Variations in composition of pasture herbage

Changes in the chemical composition of pasture samples from five dairy farms were observed over a 2-year period. Many of the minerals were at their lowest concentration in samples taken in the spring and early summer. At these times the concentrations of P, Mg and Na were often less than sufficient to meet the calculated requirements of the dairy cow fed on pasture alone. Cu and Co concentrations in the herbage were also generally low relative to the needs of the dairy cow.     

Population and classification of intrapopulation units of helminths

The study of the population problems revealed that the population is an elementary evolution unit of a species with biparental way of reproduction. This is a general theoretical definition which the author elaborated in detail for the helminths. With regard to the complicated intraspecific structure of these parasites also the classification of intrapopulation helminth units is proposed.     

On the topical problems of species in general and in relation to helminths

In the light of the present knowledge of species, the author suggests to accept ten features of species and the general definition of species proposed by Zavadsky (1961, 1968), together with the definition by Mayr (1940) characterizing more concretely the species at the level of biparentally reproducing organisms. The definition by Timofeeff-Ressovsky et al. (1973) may be used for exclusively autogamous species of helminths. From the viewpoint of the species as a taxonomic unit, the paper presents proposals for establishment of a practical standard which would better suit the theoretical idea about the helminth species than it was the case till the present.     

Rouging wild oats

Over a period of three seasons the effectiveness of rouging wild oats in cereal crops with a patented herbicide glove was compared with hand pulling. Time spent by one operator in searching for the wild oats was found to remain relatively constant at 1.25–1.5 h/ha over a wide range of wild oat populations. If this searching time was excluded, treatment of the actual wild oat panicles was about three times as fast with the glove (1450/h) as by hand-pulling (538/h). The implications of this and of the saving in time spent in carrying off and disposing of’pulled’ wild oats are discussed. Solutions of 5% and 10% w/v glyphosate applied to either the stem or the panicle of the wild oats prevented the formation of viable seed. It did not, however, prevent some inviable wild oat seed appearing in the harvested grain; without additional cleaning these would have prevented the sale of the grain for seed but not into E.E.C. intervention. Extirpation de la folle-avoine Durant one période de trios saisons, les auteurs ont compare l'efficacité de l'extirpation de la folle avoine dans des cultures de céréales au moyen d'un gant herbicide breveté et en pratiquant I'arrachage manuel. Le temps passé par un opérateur à la recherche des pieds de folle-avoine s'est révélé relativement constant: 1,25 à 1.5 h/ha pour un large échantillonnage de populations de folle-avoine. Si l'on enlève ce temps de recherehes, I’operation sur les panicles présentes de folleavoine a été environ 3 fois plus rapide avec le gant (1 450/h) quä la main (538/h). Les conséquences de ce résultat et de lëconomie de temps passéâ transporter et â détruire les plants de folleavoine arrachees sont discutées. Des solutions de glyphosate à 5% ou 10% (poids pour volume) appliquées soit sur la tige soit sur la panucle des follesavoines ont empèche la formation de semences viables. Toutefois, cette opération n'empeche pas la présence d'un certain nombre de semences non viables de folle-avoine dans le grain recolté; sans nettoyage supplémentaire, ces graines d'adventices auraient empéché la commercialisation du grain récolté comme semence, mais pas à I'intérieur de la C.E.E. Manuelle Bekämpfung von Flughafer über drei Vegetationsperioden wurde die effizienz der manuellen Flughaferbekämpfung in Getreidebestanden mit hilfe eines ‘herbizid-Handschuhs’ verglichen mit dem Aufwand beim Jäten von Hand. Die von einer Arbeitskraft benötigte Zeit für das auffinden der Flughaferpflanzen blieb über einen weiten Bereich der Besatzdichte an Flughafer mit 1,25–1,5 h/ha verhältnismässig konstant. Lässt man diesen Zeitaufwand uberücksichtigt, dann erfolgte die Behandlung der Flughaferrispen mit dem Handschuh etwa dreimal so schnell (1450/h) wie durch Jäten von hand (538/h). Die hieraus sowie aus der Ersparnis an Zeit, die sonst für Abtransport and Ablagerung der gejateten Flughaferpflanzen benötigt worden wäre, zu ziehenden Folgerungen werden diskutiert. Lösungen von 5% oder 10% (Gew./Vol.) Glyphosat entweder am Halm oder an der Rispe der Flughaferpflanzen angebracht. verhinderten die Bildung von keimfahigen Samen. Sie konnten aber nicht verhindern. dass dem Getreide nach der Ernte einige nicht keimfähige Flughafersamen beigemengt waren. Hierdurch bedingt wäre ohne zusätzliche. Reinigung ein Verkauf des Getreides als Saatgut nicht möglich gewesen, wohl aber ein Verkauf an die EG-Interventionsstelle.     

