使它隆防除麦田阔叶杂草的效果

我场丘陵山区麦田,近年来阔叶杂草发生严重。经调查,麦田阔叶杂草有猪殃殃、大巢菜、婆婆纳、播娘蒿、繁缕、泥糊菜等29种,分属16个科,其中以猪殃殃发生量最大,占麦旧阔叶杂草的83.3％,大巢菜占4.3％,婆婆纳占2.8％,其他阔叶杂草占9.6％。根据试验,百甲合剂、苯甲合剂、苯百合剂、2甲4氯等对麦田猪殃殃、大巢菜等虽有较好的防除效果,但因对气候、作物生育期要求严格,稍有不当,易造成药害或防效较差。为探索防除麦田阔叶杂草的新药种,1990年3月,采用20％使它隆进行试验示范,取得了较好的防除效果。     

麦田阔叶类杂草危害损失测定及防除指标的研究

我县麦田杂草以猪殃殃(Galium aparine var. tenerum)、荠菜(Capsella bursapastoris)、牛繁缕(Malachinm aquaticum)、波斯婆婆纳(Veronica persica)、卷耳(Cerastium viscosum)、早熟禾(Poa annua)、棒头草(Polypogon fugax)等为主。据1986～1987年普查,除少数低洼田外,一般麦田前4种杂草的发生多度达91.92％。稻棉轮     

陕西省小麦主产区麦田杂草发生及危害情况调查

采取倒置W 9点取样法对陕西省小麦主产区的麦田杂草进行了调查,明确了主产区麦田杂草的发生种类及优势杂草的危害趋势。调查到麦田杂草共49种,隶属于21科。其中,禾本科杂草占30%,阔叶杂草占70%。优势杂草有节节麦、多花黑麦草、野燕麦、看麦娘、鬼蜡烛、播娘蒿、猪殃殃、婆婆纳、蓟、荠等10种。禾本科杂草占生长优势,阔叶类杂草占数量优势。节节麦近年来危害迅速加大,成为麦田恶性禾本科杂草。阔叶杂草对常年使用的苯磺隆等药剂已经产生抗药性,防控效果降低。     

洛阳市麦田杂草初步调查研究

采用倒置“W”九点取样法对洛阳市旱茬麦田杂草的发生情况进行了初步调查。结果表明,该地区麦田杂草有12科24种,其中禾本科和十字花科种类最多,各占杂草总调查种类的25％,菊科、石竹科、旋花科各占8.3％;以一年生杂草为主,占70．8％。相对多度达30以上的杂草依次有播娘蒿、麦家公、离子草、野油菜4种,其中播娘篙和麦家公两种双子叶杂草的相对多度分别达52.34和45．80,明显为当地麦田杂草的优势种群。     

南京市六合区小麦田杂草种类调查及防除对策

麦田杂草是影响小麦生产水平提高的重要因素之一。通过调查,南京市六合区小麦田杂草有15科22种,其中相对多度大于10%的杂草有日本看麦娘、猪殃殃、菵草、野老鹤草、蛇床、看麦娘、牛繁缕、大巢菜等8种,其中日本看麦娘、猪殃殃和菵草的相对多度大于40%,是全区小麦田杂草的优势种群。文中针对麦田杂草发生危害的现状,提出了农业措施与化学措施相结合的综防策略。     

仙桃市小麦田杂草发生危害动态监测

仙桃市小麦田杂草多达24科42种,禾本科中早熟禾、野燕麦、罔草,其它科中猪殃殃、繁缕、婆婆纳、老鹳草等杂草为我市小麦田优势种群。旱地小麦田杂草优势种群有婆婆纳、猪殃殃、野燕麦、繁缕、早熟禾,稻茬小麦田杂草优势种群有早熟禾、罔草、婆婆纳、繁缕、老鹳草、猪殃殃等。与30年前相比,杂草种类和发生程度有明显的变化。     

防除冬麦田阔叶杂草新药剂评价

近几年,我省对防除冬麦田阔叶杂草的三种新除草剂百草敌(Banvel)、使它隆(Sta-rane)、阀叶散(Harmony)进行了试验和比较,现将试验情况简介如下。一、江苏省麦田阔叶杂草发生与防除概况这些年来,随着少、免耕技术的推广,麦田阔叶杂草的危害日趋严重,成为影响我省三麦增产的严重障碍。江苏省冬麦田阔叶杂草种类较多,其中猪殃殃、牛繁缕、巢菜、附地菜、荠菜等分布范围广,全省均有不同程度的发生。在一些地区,猪殃殃、牛繁缕已成为当地麦田主要的恶性杂草或优势种杂草。在苏南及沿江地区,散米荠也有较普遍的发生,在淮北地区播娘蒿、李家公普遍发生,与猪殃殃等同时危害,在沿海地区,婆婆纳是麦田主要的阔叶杂草之一。     

