摘要:

Summary.Detached leaves treated with 2,4‐DB were used to demonstrate that the foliage ofAcer macrophyllumPursh. possesses the enzyme systems necessary for oxidation of the 2,4‐DB side chain. Absorption and translocation studies showed that 2,4‐DB was absorbed less but translocated more than some other phenoxy herbicides which have been tested on this species. Studies with excised stem phloem and excised roots showed that different plant tissues are not equally capable of decarboxylating 2,4‐DB. An experiment with intact plants established that 2,4‐DB was translocated unchanged, and that the primary product of the oxidation of 2,4‐DB is 2,4‐D. The results are discussed with respect to the translocation characteristics of this herbicide in bigleaf maple.Caractères de l'absorption, de la migration et du métabolisme de l'acide 4‐(2,4‐dichlorophénoxy) butyrique dans l'éra

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00894.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.In a number of plant species, the biological activity of diquat and paraquat was increased by an increase in environmental humidity. This improved activity resulted from an increase in both uptake and movement.High humidity was more effective after treatment than before it, and durations of 8 hr or more were required to produce the maximum effect. When periods of low humidity of up to 16 hr were interposed between treatment and high humidity, there was no significant effect on the activity of diquat in darkened tomato or sugar beet.The increase in activity occurred both in the dark and in the light, and it is therefore concluded that humidity does not exert its effect by modifying the degree of stomatal opening.Experiments were carried out with wheat using two air humidities combined with different soil moisture contents, ranging from saturated down to only 30% of water‐holding capacity. Greatest movement occurred where high air humidity was combined with low soil moisture, and least where low air humidity was combined with high soil moisture. It is concluded that diquat and paraquat would be most effective in the field when sprayed under dry soil conditions in late afternoon or evening when increased humidity (and darkness) can follow soon after treatment.Les sels quatemaires de bipyridyliumEffet de l'humidité atmosphérique et de l'humidité du sol sur l'absorption et la migration du diquat et du paraquat dans les pl

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00895.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.Paraquat, amitrole‐T and disodiumn methylarsonate (DMA) were evaluated for the control of the stoloniferous grassPaspalum conjugatumin young rubber plantations in Malaya. The herbicides were tested alone, in mixtures and in split applications. Paraquat at 0–5 lb/ac gave good initial desiccation but regeneration was extremely rapid and repeated sprays of 0–25 lb/ac were required for a long period of suppression. Amitrole‐T at 15 lb/ac was very slow to act but gave complete kill after 10 weeks. DMA at 8–12 lb/ac gave marked suppression, but regeneration rapidly developed after 8 weeks. Mixtures of either amitrole‐T or DMA with paraquat gave less than the expected additive effects of the components, indicating an antagonistic action. Sub‐lethal rates of amitrole‐T or DMA applied to regenerating shoots after paraquat treatment gave results inferior to those from higher rates of the herbicides alone.When paraquat was applied 2 weeks after an initial sub‐lethal dose (0.375 lb/ac) of amitrole‐T, desiccation was rapid and complete eradication was achieved; this did not occur when a low rate of DMA was used as the first spray. In terms of both speed of kill and final effect, a split application of a low rate of amitrole‐T followed by paraquat was the most effective treatment. A possible explanation of the apparent synergism between amitrole‐T and paraquat applied in this way is advanced and suggestions for further work outlined.Une méthode améliorée pour la lutte centrePaspalum conjugatum avoc

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00896.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.Using autoradiographic techniques, the long‐distance transport of ‘ethylene’14C‐labelled diquat dibromide was studied. It was confirmed that a period of darkness after diquat application was necessary for reliable systemic action during a subsequent light exposure. Darkness was necessary in the region where the herbicide was applied, and then only to allow adequate penetration of diquat. This was its only role.Desiccation following death, with the transfer of free water containing diquat to other leaves are the primary forces of long‐distance transport; light is essential only for rapid toxic action and not directly for transport. Orthophosphate‐32P and urea‐14C applied topically with unlabelled diquat were distributed in the same pathway as the herbicide and not in the phloem. These results are discussed.Nouvelles recherches sur l'influence de la lumière et de l'obscurité sur le transport à longue distance du diquat dansLycopersico

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00897.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Résumé.L'acidc 4‐aniino‐3,5,6‐tricbloropicolinique (piclorame) a été expérimenté pour lutter conirePolygonumsp. etMatrîcariasp. utilisé seul à la dose de 120 g é.a. ha ou assocîé a divcrses auxines de synthèse.Utilisé seul le piclorame s'est révélé d'une efficacité rcmarquable surPolygonum convolvulusL.,P. aviculareL.,Galium aparineL, etMatricaria inodoraL. En revanche le spectre d'activité de ce produit est assez ètroit et on peut en particulier citer parmi les espècearésistantes à dose de120 g é.a. ha:Fumaria ojficinalisL.,Viola tricolorL.,Cirsium arvenseL,Sinapissp. etPapaversp. De plus la sé1ectivité du prodiul reste faible s'il n'eat pas utiliséà une époque bien définie qui correspond au momentoùl'épi est à environ 1 cm du plateau de tallage.Des quinze formulas expérimentées les associations permettant d'apportcrk l'ha 10 à 30g é.a. de piclorame associéà 240 g é.a de 2,4‐D plus 240 g é.a. de MCPA plus 1760gé.a. de mécoprop assurent un contrôle trcs satisfaisant dePolygonumsp.,Galium aparine, Matricaria inodoraetChrysanthemum segetumL. tout en gardant une bonne sélectivitéà l'égard du blé d'hiver.Tri