An evaluation of sand-culture techniques for studying the tolerance of fruit crops to soil-acting herbicides

Sand-culture techniques for determining the tolerance of fruit crops to herbicides applied to the roots were investigated. Of the methods examined, a single application to pots with a closed drainage system was the most useful provided they were protected from rain. A semi-automatic system for applying herbicides was developed for use where repeated treatment was required. Visual scoring of plant condition was the most informative method of assessing response and was reliable. Results correlated well with weight measurements of leaves, shoots or whole plants. For each herbicide ED50 values were derived from dose-response curves and used to express relative tolerance. The slopes of these curves provided an indication of the rate of change of response with dose. The relative tolerance of a range of fruit crops to simazine corresponded to known relative tolerance in field conditions in the U.K. It is concluded that sand-culture techniques can be used as a preliminary screen to find new soil-acting herbicides for perennial crops and to detect differences in tolerance between cultivars. They also enable the direct influence of plant and seasonal factors on response to root-applied herbicides to be studied. Large numbers of treatments can be tested in a small area with the certainty of obtaining positive results. Evaluation des techniques de culture sur sable pour l'étude de la résistance des cultures fruitières aux herbicides agissant par le sol Les auteurs ont étudiè les techniques de culture sur sable pour déterminer la résistance des cultures fruitiéres aux herbicides racinaires, Parmi les méthiodes examinées, celle comportant une seule application, avec un systéme clos de drainage, s'est révélée la plus pratique, à condition qu'elle comporte une protection contre la pluie. Un systéme semi-automatique pour l'application des herbicides a été mis au point pour les cas où des traitements répétés sont nécessaires. L'observation visuelle du comportement de la plante s'est montreée la méthode la plus instructive pour apprécier les réactions; c'est aussi une méthode súre. Les résultats ont montré une bonne concordance avec les mesures pondérales des feuilles, des pousses, ou des plantes entiéres. Pour chaque herbicide, les valeurs de la E.D. 50 ont ét? déduites des courbes de réaction en fonction de la dose et utilisées pour exprimer la résistance relative. La pente de ces courbes a fourni une indication sur le taux de modification de la réaction en fonction de la dose. La résistance relative d'une série de cultures fruitiéres ? la simazine a correspondu ? la résistance relative constatée au champ dans les conditions du Royaume-Uni. Il en est conclu que les techniques de culture sur sable peuvent être utilisées comme tests de sélection primaire pour découvrir de nouveaux herbicides agissant par le sol pour le désherbage des cultures pérennes, ainsi que pour déceler les différences de résistance entre cultivars. Ces techniques rendent ègalement possible l'étude de l'influence directe de la plante et des facteurs saisonniers sur les réactions aux herbicides racinaires. De nombreux traitments peuvent ètre étudiés sur une surface réduite avec la certitude d'obtenir des résultats positifs. Beurteilung von Sandkulture-Techniken für die Untersuchung von Obstgewächsen aufihre Toleranz gegenüber Bodenherbiziden Es wurden Sandkultur-Techniken zur Bestimmung der Toleranz von Obstgewächsen gegenüber bodenapplizierten Herbiziden geprüft. Von den geprüften Methoden war die einmalige Herbizidgabe zu Gefässen mit einem geschlossenen Drainage-system das brauchbarste Verfahren, unter der Voraussetzung. daß die Gefässe vor Regen geschützt waren. Für die Fälle, in denen eine mehrmalige Herbizidapplikation zu erfolgen hat, wurde ein halbautomatisches System entwickelt. Das informativste und zuverlässigste Auswertungsverfahren war die visuelle Bonitur. Die Ergebnisse waren mit Messungen des Gewichts, der Blätter, Sprosse oder der ganzen Pflanzen gut korreliert. Für jedes Herbizid wurden mit Hilfe von Dosis-Wirkungskurven ED₅₀-Werte ermittelt und als Maß der relativen Toleranz benutzt. Die Steigung der Dosis-Wirkungskurven ermöglichten es. die Abhängigkeit von Aufwandmenge und Reaktion zu erfassen. Bei einer Reihe von Obstgewächsen entsprach die relative Toleranz den Werten. die in Großbritannien unter Feld-bedingungen ermittelt wurden. Die Ergebnisse lassen den Schluss zu, dass Sandkultur-Techniken als erster Schritt bei der Suche nach neuen Bodenherbiziden in mehrjährigen Kulturen verwendet werden können, womit auch Toleranzunterschiede zwischen Sorten erfasst werden können. Derartige Verfahren ermöglichen es auch, den Einfluss von Pflanzen und Klimafaktoren auf die herbizidwirkung zu studieren. Mit diesen Techniken können auf kleiner Fläche brauchbare Ergebnisse erzielt werden.     

