THE USE OF A LOW DOSE OF ATRAZINE ALONE AND IN MIXTURES WITH OTHER HERBICIDES IN THE MAIZE CROP

Summary. Linuron, 2,4-D-aniine, propachlor, pyriclor and cypromid, singly and mixture with atrazine, were compared with atrazine and fluromidine alone for effectiveness of weed control in maize on Oxford clay soil. Pre-emergence applications were made under wet conditions and atrazine, even at 0·28 kg/ha a.i. gave an excellent control of three main weeds, Stellaria media, Veronica spp. and Polygonum aviculare , and at 0·56 kg/ha also killed Aethusa cynapium. Fluromidine was comparable with atrazine, but linuron,2,4-D-amine, propachlor and pyriclor were less effective. Post-emergence treatments were less satisfactory. High doses of atrazine were needed for good weed control. Acynapium was resistant to pyriclor and cypromid and P. aviculare to fluromidine. 2,4-Daminewas ineffective, but atrazine/2,4-D-amine mixtures were more effective than the individual components for the control of P. aviculare. Pyriclor, at 0·56 kg/ha pre-emergenceand cypromid at 2·24 kg/ha post-emergence directly reduced the yield of the crop.
Utilisation de I'atrazine à faible dose, seule et en mélange avec d'autres herbicides, dans les culturesde maïs     

THE DEVELOPMENT OF SELECTIVE HERBICIDES FOR KALE IN THE UNITED KINGDOM

Summary. The purpose of this paper is firstly to describe the background of an investigation started in 1961 to develop new herbicides for the control of weeds in agricultural kale, Brassica oleracea vars. acephala D.C. and fruticosa Metz, and secondly to present the results of four experiments concerned with the effects of weeds on the yield of kale. The results of the herbicide investigation are to be presented in subsequent papers.
Kale as grown in the United Kingdom is a valuable fodder crop and relatively easy to grow, but beset by weeds against which existing mechanical and chemical methods of control have not usually been successful. The effect of weed competition on the yield of four farmers'crops was investigated in 1961 and 1962. When grown entirely free of weeds, the crops provided yields in the range of 20.9–34.5 tons of green material per acre. Where no attempt was made to control the weeds, the yields were reduced by 9.4, 14.5 and 18.9 tons/ac, respectively, in three experiments. In no case did kale, hoed only between the rows, produce as high a yield as the weed-free crop. Although variable in effect, uncontrolled weed growth early in the life of the crop always lowered the yield of kale.
Le développement de l'usage des herbicides selectifs pour le chou fourrager dans le Royaume-Uni. La plante cultivée, les mauvaises herbes et le problème     

THE DEVELOPMENT OF HERBICIDES FOR POTATOES

Summary. Since 1961 the Weed Research Organization has been testing and developing herbicides for weed control in potatoes. Inthe three experiments which are reported, herbicides were compared with other forms of weed control. The first experimentin 1961 was exploratory and compared yields following hand-weeding versus no weed control versus several promising herbicides. The highest yield was produced by the hand-weeded crop. Several herbicide treatments applied before crop emergence gave useful selective weed control.
Assuming weed control to be necessary, selected herbicides were then compared in 1962 and 1963 with conventional mechanical cultivations. In both years successful weed control by herbicide resulted in a higher yield of potatoes than did mechanical cultivation although the soil-acting chemical used in 1962 caused some crop damage. The 1963 experiment included triangular planting patterns, at normal and high plant densities. Increases both in gross and marketable yield were obtained at normal plant density with the triangular arrangement as compared with the row crop. The high plant population resulted in the largest gross yield but a lower yield per plant and smaller average tuber size.     

除草剂二元混用的增效评价及配方控制的研究

作者介绍了除草剂二元混用的增效评价方法和配方控制的研究结果。参照型评价方法的比较研究指出,Colby 法、类 Colby 法(MSM)、双参数法、剂量换算法(ADM)和回归分析法均能不同程度地反应出除草剂混用的增效作用,其中类 Colby 法的准确性较差,剂量换算法和 Colby 法较好。Colby 法的优点是计算简单。微分法正确表达了除草剂相互作用的内在关系,在理论上更为正确,具有估价相互作用的性质、大小和来源以及控制最佳配方等多种功能。剂量—反应回归多项式可控制配方区间和最经济配比,这一控制方法的精度可满足统计学要求。     

