bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLE CROPS
Authors: LETTUCE I. , WAY J. M.
Published: July 2006

Summary. The effect of sub‐lethal doses of MCPA‐sodium on the growth, yield and marketability of summer cabbage lettuce was studied in seventeen replicated field experiments.

Initial epinasty was produced by doses as low as 0.002 lb/ac a.e., and formative effects of the leaves developed at doses below 0.01 lb/ac. In plants treated at early or intermediate growth stages, two distinct types of formative effects occurred, With doses in the range 0.0025‐0.03 lb/ac, a zone of characteristic abnormal leaves developed. This reduced the marketability of the crop and the maturity was delayed, but the weight per plant at harvest was not affected. At higher doses these a abnormal leaves were not evident but the whole plant became distorted, growth was suppressed and few marketable plants were produced. In plants treated at the hearting stage, plant weight and maturity were not affected, but the marketability was reduced at doses of 0.01 lb/ac and above. The effects produced by MCPA in cos and curly crisp lettuce were compared with those produced in cabbage lettuce.
A PRELIMINARY STUDY OF THE COMPETITION BETWEEN KALE AND THREE WEED SPECIES OF THE GENUS POLYGONUM
Authors: HAMMERTON JOHN L.
Published: July 2006

Summary. The results of a pot experiment on the mutual interference between kale and three weed species are reported. The puts were sunk in soil and surrounded by kale plants so as to provide illumination conditions similar to those likely to be found in a field crop of kale. Of the three weed species, Polygonum lapathifolium appeared to be the most, and P. aviculare the least, competitive towards kale. P. persicaria was slightly less competitive than P. lapathifolium. The two latter species were much higher in dry‐matter production than P. aviculare and showed greater responses to changes in the number of kale or weed plants per pot.
A COMPARISON OF METHODS OF RECORDING HERBACEOUS WEEDS IN WEED CONTROL EXPERIMENTS
Authors: RIEPMA P. , WENG WONG PHUI
Published: July 2006

Summary. In herbicide studies close correlation between results given by the square quadrat method and by a point quadrat method for assessing the number and frequency of weed species was found. Marked correlations between the density obtained by the square quadrat and the cover and yield indices obtained by the point quadrat method were observed.

Treatment discrimination using the point quadrat was as good as that obtained with the square quadrat and it is concluded that the point quadrat method is suitable for assessing weed control in low‐growing vegetation.

Comparaison de méthodes de notation des mauvaises herbes herbacées dans les essais de désherbage
ESSAIS EN PLEIN CHAMP DE DESHERBAGE SELECTIF DES BETTERAVES PAR LE CHLORO‐AMINO‐PHENYL‐PYRIDAZONE (PCA)
Authors: LHOSTE J. , D'ILLE H. , CASANOVA A. , DURGEAT ET L. A.
Published: July 2006

Résumé. Les auteurs poursuivant leurs études concernant les possibilités d'application de désherbants chimiques sélectifs en culture de betterave industrielle relatent les résultats qu'ils ont obtenus en utilisant dans ce but le chloro‐amino‐phénylpyridazone (PCA) associé ou non à la cyclo‐octyl‐diméthylurée (OMU).

La méthode expérimentale est décrite en détail. L'appareil épandeur d'herbicide est le pulvérisateur logarithmique conçu par Dr H. G. van der Weij.

Les résultats obtenus avec le PCA sont en accord avec ceux mentionnés par Fischer (1963). Le PCA n'est pas phytotoxique pour les betteraves, excepté pendant le stade dit‘cotylédons étalés'. Le mélange PCA + OMU est phytotoxique appliqué en post‐émergence.

L'effet de ces deux herbicides est satisfaisant. La dose minimum de 2,5 kg/ha pour le PCA et celle de 1,6 kg/ha de PCA + 0,4 kg/ha d'OMU s'est révélée efficace dans les conditions de nos expérimentations.

Feldversuche zur selektiven Unkrautbekämpfung im Zuckerrübenbau durch Chlor‐Aminophenylpyridazon
SELECTIVE CONTROL OF CHENOPODIUM ALBUM IN KALE WITH METHYLMERCAPTO TRIAZINES
Authors: BAKER G. , HOLMES H. M. , PFEIFFER R. K.
Published: July 2006

Summary. Following the discovery by J. G. Elliott and T. I. Cox in 1961 of the specific selective properties of certain methylmercapto triazines for the control of Chenopodium album in kale (Brassica oleracea var. acephala), extensive investigations of this subject were carried out by the authors in 1962. The work resulted in a practical recommendation to British farmers in 1963.

2‐Methylmercapto‐4‐methylamino‐6‐isopropylamino‐1,3,5‐triazine (G 34360) showed significantly higher selectivity than simetryne. The dose giving an optimum degree of selective control varied according to humidity and moisture. A dose of 4 oz/ac was sufficient for kale grown under moist conditions, while 6 oz/ac was required under condition of low rainfall and atmospheric humidity.

The development stage of the kale was critical and the herbicide was sufficiently safe only when applied after the kale had three leaves. No differences in response were observed between marrow‐stem and thousand‐head kale. Volume rates from 10 to 80 gal/ac were compared, but no clear differences were found.