麦田杂草综合防除技术研究初报

我县栽培制度主要有单季稻—麦、杂粮—后季稻—麦、旱作—麦三种,分别形成单季稻茬、后季稻茬、旱茬三种茬口麦田。近年来,麦田草害日益严重,大有超过病虫危害的趋势。其中,引起严重危害的杂草主要有看麦娘、猪殃殃、牛繁缕、波斯婆婆纳、荠菜、卷耳和硬草等数利,它们合计占我县麦田总草量的95％以上。1983～1988年我们在综合控制麦田草害方面开展了一些工作,现将几年来的主要研究结果报告如下。     

不同除草剂对11种冬小麦田阔叶杂草的防除效果比较

小麦田除草剂的长期使用,造成麦田杂草群落发生变化。为建立不同区域优势杂草种类的化学防除技术,本研究采用室内盆栽法测定了14种除草剂对11种冬小麦田阔叶杂草的防除效果。结果表明,灭草松可以较好地防除冬小麦田野老鹳草、牛繁缕、大巢菜、紫堇、小藜、阿拉伯婆婆纳、播娘蒿、猪殃殃、麦家公等阔叶杂草;吡草醚对野老鹳草、牛繁缕、小藜、阿拉伯婆婆纳、播娘蒿、猪殃殃、麦家公、荠菜等8种杂草防效突出。辛酰溴苯腈可很好地防除牛繁缕、大巢菜、小藜、阿拉伯婆婆纳、播娘蒿、麦家公等6种阔叶杂草;唑草酮对野老鹳草、牛繁缕、阿拉伯婆婆纳、播娘蒿、猪殃殃等5种杂草防效突出。这4种除草剂及其适用浓度与其他供试药剂相比杀草谱更为广泛,对阔叶杂草防效较好。根据不同区域优势杂草种类,合理选用高效除草剂进行防除。     

钟祥市小麦田杂草危害现状调查

钟祥市小麦田杂草有17科、29种,其中单子叶杂草3科、10种,双子叶杂草14科、19种。单子叶杂草以棒头草、早熟禾、燕麦、马唐、半夏为主,占杂草总量的27.05%,双子叶杂草以铁苋菜、猪殃殃、婆婆纳、繁缕为主,占杂草总量的67.48%。     

Relationships between soil properties and the occurrence of the most agronomically important weed species in the field margins of eastern Arkansas – implications for weed management in field margins

The work presented in this study adds to previous research on the occurrence, distribution and growth habitat of common weeds along roadsides in the Mississippi River Delta region of eastern Arkansas, USA. It addresses the relationships between soil properties (i.e. defined as a group of individual soil characteristics or attributes such as P, K, Ca, Mn and other nutrients) and the most agronomically important weeds of which the occurrence at field margins accounted for ≥ 10% of the total sampling sites. These were three broad‐leaved weeds (Amaranthus palmeri, Ipomoea spp. and Sida spinosa) and four grass weeds (Echinochloa crus‐galli, Urochloa platyphylla, Sorghum halepense and Digitaria sanguinalis). Soil properties were used as explanatory variables for weed occurrence (presence–absence) using partition analysis; the occurrences of the weeds under examination were partitioned by the application of a decision‐tree method. The most important soil properties explaining the occurrence of these weeds in field margins were extractable soil nutrients, specifically sodium, boron and copper content, as well as soil physical attributes, in order of importance, bulk density, silt content, field moisture capacity, hydraulic conductivity, wilting point, available water and clay content. Soil chemical properties proved least reliable in explaining weed occurrence at roadside field margins. Knowledge of the relationships between soil properties and weed occurrence can add to our understanding of weed biology and hence enhance the efficiency of weed management strategies. For example, the occurrence of A. palmeri, in soils with high bulk density (>1.4 g cm^?3) and low organic matter content (<2.7%) and thus lower residual herbicide activity, will require integrated weed management of this species in field margins. This is of interest given the occurrence of herbicide resistance in roadside arable weeds, mainly A. palmeri, E. crus‐galli and S. halepense, in the Mississippi River Delta region of eastern Arkansas and other parts of the world.     