SELECTIVITY OF SOME NEW HERBICIDES FOR DIRECT-SEEDED FLOODED RICE IN THE TROPICS

Summary. Granular formulations of several new herbicides were tested for control of weeds in direct-seeded tropical rice. S -(4-chlorobenzyl)- N N -diethylthiolcarbamate (benthiocarb) and N -(butoxymethyl)-2-chloro-2',6'-diethylacetanilide (CP 53619) showed a high degree of selectivity between rice and weed seedlings. Applied 6 days after seeding, when grass weeds were at the 1-2-leaf stage, both herbicides gave excellent control of Echinochloa crus-galli and other weeds, and caused little or no damage to rice cv. IR22.     

青海高原农田野燕麦发生特点及除草剂应用技术的初步探讨

本文对青海高原农田野燕麦的发生特点,如出苗、生长发育、繁殖和传播、种籽抗逆性等进行了初步试验。为认识野燕麦的危害性和制定防除措施提供了依据。在化学除草方面,试验了十几种除草剂和不同的应用条件,初步认为“深埋药”、“狠抓水”、“防耗损”、“促生长”是保证药效的重要环节。对旱地除草剂的应用有一定参考意义。     

THE USE OF THREE SIMPLE,RAPID BIOASSAYS ON FORTY-TWO HERBICIDES*

Three rapid bioassays were tested on forty-two herbicides having several different modes of action. A 50% or greater inhibition of growth was found at 1 ppm with thirty-one herbicides in one or more of the bioassays. Of the remaining eleven herbicides, seven were detected at 10 ppm, two at 20 ppm and two at 30 ppm. The techniques used were a Chlorella bioassay, a root bioassay with sorghum, oat and cucumber and a shoot bioassay with sorghum and oat. The duration of the bioassays was 1, 2 and 4 days respectively. As a general rule, the Chlorella bioassay was especially sensitive to photosynthetic and respiratory inhibitors but not sensitive to herbicides with other modes of action, whereas the root and/or shoot bioassays were sensitive to most of the herbicides except the photosynthetic inhibitors. The use of the three bioassays simultaneously is suggested as a possible method for primary screening of herbicides.     

THE CONTROL OF WEEDS IN TEA BY HERBICIDES IN MAURITIUS

Summary. Weed control experiments carried out in tea plantations showed that diuron at doses 2·4, 3·2 and 4·8 lb/ac a.i. resulted in better and more persistent weed control than siamazine.
Shoot absorption experiments carried out on three tea jats, dark, medium and light, showed that the tea jats differed in their tolerance to both diuron and simazine, the light one being the most susceptible.
A difference IN the expression of phytotoxic effects between leaf and root absorption was observed for diuron only. At equivalent doses, 2-year-old plants were in general more susceptible to diuron than to simazine.
Diuron and simazine used alone at 2·4, 3·2 and 4·8 lb/ac a.i. or with addition of sodium chlorate at 6 lb/ac to improve the kill of emerged weeds, did not affect yield of either pruned unpruned 6-year-oId tea. Dalapon, on the other hand, at 6 lb/ac significantly reduced the yield of unpruned tea but not of pruned lea.
Le désherbage chimique du théè l'lle Maurice     

大豆苗前除草剂多元混用的研究

本试验采用5因素、5水平的正交回归旋转设计的方法,于1983—1984年在哈尔滨、佳木斯和牡丹江地区的850农场作了5种大豆苗前土壤处理防草剂多元混用的研究。结果表明,一元(单用)时,异丙甲草酸、豆科威和茅毒的效果好,而Galex与Codal较差。多元混用时,以中等用量混用为好。在亩产超过100公斤的165个混用组合中,81.2％的组合出现在不用Galex的情况下,多数组合集中在茅毒、豆科威、异丙甲草胺和Codal的中等水平上。     