Destruction sélective de Chenopodium album L. dans le chou fourrager avec les méthylmercaptotriazines
DORMANCY IN HOMERIA BREYNIANA (L.) LEWIS
Authors: PEARCE G. A.
Published: July 2006

Summary. The variation in the percentage of dormant corms of Homeria breyniana between sites and years was shown for a 3‐year period. The highest dormancy count of 61 % was obtained at Wagin in 1959 while the lowest count of 1% was also obtained in 1959 at Muchea. It was demonstrated that soil surface cover plays an important part in corm dormancy. In 1961 the removal of the surface cover by burning almost eliminated dormancy. Removing the cover at three dates during the summer did not affect the germination of corms during the late autumn. Moreover, corms left in the soil throughout the summer exhibited no physiological dormancy in April. In laboratory tests the percentage germination steadily decreased as the test temperatures were reduced from 25 to 5° C. Soil temperatures follow a similar decline in Western Australia during April and May. Light rains of 12 and 14 points (100 points = 1 in.) gave a significant increase in soil moisture where the surface was bare. Sufficient moisture penetrated to cause a general germination of corms and this resulted in H. breyniana emerging on bare soil some 3 weeks earlier than where surface cover was present. The diurnal temperature range at this time was 54–68° F. The break of the season (the beginning of the growing season) did not occur until 17 days later, and the diurnal soil temperature range had dropped to 49–54° F. Corms subjected to germination tests at these two temperature ranges gave a 90% and 70% sprouting respectively.

La dormance des bulbes de Homeria breyniana (L.) Lewis
A PRECISION SPRAYER FOR SMALL EXPERIMENTAL FIELD PLOTS*
Authors: GROVER R. , CLARKE H.
Published: July 2006

Summary. Large‐scale field testing of herbicides nccessitales the use of small experimental plots. Most of the available small‐plot experimental sprayers do not have any mechanical control of the speed of the spray boom and thus depend on the speed of the operator or an pushed by or mounted on various types of vehicles. Inability to attain a desired speed of the spray boom over a short distance by mechanical means has hindered the development of a precise small‐plot sprayer. This problem was resolved by the attainment of the desired speeds prior to the release of the spray boom. The principal parts of the unit are: (1) speed control and drive mechanism with an endless cable running at speeds of 1, 2 and 3 miles/hour; (2) boom‐carrier which may be locked to the continuously running cable; (3) rotary gear pump; (4) pressure regulator; and (5) spray boom with two ‘even spray Teejet’ nozzles. The entire machine is 6 ft wide and 13 ft in length and sprays a plot 5 ft wide and 10 ft long. The unit is mounted on four wheels for transport from plot to plot. During its initial trials in the field, the unit has shown precision, accuracy and repeatability in small‐plot spraying, seldom attained by small‐plot sprayers. In addition the unit is simple in design and can be easily assembled by an experienced mechanic.

Un pulverisateur de précision pour petites parcelles experimentales
UNTERSUCHUNGEN ÜBER DIE URSACHEN DES VERMEHRTEN AUFLAUFENS VON UNKRÄUTERN NACH MECHANISCHEN UNKRAUTBEKÄMPFUNGS‐MASSNAHMEN (NACHAUFLAUF)
Authors: MÜLLVERSTEDT R.
Published: July 2006

Zusammenfassung. Investigations on the causes of increased emergence of weeds following mechanical weed control measures

Um den Grund für vermehrtes Auflaufen von Unkrautsamen nach mechanischen Unkrautbekämpfungsmassnahmen (Nachauflauf) zu finden, wurden die drei denkbaren Faktoren bei Avena fatua, Sinapis arvensis, Alopecurus myosuroides und Galium aparine untersucht. Das Licht war dabei ebenso ohne Einfluss wie die mögliche Verlagerung von Unkrautsamen durch das Eggen in keimgünstige Bodentiefen. Gegenüber dem Licht erwiesen sich die untersuchten Arten bei der Keimung indifferent. Beim Eggen wurden grössere Samen im Lehmboden vorzugsweise aufwärts, kleinere Samen dagegen abwärts bewegt, mithin entgegengesetzt zu den keimgünstigen Tiefen. Die mit dem Eggen verbundene Bodendurchlüftung führte dagegen im Vergleich zu den un‐belüfteten Kontrollen zu gesichertem Mehrauflauf, so dass die bessere Luftdiffusion in den durch Eggen gelockerten Boden als Grund für den Nachauflauf anzusehen ist.
ABSORPTION AND TRANSLOCATION OF RADIOACTIVE HERBICIDES IN SUBMERSED AND EMERSED AQUATIC WEEDS*
Authors: FUNDERBURK H. H. , LAWRENCE J. M.
Published: July 2006

Summary. Absorption and translocation of labelled herbicides by a submersed weed, waterstargrass (Heteranthera dubia (Jacq.) MacM.) were studied. Autoradiographs showed that simazine (or the labelled carbon atom) and 2,4‐D‐butoxyethyl ester moved both from roots to shoots and from shoots to roots. Ametryne, prometryne, fenac and 2,4‐D (acid) moved to a slight extent from shoot to root, but no movement from root to shoot could be detected in the autoradiographs. However, counting data indicated that small amounts of these four compounds, not recorded on autoradiographs, may move from root to shoot. Radioassay did not detect diquat or paraquat movement to the roots or to the upper portions of the shoots, but the autoradiograph of one plant receiving a root application of paraquat showed slight movement into the lower portion of the stem.

Absorption and translocation of labelled herbicides by an emersed weed, alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.), were also studied. Darkening of film indicated that relative mobility of root‐applied herbicides was as follows: ametryne = fenac = prometryne = simazine>diquat = paraquat> 2,4‐D (acid) = 2,4‐D‐butoxyethyl ester. There was little movement of foliage‐applied simazine, ametryne and prometryne. There was slight downward movement of foliage‐applied fenac, diquat and paraquat, and considerable downward movement of 2,4‐D (acid) and 2,4‐D‐butoxyethyl ester, which accumulated in the nodal regions of the stem.

Radiolabelled phosphorus moved in both directions in both plants and there was more movement in an upward direction in both species.

Absorption et migration d'herbicides radio‐actifs dans des mauvaises herbes aquatiques immergées et émergentes
THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLECROPS
Authors: WAY J. M.
Published: July 2006

Summary. The effects of sub‐lethal doses of MCPA‐sodium on the morphology and yield of red beet, turnip and onion and on the morphology of spinach were studied in field and glasshouse experiments. Epinastic responses of beet were seen at 0.003 lb/ac a.c., but no serious formative effects or yield reductions occurred below 0–07 lb/ac and plants were only killed by doses above 0–1 lb/ac. Spinach was affected at 0–06 lb/ac, the lowest dose used, but the plants were not killed at 0–33 lb/ac. Epinasty in turnip occurred at 0–002 lb/ac, and at 0–01 lb/ac many of the roots were abnormal, while spraying with 0–1 lb/ac and above resulted in severe distortion or death of the plants. Onion was the least affected of all the crops studied. When a welting agent was included in the spray epinasty occurred at 0–3 lb/ac, but there were no serious formative effects or yield reductions below 1–0 lb/ac. The symptoms of injury in onion were often transitory because the affected parts were replaced as the bulb developed.

Effets de doses sub‐léthatles de MCPA sur la morphologie et If rendement des cultures légumiéres. V. Betteraves, Epinards, Navets et Oignons
OBSERVATIONS ON THE EFFECT OF HERBICIDES ON YOUNG COCONUTS
Authors: ROMNEY D. H.
Published: July 2006

Summary. Phytotoxic effects of eight herbicides on young coconuts were assessed by recording visual symptoms of injury and growth following treatment. The growth‐regulators 2,4‐D, 2,4,5‐T and MCPB were lethal at the normal doses used for annual weed control. Dalapon at 5–9 lb/ac applied in 100 gal/ac of water caused yellowing and necrosis of the foliage, reduced growth, and sometimes killed the whole plant, while doses down to 2.2 lb/ac caused some fusion of the pinnae. Monuron at 3.2 and 6.4 lb/ac resulted in serious frond damage and reduced growth, and some frond injury occurred at 1–6 lb/ac. Diquat at 0.25–1.0 lb/ac and paraquat at 1.0–l.5 lb/ac caused extensive necrosis of existing fronds but there was no appreciable reduction in new growth. Amitrole produced considerable chlorosis both at 3.1 and G.3 lb/ac, but only the higher dose caused a reduction in growth.

Essai d'herbicides sur jeunes cocotiers
HERBICIDAL EFFECTS ON CERTAIN SOIL MICROBIAL ACTIVITIES IN SOME BROWN SOILS OF SASKATCHEWAN
Authors: CHANDRA PURNA
Published: July 2006

Summary. Amitrole, 2,3,6‐TBA, 2,4‐DB and di‐allate were applied at normal field rates to a loam soil in a preliminary study, The toxic effects, as measured by nitrification studies, persisted for 8 weeks after application. After a further 8 weeks this depressive effect was decreased.

Residual effects were assayed by measuring the nitrification rate of soils following the application of the same four herbicides at two rates to four different soils. The residual effects of amitrole, di‐allate, 2,3,6‐TBA and 2,4‐DB were overcome 34, 28, 32 and 44 weeks respectively after treatment. Total microbial counts were also corelated with the nitrification rate of the soils. The trend of disappearance of the toxic effect of these chemicals was similar in all the soils in these laboratory investigations.

Under field conditions the residual effect of amitrole, 2,3,6‐TBA and 2,4‐DB had disappeared by the end of 52 weeks, as far as could be determined by studies of nitrate production, ammonification and total counts of microorganisms. A second application of the chemicals 56 weeks after the initial treatment affected nitrification in the laboratory for only half as long, indicating adaptation of' the microorganisms to the herbicides

Effels des herbicides sur certaines activités des microorganismes du sol
ANALYTISCHE UNTERSUCHUNGEN VON TRIAZ1N‐HERBIZIDEN
Authors: STAMMBACH K. , KILCHHER H. , FRIEDRICH K. , LARSEN M. , SZÉKELY G.
Published: July 2006

Zusammenfassung. Die vorliegende Arbeit beschreibt die analytische Reinheits‐prüfung einer Auswahl von Triazin‐Herbiziden am Beispiel von Atrazin, Atraton und Prometryn mit Hilfe der Dünnschicht‐ und der Gas‐Chromalographie.

Investigations on the analysis of triazine herbicides
THE METABOLISM OF HERBICIDES*
Authors: BRIAN R. C.
Published: July 2006

Summary. A knowledge of the metabolism of herbicides within plants is of importance in a number of ways. Thus, whilst governmental control of the toxicity of potential herbicides is being exercised by fixing acceptable levels of residues, information may also be required an the toxicity of their possible metabolites. This aspect is not pursued but metabolism of chemicals by plants is divided into that which: (1) militates against their efficiency (deactivation), (2) introduces useful biological properties, (3) is essential to their biological activity (activation).

The metabolism of the important herbicides of each class is reviewed briefly and its effect on their use in the field described where possible. Emphasis, however, is given to the unique mode of action of the bipyridylium quaternary ammonium compounds—diquat and paraquat—as herbicides in the last class, depending for their activity on a reduction by the plant In toxic free radicals. Evidence for the participation of free radicals in their herbicidal activity is presented, and their physical and biological properties described. Physiological processes involved in this free radical production are discussed and also hypotheses concerning their mode of action.

Le métabolisme des herbicides
THE INFLUENCE OF DALAPON ON GROWTH AND DEVELOPMENT OF AUTUMN‐SOWN SUGAR BEET*
Authors: ELLERN S. J. , MARANI A.
Published: July 2006

Summary. In order to determine the phytotoxicity of dalapon—sodium to October‐sown sugar beet in southern Israel, a substantially weed‐free field was sprayed on three dates with 1·1, 2·2, 4·5 and 9·0 kg/ha a.e. Samples of beet were taken on five dates between February and July. The 9–0 kg/ha rate of dalapon caused a significant reduction in the weight of both roots and the other beet components. At 4·5 kg/ha phytotoxic effects were less marked. It is concluded that dalapon at rates lower than 4·5 kg/ha, applied between mid‐November and mid‐January, should be a safe treatment for October‐sown sugar beet where grasses rather than broad‐leaved weeds predominate.

