THE PERSISTENCE AND PENETRATION OF LARGE DOSES OF SIMAZINE IN UNCROPPED SOIL

Summary. The residues remaining in the soil from repeated annual application of simazine at 2–8, 5–6, and 22–4 kg/ha to uncropped plots on a loam soil were measured by chemical or bioassay methods at various intervals after treatment.
The total simazine residue present 12 months after the last of three treatments with 2–8 kg/ha and 8 months after the last of five treatments with 5–6 kg/ha was less than 10% of the annual dose. This rapid decomposition is considered consistent with the soil and climatic conditions. In contrast a much larger residue (a mean value of 1·7 kg/ha) was found on plots sampled 21/2 years after the last of two annual applications of simazine at 22·4 kg/ha and the reduction in the amount of residue during the next 12 months was only of the order of 25%.
In all treatments the highest concentration of simazine was found in the surface layers of the soil but measurable residues were detected to 60 cm depth, 31/2 years after the last 22·4 kg/ha application.
There was considerable variation in the total residues recovered between replicate plots and between different positions on the same plots in all treatments regardless of the depth of the sample. The possible causes of this variation are discussed.
Persistance et pénétration de fortes doses de simazine dans un sol non cultivé     

EVALUATION OF HERBICIDE PERSISTENCE IN SOIL*

Summary. The persistence of ten herbicides in soil was tested in the glasshouse over a 5–month period, using an oat bioassay. Simazine and diuron were highly persistent, atrazine persistent, fluometuron, trifluralin, bromacil and noruron moderately persistent, and pyrazon, prometryne and ametryne of short persistence. Six of these herbicides were also included in a field experiment consisting of logarithmically sprayed strips on which oats were sown at ten intervals of 1 month; changes of herbicidal activity with time were evaluated by measuring the length of the strip showing herbicidal injury. Results corroborate those of the glasshouse experiments except for trifluralin which was more persistent in the field. Disappearance curves were generally sigmoidal. The more persistent compounds showed a long period of slow disappearance followed by rapid disappearance.     

PERSISTENCE OF PHYTOTOXIC RESIDUES OF TRIAZINE HERBICIDES IN SOIL

Summary. A bioassay technique for the determination of phytotoxic residues of triazine herbicides and monuron in soil from field plots is described. The effect of a dilution series with untreated soil on shoot growth of Italian ryegrass ( Lolium multiflorum Lam.) is compared with that in a corresponding assay at the lime of application of the herbicide. This method was used to compare the persistence of residues of simazine, propazine, prometon and monuron, and to compare persistence in 3 years and in three soil types. The time required for disappearance of 80% of the activity following application of 2 lb/ac of simazine varied from 7 to 27 weeks, according to the year. Prometon was the most persistent of the triazines tested.
Persistance de résidus phyloloxiques d'herbicides à base de triazines dans le sol     

EFFECT OF CULTIVATION ON THE NUMBERS OF VIABLE WEED SEEDS IN SOIL

Summary. In a 6-year experiment with a naturally occurring population of viable weed seeds, the numbers in the top 9 in. of soil decreased exponentially from year to year in the absence of further seeding. The rates of loss were equivalent to 22% per year in undisturbed soil, 30% per year on plots dug twice a year (March and September) and 36% per year on those dug four times a year (March, June, September, December). Seed numbers of individual species also decreased exponentially, although not all at the same rates.
On the dug plots, the numbers of seedlings that emerged each year decreased exponentially once the regimes had become established. The proportions of the viable seeds which gave rise to seedlings in the course of a year were 7 % on plots dug twice and 9 % on those dug four times a year; although there was some variation, these proportions remained much the same from year to year. On undisturbed soil the number of seedlings that emerged declined rapidly, and in the 4th year represented no more than 03% of the viable seeds still present in the top 9 in. of soil.     

THE RELATIONSHIP BETWEEN THE HERBICIDAL EFFECT OF 2,6-DICHLOROBENZONITRILE AND ITS PERSISTENCE IN THE SOIL

Summary. A series of experiments with 2,6-dichlorobenzonitrile is described. It is demonstrated that 2,6-DBN is highly phytotoxic when applied as a soil drench or preemergence spray in the greenhouse, but measurement of crop and weed responses in the field, accompanied by quantitative assessment of the chemical residues in the soil, indicates that the persistence of 2,6-DBN following surface application is short under both tropical and temperate (winter) conditions. It is, however, extended from a few days to several weeks if the chemical is incorporated into the soil immediately after application. Under tropical conditions the effect of 4 lb/ac applied to the surface is roughly equated to 2 lb/ac immediately watered-in, 1.5 lb/ac immediately raked-in, or 1 lb/ac both watered- and raked-in, and a delay of 4 hours between application and incorporation is shown to reduce the effectiveness of the chemical by about half. The lack of persistence of 2,6-DBN when applied to the soil surface, and the modifying influence of soil incorporation and watering is attributed to its high vapour pressure (5 × I0⁻⁴ mm Hg at 20° C) and its relatively low solubility in water (20 ppm at 25° C).
Le rapporl entre l'activité herbicide du 2,6-dichlorobenzonitrile et sa persistance dans le sol     