A COMPARISON OF THE 'VIBRAJET' NOZZLE AND A FAN JET FOR OVERALL APPLICATION OF BIPYRIDYL HERBICIDES

Summary. The 'Vibrajet' nozzle is designed to produce relatively large droplets with 'low drift' characteristics. This system was evaluated for the overall application of paraquat, diquat and morfamquat in a number of agricultural situations in comparison with a fan jet. The biological efficiency achieved with the 'Vibrajet' nozzle was of the same order as that of the fan jet at the rates of application of the herbicides currently recommended in the United Kingdom. Five variables which affect the field performance of a spray system were investigated: volume of spray applied, concentration of wetter in the spray, rate of chemical applied, spray pressure and size of orifice. Changes in these factors made little improvement to the biological efficiency of the 'Vibrajet' nozzle.
Comparaisnn de la buse 'Vibrajet' et d'une bitse pinccau pom Vapplication generalisee des herbicides bipyridiliques     

THE CONTROL OF WEEDS IN POTATOES BY PREEMERGENCE APPLICATION OF HERBICIDES

Summary. Trials in 1959, 1960 and 1961 failed to show significant differences in yield between potatoes (Solanum tuberosum L.) of three varieties receiving from seven to nine separate tractnr cultivations and similar potatoes in which the weeds were well controlled by pre-emergence applications of a mixture of dinoseb(6.0 lb/ac)*and dalapon (2.5-5.0 lb/ac), With less effective herbicide treatments. including simazinc and 2,4-DES, there were significant reductions in yield.
Preliminary taint tests in 1959 on cooked tubers suggested that slight tainting might have been caused by one of the treatments, but tests on potato crisps made from the 1959 and 1960 crops were completely inconclusive. Tubers from all the treatments in the 1959 and 1960 trials sprouted normally in the spring after harvest.
Le désherbage des pommes de terre par des herbicides de pré-émergence     

THE DEGRADATION OF TRIAZINE AND URACIL HERBICIDES IN SOIL*

Summary. The rates of degradation of three triazine and two uracil herbicides were followed at 13·2 and 31·2°C in one soil. Soil was treated with 8 ppm of 2-chloro-4-ethyl-amino-6-isopropylamino-1,3,5-triazine (atrazine), 2-chloro-4,6-bisethylamino-1,3,5-triazine (simazine), 2-mcthylthio-4-ethylamino-6-isopropylamino-1,3,5-triazine (ametryne), 3-sec-butyl-5-bromo-6-methyluracil (bromacil) and 3-tert-butyl-5-chloro-6-methyluracil (terbacil) and monthly samples analysed chemically to determine the amounts remaining. Evaluation of the rate constant at two temperatures permitted calculation of the energy of activation from the Arrhenius equation. It was determined to a first approximation that soil degradation followed a first order rate law with no lag period and that the rate could be related to molecular structure. The energies of activation in kcals/mole were: atrazine 10-8, simazine 9-2, ametryne 6-1, bromacil 3-0, and terbacil 6-1. These values suggest breakage of the common carbon-chlorine bond in atrazine and simazine but breakage of a different bond in ametryne. Examination of bond energies and known mechanisms of breakdown for triazines supported the hypothesis of breakage of the bond at the two position. The data on decomposition of the uracils indicate that the carbon-halogen bond was broken in each molecule. Dégradation des triazines et des uraciles herbicides dans le sol Résumé. Les taux de dégradation de trois triazines et de deux uraciles herbicides ont été observés α 13,2 et 31,2° C dans un sol. Ce sol a été traitéà la concentration de 8 ppm avec la 2-chloro-4-éthyIainino-6-isopropylamino-1,3,5-triazine (atrazine), la 2-chloro-4,6-biséthylamino-l,3,5-triazine (simazine), la 2 méthylthio-4-éthylamino-6-isopropylamino-1,3,5-triazine (amétryne), le 3-sec-butyl-5-bromo-6-méthyluracile (bromacil) et le 3-tert-butyl-5-chloro-6-méthyluracile (terbacil). Des échunlillons ont été analysés chimiquement tous les mois pour déterminer les résidus. L'évaluation du taux constant à deux températures a permis le calcul de l'energie d'activation d'aprés l'équation d'Arrhenius. Selon une premiére approximation, la dégradation a suivi une loi de taux de premier ordre sans période de retard et le taux peut être reliéà la structure moléculaire. Les énergies d'activation en kcals/mole furent: atrazine 10,8, simazine 9,2, amétryne 6,1, bromacil 3,0 et terbacil 6,1. Ces valeurs suggérent une rupture d'une liaison carbone-chlore dans I'atrazine et la simazine mais la rupture d'une liaison différente dans l'amétryne. L'examen des énergies de liaison et des mécanismes connus de dégradation pour les triazines amène à formuler l'hypothése de la rupture d'une liaison en position deux. Les résultats relatifs aux uraciles indiquent tjue la liaison carbone-halogéne a été rompue dans chaque molécule. Der Abbau von Triazin- und Uracilherbiziden im Boden Zusammenfassung. Die Abbaurate von 3 Triazin- und 2 Uracilherbiziden im Boden wurde bei 13,2 und 3l,2°C untersucht. Aus dem mit 8 ppm 2-Chlor-4-athylamino-6-isopropylamino-1,3,5-triazin (Atrazin),2-Chlor-4,6-bisathylamino-[3,5-lriazin (Simazin), 2-Methyllhio-4-athylamino-6-isopropylamino-1,3,5-triazin (Ametryn), 3-scc-Butyl-5-brom-6-methyluracil (Bromacil) und 3-tert-Butyl-5-chlor-6-methyluracil (Terbacil) behandelten Bodenrückständen wurden monatlich Proben entnommen und chemisch die Rückstände erniittelt. Die Bestimmung der Geschwindigkeitskonslantcn bei zwei Temperaturen eriaubte die Borechnung der Aktivicrungscnergic nach der Arrhenischen Gleichung. In erster Annäierung verlief der Abbau als Prozcss erster Ordnung ohne Latenzphase und die Abbaurate stand in Beziehung zur Struktur des Molekuls. Die Aktivierungsenergie betrug fur Atrazin 10,8, Simazin 9,2, Ametryn 6,1, Bromacit 3,0 und Terbacil 6,1 kcal/Mol. Diese Werte lassen für Simazin und Atrazin einen Bruchder der bcide Herbizide gemeinsamen Kohlensloff-Chlorbindung vermuten, wahrend im Falle des Ametryn eine andere Bindung hiervon betroffen war. Die Prufung der Bindungsenergien und der bekannten Abbau me chanismen bei Triazinen unterstCitzcn die Hypothcse, dass der Bruch in der 2-Position erfolgte. Die Ergebnisse fur die Uracile deuten darauf hin, dass bei beiden Moleküien der Abbau an der Kohlenstoff-Halogenbindung ansetzte.     

