyl bromide in the exhaust air stream during aeration. The rate was shown to follow two consecutive pseudo‐first‐order decay curves. The first component of the curve resulted primarily from removal of MB from the free air space in the chamber, and the second component resulted from the desorption of MB from the apples. Estimates of the concentration of MB residue in apples were obtained from the regression parameters for the second decay curve. The technique gave good estimates of the residue concentration over a wide range of fumigation conditions and ventilation rates, and may be useful for determining the duration of aeration period required to achieve a proposed residue tolerance of 0.2 mg kg−1methyl br

ISSN:0031-613X    

DOI:10.1002/ps.2780290104

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractMarked changes in the relative toxicity of topically‐applied abamectin were found between larval instars ofSpodoptera littoralis, toxicity decreasing up to the fifth instar but increasing over 500‐fold (at LD50level) in the sixth instar. By contrast, the toxicity of abamectin remained constant from fifth to sixth instarHeliothis armigeraand there was an increase in the toxicity of two chemically unrelated insecticides, malathion (4‐fold) and lambda‐cyhalothrin (2.5‐fold), from fifth to sixth instarS. littoralis. Prior topical application or injection of the microsomal oxidase inhibitor, piperonyl butoxide (PB) increased the toxicity of abamectin (6–8 and 16‐fold respectively) against fifth instarS. littoralis, while topically‐applied PB increased the proportion of radioactivity present as abamectin in the ventral nerve cord of this instar following topical application with [3H]abamectin. Topically‐applied PB also enhanced the toxicity of abamectin against third (4‐fold) and fourth instar (5‐fold)S. littoralisbut had no significant effect on sixth instarS. littoralis, fifth instarH. armigera, or on the toxicity of malathion and lambda‐cyhalothrin against fifth instarS. littoralis. Topical application of the esterase inhibitor,S,S,S‐tributyl phosphorothioate (DEF) significantly increased the toxicity of abamectin at the LD50level (3‐fold) against fifth instarS. littoralis. The toxicity of injected abamectin against fifth instarS. littoraliswas greater (20‐fold) than with topical application but injected abamectin was less toxic (2‐fold) against sixth instarS. littoralisand had no significant effect on fifth instarH. armigera. It is suggested that differential toxicity of abamectin is due in part to greater metabolism and reduced penetration in fifth instarS. littoralisthan in sixth instarS. litto

ISSN:0031-613X    

DOI:10.1002/ps.2780290105

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

Abstract2,6‐Difluorobenzoic acid, one of the two primary diflubenzuron metabolites, is rapidly and completely degraded in soil. Times to 50% disappearance were 9 and 12 days in two agricultural soils. [14C]Carbon dioxide was an ultimate product of the ring‐14C‐labelled compound. A part of the radioactivity, increasing with time to one third of the applied dose of 1 mg kg−1, could not be extracted from t

ISSN:0031-613X    

DOI:10.1002/ps.2780290106

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractBobwhite quails were treated with imazalil for 8 weeks. The fungicide was given admixed in the food at 0, 100, 300, 500 and 1000 mg kg−1. Even at the highest dose tested, imazalil did not affect the liver weight or the hepatic microsomal protein content. In treated quails, no significant induction of cytochrome P‐450 or NADPH‐cytochrome c‐reductase activity was observed. Furthermore, imazalil did not induce or inhibit 7‐ethoxyresorufin or 7‐ethoxycoumarin O‐deethylase in quail microsomes. Only a slight but significant increase by 35% and 49% in aniline hydroxylase activity was measured for the 500‐ and 1000‐mg kg−1dose levels, respectively. After a drug‐free period of one week, aniline hydroxylase activity returned to control values, indicating that the effect was fully reversible. It is concluded that imazalil does not induce or inhibit drug‐metabolizing enzymes in the quail, even at doses which exceed by far the maximum levels currently used to dress seed under field c

ISSN:0031-613X    

DOI:10.1002/ps.2780290107

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractTo help explain the increased residual activity of a deltamethrin suspension concentrate (SC) formulation against grasshoppers, the persistence, location and nature of residues from the SC and an emulsifiable concentrate (EC) formulation have been compared. Wheat plants were sprayed in a cabinet sprayer at 7.6 g ha−1for the EC and 5.6 g ha−1for the SC, then weathered outdoors for 16 days. With the SC formulation, residues were more persistent, more residues were located on the exterior of the leaves, and less deltamethrin was converted to inactive isomers. Eight days after spraying, the exterior deltamethrin residues were 0.13 μg plant−1from the SC versus 0.06 μg plant−1from the EC. Thus, more residual deltamethrin is available to grasshoppers with the SC fo

ISSN:0031-613X    

DOI:10.1002/ps.2780290108

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA series of analogous tetracyclic 1, 12b‐dihydro‐4H‐1,2,4‐triazino[4,3‐f] phenanthridines and 4H,12bH‐1,2,5‐oxadiazino[5,6‐f]phenanthridines was prepared and tested for control of Erysiphe graminis f. sp. tritici (the causal agent of powdery mildew in wheat). Several analogs showed exceptional activity at doses as low as 6.25 mg litre−1with substituted analogsVII, X, andXIVbeing the most potent. Singly substituted tetrahydrotriazinyl or oxadiazenyl rings with lipophilic aromatic components appeared to be the key requirements for optimal powdery mildew control. Substitution of the heterocyclic ring with multiple groups at

ISSN:0031-613X    

DOI:10.1002/ps.2780290109

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe toxicity of phosphine, methyl bromide, 1,1,1‐trichloroethane (methyl chloroform) and carbon dioxide and mixtures of phosphine + methyl bromide, methyl bromide + methyl chloroform, phosphine + carbon dioxide, and methyl bromide + carbon dioxide to one‐ to two‐day‐old pupae ofTribolium castaneumHerbst was studied. Joint action ratios estimated at LD50and LD90for a 24‐h exposure indicated no enhancement of toxicity for mixtures of phosphine and methyl bromide, or methyl chloroform and methyl bromide on the pupae. Carbon dioxide up to 40% in air enhanced the toxic action of phosphine as well as of methyl bromide. Higher levels of carbon dioxide, however, failed to improve the toxicity of phosphine or methyl bromide proportionately. Carbon dioxide used alone produced a maximum of 11% mortality of the pupae exposed to 10–70% levels for 24 h. The order of toxicity of the fumigants both at LD50and LD90was phosphine>methyl bromide>methyl

ISSN:0031-613X    

DOI:10.1002/ps.2780290110

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractTreating the outer surfaces of isolated cuticles of Seville orange (Citrus aurantium L.) and pear (Pyrus communis L. cv. Bartlett) leaves with a number of nonionic (polyoxyethylene) surfactants increased their permeability to water by factors ranging from 4.1 to 14.7 and from 7.2 to 152.4, respectively. However, sodium dodecylsulphate, an anionic surfactant, had little effect on water permeability. In both species the major aliphatic constituents were n‐alkanes, 1‐alkanols and n‐alkyl esters. None of the surfactant treatments altered the amounts or composition of waxes in the cuticles used for transport measurements. The reasons for the apparent absence of solubilization or dissolution of cuticular waxes by nonionic surfactants are discussed and a hypothesis is presented for the mechanism by which activator adjuvants may increase the permeability of plant cut

ISSN:0031-613X    

DOI:10.1002/ps.2780290111

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY