化学除草药害的预防与解毒

除草剂使用不当 ,发生药害的机率是很高的。因此 ,必须慎重地施用化学除草剂。第一 ,要认真选准除草剂。除草剂的品种繁多 ,有杀单子叶杂草的 ,有杀双子叶杂草的 ,有兼杀两类杂草的。不同除草剂的杀草功能是有区别的。如种植的水稻、玉米等单子叶作物 ,应选用以除双子叶杂草为主的除草剂 ;种植的棉花、大豆、花生、芝麻、瓜类等双子叶作物 ,应选用以除单子叶为主的除草剂。对下茬作物有影响的除草剂 ,应区别不同茬口选择施用。第二 ,要严格掌握施药时间和浓度。属芽前除草的 ,要在作物播种后出苗前施用。属芽后除草的 ,在作物子叶展开后即可…     

河南省南阳市草坪主要杂草种类与防除

2002~2004年采用目测法对南阳市区及辖区7个县市的1.2万m2草坪杂草种类及分布进行调查并统计。结果表明,主要杂草有22科49种,其中单子叶杂草2科11种,双子叶杂草20科38种,危害较重的有香附子、狗牙根、马唐、狗尾草、牛筋草、艾蒿等。根据杂草分布情况,提出对该地区草坪杂草进行综合防除措施。     

化学药剂防除花生田杂草技术

化学药剂防除花生田杂草技术王克（河北滦县植保站，０６３７００）花生是滦县主要经济作物，历年播种面积２７万亩左右，据调查我县花生田杂草以单子叶禾本科马唐为主，占８０％以上，其次是牛筋草、稗草、狗尾草、莎草等，少数农田有多年生杂草白茅、芦苇草等。双子叶杂...     

河北省谷子田常见杂草种类及发生规律与化学防除

采用随机区组试验方法,进行谷田杂草常见种类调查,并对其中主要发生种类的发生规律进行了研究.结果表明,河北省谷田常见杂草38种,分属15个科,发生基数较大的杂革有20种.春播谷田以双子叶杂草为主,占杂草总数的60.08％,夏播谷田以单子叶杂草为主,占杂草总数的64.38％.春播谷田杂草发生有3个蜂期,分别为5月中旬,6月下旬,7月上、中旬.夏播谷田杂草发生仅1个峰期,一般为7月上、中旬;其化学防除以44％单嘧·扑灭WP1 800 g/hm2为最经济、有效使用剂量,可有效防控整个谷子生长期的杂草.     

单轴等效线法评价精喹禾灵与灭草松相互作用的研究

为正确评价单子叶杂草防除剂与双子叶杂草防除剂的相互作用,以精喹禾灵与灭草松混用为实例对等效线法进行了改进,提出单轴等效线法及其增效倍数的计算方法。该研究结果表明,两种药剂混用对马唐Digitaria sanguinalis和反枝苋Amaranthus retroflexs均有增效作用,其平均增效倍数分别为0.42和0.34。采用单轴等效线法可以正确评价单子叶杂草防除剂与双子叶杂草防除剂的相互作用。     

麦田杂草损失率测定及防除指标研究

近几年来,由于耕作制度的变化,稻麦连作面积扩大和麦田少免耕技术的逐步推广,麦田杂草群落也发生了很大变化,草害也逐年加重。我市80年代后期麦田杂草以猪殃殃、繁缕、芥菜等双子叶杂草为主,占总草量的gi．92％。随着稻一麦一稻耕作制面积的不断增大,禾本科杂草逐年加重,看麦娘、硬草。棒头草等已成为稻茬麦田的主要杂草群落。1994年调查,禾本科杂草已占杂草总数的54．9％。麦田杂草已衍化为单双子叶杂草混生群落为主。为了解单双子叶杂草对小麦产量的影响。单双子叶杂草之间的相互关系,及单双子叶杂草混生条件下的防除指标,我们…     

麦田阔叶杂草新型除草剂：巨星的性能及施用技术

麦田阔叶杂草新型除草剂──巨星的性能及施用技术湖北省植保总站顾卫东麦田杂草主要有单子叶杂草和双子叶杂草（阔叶杂草）两大类。多年进行的麦田化学除草，多数是针对单子叶杂草的。这样的麦田杂草草相发生了变化，单子叶杂草得到了有效地控制，而阔叶杂草成为优势群落...     

土壤消毒剂防除烤烟苗床杂草试验

用土壤消毒剂98%溴甲烷、32.7%维博亩水剂、32.7%威百亩水剂、98%棉隆颗粒剂、35%威百亩水剂对烤烟苗床土壤进行处理,播种后20 d,6种药剂对单子叶杂草的防效分别为56.78%、80.42%、75.36%、63.64%、81.78%,对双子叶杂草的防效分别为79.28%、86.21%、89.02%、81.52%、88.69%。播种后40 d 6种药剂对单子叶杂草的鲜重防效分别为75.39%、81.67%、80.27%、72.64%、82.38%,对双子叶杂草的鲜重防效分别为85.25%、92.46%、90.58%、82.69%、91.47%;方差分析结果表明,35%威百亩水剂、32.7%维博亩水剂和32.7%威百亩水剂防效相当,但与溴甲烷、棉隆的防效差异达极显著水平。     

江苏省如东县油菜田杂草的发生与防除研究

研究结果表明。江苏省如东县油菜田杂草有l0科20种，优势种群为硬草和繁缕。田间有3个出草高峰，一峰在油菜栽后l0～15d。二峰在油菜栽后45—55d。三峰在第二年春季气温回升后。化除药剂，土壤处理以都尔为最好。其次是油除，第三是丙广；茎叶处理。好实多对双子叶杂草有较好的防效，盖草灵和稳杀得对单子叶杂草有较好的防效，盖草灵 好实多对单子叶杂草和双子叶杂草均有较好的防效。因此在化除时应根据田间不同的草相。选择相应的除草剂品种。     

济宁市麦田杂草种类及优势种

济宁市麦田杂草共28科77种,蕨类植物1科1种,双子叶植物23科56种,单子叶植物4科20种。杂草种类和数量较多的为禾本科(15种)和菊科(8种),分别占杂草总数的19.5%和10.4%。     

Major Changes in Fusarium spp. in Wheat in the Netherlands

The re-emergence of fusarium head blight throughout the world and especially in Western Europe prompted a survey of the situation in the Netherlands. To allow for a high throughput screening of large numbers of samples, a diagnostic PCR method was developed to detect the most common species of Fusarium occurring on wheat. Seven primer pairs were tested for their ability to identify isolates of Fusarium avenaceum, F. culmorum, F. graminearum, F. poae, F. proliferatum and Microdochium nivale var. majus and M. nivale var. nivale. Each primer pair only generated a PCR product with the corresponding Fusarium species and all PCR fragments had different molecular sizes. This allowed the generation of these amplicons using a mixture of all seven primer pairs. The robustness of this multiplex PCR encouraged us to screen a large series of isolates collected in 2000 and 2001. In both years 40 fields were sampled leading to a collection of 209 isolates from 2000 and 145 isolates from 2001. The results of the multiplex PCR demonstrated that F. graminearum was the most abundant species in the Fusarium complex on wheat in both years. This is in sharp contrast to reports from the 1980s and early 1990s, which found F. culmorum as the predominant species. Primers derived from the tri7 and tri13 genes, which are implicated in the acetylation and oxygenation of the C-4 atom of the backbone of the trichothecene molecule, were used to discriminate between deoxynivalenol and nivalenol (NIV) producers. The populations of F. culmorum and F. graminearum both showed a slight increase in NIV-producers in 2001.     

Effects of temperature onPhytophthora porri in vitro,in planta,and in soil

Cardinal temperatures for mycelial growth ofPhytophthora porri on corn-meal agar were <5 (minimum), 15–20 (optimum) and just above 25 °C (maximum). The number of infections after zoospore inoculation of young leaf plants was relatively low at supra-optimal temperatures, but was not affected by sub-optimal temperatures. Even at 0 °C plants were infected. The incubation periods needed for symptom formation were 36–57 d at 0 °C, 13–18 d at 5 °C, and 4–11 d at > 11 °C, and were fitted to temperature between 0 and 24 °C with a hyperbolical model (1/p=0.00812^*T+0.0243). Oospore germination, reported for the first time forP. porri, was strongly reduced after 5 h at 45 °C, and totally absent after 5 h at 55 °C. Soil solarization for six weeks during an exceptionally warm period in May–June 1992 in The Netherlands raised the soil temperature at 5 cm depth for 17 h above 45 °C, but did not reduce the initial level of disease in August significantly.     

Chemical Weed Control in Tobacco in Trinidad

Abstract

Ramie, the vegetable fibre, is obtained from the stem of Boehmeria nivea (L.) Gaud, and is used in many textile products. It is grown in tropical, sub-tropical and temperate regions and the main countries where it is grown are China, Brazil and the Philippines. However, it is only a minor crop in terms of world trade. The diseases of ramie are discussed in relation to their occurrence, symptoms and control measures. The major and most widespread diseases are white fungus caused by Rosellinia necatrix, leaf spot caused by Cercosporo spp. and Phyllosticta spp., seedling rot caused by Rhizoctonia solani, cane rot caused by Macrophomina phaseolina and eye rot caused by Myrothecium roridum. A number of diseases of minor importance are also reviewed.     

Viruses of pepper in plastic houses in Crete

During a survey of virus diseases affecting pepper grown in plastic houses in Crete, during 1984–1986, tomato mosaic virus (ToMV) and tobacco mosaic virus (TMV) were detected. The most common virus was TMV, being present in samples of alle pepper cultivars carrying the L₁ resistance gene, while ToMV was isolated only from susceptible pepper cultivars. According to responses ofCapsicum spp. the isolates from 640 samples checked were classified into three pathotypes: P₀, P_1.2 and P_1.2.3. Results of this study show that P_1.2 represents at present the major threat to the Cretan pepper industry.Samenvatting Bij een in de jaren 1984–1986 gehouden inventarisatie van virusziekten in paprika in plastic-foliekassen op Kreta werd zowel het tabaksmozaïekvirus (TMV) als het tomatemozaïekvirus (ToMV) aangetoond. TMV kwam zeer algemeen voor: het werd aangetroffen in alle monsters van de paprikarassen met het resistentiegen L₁. ToMV werd alleen geïsoleerd uit planten van vatbare paprikarassen. Volgens de waargenomen symptomen die de isolaten van 640 monsters opCapsicum spp. vertoonden, konden de isolaten in drie pathotypen, nl. P₁, P_1,2 en P_1,2,3, worden geklassificeerd. Uit het onderzoek is gebleken dat P_1,2 de belangrijkste bedreiging vormt voor de teelt van paprika op Kreta.     

Buried seeds in arable soils in Scotland

Soil from arable areas in Scotland was examined macroscopically for seeds. In terms of the percentage of sites at which they were recorded, Chenopodium album L. (33%), Poa annua L. (22%), Polygonum aviculare L. (41%), Polygonum persicaria L. (39%), Spergula arvensis L. (42%) and Stellaria media (L.) Vill. (44%) were the most common species found. They accounted for 78% of the seeds recovered. There were eighty different species found over the 5 years of the survey. Estimated total weed populations (m^?2) ranged from nil to 170000 with an average of 16000 m^?2 in the top 20 cm of soil.     

会宁剖面MIS3阶段黄土元素地球化学特征及气候变化

在会宁剖面元素地球化学数据分析和气候替代指标分析的基础上，重建了会宁地区约20～70 ka的古气候特征和序列。研究表明：Ba、Rb、Sr、Ti、Fe₂O₃、SiO₂、Al₂O₃、MgO、K₂O等在剖面上都有随深度的减小含量随之增加的趋势；CaO、Na₂O等在剖面上有随深度的减小含量随之减小的趋势。MIS3气候略显温湿，可划分为3个阶段：早期(L₁S₁S₂)，55.5～45.9 ka，气候为弱温湿；中期(L₁S₁L₁)，45.9～27.3 ka，气候为干冷；晚期(L₁S₁S₁)，27.3～23.8 ka，气候为温湿；会宁剖面较明显地记录了5次Heinrich事件。     

玛纳斯河流域绿洲土壤春季盐渍化研究

运用经典统计学和冗余分析方法,对玛纳斯河流域绿洲土壤全盐量（TS）、pH、电导率（EC）、钠吸附比（SAR）和盐分离子组成的空间分布特征进行了分析。结果表明：土壤全盐量呈现明显的底聚特征,各层土壤全盐量均值在5.80~9.02 g•kg^-1,表现为轻度至中度盐化;各层土壤中,pH在8.2~8.4、EC在0.70~1.38 mS•cm^-1、SAR在0.25~0.64,未出现碱化现象。冗余分析表明：不同层次土壤中,Ca ²⁺与SO ₄^2-、Na⁺与SO₄^2-保持较好的关联性。TS的空间分布,在 0 ~70 cm 全剖面上主要受控于Na^+、SO₄^2-、Ca ²⁺和Mg ²⁺;分层与全剖面的情况略有不同,但Na⁺、SO₄^2-在各个土层仍为最主要的控制离子。EC在全剖面上的空间分布受控于 Na⁺、SO₄^2-;50 ~70 cm 土层主要受Na⁺与Cl^-的控制,其他土层与全剖面相同。 pH受控于CO₃^2-;除0~10 cm土层受HCO^-₃影响外,其他土层与全剖面相同。SAR在全剖面的空间分布受环境因子的影响较小,除50~70 cm土层受Cl^-因子的制约外,0~50 cm土层未表现出明显的控制因子。     

Recent Progress in Breeding for Fireblight Resistance in Apples and Pears in North America1

Resistance in apple is evaluated by needle–inoculation of succulent shoot tips with 10⁶–10⁷ cells of a virulent isolate of Erwinia amylovora (Burr.) Winslow et al. (the incitant of fireblight) and measurement of the resulting cortical lesion when extension is complete. Data are now available on practically all commercial cultivars, some of which have a useful level of resistance. Some newer cultivars, particularly those with resistance to scab (Venluria inaequalis [Cooke] Wint.) derived from Malus floribunda, have good resistance to E. amylovora. A very high level of resistance is present in Asiatic Malus species, including M. x robusta, M. x sublo–bata, M. x atrosanguinea, and M. prunifolia, and in the North American species M. fusca. This type of resistance appears to be inherited polygenically, and because of its detectability in young seedlings can be used conveniently in breeding. Objectives of pear breeding programs are aimed at developing superior fruit quality combined with resistance to fireblight, psylla, and Fabraea leaf spot. Many high quality cultivars of Pyrus communis are extremely susceptible to E. amylovora and sensitivity appears to be controlled by a dominant gene Se. A high level of resistance is present in P. ussuriensis but varies considerably between clonal selections of other Pyrus species. Pear seedlings from controlled pollinations are artificially inoculated in the glasshouse with a similar bacterial suspension as used for apples, and only the most resistant ones are selected and planted in the field for future evaluation. In Beltsville, heritability studies of crosses between non–sensitive parents have indicated that selection for resistance within progenies results in a high degree of genetic gain. Interspecific hybridization has an advantage over P. communis crosses mainly when insect or fungus resistance is required.     

Host Range ofVerticillium dahliae in cultivated species in Crete

To determine the host range ofVerticillium dahliae among the cultivated species in Crete, Greece, studies were carried out during 1992–2000. Based on disease symptoms observed on 28 vegetable and forage species grown in a field naturally infected byV. dahliae, and an extensive survey of the most common cultivated species grown under natural conditions, seven hosts belonging to four botanical families not previously reported as susceptible to Verticilliun wilt, and 12 hosts belonging to seven families new for Greece, were recorded. The worldwide new hosts are: anise (Anethum graveolens), chard (Beta vulgaris ssp.cicla), chickpea (Cicer arietinum), wild sweet pea (Lathyrus ochrus), lentil (Lens culinaris), marigold (Tagetes erecta) and vetch (Vicia sativa). These species could be infected by their hosts-of-originV. dahliae isolates during pathogenicity tests. http://www.phytoparasitica.org posting Jan. 13, 2002.     

Invasive and quarantine pests in forests in Slovakia1

Biological invasions of insects, plants, and fungal pest species often cause substantial disturbance to forest ecosystems and as well as severe socioeconomic impacts. Central Europe acts as a ‘bridge’ between Western and Eastern Europe both ecologically and as an important transit corridor for people. Human activity, including the movement of material goods, increases the risk of invasions. Some species introduced in the past have been established, becoming common and causing serious problems (such as Dreyfusia nordmannianae or Hyphantria cunea). The status, importance and spatial distribution in Slovakia of seven different forest pests recently introduced into Slovak forest ecosystems (Cameraria ohridella, Coleotechnites piceaella, Cryphonectria parasitica, Dothistroma septospora, Ips duplicatus, Parectopa robiniella, Phyllonorycter robiniellus) as well as two others not yet recorded in Slovakia (Anoplophora glabripennis, Phytophthora spp.) is discussed.