地产蛭石在干旱地区直接施用的研究

本试验利用地产混合蛭石直接施入土壤,观察蛭石的不同用量对土壤主要物理性状,土壤持水力、土壤水分常数,根区速效养分,作物生理功能及产量等综合影响的结果表明:每放施用地产混合蛭石240kg,120kg与对照比较,不仅分别增产15.5%、13.43%,而且还可改善种子品质。     

THE EFFECTS OF SOIL CULTIVATION TECHNIQUES ON THE GROWTH AND YIELD OF THE RASPBERRY CROP

Summary. Five management systems for the control of weed and sucker growth were compared over 8 years in a plantation of raspberries (Rubus idaeus) grow-n on the stool system. Traditional intensive cultivations consistently produced the tallest cane, which contributed to that treatment outyielding all others for the first 5 cropping years. Reduced cultivation systems, involving rotary cultivation and hoeing, or simazine and hoeing, outyielded non-cultivation systems which depended on herbicides alone. Lower numbers of fruiting canes, as well as poorer cane quality on non-cultivated plots, were associated with failure to remove raspberry sucker growth between the stools during the growing season on these plots. The introduction of mechanical removal of between-stool growth considerably improved the yield of one uncultivated treatment. Possible beneficial effects of cultivation included the improvement of cane growth by ridging the crop, the concentration of crop growth in the stool itself by regular pruning of extension growth into the alleys and between the stools, and the prevention of competition between fruiting cane and suckers growing outside the stool area. Analysis of the component operations of the old system shows that their useful features can be incorporated into modern systems of mechanised plantation management which depend largely upon herbicides for weed control. Les effets des techniques culturales du sol sur la croissance et le rendement du framboisier Résumé. Cinq systémes de conduite du désherbage et de limitation des drageons ont été connpariés durant 8 années dans une plantation de framboisiers (Rubus idaeus) conduite selon le systéme des pieds-méres. Les façons culturales intensives traditionnelles produisirent les tiges les plus développdes, comme il est logique, ce qui contribua à I'obtention, par ce mode de culture, d'un rendement suptérieur à tous les autres pendant les cinq premières années. Les systèmes mettant en oeuvre des façons culturales réduites, parmi lesquelles la houe rotative et le sarclage ou la simazine et Ie sarclage, donnerènt des rendements supèrieurs à ceux n'utitisant que des herbicides sans faêons culturales, Sur les parcclles non cultivtées un nombre plus faible de tiges fructifères et une moins bonne quality des tiges ont Hi associes é l'absence d'enl Hement des drageons poussant entre les pieds méres, pendant la période croissance, dans ces parcelles. L'enlevément mécanique de ces drageons poussant entre les pieds méres augmenta considér a blement le rendement d'un traitement sans façons culturales. Les effets bénéfiques possibles des façons culturales sont dus à ramélioration de la croissance des tiges par le buttage, à la concentration de la croissance dans les pieds méres eux-mémes par Elimination des repousses dans les allées et entre les pieds de framboisiers, et à la prevention de la compétition entre les tiges fructiféres et les drageons poussant en dehors des pieds méres. L'analyse des opérations effectuées dans l'ancien systéme montre que leurs caractéristiques usuelles peuvent être introduites dans les systémes modernes de conduite mécanisée des plantations qui font une importante utilisation des herbicides pour effectuer le déshcrbage. Der Einfluss von Bodenbearbeitungsmcissnahmen auf das Wachstum und den Ertrag von Himbeeren Zusammenfassung. In einer Himbeerpflanzung (Rubus idaetts) mit Stockerziehung wurden fünf Be trie bs form en bezüglich der Unkrautbekämpfung und des Wachstums der Schösslinge über einen Zeitraum von acht Jahren verglichen. Die traditionellen intensiven Bear bei tungsm ass nahm en brachten durchweg die grössten Sträucher. So übertraf diese Behandlungsweise alle andercn während der ersten fünf Anbaujahre. Systeme mit vermindcrter Bodenbearbeitung, hierzu zählen Frasen und Hacken oder Simazin und Hacken, úbertrafen Systeme ohne Bodenbearbeitung, in denen nur Herbizide eingesetzt wurden. Neben einer geringeren Anzahl von beerentragenden Straüchern und einer geringeren Qualität der Sträucher auf den unbearbeiteten Parzellen blieb noch die Entfernung des Schösslingswachstums zwischen den Stöcken wahrend der Wachstumspcriode in diesen Parzellen aus. Die Einführung einer mechanischen Entferniing des Wachstums zwisehen den Stöcken verbesserte den Ertrag einer unbearbeiteten Variante beträchtlich. Mögliche positive Effekte der Bodenbearbeitung beinhalten die Verbesserung des Wachstums der Sträucher durch Furchenbildung, die Konzentriening des Wachstums auf den Stöck selbst durch regelmassiges Entfernen des weiteren Wachstums in den Reihen und zwischen den Stöcken und das Verhindern einer Konkurrenz zwischen fruchttragenden Sträuchern und Scbosslingen, die ausserhalb des Stockbereiches wachsen. Eine Analyse der Teilwirkungen des alten Systems zeigt, dass dessen nütliche Bestandteitc in die modernen Systeme der mechanisierten Anbauformen, welche hauptsächlich auf einem Einsatz von Herbiziden zur Unkrautbekämpfung beruhen. Einbezogen werden können.     