Effet du dalapon sur la croissame ei lé développement de la betterave sucrière semée en automne
THE EFFECT OF MCPA ON THE AMINO ACID AND SUGAR COMPOSITION OF VICIA FABA LEAVES
Authors: MacLEOD D. G.
Published: July 2006

Summary. The effect of spraying Vicia faba leaves with 5000 ppm MCPA is described. Three to 4 days after spraying, a marked increase (× 5 approx.) was found in the concentrations of leucine iso‐leucine and valine in the leaves. No significant changes were detected in the other amino acids. Treatment with MGPA also caused a significant increase (× 4 approx.) in the glucose and fructose content of the leaves. Detached leaves (sprayed and unsprayed), when kept in a moist atmosphere for 3–4 days, exhibited very similar increases in amino acids and sugars to sprayed intact plants. Experiments using 14CO2 revealed that in short term photosynthesis (30 min) of sprayed and unsprayed plants, 80–90% of the radioactivity was incorporated in sucrose, with about 5% in each of glucose and fructose. Over photosynthelic periods of 4 days, glucose and fructose were found to be almost as heavily labelled as sucrose in sprayed plants, but in the controls the distribution of radioactivity was similar to that in short term photosynthesis. It is suggested that the build up of amino acids and sugars in plants treated with MCPA is due to an interruption of the translocatory flow from the leaves, and that this build up of metabolites may be a contributory factor in the toxic action of this herbicide.

Effet du MCPA sur la composition en amino‐acides et en sucre des feuilles de Vicia faba
THE EFFECTS OF SUB‐LETHAL DOSES OF MCPA ON THE MORPHOLOGY AND YIELD OF VEGETABLE CROPS
Authors: WAY J. M.
Published: July 2006

Summary. The effects of 2,4‐D, 2,4,5‐T, mecoprop and 2,3,6‐TBA were compared with those of MCPA on the morphology and yield of lettuce, cabbage, cauliflower, Brussels sprout, carrot, parsnip, French and broad bean, red beet, spinach, turnip and onion. Although the relativie phytotoxicity of MCPA, 2,4‐D, 2,4,5‐T and mecoprop varied according to the crop, the morphological abnormalities produced by the different compounds were essentially similar, except that in lettuce and cabbage sperilic foliar symptoms appeared to be associated with 2,4‐D. 2,3,6‐TBA caused less epinasty and usually fewer root and stem abnormalities, but in some crops, notably French and broad bean, red beet and spinach, it produced severe injury symptoms which were different from those produced by the other compounds.

Effets de doses sub‐léthales de MCPA. sur la morphologie et le rendement des cultures légumirres VI. Comparaison avec le 2,4‐D, le 2,4,5‐T, le micoprop et le 2,3,6‐TBA
HERBICIDE MIXTURES FOR WEED CONTROL IN PEANUTS (ARACHIS HYPOGAEA L.), 1961–63*
Authors: HAUSER E. W. , PARHAM S. A.
Published: July 2006

Summary. Comparative studies of herbicides and herbicide mixtures in peanuts (groundnuts) were continued at Tifton, Georgia, U.S.A., on Tifton loamy sand during 1961–63. When applied on a dry soil surface at the ‘cracking’ stage, certain mixtures which contained dinoseb as one component with 2,4‐DES, 2,4‐DEP, or DMPA as the Other component gave control of Digitaria sanguinalis (L.) Scop. and Richardia scabra St. Hil. for the entire growing season. However, on wet soils with no subsequent rain during the first weeks or with prolonged excess moisture, mixtures were not appreciably more effective than herbicides applied singly at standard rates. Where mixtures were applied on wet soil, herbicide effectiveness was improved by timely follow‐up sprays of dinoseb at 1.5 lb/ac.

Timing of application was often critical for optimum weed control. The best time was when the peanuts were cracking the ground or when the first weeds were barely visible, whichever occurred first.

Mixtures permitted the use of the lowest rate of each compound on the weeds for which it was most effective.

A mixture of DMPA at 6 lb/ac 4—dinoseb at 3 lb/ac applied at the ‘ground‐cracking’ stage increased the average yield of peanuts.

The mixtures evaluated had no effect on shelling‐%, % sound mature kernels (SMK), mean weight per nut, or % germination. Neither did they affect taste of the peanuts or other sensory. characteristics. However, preliminary chemical analyses indicated that peanuts treated with mixtures contained more linolein and less olein than did untreated peanuts.

Essais d'herbicides et de mélanges herbicides pour le désherbage dans les arachides (Arachis hypogea L.), 1961–63
SOME EFFECTS OF THE NITROGEN SUPPLY ON THE GROWTH AND DEVELOPMENT OF ACROPYRON REPENS L. BEAUV.*
Authors: McINTYRE G. I.
Published: July 2006

Summary. The influence of the nitrogen supply on the growth and development of quackgrass (Agropyron repens L. Beauv.) was investigated by growing plants in sand culture at nitrogen levels of 210, 10–5, 5.25 and 2.6 ppm in addition to constant levels of other basic nutrients.

When these nutrient regimes were first applied the rate of leaf emergence showed a positive correlation with the nitrogen level. This effect, however, did not persist and the rate subsequently attained was similar at all levels of nutrition. Tiller emergence, on the other hand, was markedly dependent on the nitrogen supply and at 2.6 ppm N was almost completely suppressed. As a result of this effect the production of secondary rhizomes, i.e. those arising from tillers, was correspondingly reduced. There was, however, a slight increase in the number of rhizomes produced from buds on the parent shoot.

At 2.6 ppm N the dry weight of the shoots was reduced by approximately 75% as compared with the highest nitrogen level but there was no significant reduction in the weight of the roots or rhizomes. The shoot/root ratio was thus considerably decreased at the lower ni trogen levels.

By varying the nitrogen supply it was also possible to control quite precisely the behaviour of the rhizome buds. At 2.6 ppm and 10.5 ppm the buds ceased to grow when 2–6 mm in length, the size attained being determined by the nitrogen level. At 210 ppm, however, the onset of dormancy was eliminated and all of the buds grew out as lateral branches. Bud growth could also be induced at a low nitrogen level (5.25 ppm) by removing the rhizome apex.

The significance of these results is discussed in relation to the ecology of the plant and to the problem of apical dominance.

Influence de diverses dases d'azote sur la croissarce et le développent d'Agropyron repens L. Beauv.
NEBURON, A SELECTIVE HERBICIDE FOR USE IN TROPICAL LEGUMES
Authors: RIEPMA P.
Published: July 2006

Summary. The effect of pre‐ and post‐emergence applications of neburon on the growth of Pueraria phaseoloides and Centrosema pubescens has been tested. Pueraria phaseoloides was adversely affectcd by both applications, seprately and combined, the effect being greater on a sandy soil than on a clay soil. Centrosema pubescens showed greater tolerance, and was little affected by post‐emergence treatment but pre‐emergence treatment showed some adverse effect.

The check to growth of the legumes could be offset by increased rates of sowing. It appears that neburon might be suitable as a selective herbicide for application in tropical legumes.

Le néburon, herbicide sélectif pour les cultures de légumineuses tropicales
THE GENETIC RESPONSE OF BARLEY TO DDT AND BARBAN AND ITS SIGNIFICANCE IN CROP PROTECTION
Authors: HAYES J. D. , PFEIFFER R. K. , RANA M. S.
Published: July 2006

Summary. The response of eleven barley varieties to DDT and barban was assessed in field and glasshouse trials. Chlorosis following the application of DDT and minimal doses of barban is an all‐or‐nothing effect, whereas in apical inhibition there are several degrees of resistance. The criteria used to assess the eflect of barban on apical inhibition were fresh weight of seedlings, fertile tiller production at maturity and visual estimates of damage at the seedling stage and at maturity. Inheritance studies showed that resistance to the chlorosis reaction of both DDT and barban is controlled by single recessive genes independently inherited.

Resistance to apical inhibition, on the other hand, appears to be quantitatively inherited. When F2 and F3 segregating populations in the field were sprayed with barban, the proportion of resistant plants in successive generations was markedly increased.

The authors conclude that collaboration between plant breeder and pest control specialists could lead to a far more efficient control of weed, pest and pathogen by the development of varieties of crop plants with a high degree of tolerance to the chemical employed, especially under conditions where selectivity is narrow and delicate, such as in the control of other monocotyledonous plants in cereals.
GRUNDSäTZLICHE UNTERSUCHUNGEN ZUR ANWENDUNG VON SIMAZIN UND ATRAZIN IN WINTERWEIZEN
Authors: HAFNER K.
Published: July 2006

Zusammenfassung. In mehrährigen Feldversuchen zur Bekämpfung von Ackerfuchsschwanz (Alopecanus mytosuroides) zeigten Simazin und Atrazin nur eine geringe Selektivitätsschwelle gegenuüber Winterweizen. Im einzelnen ergaben sich folgende Ergebnisse: 1. Mit Aufwandmengen von 0,375–0,5 kg/ha Simazin bzw. 0,25–0,375 kg/ha Atrazin wurde eine zufriedenstellende Unkrauiwirkung bei guter Getreideverträglichkeit erzielt. 2. Bei unterschiedlicher Empfindliclikeit in den einzelnen Entwicklungsstadien erwies sich der Weizen im 3–4‐ Biattstadium am verlräglichsten. 3. Durch Trockenheit zum Behandlutigszetipunkt wurde die Wirkung unterbunden. 4. Frostgeschädigtes Getreide wies eine erhöhte Empfindlichkeit auf.

Studies on the use of simazine and atrazine in winter wheat
THE EFFECT OF HERBICIDES ON THE RELATION BETWEEN COVER INDEX AND YIELD INDEX
Authors: RIEPMA P.
Published: July 2006

Summary. The effect of herbicide application on the relation between first and total number of contacts using the point quadrat method was studied. It was found that none of the herbicides tested — paraquat, dalapon, disodium methylarsonate, cacodylic acid and amitrole — affected the relationship appreciably, although differences in control were obtained. It is concluded that once the relation between first and total contacts is established in a particular field, the percentage weed control can he obtained with first contacts only, and the percentage weed control for total contacts calculated if necessary.