Weeds and weed management in irrigated lentil in northern Sudan

Weeds are a major constraint to increasing production of lentil (Lens culinaris Medik.) in Sudan, Field studies were conducted to determine the yield loss due to weeds, to identify the critical period of weed interference, to evaluate the activity of different herbicide mixtures in controlting weeds and their selectivity for lentil, and to evaluate different methods of weed control for developing an integrated weed management practice. At Rubatab. unrestricted weed growth accounted for up to 84% loss in yield. The critical period of weed control was between 2 and 4 weeks after sowing. However, a weeding regime experiment at Dongola, a cooler location with a longer growing season, indicated that the critical period was between 4 and 6 weeks after sowing. suggesting that the critical period might vary with the environmental conditions. The herbicides imazethapyr (0.05 kg a.i. ha^-1), terbutryn (1.0 kg a.i. ha^-1) and prometryn (1.0 kg a.i. ha^-1), each in a tank mixture with pendimethalin (1.2 kg a.i. ha^-1), were tolerated by lentil, controlled weeds effectively and significantly increased yields at Wad Hamid. Their efficacy in controlling weeds at Rubatab was low, however, because of the presence of Tephrosia apollinea (Del.) DC. and Melilotus indica (L.) All., which tolerated these herbicides. Efficacy was also reduced in heavier soils. One supplementary hand-weeding at 4 weeks after sowing enhanced the performance of these herbicides under such conditions. A tank mixture of oxyfluorfen (0.24 kg a.i. ha^-1) with either terbutryn (1.0 kg a.i. ha^-1) or prometryn (1.0 kg a.i. ha^-1) also provided good weed control and increased yield of lentil at Wad Hamid. Application of a higher dose (1.5 kg a.i. ha^-1) of terbutryn and prometryn caused phytotoxicity. Irrigation before seed-bed preparation reduced grass and broad-leaved weeds by 58% and 40% respectively, and gave a 30% increase in grain yield over no irrigation. Pre-emergence application of oxyfluorfen (0.24 kg a.i. ha^-1) and a supplementary hand-weeding at 4 weeks after sowing gave excellent control of weeds and increased lentil yield by 57% over the weedy control. Thus, use of presowing irrigation, pre-emergence herbicide and one hand-weeding form an effective integrated package for controiling weeds in northern Sudan.     

Long‐term changes in weed occurrence,yield and use of herbicides in maize in south‐western Germany,with implications for the determination of economic thresholds

In 393 field experiments in Baden‐Württemberg region in south‐western Germany, herbicide efficacy, yield loss and crop tolerance of maize (Zea mays) were investigated between 1981 and 2011. The collected data served to determine changes in weed frequencies, in herbicide use, yield loss functions and economic thresholds (ETs). Over 60 weed species were reported. Chenopodium album and Galium aparine were the most frequent broad‐leaved weeds, the former becoming more frequent over time. Species of the genera Lamium, Polygonum, Veronica and Matricaria occurred in about every fifth trial. Alopecurus myosuroides and Echinochloa crus‐galli were the most frequent grass weeds; the former declining in frequency by 1.1% per year, the latter increasing by 1.5%. Results suggest a weed population shift towards thermophilic species. aceto‐lactate‐synthase and 4‐HPPD‐inhibitor herbicides became important in the 1990s. Pendimethalin and bromoxynil have been integral components of weed control since the 1980s. ETs, the point at which weed control operations provide economic returns over input costs, ranged between 3.7% and 5.8% relative weed coverage. Without weed control, no yield increase was found over 24 years. Yield increased by 0.2 t ha ^{? 1} year ^{? 1}, if weeds were controlled chemically. Despite intensive use of effective herbicides in maize, problematic weed species abundance and yield losses due to weed competition have increased in Baden‐Württemberg over a period of 30 years.     