THE PERSISTENCE AND MOVEMENT OF FLUORODIFEN IN SOILS AND PLANTS

Summary. Miller clay and Lufkin sandy loam soils were treated with fluorodifen (4-nitrophenyl 2-nitro-4-trifluoromethylphenyl ether) at 3–4 and 5 kg/ha. The disappearance was monitored using electron-capture gas chromatography. Less than 10% of the herbicide remained 6 months after application. Persistence was increased by incorporation in the loam but not in the clay soil. Little leaching was detected in either soil. Fluorodifen was applied to both roots and leaves of soybean (Glycine max (L.) Merr.), grain sorghum (Sorghum vulgare Pers.), peanut (Arachis hypogaea L.) and morning glory (Ipomoea purpurea L.). The herbicide was absorbed by the treated tissue, but limited trans-location into other plant parts was detected by gas chromatography, autoradiography and liquid scintillation spectrometry. Following root application, higher concentrations of fluorodifen were found in the lower stems of morning glory and grain sorghum than in other species. La persistance et la migration du fluorodifene dans divers sols et plantes Résumé. De I'argile de Miller et des sols sablo-limoneux de Lufkin ont été traités avec du fluorodiféne (4-nitrophényl 2-nitro-4-trifluorométhylphényl éther) à 3, 4 et 5 kg/ha. La degradation a été suivie en utilisant la chromatographic en phase gazcuse avec détecteur à capture d'électrons. Aprés 6 mois d'application il ne fut détecté que moins de 10% de l'herbicide. La persistance fut accrue par l'incorporation dans le sol limoneux mais non dans le sol argileux; il ne fut mis en évidence qu'un faible lessivage dans les deux sols. Le fluorodifene fut appliquéà la fois sur les racines et sur les feuilles du soja (Glycine max (L.) Merr.), le sorgho à grains (Sorghum vulgare Pers.), l'arachide (Arachis hypogaea L.) et le volubilis (Ipomoea purpurea L.). L'herbicide fut absorbs par les tissus traites, mais il ne fut décelé qu'une migration limitée dans les autres parties de la plante, au moyen de la chromatographie en phase gazeuse, de l'autoradiographie, et de la spectrométrie à scintillation liquide. A la suite d'application par les racines, les concentrations de fluorodifene constatées dans les tiges basses du volubilis et dans le sorgho à grain furent supérieures à celles trouvées dans les autres espéces. Persistenz und Translokation von Fluorodifen in Böden und Pflanzen Zusammenfassung. Miller-Ton und Lufkin-Lehmboden wurden mit 3,5 und 5 kg/ha Fluorodifen (4-NitrGphenyl 2-nitro-4-trifluoromethyIphenylather) behandelt. Der Verlust der Aktivsubstanz wurde mit Hilfe der Elektroneneinfang-Gaschromatographic bestimmt. Sechs Monate nach der Behandlung waren weniger als 10% der ursprünglich ausgebrachten Aktivsubstanz noch nachweisbar. Die Persistenz war im Lehmboden, nicht jedoch im Tonboden, durch Inkorporation erhöht; in keinem Boden war nennens-werte Einwaschung zu beobachten. Fluorodifen wurde bei Sojabohnen (Glycine max (L.) Merr.), Körner-Hirse (Sorghum vulgare Pers.), Erdnuss (Arachis hypogaea L.) und Ipomoea purpurea L. sowohl über das Blatt als auch über die Wurzel angewandt. Das Herbizid wurde in das brhandelte Gewebe aufgenommen. Es erfolgte jedoch nur cine geringe Translokation in andere Pflanzenteile, wie die Untersuchung mit Hilfe der Gaschromatographic, Autoradio-graphic und Flüssigkeits-Scintiliations-Spectrometrie ergab. Nach Wurzelapplikation wurden in den unteren Sprossteilen von Ipomoea purpurea und Sorghum vulgare grössere Fluorodifen-Konzentrationen gefunden als bei den anderen Arten.     

FACTORS RESPONSIBLE FOR THE TOLERANCE OF BLACKCURRANTS TO SIMAZINE

Summary. Evidence is presented that blackcurrants show a considerable tolerance to simazine when the entire root system is exposed to a uniform concentration of the herbicide in sand and water culture. The tolerance of this species under field conditions does not therefore seem to be primarily due to root development being limited in the surface soil to which simazine is applied. Accordingly, experiments were carried out using simazine, labelled in the ring with ¹⁴C, to determine whether there were restrictions to the uptake of the herbicide by the roots and its translocation to the xylem sap and leaves, and whether there was extensive breakdown of simazine in the plant. The results of these experiments are compared with those on two susceptible species, barley and marrow.
Although simazine appeared to be metabolized to a greater extent in blackcurrants, and was less readily translocated from the roots, than in the susceptible species, a substantial proportion of the labelled material in the leaves was present as unchanged simazine. Studies on the effects of simazine on the rate of transpiration of detached leaves of the three species suggested that in blackcurrants there was a restriction to movement of the herbicide from the conducting tissue in the leaves to the mesophyll; this was confirmed by autoradiographs. It is suggested that this restriction, combined with partial breakdown of the herbicide in the leaves, may be responsible for the tolerance of blackcurrants to simazine.
Résistance du cassissier à la simazine     

THE USE OF ADSORBENTS AND SIMAZINE ON NEWEY PLANTED STRAWBERRIES

Summary. A series of field trials was conducted to determine if the tolerance of newly planted strawberry runners to simazine could be increased by placing adsorbents in the vicinily of the root zone at planting time. Powdered steam-activated charcoal was found to be the most suitable of seven adsorbents tested. Dipping the roots of runners in charcoal before planting was more effective and practicable than placing a similar quantity of charcoal around each runner at planting time. No significant damage was recorded in several trials in which dipped runners were sprayed with simazine at 1 lb/ac within a few days of planting.
Although new roots are likely to take up the herbicide as they grow away from the charcoal-protected area around the plant, the protection provided by the adsorbent appears to be sufficient to enable the young plants to develop satisfactorily.
Utilisation d'adsorbants et de simazine sur des fraisiers récemment plantés     

禾谷丝核菌在土壤中生长的研究

 1980年从小麦发病的茎秆上分离到病菌,并对小麦等多种植物进行了致病力测定。     

THE INFLUENCE OF SIMAZINE ON SHOOT AND ROOT GROWTH OF APPLES AND PLUMS

Summary. In loamy soil with a low humus content (0·8% organic carbon) simazine at a concentration of 2'5 ppm reduced growth of shoots, roots and trunk diameter in 1-year-old scions of five apple varieties on M IX rootstock. The most susceptible was Cox's Orange Pippin; 5 ppm was lethal for this variety only. In experiments with vertically divided pots, where one part of the root system developed in soil with simazine (2–5 ppm and 5–0 ppm for apple and 5·0 ppm for plum) and the other part in simazine-free soil, there was less effect on shoot growth and less leaf damage than where all the soil contained simazine. Growth of that part of the root system in soil containing simazine was stimulated.     