L'effet des herbicides sur la relation entre l'indice de couverture et le rendement
THE GROWTH IN VITRO OF MICRO‐ORGANISMS IN THE PRESENCE OF SUBSTITUTED PHENOXYACETIC AND PHENOXYBUTYRIC ACIDS
Authors: SHENNAN JEAN L. , FLETCHER W. W.
Published: July 2006

Summary. The growth has been tested in vitro of selected species of fungi, yeasts, bacteria, actinomycetes and green algae in the presence of the acetic and α‐butyric acid forms of MCPA, 2,4–D and 2,4,5–T. The results show that at concentrations approximating to field rates of application, these chemicals were harmless. At much higher concentrations (above 500 ppm), however, the α‐butyric acids were found to be highly toxic whereas the acetic acids has no effect on growth.
LA LUTTE CONTRE LES RESSEMIS DANS LES CULTURES PORTE‐GRAINES DE GRAMINÉES FOURRAGÈRES
Authors: de GOURNAY X. P.
Published: July 2006

Résumé. L'auteur donne les résultats de deux années d'essais à propos des ressemis. Au cours des premiers essais réalisés en cultures adultes dans des conditions normales en 1961–62, quelques produits ont donné de bons résultats; c'étaient le chlorpropham, le dichlobénil, la simazine et certaines autres triazines. L'année suivante le dichlobénil a de nouveau permis un bon désherbage sans jamais léser gravement les plantes‐mÈres; souvent insuffisante, l'action de la prométryne a été extrêmement irréguliÈre; dans quelques cas la simazine et le chlorpropham ont quasiment anéanti la culture; bien qu'il soit assez efficace contre quelques graminées adventices annuelles, le diuron ne présente aucun intérêt dans les plantations françaises de graminées fourragÈres. Quelques essais de rendement confirment les notations visuelles qui forment la trame de cet exposé.
DIRECT‐DRILLING OF CEREALS AFTER USE OF PARAQUAT
Authors: JEATER R. S. L. , McILVENNY H. C.
Published: July 2006

Summary. Cereal crops were grown at Jealott's Hill in 1962 and 1963 without cultivations, following the use, before drilling, of paraquat to kill unwanted vegetation. This investigation was extended with a series of trials at outside centres. Three trials with winter wheat were drilled in the autumn of 1963, two into pasture and one into stubble. Three barley trials were drilled into stubble in spring 1964.

All the autumn trials and one spring trial compared direct‐drilling with normal cultivations at two levels of nitrogen. The other two spring trials compared rates and times of application of paraquat without any plough comparison.

Individual trials showed significant yield differences between direct‐drilling and ploughing, but there was no consistent advantage in favour of either technique.

Spraying in advance of drilling generally resulted in similar yields to spraying and drilling on the same day. Winter wheat drilled into pastures showed some retardation of spring growth when spraying and drilling had been carried out on the same day.

When averaged over times of application, yields after spraying paraquat at 2 lb/ac were significantly higher than after 1 lb/ac.

In the trials where two levels of nitrogen were included crops responded to an increase from 60 to 120 units nitrogen/ac as top dressing for winter wheat and from 60 to 90 units nitrogen/ac combine‐drilled for spring barley; the response was not always significant.

Semis direct de céréales après application de paraquat
EFFECTS OF RATE OF FORMATION OF 2,6‐DICHLOROBENZONITRILE ON ITS TOXICITY TO PLANTS
Authors: MILBORROW B. V.
Published: July 2006

Summary. The toxicity of thirty 2,6‐dichlorophenyl compounds to seven species of plant is recorded as log10 dose in μg of compound per cm2 of soil surface that reduces the growth of the young plants to 50% of controls during a 10‐day period (Growth Inhibition dosage 50% or GID50). The compounds are broken down in soil with the release of 2,6‐dichlorobenzonitrile; those that break down rapidly show a greater range of GID50 values than those that break down slowly. This change in selectivity was found to be related to the relative fresh weight growth rates of the different species.

Effet de la vitesse déformation du 2,6‐dichlorobenzonitrile sur sa toxicité pour les plantes

Résumé. La toxicité de trente dérivés du 2,6‐dichlorobenzonitrile vis‐à‐vis de sept espèces de plantes est exprimée par le log10 de la dose en μg de produit par cm2 (Growth Inhibition Dosage 50% ou GID50) qui réduit de 50%, par rapport aux témoins, la croissance de jeunes plantes pendant une durée de 10 jours. Les produits son t décomposés clans le sol avec libération de 2,6‐dichlorobenzonitrile. Ceux qui sont décomposés rapidement montrent une plus grande variation de la GID50 que ceux qui sont décomposés lentement. Cette variation dans la sélectivité est en relation avec les taux de croissance, exprimés en poids frais, des différentes espèces.

Der Einfluss der Bildungsgeschivindigkeit von 2,6‐Dichlorbenzonitril auf seine Toxicität bei Pflanzen

Zusammenfassung. Die Wirksamkeit von dreissig 2,13‐Dichlorphenylverbindungen gegenüber sieben verschiedenen Pflanzenarten wird als log10 Dosis in μg der betreffenden Verbindung pro cm2 Bodenoberfläche ausggedrückt. Dirser Giftgehalt reduziert das Wachstum der jungen Pflanzen zu 50% von dem der Versuchspflanzen in einer 10‐tägigen Zeitspanne (Growth Inhibition Dosage 50% oder GID50). Die Verbindungen werden im Boden abgebaut, indem 2,6‐Dichlorbenzonitril entweicht; die rasch abbaubaren Verbindungen zeigen einen grösseren Umfang von GID50 Werten als diejenigen, die langsamer zersetzt werden. Man fand, dass dieser Wechsel in der Selektivität in Beziehung stand zu den relativen Frischgewichtswachstumsraten der verschiedenen Pflanzenartea.
SURVIVAL OF SEEDS OF WILD OATS (AVENA FATUA L, AND AVENA LUDOVICIANA DUR.) AND CHARLOCK (SINAPIS ARVENSIS L.) IN SOIL UNDER LEYS
Authors: THURSTON JOAN M.
Published: July 2006

Summary. Survival of wild oat seeds (mainly Avena fatua) under leys on clay soils was investigated in two field experiments. During the first year under ley the number of seeds decreased by 41 % and 86% respectively. Subsequent decreases were less, and after 5 years under ley there were still enough of the original seeds left to produce infestation of a cereal crop. These results suggest that a long ley is not an efficient way of eliminating wild oat seeds from soil, and that a 1‐year ley may be almost as effective as one of 5 years.