黄淮海地区稻茬小麦田杂草组成及群落特征

为明确黄淮海地区稻茬小麦田杂草组成及群落特征,采用倒置W型九点取样法对黄淮海地区稻茬小麦田杂草进行了调查,并进行了区域聚类分析。调查结果表明:从杂草种类来看,黄淮海地区稻茬小麦田杂草共有49种,隶属于17科45属,其中禾本科、菊科、十字花科和石竹科种类最多,分别有10、8、7和6种;从杂草优势度来看,优势杂草有7种,分别为看麦娘Alopecurus aequalis、硬草Sclerochloa kengiana、猪殃殃Galium aparine、牛繁缕Malachium aquaticum、稻槎菜Lapsana apogonoides、荠菜Capsella bursa-pastoris、日本看麦娘A. japonicus,区域性优势杂草有6种,分别为野老鹳草Geranium carolinianum、碎米芥Cardamine hirsuta、大巢菜Vicia gigantea、通泉草Mazus japonicus、菵草Beckmannia syzigachne、委陵菜Potentilla chinensis,这13种杂草是构成黄淮海地区稻茬小麦田的主要杂草,此外还分布有一般性杂草36种;从杂草区域分布来看,江苏省北部稻麦轮作区小麦田物种丰富度最高,有40种,明显高于其它稻麦轮作区小麦田,香农指数和均匀度指数也以该区域最高,分别为2.63和0.71,辛普森指数则以山东省临沂库灌稻麦区最高,为0.27。聚类分析结果表明,黄淮海地区稻茬小麦田杂草群落可以划分为4组,河南省南部稻麦轮作区和山东省临沂库灌稻麦轮作区杂草群落结构相似构成1组,河南省北部沿黄稻麦轮作区和山东省沿黄稻麦轮作区杂草群落结构相似构成1组;江苏省北部稻麦轮作区和山东省济宁滨湖稻麦轮作区各自单独成组。     

Competitive interactions between chick-pea genotypes and weeds

Growing chick‐pea in sustainable systems requires the use and development of more competitive genotypes which can complement the effects of reduced input weed control. A 2‐year study assessed the competitive ability of 13 genotypes grown in either the presence or absence of weeds, in a split‐plot design including the weeds in pure stands. Crop and weed density, phenology, relative biomass of crop (RB_c) and weeds (RB_w), crop yield characters, crop biometric traits in the absence of weeds, relative biomass total of mixtures (RBT) and crop competitive ability (C_b = ln RB_c/RB_w) were recorded. Lines C136, C120, C101 and C106, and cultivars Pascià, Visir and Sultano gave the best seed yield in the absence of weeds (1.8–2.0 t ha^?1 DM). Weeds reduced yield by 75% and 83% in C136 and C133 and by 87–97% in the other genotypes. Weed biomass in mixture (mainly Chenopodium album) averaged 4.42 t ha^?1 DM. Chick‐pea genotypes C136 and C133 were the most competitive, but weeds were more competitive than any of the chick‐peas. C_b was correlated directly to the height of first fertile pod (r² = 0.84) and inversely to the insertion angle of primary branches to the vertical (r² = 0.77). Intergenotypic variation for competitive ability could be exploited in integrated weed control using more competitive genotypes, or used in breeding programmes aimed to develop highly competitive cultivars on the basis of easily screenable characters.     

Weed competition and control in sugarcane

Losses of about 40% in cane yields due to natural stands of weeds were found in experiments conducted in sugarcane var. Co 527 in the year of planting at Guneid Sugarcane Research Station, Sudan. Weed competition lowered millable stalks per metre row by 32%, stalk height by 24%, stalk thickness by 15% and number of nodes per stalk by 14%. Tillering was the growth phase most affected by weed competition. Cane yields were increased as number of hand weedings increased, but four weedings were not markedly better than three. The average yield (67·04 t ha^?1) obtained from four weedings was not significantly (P= 0·05) better than that of three weedings carried out at 3, 6 and 9 weeks after cane planting. Juice analysis components were also affected by weeds and a 15% reduction in sucrose recovery was recorded. Reductions in the other components were only 4–7%. Atrazine and diuron (3·3 kg ha^?1), metribuzin (2·4 kg ha^?1) and metribuzin (1·3 kg ha^?1) in tank mixture with diuron (1·5 kg ha^?1) gave excellent residual weed control of the dominant weed species, Ipomoea cordofana Choisy., Brachiaria eruciformis (Sm.) Griseb., Corchorus fascicularis Lam., Ocimum basilicum L. and Dinebra retroflexa (Vahl) Panz., for most of the first growing season. Excellent control of weeds achieved by the herbicide treatments resulted in comparable yields to frequently-weeded cane. These herbicides were not phytotoxic to sugarcane var. Co 527.     