NOTE ON THE BIOASSAY OF CHLORPROPHAM IN SOIL

Summary. A method for the bioassay of chlorpropham in soil from field plots is described which involves the preparation of mixtures of treated soil with untreated soil and the determination of the dilution required to produce 50% inhibition of primary root growth in buckwheat ( Fagopyrum esculentum Moench). Using this method, it was found that the period required for 90% disappearance of chlorpropham from a sandy foam ranged from 3 to 14 weeks, according to the prevailing temperature and soil moisture conditions. When applications of 1 and 2 lb/ac were compared, the percentages of chlorpropham remaining at any one time were similar.
Dosage biologique du chlorpropham dans le sol     

耕作措施对江苏棉麦二熟田天敌种群数量影响的研究

1987～1988年在江苏省盐城棉、麦二熟田研究的结果表明,大麦和棉花的收割及收割前后的耕作措施是影响害虫天敌种群数量的主要因素。夏季大麦收割后大量天敌随麦株运走,如将收割下来的麦株在田间放置一定时间,天敌就可逐渐转移到棉株上而保留下来,棉花收获后,原有捕食性天敌即大量转移或死亡。棉茬地种植越冬作物,增加地面覆盖是保护天敌越冬,大量增加来年天敌数量的有效措施。     

涕灭威在棉籽和土壤中的残留研究

采用气相色谱火焰光度检测器测定了涕灭威及其有毒代谢物在棉籽和土壤中的残留,并对文献报道的方法作了改进。该方法的回收率为85—105％。在棉籽和土壤中的最小检测量分别为0.006ppm和0.004ppm。两年内在8个地区进行涕灭威在棉花上的田间和小区试验结果表明,涕灭威主要滞留在0—10cm的土壤中,最高检出量为0.039ppm,而残留量与施药量呈正相关;在施药量大于1.2kg/ha时,棉籽中有涕灭威检出,平均检出量为0.023ppm,最高检出量为0.035ppm。     

THE EFFECT OF CHLORMEQUAT SEED-PARENT TREATMENT ON THE RESISTANCE OF WHEAT SEEDLINGS TO TERBUTRYNE AND SIMAZINE

Summary. The effects of pre-sowing treatments with terbutryne (4-ethylamino-2- niethylthio-6-t-butylamino-1,3,5-triazine) and with simazine (2-chloro-4,6-bisethyl-amino-1,3,5-triazine) on seedling mortality of wheat grown from regular seed and from seed containing about 40 ppm chlormequat (2-chloroethyl trimethylammonium chloride), due to a late chlormequat treatment of the seed-parent, were tested in two pot experiments. In another pot experiment the effects of pre-sowing and post-emergence treatments of terbutryne on dry matter accumulation and moisture content in SPT (= Seed-Parent Treated) and regular wheat seedlings were examined.
No significant differences in simazine resistance between regular and SPT seed were found. However, there was a marked and significant increase in terbutryne resistance of SPT over regular seeds, which was expressed by a longer period to 50% seedling mortality as well as by a lower daily increase in mortality. Growth retardation, caused by pre- sowing as well as by post-emergence terbutryne treatments, was appreciably less in the SPT seedlings than in the regular ones. The higher terbutryne resistance of the SPT seedlings may be attributable to their higher moisture content induced by the chlormequat.
Effet du traitement des pieds meres avec le chlorméquat sur la résistance des plantules de blé a la terbutryne et à la simazine     

SOIL EROSION AND THE WATER & SOIL CONSERVATION IN THE LOESSIAL HILLY AREA OF SOUTHERN NINGXIA

<正> 1. General Situation of Soil Erosion The loessial hilly area of southern Ningxia, Situated at the south of Ningxia Hui Au-tonomous Region, middle-upper reaches of the Yellow River, part of Chinese Loess Pla-teau, covers an area of 1500 square kilometers with an annual mean temperature of 5-8℃,a precipitation of 300-500mm of which 70% taking place concentratively during the peri-od between June and September in form of rainstorm, The annual evaporation is     

OCCURRENCE AND PERSISTENCE OF PICLORAM IN GRASSLAND WATER SOURCES

Summary. At 2 weeks following application, concentrations of picloram in surface runoff water collected adjacent to a South Texas grassland treated with 1·1 kg/ha ranged from 0·055 to 0·184 ppm as detected by gas chromatography. Picloram in surface runoff water diminished with time and amount of rainfall as a decay function. Picloram was not detectable in a flowing stream 0·8 km below a 32-ha area treated with 1·1 kg/ha. Residual picloram was not detected in domestic water wells at any time up to 2 years following treatment of adjacent areas with 1·1 kg/ha.
Dissipation of picloram from treated livestock-watering ponds was concentration-dependent, with the final losses resulting largely from dilution. Initial loss rates in the ponds ranged from 14 to 18%/day but decreased to less than 1%/day at 100 days following treatment. After 100 days, when the concentrations were less than 0·005 ppm, the primary changes in picloram content appeared to be due to dilution from rainfall or to concentration by runoff from adjacent treated areas.