宁夏黄土高原风沙区畜牧业发展的资源、环境问题及对策

本文对宁夏黄土高原风沙区着重从大农业生态经济系统中人口、资源和环境间协调的角度出发,探讨该区畜牧业的主要自然和人为限制因素及产生的问题,畜牧业发展的潜力及今后的主要对策等。     

THE SPEED OF ATTAINMENT OF SORPTION EQUILIBRIA IN SOME SYSTEMS INVOLVING HERBICIDES

Summary. Measurements were made of the time taken for equilibrium to be established during adsorption and desorption under aqueous slurry conditions using monuron, linuron, atrazine and chlorpropham with a variety of adsorbents. An appreciable time was taken for equilibria to be established in adsorption processes, although with one exception, this period was 24 hr or less. Desorption processes were generally rather slower and in seven cases out of eighteen equilibrium was apparently not established in 72 hr. However, in all but two cases it seemed likely that the sorption process was reversible or nearly so.
Possible explanations for differences of equilibrium times are discussed together with implications the results might have on the interpretation of leaching phenomena.
Vitesse à laquelle est atteint I'équilibre d'adsorption et de désorption dans certains systèmes impliquant des herbicides     

SOME ASPECTS OF THE USE OF BARBAN FOR WILD OAT CONTROL IN WINTER WHEAT

Summary. A study of the emergence and development of Avena fatua in winter wheat showed that after the mild winter of 1960/61 autumn-germinated wild oats constituted a far more serious weed problem than spring-germinated plants. It was concluded that the application of barban should be timed in relation to these autumn-germinated plants. As an extension of their work on spring cereals, the authors investigated the effect of barban on the yield ratio of winter wheat and cultivated winter oats grown as a mixture. A reduction in the oats fraction as a result of barban treatment was accompanied by an increase in wheat giving a total yield which was almost the same as untreated. Experimental data are also presented on the occurrence, and significance of an interesting variation in crop tolerance during the winter. No obvious correlation was found between increased crop sensitivity and development stage or temperature. The capacity of the crop to recover was found to be high.
Quelques données sur l'utilisation du barbane dans la lutte contre la folle avoine dans le blé d'hiver