The role of weeds in the epidemiology of pospiviroids

Many weeds that are closely associated with horticultural activities are known as natural reservoirs of plant viruses. However, whether these weeds can also serve as hosts of pospiviroids is not well known. Pospiviroids are naked, non‐coding RNA pathogens that cause severe economic damage in many solanaceous crops. In this study, we examined the overall risk of pospiviroid spreading from weeds to economically important crops, by combining the results from previous inoculation studies with new results coming from a survey, a contact experiment and an inoculation experiment. A survey of commercial ornamental glasshouses revealed that ornamental plants mainly belonging to the Solanaceae harbour pospiviroids, in contrast to weed species sampled in the same places. No new weed hosts could be identified after testing weeds that grew in contact with Tomato apical stunt viroid (TASVd)‐infected plants of tomato (Solanum lycopersicum) and jasmine nightshade (Solanum jasminoides) in an experimental glasshouse. Finally, in mechanical inoculation experiments with TASVd, none of the six tested weed species were determined to be a host at 6 weeks after inoculation. Commonly occurring weed species therefore do not appear to play a significant role as reservoir hosts for pospiviroids. This does not rule out other potential weed hosts that have not yet been tested. Inoculation studies should include rigorous experimental protocols with a sufficient number of replicated as well as adequate positive controls. The information gained through this study may prove useful in future risk assessments for the pospiviroid group.     

Winter annual grassy weeds increase over‐winter mortality in autumn‐sown wheat

Over‐winter mortality, that is, winterkill, reduces cereal crop competitive ability and yield. While management and environmental variables are known to affect winterkill, the extent to which weeds contribute to increased winterkill is largely unknown. Winter annual weeds may increase winterkill through resource competition and by increasing incidence of and damage from plant pathogens that cause winterkill. We evaluated the impact of summer annual (Avena fatua) and winter annual (Bromus tectorum) weeds on the over‐winter survival rate of winter wheat over three winters, during which plots were covered with snow. Pink snow mould (Microdochium nivale), a winterkill pathogen known to infect B. tectorum and winter wheat, was common in wheat stands. In weed‐free treatments, mortality rates were initially near zero, but increased by nearly 45% in each subsequent winter, presumably due to an increase in snow mould disease in continuously cropped winter wheat. Whereas A. fatua infestation had no impact on crop survival rates, winter wheat survival in B. tectorum‐infested plots was 50% less than the weed‐free control in the second and third years of this study. Among B. tectorum‐infested plots, winter wheat over‐winter survival declined with increasing weed seed produced in the previous summer. Overall, this study demonstrated that winter annual weed infestations can reduce crop stand densities below replanting thresholds by reducing fall‐sown cereal winter survival. The effects of winter annual weeds on winter wheat may be meditated by increased proliferation of snow mould disease.     

Radar Studies of Insects

Abstract

Yield and weed growth in dry-seeded rice (Oryza sativa L.) were unaffected by method of seeding. Weeds depressed rice yields by 95%. Fourteen weed species were found growing in association with dry-seeded rice at maximum flowering of the weeds. Echinochloa colona (L.) Link and Leptochloa chinensis (L.) Nees were the major weeds. A dramatic change in the weed flora was observed in transplanted rice planted immediately after the harvest of the dry-seeded crop. Only five species grew in association with the transplanted crop. Monochoria vaginalis (Burm.) Presl. dominated. E. colona and L. chinensis were present in transplanted rice but were only minor weeds. The number of weeds in the transplanted crop was less than 50%, and weighed only 5% as much as those in the dry-seeded crop. There was no carryover of the weed control treatments from the dry-seeded crop to the transplanted crop.     

Nature and importance of weeds in sorghum in the Yemen Arab Republic

Abstract

Grain sorghum (Sorghum bicolor (L.) Moench) is the dominant crop in North Yemen agriculture, covering about 70–80% of the arable land. Weed control is still carried out mainly by hand. Many of the weeds are used as fodder for animals. A total of 137 weeds was collected in sorghum. Most frequent were Cynodon dactylon (L.) Pers. and Cyperus mtundus (L): their importance decreased, however, under a well‐established sorghum crop providing good shade cover and under conditions of increased crop fertilization with mineral nitrogen. Under these conditions, for example, Commelina spp. and Flaveria trinerva (Spreng.) Mohr became commoner. Thus increased use of nitrogen altered the nature and hierarchy of the weed flora. Relationships between the indicator figures of the weeds and the habitat, as defined by Ellenberg, were confirmed. Traditional methods of weed control have so far worked well, as witness an average cover of 60% sorghum and 20% weeds. In future, however, rising costs and labour shortages will increase the demand for less time‐consuming weed control strategies.