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00898.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.Trials were conducted in East Anglia to compare direct‐drilling following paraquat at 1 and 2 lb/ac with normal cultivations for both winter wheat and spring barley. The three treatments were compared at two levels of nitrogen.With direct‐drilled winter wheat, yields were higher after using paraquat at 2 lb/ac and at this rate there was little difference between direct‐drilling and normal cultivations when 100 units of nitrogen were applied in spring. When only 50 units were given the results were more variable, with direct‐drilling significantly outyielding normal cultivations in one trial, being outyielded in another and showing no difference in the third.Yields of spring barley were slightly higher after paraquat at 2 lb/ac as compared with 1 lb/ac, but not significantly so. The time of application of paraquat influenced yield; when applied in December yields from direct‐drilling and normal cultivations were similar, but when applied in February higher yields were recorded with normal cultivations.Comparaison des doses de paraquat a utiliser avant un semis direct

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00899.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.Thiocarbamate herbicides were applied with incorporation devices and new subsurface application equipment on loamy sand at Tifton, Georgia, U.S.A. Subsurface‐applied ethylN,N‐dipropylthiolcarbamate (EPTC),S‐propyl bulylethylthiocarbamate (pebulate), andS‐propyl dipropylthiocarbamate (vernolate) generally gave better control ofCyperus esculentusL. andRichardia scabraSt Hil, but injured peanuts more than applications made on the soil surface and then incorporated into the soil. For soil incorporation, the power‐driven rotary hoe was generally better than a disc harrow.Depth of subsurface placement critically affected herbicidal activity, especially onCyperus esculentus;placement 1·5 in. below the soil surface gave more effective control than placement at 5·5 in.Réactions deCyperus esculentus,deRichardia scabraet de l'arachide mix herbicides à base de thiocarbamate, en relation avec la methode de placeme

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00900.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.The mineral content ofElodea canadensisandLagarosiphon majorgrowing in two lakes near Rotorua showed seasonal variation and was influenced by the nutrient status of the water. Large quantities ofL. majoroccur in Lake Rotorua and the average mineral content found was 3·9% N, 0·5% P, 2·6% K and 0·7% Mg (dry‐weight basis), a level which indicates potential commercial value.Variations de la composition chimique de deux mauvaises herbes aquatiques des lacs de Nouvelle

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00901.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Summary.A bay in Lake Rotoiti was completely cleared of a heavy infestation ofLagarosiphon majorby means of diquat at a concentration of 05 ppm. Weed kill was alow and there was no reduction of dissolved oxygen in the area, probably because of the cool weather at the time (April). Considerable numbers of planktonic algae developed, but after a few months it was apparent that herbicide treatment had caused an exchange ofLagarosiphonfor a less massive growth ofNileltaspecies. Some of the changes in bio‐logical production were measured and an explanation of the observed plant succession is offered.Quelques effets de la destruction des mausaises herbes aquatiques dans le lac Rotoiti, en Nouvelle‐Zé

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00902.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY

摘要:

Résumé.Divers auteurs proposent d'expliquer les propriétés herbicides du 2,4‐D par les modifications qu'il provoque dans le métabolisme auxinique mais leurs hypothèses à ce sujet sont souvent divergentes.L'action du 2,4‐D sur la croissance et sur le catabolisme de l'AIA a étéétudiéein vitroet invivochezHordeum hexastichumetTriticum iativumcullivés à l'obscurité'. Chez ces deux espdèes, l'accroissement des concentrations dc 2,4‐D inhibe la germination ct la croissance.Des extraits de la coléopiile et de la premiére feuilled'Hordeummontrèrent une activitéélevée de l'auxine‐oxydase, mais les extraits deTriticumfurent inactils s'ils n'étaient pas additionnés de co‐facteurs tels que MnCl2et le 2,4‐dichIorophénol: ils contiennent des inhibiteurs de la déradation enzymatique de l'auxine.L'addition de 2,4‐Din vitrone modifia pas la destruction de l'AIA par les extraitad'Hordeumou deTriticum;l'inhibition du catabolisme de l'AIA, dansHordeum, par des extraits bouillis deTriticum, ne fut pas modifie en présence de 2,4‐D. L'activité tlr l'auxine‐oxydase d'extraitsd'Hordeumet deTriticumpoussani en présence de 2,4‐D fut exactement identique à celle des témoins, la comparaison etant faite stir la base d'un poids fraiségal.L'inhibition, dans les exlraits deTriticum, ne fut pas affecteé par le 2,4‐D.L'action herbicidedu 2,4‐Dpursurses deux espèces, à l'obscurité, nepeut, en conséquence, èire expliqueté par une perturbation du cataboiistne de l'auxine par les auxines‐oxydases.2,4‐di

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1966.tb00903.x

出版商:Blackwell Publishing Ltd    

年代:1966

数据来源: WILEY