When a ley was ploughed, the number of wild oats germinating decreased as the number of years under ley and the age of the seeds increased, but was scarcely affected by the weather. In contrast, charlock (Sinapis arvensis) germination did not decrease with increasing age of seeds up to 5 years, but was greatest in years with most rain during April and May.

Survivance de semences de Folle Avoine (Avena fatua L. et A. ludovieiana Dur.) et de Moutarde des champs (Sinapis arvensis L.) dans le sol sous prairie temporaire
STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.
Authors: HAMMERTON J. L. , STONE M.
Published: July 2006

Summary. Seeds of Polygonum lapathifolium were collected from eight localities during 1962. Plants of these populations were grown in the field and sampled at fortnightly intervals during June and July 1964. There were significant differences between populations in dry weight, leaf area index and nitrogen content at all samplings, and populations also differed in date of flowering and in certain morphological feature. Smooth curves were fitted to some of the growth data, and an account of the fitting procedure is given. For comparison, certain growth functions were calculated from the smooth curves as well as from the observed data. The populations differed in relative growth rate, net assimilation rate, relative nitrogen absorption rate and in certain other calculated functions, A number of growth attributes were significantly correlated with the latitude, longitude or length of the growing season of the locality of origin, and it is tentatively suggested that the populations represent climatic ecotypes.

Études sur des espèces de mauvaises herbes du genre Polygonum L. II. Variations physiologiques dans P. lapathifolium L.
STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.
Authors: HAMMERTON J. L.
Published: July 2006

Summary. Two experiments are described in which plants of Polygonum lapathifolium were grown with barley in small field plots and sprayed with 2‐(2‐4‐dichlorophenoxy)propionic acid (dichlorprop) at a range of dose rates. Counts of the number of living plants before spraying and at intervals after spraying enabled the progress of mortality to be followed and the final mortality to be calculated. Probit analysis showed that there were considerable differences in LD50 among five populations from different localities of origin. In a second experiment, in which P. lapathifolium plants were sprayed at three stages of growth, there were large differences in LD50 between two populations at all three stages of growth, but no consistent or regular trend in LD50 with stage of growth.

Etudes d'espèces de mauvaises herbes appartenant au genre Polygonum L. III. Variations de la sensibilité de P. lapathifolium L. à l'acid 2‐(2,4‐dichlorophénoxy) propionique
THE FATE OF PARAQUAT APPLIED TO PLANTS
Authors: SLADE P.
Published: July 2006

Summary. Paraquat dichloride was applied to maize, tomato and broad bean plants as droplets of an aqueous solution and analysed al intervals. It was shown to be degraded under some conditions, but the amount of degradation was least under conditions which would have been most favourable for metabolism of the chemical. The analytical results and results from cation‐exchange paper chromatography and thin layer chromatography showed that the degradation was caused by photochemical decomposition on the surface of the leaves of the plants, not by metabolism. The degradation was not observed in the dark, and only occurred to a significant extent in daylight in the summer.

Two photochemical degradation products from methyl‐labelled paraquat‐14C dichloride, viz., 4‐carboxy‐l‐(methyl‐14C)‐pyridinium chloride and methylamine‐14C hydrochloride, were isolated from plants sprayed with the herbicide.

Le devenir du paraquat dans les plantes traitées
THE ABSORPTION AND TRANSLOCATION CHARACTERISTICS OF SEVERAL PHENOXYALKYL ACID HERBICIDES IN BIGLEAF MAPLE*
Authors: NORRIS L. A. , FREED V. H.
Published: July 2006

Summary. Studies of the influence of formulation, degree of chlorination of the benzene ring and structure of the side chain of some phenoxyalkyl acid herbicides on absorption and translocation were made in a woody plant, Acer macrophyllum Pursh. In an experiment in which the leaves were treated with 2,4‐D or 2,4,5‐T as the acid, triethanolamine salt or 2‐ethylhexyl ester formulations, it was found that absorption increased with decreasing polarity of the molecule. The lower relative mobility of the ester formulations was offset by their greater absorption which resulted in greater accumulation in the roots when compared with the other herbicides. In treatments where dichlorprop or fenoprop formulated as the 2‐ethylhexyl esters were applied, a definite effect of chemical structure was observed on both absorption and translocation. The results of these tests and their implications in the response of big leaf maple are discussed.

Caractères de l'absorption et de la migration de quelques herbicides du groupe des acides phénoxyalkyles dans l'érable a grandes feuilles Acer macrophyllum Pursh.
STUDIES OF THE RESPONSE OF PLANTS TO ROOT‐APPLIED HERBICIDES
Authors: LYNDSAY RUTH V. , HARTLEY G. S.
Published: July 2006

Summary. Applications of several herbicides ‐were made to roots and to the bases of shoots of peas, cucumber, mustard and barley grown in soil, sand or water culture.

Localized applications (variation horizontal) of atratone and MCPA to roots of peas and barley in soil produced effects similar to those observed in water euluire, described in Pan I. Airatone killed the plants whether available to the whole or to only a portion of the root system whereas MCPA affected only the roots with which it was in direct contact, and growth continued when a portion of the root system was in herbicide‐free environment.

In water culture, MCPA was more effective when applied to the lower (younger) roots with the upper (older) roots kept dry than when twice the concentration was applied evenly to the whole root system in water. When all the roots were kept wet the effect of application to the upper roots was greater than the effect of application to the lower roots. The response of plants to atratone was not appreciably altered whether applications were made to the upper or lower parts of the root system in water culture. Variations in water level had little effect.

Even when the herbicide solution was confined to the stem or hypocotyl, atratone and DNOC were little, if any, less effective than when applied to roots. MCPA, both as ester and sodium salt, was significantly less effective.

