A COMPARISON OF METHODS OF RECORDING HERBACEOUS WEEDS IN WEED CONTROL EXPERIMENTS

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     

五氯酚钠防除稻田杂草的试验

在旱秧田、水秧田、旱直播田和水直播田的试验中,播前施用五氯酚钠,每公顷5—20公斤,除草效果不够良好。但在插秧本田的试验中,插前每公顷施用五氯酚钠15—30公厅对防除稗草(Echinochloa crusgalli (L.) Beauv.)和球穗莎草(Cyperus globosus All.)的效果极为良好。以在插秧前一天,每公顷施用30公斤效果最好,对稗草和球穗莎草的防除效果分别达到92.7%和79.6%。插后处理,每公顷施用五氯酚钠15公斤,效果也较好。另外的试验,观察了五氯酚钠不同剂型:颗粒剂、混土、溶液等的防除效果。防除稗草用颗粒剂和混土处理要优于溶液处理;防除球穗莎草则以溶液处理为最好。各处理对水稻均无药害,所有用五氧酚钠处理区的产量均高于不除草区,但较两次人工除草的为低。本文讨论了在秧田和直播田用五氯酚钠防除稗草效果较差的原因。     

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     

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     

水稻恶苗病防治研究

水稻恶苗病近年来成为陕西汉中地区影响水稻产量的严重病害。1979年前后,曾在早金凤5号等品种上严重发生,病苗率高达43.40%。1981年又在杂交稻的威优系统上严重危害,勉县东风公社发病面积占插秧面积的76%,较重田块病株率20～30%。1982年全地区发病较重面积16.2万亩,严重地威胁着水稻生产,成为一个亟待解决的问题。一、汉中地区恶苗病的诊断1982年,很多社队从秧田阶段起就陆续出现数量较多的徒长苗、矮化苗及高度虽基本正常,但苗黄瘦弱等多种类型。移栽大田后,仍不断出现苗期类似症状及早穗型,枯     

麦田阔叶杂草经济阈值及防除研究

作者对麦田阔叶杂草调查结果表明,麦田常发生阔叶杂草２０种,为害严重的８种,发生特点是前早、中缓、后快。作者选用高重积作为麦田阔叶杂草群落划分的标准。研究表明,阔叶杂草的各项生物指标经相关检验,以鲜重与小麦产量间关系密切。     

杂交水稻对杂草的生态控制作用

杂交稻田有杂草3～4种，杂草覆盖度为1.6%，分别比粳稻田低66%和95%。杂交稻汕优63对鸭舌草、矮慈姑和水竹叶的控制效果平均为89%。在无芒稗50株/m     

应用楝科植物防治柑桔害虫试验

本文应用楝科植物(印楝、川楝、苦楝)种籽油及其抽提物对柑桔木虱及其他害虫进行一系列的忌避拒食及触杀作用试验,证明印楝油有明显的忌避及拒食作用。印楝油对柑桔潜叶蛾有良好的防效。印楝、川楝及苦楝油对柑桔红蜘蛛也有较强的触杀作用。应用楝科植物杀虫剂可兼治几种害虫,对人畜安全,不污染环境,不会引起抗药性的产生,而且对害虫天敌也比较安全。