The effects of paraquat and glyphosate residues in sprayed herbage on the development of seedlings of a normal and a paraquat-tolerant variety of Lolium perenne

Paraquat and glyphosate were sprayed on to simulated swards in a glasshouse experiment. Residues of these herbicides depressed emergence, growth and survival of Lolium perenne seedlings sown after spraying.
Residues of paraquat applied at a rate (1·5 kg ha^-1) within the range normally used for sward destruction killed nearly all seedlings of a normal L. perenne variety, Barlenna, but had much less effect on the paraquat-tolerant variety, Causeway. It was estimated that Causeway was almost nine times as tolerant of paraquat residues as Barlenna. Sowing at a depth of 20 mm gave some protection against paraquat residues. A delay of 10 d between spraying and sowing had equivocal effects. It was concluded that residues of paraquat used for killing swards before direct drilling may hinder the establishment of normal L. perenne varieties but not of paraquat-tolerant varieties.
Residues of glyphosate had equal effects on the two varieties and the effects were severest on seedlings sown on the soil surface immediately after spraying. It is thought to be unlikely that glyphosate residues in sprayed herbage would be a problem in direct drilling.     

The effect of time of initial defoliation and height of defoliation on the productivity of perennial ryegrass swards

Over a 3-year period the productivity of perennial ryegrass ( Lolium perenne L., cv. S24) swards as influenced by variations in the time of initial defoliation and close (2·5 cm) and lax (8 cm) defoliation was studied. Treatments with initial defoliations in the early vegetative stage, stem elongation and flowering stages of growth gave higher annual yields than treatments in which the initial defoliation was taken at an intermediate stage of growth when the majority of the stem apices had just been elevated above the height of defoliation. Initial defoliation treatments which removed a high proportion of apical meristems while the yield at the initial defoliation was still low produced the lowest annual yield. Consistent lax defoliation reduced yield by 14·5% compared with continual close defoliation. However, taking an initial lax defoliation followed by subsequent close defoliations produced a slight yield advantage of 4·8% over consistent close defoliation. The results are discussed in relation to other research findings and the practical implications commented upon.     

Regulating the content of white clover in mixed swards using grass-suppressing herbicides

A preliminary investigation evaluated six grass-suppressing herbicides applied on two occasions in late winter to a predominantly ryegrass ley containing only 15% ground cover of white clover. Substantial increases in clover growth, estimated visually, and flower head numbers per unit area were recorded in the first summer after treatment with 2·8 kg ha^-1 carbetamide, 0·8 kg ha^-1 propyzamide and 0·6 kg ha^-1 paraquat. To achieve these increases, visual estimates suggested that spring growth of grass was reduced by 40–80%. However, grass growth recovered fully by mid-summer on the majority of the treatments.
The following year five of the herbicides were compared in a field experiment. Dry matter (DM) and nitrogen (N) assessments of the grass and legume components were made at three harvests in the first growing season and a single harvest in the second year. Carbetamide, paraquat and, especially, propyzamide increased the proportion of clover in the DM (to 89% in the case of 1·2 kg ha^-1 propyzamide); in general, using herbicides to raise clover contents above 20% lead to reductions in spring grass growth of about 70%. However, such reduction was offset by subsequent increased growth so that total annual yields were largely unaffected. The increased legume content resulted in an increased N concentration in both grass and legume components, measured in the second summer. At this time, the greatest increase in total N yield (up to 35%) was recorded from 0·6 kg ha^-1 propyzamide. Potential uses to achieve legume dominance by grass-suppression are suggested and the needs for further research are outlined.     

The influence of sowing date, harvest date and seed rate on the yield of forage peas

A series of preliminary trials is described to assess the potential and some of the cultural requirements of new cultivars of forage peas grown as pure stands in the west of Scotland. Optimum sowing date was late March for harvesting 15 weeks later to leave sufficient of the growing season for a catch crop or the establishment of a grass sward. Yield of dry matter (DM) at harvest was approximately 6 t ha^-1 but DM concentration varied greatly with season. The digestibility of the organic matter was of the order of 0·700 and the crude protein concentration in the DM 170 g kg^-1. DM yield increased with increasing seed rate up to 200 kg ha^-1 the maximum rate tested.     

The Effects of Wind on the Extension Growth of Pinus contorta Douglas

The effect of wind on the extension growth of young Pinus contortawas investigated using a controlled environment wind tunnel.Extension rates of leader and lateral shoots were reduced byabout 20 per cent by high wind speed. The ratio of the finallength of the laterals to that of the leaders (‘apicalcontrol’) was unaffected, as was the radial growth ofstems. Water potentials were slightly higher in plants subjectto high wind. In another experiment, rates of needle extensionwere reduced 30 per cent by wind. The experiments are discussedin relation to field observations by others and it is arguedthat wind is a potent ecological factor adversely affectingtree growth.