Partial replacement of solution in the root zone by sand and air did not reduce the activity of atratone at a given concentration. Similar replacement in the zone of the stem or hypocotyl greatly reduced the effectiveness of all herbicides. When sand of low water content was used, atratone and MCPA‐sodium became quite ineffective via the stem, but DNOC and MCPA‐ethyl ester remained active.

Études sur les réactions de certaines plantes á des herbicides appliqués aux racines II. Observations nouvelles sur l'effet de l'application localisée.
STRUCTURE‐ACTIVITY RELATIONSHIPS OF ALKYL‐ PHENOL ETHYLENE OXIDE ETHER NON‐IONIC SURFACTANTS AND THREE WATER‐SOLUBLE HERBICIDES
Authors: SMITH L. W. , FOY C. L. , BAYER D. E.
Published: July 2006

Summary. Several alkylphenol ethylene oxide ether non‐ionic surfactants were tested in aqueous foliar sprays with dalapon, amitrole and paraquat for (heir enhancement of phytocidal activity against Zea mays L. With three homologous series of surfactants studied (octyl‐, nonyl‐ and laurylphenol types), the herbicide, the surfactant concentration and the hydrophilic constitution (ethylene oxide content) of the surfactant molecule all markedly influenced maximum toxicity. Smaller apparent differences in effectiveness were also attributable to the hydrophobic (alkylphenol) portion of the surfactant. The results arc discussed in relation to possible cuticle‐spray solution interactions and their influence on herbicide penetration.

Relations entre la structure et l'activite de produits tensio‐actifs non ionigues, a base d'éther d'oxyde éthylénique et d'alkylphénol, en présence de trois herbicides hydrosolubles
A NEW TECHNIQUE FOR THE ACCURATE AERIAL APPLICATION OF HERBICIDES TO DRAINAGE CHANNELS WITH NEGLIGIBLE SPRAY DRIFT
Authors: ROBSON T. O. , LITTLE E. C. S. , JOHNSTONE D. R. , HILL R. F.
Published: July 2006

Summary. Difficulties of access met with in Britain when applying dalapon to emergent water weeds in drainage channels led to work starting in 1964 on the development of a method of accurate aerial application of aqueous solutions of herbicide. The narrow, sinuous nature of the targets and the proximity of susceptible crops made it necessary to minimize spray drift and maintain a constant height and a slow speed. Nozzles designed to give large droplets were tested for droplet size and distribution. Selected nozzles were then tested from a helicopter in the field and the effect of their spray characteristics on the biological performance of dalapon was assessed. No daman occurred as a result of spray drift and satisfactory control of Phragmites communis, Typha angustifolia and T. latifolia was achieved with a lower dose of dalapon in a lower volume of spray than previously considered necessary for ground applications.

Une nouvelle technique pour l'application précise d'herbicides par voie aérienne sur les canaux de drainage, avec des risques négligeables d'entrainement
COMPARISION OF RATES OF PARAQUAT PRIOR TO DIRECT‐DRILLING CEREALS
Authors: JEATER R. S. L. , LAURIE D. R.
Published: July 2006

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 de dreales
FLUCTUATIONS IN THE CHEMICAL COMPOSITION OF TWO LAKEWEEDS FROM NEW ZEALAND
Authors: FISH G. R. , WILL G. M.
Published: July 2006

Summary. The mineral content of Elodea canadensis and Lagarosiphon major growing in two lakes near Rotorua showed seasonal variation and was influenced by the nutrient status of the water. Large quantities of L. major occur 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‐Zélande
STUDIES ON WEED SPECIES OF THE GENUS POLYGONUM L.
Authors: HAMMERTON J. L.
Published: July 2006

Summary. Seeds ni Polygonum lapathifolium from several sources or after certain treatments were subjected to various periods of moist chilling and then incubated for 3 weeks, during which time the numbers that germinated were recorded.

Populations from different localities differed in both seed weight and in the response of the seeds to chilling, but no relationships between the response and the environment of the locality of origin were found. Seeds from individual plants and from single inflorescences within populations also varied in both seed weight and germination with and without chilling. Application of dichlorprop to the parent plants was found to affect seed weight and % germination, the effect varying with both population and dose.

Etudes sur des espèces de mauvaises herbes du genre Polygonum L.

IV. Variations du poids et des modalités de germination des semences chez P. lapathifolium L.
UNTERSUCHUNGEN ZUR KONKURRENZWIRKUNG VON KULTURPFLANZEN UND UNKRAUTERN AUFEINANDER
Authors: KOCH W.
Published: July 2006

Summary. Pot experiments on the competitive effects of charlock (Sinapis arvensis L.) on oats and wild oat (Avena fatua L.) on barley had the following results:

(1) During the period up to tillering there was an appreciable effect of the weeds on crop growth with depression in plant weight of 10–15% from that in the absence of weeds.

(2) The greatest competitive effect occurred up to the middle of shooting of the cereals, when there were depressions in plant weight of 25–32%.

(3) After this stage, the competitive effects of the weeds were much less in pots with a high nutrient level, and at low nutrient level there was almost no competitive effect.

(4) The reduction in growth at the time of weeding was somewhat less at the low nutrient level than at the high nutrient level, and it is concluded that at the high level the competitive ability of the weeds was favoured more than that of the cereal crops.

(5) The cereals were not able to overcome the initial damage caused by the weeds even when the weeds were removed at the beginning of tillering. A partial recovery did how ever occur at the high but not at the low nutrient level.

(6) Both combinations, oats with charlock and barley with wild oat, behaved similarly, but some differences could be observed.

Compétition entre plantes cultivées et mauvaises herbes II. Action des mauvaises herbes annuelles sur les céréales