摘要:

AbstractExperiments on the control of wheat bulb fly larvae by seed dressings compared four organophosphorus compounds in standard siliceous earth formulations with special formulations of the same compounds in polyvinyl acetate, polypropylene or wax. The special formulations allowed more insecticide to be placed on the seeds without affecting germination. Counting shoots damaged by wheat bulb fly larvae showed that: siliceous earth formulations of diazinon gave good control which was not improved by special formulations; control with siliceous earth formulations of dimethoate was poor and was improved only little by the special formulations; and control with siliceous earth formulations of parathion and dichlofenthion was moderate and was improved by special formulations, especially polyvinyl acetate and polypropylene. The results suggest that special formulations are of most value with compounds that are moderately effective but where the amount of insecticide in standard seed dressings cannot be increased without damaging the plants.

ISSN:0031-613X    

DOI:10.1002/ps.2780010101

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe development of large complex irrigation systems presents problems of pest control which are likely to become increasingly difficult to solve by established application methods. By applying a chemical at one point in such a system use can be made of the flow of water through the system to effect the necessary distribution. This technique has been used most effectively with the molluscicide Frescon (N‐tritylmorpholine). However, the complexity of many irrigation systems precludes the optimisation of the necessary rate of addition of molluscicide by any simple method.In this paper a mathematical model of an irrigation system is described which enables a detailed study of this type of application to be made with speed and economy. An analogue computer has been used to solve the equations subject to the operating conditions of the irrigation syste

ISSN:0031-613X    

DOI:10.1002/ps.2780010102

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractDetails are given of the methods of analysis used in the determination of Organophosphorus pesticide residues in each of the food groups into which the total diet samples were divided. Residues of only 6 pesticides were detected. Malathion was the most commonly found, mainly in the cereal foods group of the diet, but all the residues were at low levels.

ISSN:0031-613X    

DOI:10.1002/ps.2780010103

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe extent to which methyl bromide was retained by fumigated material after treatment was followed in laboratory studies on a range of commodities exposed to the vapour at atmospheric pressure. Amounts of methyl bromide, recovered by solvent extraction and determined using gas‐liquid chromatography, were related to the temperature, moisture content and manner of post‐treatment storage.Immediately after exposure, the initial amount of free methyl bromide present was more dependent on the gas concentration used than on the time of exposure. Under the experimental conditions of exposure, the residual free methyl bromide in all commodities fumigated at 25°, except cocoa beans and groundnuts, fell to below 1 ppm within a few days when they were held at that temperature, whether spread in thin layers on trays or kept sealed in glass bottles. At lower temperatures, the rate of loss was slower, small amounts of methyl bromide being extracted from several commodities one month after treatment. The disappearance of fumigant from wheat and sultanas was more rapid from samples with higher moisture contents.A mathematical treatment of the data is presented, to assist in prediction of the behaviour of residual fumigant under storage conditions before processing. It is concluded that the risk of ingestion of harmful quantities of free methyl bromide by the consumer is small and that the occasions when relatively high residues might occur can be predi

ISSN:0031-613X    

DOI:10.1002/ps.2780010104

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe vapour phase and protectant activities of members of seven homologous series of alkyldinitrophenols against cucumber powdery mildew (Oidiumsp.) are discussed. No correlation existed between vapour activitiesin vitroorin vivoand vapour pressure, but a positive correlation between Vapour' protectionin vivoand conventional protectant activity was evident. Although vapour activity occurs with some homologues, results obtained for zone assaysin vivoare probably better explained in terms of easy movement of the compound in the leaf surface than in terms of vapour transmission. Alkyldinitrophenyl‐crotonates showed no zone activityin vivobut often good protectant activity. The possible existence of two optimum π‐values for protectant activity is suggested. No appreciable systemic activity was found with these compo

ISSN:0031-613X    

DOI:10.1002/ps.2780010105

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractResults of work in progress on the elucidation of insect responses to attractant substances of various kinds is reviewed, and the possibility of developing practical alternatives to insecticides is discussed.

ISSN:0031-613X    

DOI:10.1002/ps.2780010106

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of light on the activity of herbicides within the cell is reviewed. The herbicides are grouped according to the way their phytotoxicity is influenced by light.The largest group, which includes the ureas, triazines and uracils, interfere with photosynthesis by blocking the Hill reaction. Lack of carbohydrates and other manifestations of toxicity appear in the light and these are discussed. The bipyridylium quaternary salts, diquat and paraquat, are not phytotoxic until a free radical is formed utilising light energy via photosynthesis. The free radical is re‐oxidised by molecular oxygen, and a series of reactions are started leading to the formation of peroxide radicals which subsequently disrupts the cell.The phytotoxicity of 2,4‐dinitrpphenol and related compounds is reduced by light. This type of compound combined with a herbicide which inhibits the Hill reaction and thus photosynthetic phosphorylation may act synergistically and mixtures of this type are discus

ISSN:0031-613X    

DOI:10.1002/ps.2780010107

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of various herbicides on photosynthesis, respiration and transpiration of intact plants has been studied in a routine assembly. Simultaneous measurements were made under different experimental conditions in four small plant chambers, in which the shoots of various plant species can be accommodated.The herbicide is applied during measurement, so that the effect can be related to the photosynthetic activity of the same plants before treatment.The selectivity of various herbicides was studied by determining the capacity of a plant species to inactivate a herbicide absorbed by the roots. These and other differential effects of various herbicides on photosynthetic activity of different plant species coincide with the selective properties in the field. Such differences are also observed after leaf sprayings. The duration of the experiments is kept short.Bean plants were studied under various experimental conditions of air humidity, light intensity and temperature resulting in different transpiration rates. The decrease in photosynthetic activity owing to the presence of a herbicide in the nutrient solution at a standard concentration was more rapid at the higher transpiration rates. The total transpiration during treatment up to 50% inhibition of photosynthesis was constant under the various experimental conditions.Specific inhibitors of the photosynthetic process had a more pronounced effect on the photosynthetic activity than on transpiration rate. Some other herbicides affect transpiration as well as photosynthesis.

ISSN:0031-613X    

DOI:10.1002/ps.2780010108

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe importance of controlling the light environment of experiments involving diquat and paraquat is shown in experiments where activity is markedly dependent on the light quality and intensity before treatment and on the time of day of treatment.Activity and uptake are not directly related since treatments after low light intensities give increased activity associated with reduced uptake; following afternoon treatments, reduced activity is associated with increased uptake. Uptake increased when plants were darkened after treatment but the increase was not directly related to its duration, because after a time, uptake decreased. Three possible explanations for this decrease are considered: diquat exudation from the leaves, downward movement into the roots, and the adsorption of diquat in plant tissue. Evidence did not support exudation from leaves or downward movement into the roots.

ISSN:0031-613X    

DOI:10.1002/ps.2780010109

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe effect of light on the herbicidal acitivity of paraquat on the tropical perennial weedpaspalum conjugatumhas been studied in rubber and oil‐palm plantations in Malaya. Results showed that paraquat (at 0.5 ib/acre; gave a more rapid desiccation when applied in full sunlight but gave more persistent control when applied under the 70% shade of older trees or in the evening compared with other times of day. A simlar two‐fold improvement in the duration of weed control was achieved by the addition of the photosynthetic inhibitor bromacil (at 0.25 ib/acre) to paraquat. The response to the mixture suggested a synergistic reaction between the two compou

ISSN:0031-613X    

DOI:10.1002/ps.2780010110

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY