MOVEMENT OF 2,6-DICHLOROBENZONITRILE IN SOILS AND IN PLANTS IN RELATION TO ITS PHYSICAL PROPERTIES

Summary. The movement of the herbicide H133 (2,6-dichlorobenzonitrile) in soils and in plants is shown to be governed mainly by its relatively high volatility, its low solubility in water and its strong adsorption on lignin, on humic matter and on lipid material. Some evidence for a transformation of H133 in plants is presented.
Les déplacemcnts du 2,6-dichlorobenzonitrile dans les sols et dans les plantes et leurs relations avec les proriétés physiques     

THE EFFECT OF SOME SEED CHARACTERISTICS ON 2,6-DICHLOROBENZONITRILE TOXICITY

Summary Seeds of thirty-five species of plants were germinated in soil to which varying amounts of 2,6-dichlorobenzonitrile had been added and the doses reducing growth by 50% (GID₅₀) were obtained. An attempt was made to find correlations between growth rates, seed weights and fat contents and the GID₅₀ values. There was no significant correlation with fat contents, but there was a significant correlation of increasing growth rate with increasing susceptibility and a negative correlation of seed size with susceptibility. Seed size was inversely related to growth rate so the extent to which either factor affects the sensitivity of the plants is uncertain. There was no significant difference between the mean sensitivities of monocotyledons and dicotyledons to 2,6-dichlorobenzonitrile.
Effet de quelques caractéristiques de semences sur la toxicité du 2,6-dichlorobenzonitrile     

火生态因子与土壤动物关系的研究

１９９０．９─－１９９２．５对中国科学院内蒙草原生态系统定位站羊草草原、退化草原、大针茅草原的火烧实验研究中发现：火生态因子对表聚性强和地表自由生活的土壤动物的直接致死作用明显，春季火烧致死作用大于秋季，火烧有可能作为草原控制害虫的一种手段。火烧后出现了新的生态空间，促成了土壤动物竞争新空间的过程，其中优势类群的膜翅类表现的最为突出；常见类群的半翅类、鳞翅类等也参与了这一过程。火生态因子的间接作用使优势类群中的姬蚯蚓类，鞘翅类数量下降。火烧后的恢复过程各类土壤动物有所不同，膜翅类、鞘翅类等恢复较快，螨类等火烧后变化大，恢复较缓慢。火烧实验启发我们，严格控制下的火烧有可能作为合理利用草原的一种手段。     

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     

THE PERSISTENCE OF SIMAZINE APPLIED ANNUALLY IN THE PROLONGED ABSENCE OF SOIL CULTIVATION

Summary. Successive bioassays during 1966 and 1967 showed that simazine degradation reached 80% in 11 and 22i weeks, respectively, in soil from the 0–2 in. horizon of a gooseberry experiment to which simazine had been applied annually in the absence of soil cultivation from 1960. Where an annual farmyard-manure mulch was also applied, the same loss of residual activity was reached in 10 and 20 weeks. This mulch initially reduced the simazine level rapidly compared to that of unmulched soil, but the subsequent rates of degradation were similar. The rate of simazine degradation depended more on environmental conditions each year than on soil type. The results indicate that an annual simazine degradation in excess of 80% can be expected in Loughgall soils in conditions of non-tillage. Even if simazine applications continued indefinitely at an annual dose of 20 Ib/ac–the current dose in the gooseberry experiment–a large residue accumulation could not occur with or without a mulch.
Persistance de la simazine appliquée annuellement en l'absence prolongée de façons culturales     

THE HERBICIDAL EFFECT OF SOME SUBSTITUTED ANILIDES

Summary. The 3,4-dichloroanilides of four herbicidally active and of four inactive or weakly active phenoxyalkanecarboxylic acids were synthesized and tested for herbicidal activity, in order to study the effect of compounds comprising the two characteristic groupings within one molecule. 4-Chloro-2-methylphenoxyacetic acid, 2,4-dichloro-phenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid and a-[2,4,5-trichlorophenoxy] propionic acid were selected as representatives of active compounds; and phenoxyacetic acid, 2-methylphenoxyacetic acid, 3,5-dichlorophenoxyacetic acid and 2,4,6-trichloro-phenoxyacetic acid as inactive or weakly active compounds.
The compounds were tested in the glasshouse on wheat and white mustard as pre-and post-emergence treatments. The synthesized 3,4-dichloroanilides had no or little herbicidal activity, as compared with the high activity of the known herbicides 3,4-dichloropropionanilide and 2,4-dichlorophenoxyacetic acid. The conclusion can be drawn that the introduction of phenoxy groupings into the acid moiety of the active fatty acid-3,4-dichloroanilides as well as the introduction of the 3,4-dichloroaniline group into the carboxylic group of the active phenoxyacetic acids decreases herbicidal activity. This last phenomenon is probably due to a decreased ability to be hydrolysed.
L'activité herbicide de quelques anilides substituées     

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.     

除草剂农美利的稻田除草效果及生理作用

以 Facet(活性成份 quinclorac)为对照 ,测试了农美利的稻田除草效果。试验结果表明 :农美利是一个较优秀的直播稻田苗后除草剂 ,除草率可达 10 0 % ,适宜用量 2 mg/ m2 ,适宜使用时期为水稻一叶一心期～五叶一心期。对水稻的营养生长有一定的抑制作用 ,但其抑制效应是可逆的。农美利对水稻和稗草的生理影响研究结果表明 ,农美利的除草作用在于对光合速率、呼吸强度、叶绿素含量的影响 ,其强度在杂草与水稻之间有显著差异     

EFFECT OF TEMPERATURE ON THE ACTIVITY AND PERSISTENCE OF AMITROLE AND 2,4-D

Summary. One leaf of each of several tomato plants 5–6 weeks old maintained at 55, 70 or 85° F was dipped in 0.05 M amitrole or 0.005 M 2,4-D solution. The treated leaf was removed 1 week later. Scions taken from untreated plants were grafted to the treated plants at intervals up to 4 months after treatment.
Amitrole-treated plants maintained at 55° F were killed within 1 month but those at 70 and 85° F recovered.
Plants treated with 2,4-D showed typical symptoms when maintained at 70 and 85° F but no symptoms at 55° F. Scions grafted on plants maintained at 55, 70 and 85° F for 60 days after 2,4-D treatments exhibited typical symptoms. Grafts made more than 60 days following the 2,4-D application did not exhibit symptoms except a slight malformation on the plants held at 55° F.
New growth on the scions grafted up to 103 days after amitrole treatment on plants which had been maintained at 70 and 85° F exhibited typical amitrole symptoms (i.e. white foliage) but scions grafted after this lime did not. New shoots developing from buds on the treated plants also produced green growth 115 days after treatment but produced white foliage prior to that time.
Effet de la température sur l'activi'ité et la persistance de l'aminotriazole et du 2,4-D     

RELATION BETWEEN STRUCTURE AND HERBICIDAL ACTIVITY OF SUBSTITUTED BENZONITRILES

Summary. The herbicidal activity of substituted benzonitriles was determined by a number of tests. This activity was compared with the structure of the molecules. It was found experimentally that benzonitriles, substituted at the 2 and 6 positions by halogen or methyl, had the highest activity. Some 2,6-dichloro-1-substituted benzene derivatives showed a herbicidal activity, comparable with that of 2,6-dichlorobenzonilrile. These compounds possessed a group which could be converted into a nitrilc group.
La relation entre la structure ft l'activité herbicide des benzonitril-es substitués     

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     

香梨果实褐变与多酚氧化酶及酚类物质区域化分布的关系

在０℃、５℃及土窖中贮藏，香犁组织褐变果皮相对最重，果心次之，果肉不褐变。褐变部位的不均一性与多酚氧化酶活性和酚类物质在果实中分布的不均一密切相关。酶活性及底物含量在果实中的分布为果皮＞果心＞果肉＞。组织的褐变能力直接与底物的含量、酶活性的高低有关。     

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.     

稻田微蛛优势种与环境关系

1987、1989年研究发现,我国江南稻田微蛛有10种左右。其中食虫沟瘤蛛(Ummeliatainsecticeps)为各稻区优势种,在湖南占微蛛总量的90%左右;草间小黑蛛(Erigone graminco-lum)在周围环境棉田等较多的稻田(浙江萧山,湖南湖区)可成为优势种;驼背额角蛛(Gna—thonarium gibberum)在某些年晚稻后期(江苏苏州,湖南湘阴)可成为优势种;齿螯额角蛛(G·dentatum)则为千米以上海拔高度稻田(云南下关,贵州贵阳)的优势种;隆背微蛛等其他种类只在某些稻区常见或少见。农事活动和化学农药等只影响优势种和非优势种种群数量的增减,对优势种的形成不起主导作用。     

生态因素与钝绥螨种群数量关系及应用于防治桔全爪螨的研究

在柑桔园种植一种菊科杂草——藿香蓟覆盖地面,对桔全爪螨的重要天敌纽氏钝绥螨有明显的助长作用。柑园覆盖藿香蓟后,在夏季高温季节,可使柑桔树冠外围温度从40～45℃降至35℃以下,相对湿度增加;藿香蓟的花粉可供作钝绥螨的食料。这种小生境的改善,有利于钝绥螨种群的稳定和增长。藿香蓟草丛中的生态条件适合钝绥螨的生存繁殖,钝绥螨在藿香蓟叶片上的密度,常比在柑桔叶片上为高。在需要使用化学农药防治其他害虫或病害而引致柑桔树上的钝绥螨数量明显减少时,藿香蓟上的钝绥螨是一个重要的补充源泉。藿香蓟的生长抑制了其他杂草,大大减少用于除草的劳动力。藿香蓟可作绿肥,根系较浅,无明显与柑桔争肥现象。经多年试验,证明上述方法防治桔全爪螨的效果良好,目前这种措施已在广东省的一些柑桔产区应用。对柑桔害虫的综合防治,可利用钝绥螨防治桔全爪螨,对其他重要害虫如桔锈螨、柑桔潜叶蛾和柑桔木虱可通过采取选择性农药防治或农业技术防治而加以控制。     

用生物间遗传学研究水稻品种和稻瘟病菌之间的相互关系

在温室中,将供试的13个水稻品种和7个鉴别品种的幼苗用稻瘟病菌的11个菌株分别进行接种,以同等条件下鉴别品种对菌株的反应所确定的小种,作为供试品种对该小种的反应,然后应用生物间遗传学的原理和方法来推导品种和菌株的基因型。结果表明:供试的水稻品种和稻瘟病菌株(或小种)间存在17个限定性相应基因对,不同品种所含的抗病性基因数有所不同,其作用是在相应的无毒性菌株(或小种)存在情况下而表现出品种的抗病性基因愈多,可能表现的抗病力愈强。本研究结果为水稻抗稻瘟病育种选择抗原亲本以及生产上选用具有较多抗病基因的品种进行合理布局,提供了有重要参考价值的遗传学信息和依据。     

小麦化感作用物的提取,分离及其对白茅的杀除效果

小麦颖壳提取物经3520树脂分离后,对所得甲醇洗脱物离心,分得油类似物、上清液及沉淀物。前两个组分在300mg/L的浓度下,对白茅生长抑制率分别为100％和98％。上清液经硅胶柱分离,得7个亚组分,其中第1、3和7号亚组分在500mg/L浓度下对白茅生长的抑制率分别为95％、91％和95％。第3亚组分经葡聚糖凝胶柱分离,又分得A、B、C 3个组分,褐色粉末状的B组分在1000mg/L浓度下使白茅的生长量下降81％。从而证明小麦颖壳对白茅的化感作用是由多个化感物共同作用的结果。室内和温室及大田的测定结果表明,小麦颖壳中的甲醇洗脱物在24mg/株的剂量下对白茅生长的抑制率可达90％以上。这暗示,小麦颖壳中的甲醇可溶物可望开发成为防治白茅的生物除草剂。     

FACTORS INFLUENCING THE HERBICIDAL EFFICIENCY OF MCPA AND MCPB IN THREE SPECIES OF MICRO-ALGAE

Summary. The herbicidal activity of MCPA and MCPB was compared using three species of unicellular algae grown in liquid mineral salt medium. MCPB inhibited growth, respiration and phosphate uptake to a greater degree than MCPA and appears to be inherently toxic at concentrations of at least 2·5 × 10^?4 M. The enhanced activity of MCPB coincided with more efficient absorption. Uptake of both compounds appears to be optimal at pH conditions favouring movement as the undissociated molecule. Facteurs infiuencant l'efficacite herbicide du MCPA et du MCPB sur trois espèces d'algues micro-scopiques Résumé. L'activité herbicide du MCPA et du MCPB a été comparée en utilisant trois espéces d'algues unicellulaircs cultivées en milieu liquide renfermant des sets minéraux. Le MCPB inhibe la croissance, la respiration et l'absorption du phosphate à un degré plus éevé que le MCPA et il semble être essentiellement toxique à des concentrations d'au moins 2,5 × 10^?4 M. L'activité plus grande du MCPB coïncide avec une absorption plus complète. L'absorption des deux composés semble étre optimale aux conditions dec pH favorisant leur migration sans dissociation de la molécule. Faktoren, welche die hrbizide Wirkung von MCPA und MCPB gegen drei Mikro-Algen-Arlen beeinfiussen Zusammenfassung. Die herbizide Wirksamkeit von MCPA und MCPB wurde bei drci Arten einzelliger Algen, die in flüssigem Mineralsalzmedium angezogen wurden, vcrglichen. MCPB hemmt Wachstum, Respiration und Phosphataufnahme starker als MCPA und ist offcnsichdich in Konzentrationen von mindestens 2,5 × 10^?4 M absolute toxisch. Die bessere Wirkung von MCPB geht mit einer besseren Absorption parallel. Die Aufnahme beider Substanzen ist offensichtlich unter solchen pH-Bedingungen optimal, die den Transport in Form von undissozierten Molekülen begünstigen.