Influence of seed depth and molluscicide pellet placement and timing on slug damage, activity and survival in winter wheat

In a laboratory experiment, grey field slugs (Deroceras reticulatum) were introduced to trays of clay soil drilled with wheat seeds at 10 or 25 mm depth. Trays were left without molluscicide, or methiocarb pellets were drilled with the seeds or placed on the surface of the soil immediately after drilling. In the absence of molluscicide, there was less damage to seeds drilled at 25 mm than at 10 mm. Methiocarb pellets drilled with seeds at 10 mm depth killed slugs and reduced damage to seeds and seedlings, but the percentage of seeds killed was similar to the percentage of deeper-drilled seeds killed where no molluscicide had been applied. Pellets drilled with deeper-sown seeds did not kill slugs, or reduce damage to seeds and seedlings, whereas pellets placed on the soil surface immediately after sowing were effective in killing slugs and reducing plant damage irrespective of drilling depth. The best protection from slug damage was provided by deeper drilling combined with pellets broadcast on the soil surface. In a field experiment, methiocarb pellets broadcast immediately after drilling at two depths killed slugs and protected seedlings from damage, whereas pellets drilled with seeds were ineffective because seed-bed conditions prevented slugs from reaching seeds and pellets (only 4% of seeds were killed by slugs in the absence of molluscicide treatment). The implications of these results for slug control and for non-target fauna (wood mice and ground beetles) are discussed.     

Antifungal properties of Agapanthus africanus L. extracts against plant pathogens

Crude extracts of various Agapanthus africanus plant parts were screened in vitro against eight economically important plant pathogenic fungi. Radial mycelial growth was inhibited significantly (P<0.05) in five test organisms, while Pythium ultimum, and to a lesser extent Fusarium oxysporum and Alternaria alternata, showed a degree of tolerance. Subsequently, these crude extracts were tested in vivo in the greenhouse against Mycosphaerella pinodes, the cause of black spot or Ascochyta blight in peas. Fourth internode leaves were removed from 4-week-old pea plants, placed on moist filter paper in Petri dishes and inoculated with a M. pinodes spore suspension 30 min before and after treatment with the extracts. The control of Ascochyta blight by different concentrations of the crude extracts was measured in terms of lesion size over a 6-d period at 20 °C in a growth cabinet. All crude extracts significantly reduced lesion development caused by M. pinodes when leaves were inoculated with spores both before and after treatment with the extracts. Neither of the extracts showed any phytotoxic reaction on the leaves, even at the highest concentration applied. A combined aerial part crude extract of A. africanus was additionally evaluated against sorghum covered (Sporisorium sorghi) and loose (Sporisorium cruentum) kernel smuts under field conditions over two seasons. The extract and a standard fungicide, Thiram that served as a positive control, were applied as seed treatments 1 h after artificially inoculating separate sets of sorghum seed with smut spores. Inoculated, but untreated seeds served as a negative control. The extract reduced the incidence of both loose and covered kernel smuts significantly (P<0.05) and compared favourably with the prescribed fungicide, Thiram. Both treatments resulted in significant yield increases compared to the untreated control. From these results it was concluded that the aerial part crude extract of A. africanus possesses sufficient in vivo antifungal activity to warrant a further investigation.     

Use of pesticides to determine relative importance of pest and disease factors limiting establishment of sod-seeded lucerne

The most likely reasons for seeding failures of sod-seeded lucerne ( Medicago sativa L.) were determined from eight field experiments, where the effects of a range of pesticides on the establishment of and damage to lucerne were compared. The experiments were conducted during 1979–80 at four sites near Ithaca, N.Y., USA. Pesticides evaluated were: methyl bromide (MeBr), carbofuran, acylalanine (1979, 1980); fonofos, diazinon, methiocarb, metaldehyde and combinations of carbofuran with methiocarb or metaldehyde (1980). Seeded areas were pretreated with glyphosate for vegetation control.
In 1979 seedling losses were decreased by carbofuran and methyl bromide whereas in 1980 seedling losses were decreased by methyl bromide at two sites and by methiocarb at all sites. Methiocarb was the only pesticide to reduce defoliation damage. The effect of combining methiocarb and metaldehyde each with carbofuran tended to be additive in terms of reducing seedling numbers and damage, and increasing yield. Treatment effects on lucerne yield were still apparent up to 12 months after seeding. Based on the consistent results of methiocarb, it was concluded that molluscs were probably the main factor limiting the establishment of sod-seeded lucerne but an arthropod component also appeared to be involved.     

The effects of pesticides and crop rotation on the soil-inhabiting fauna of sugar-beet fields. Part I: The crop and macroinvertebrates

The effects of two insecticide treatments (seed-furrow aldicarb, and gamma-HCH sprayed overall), herbicide and crop rotation on pest attack to sugar-beet seedlings, and pest and predator populations, were studied in a 3-year field trial. On continuous-beet plots without insecticide, seedling establishment declined sharply from the first to the third year of the trial due to a build-up in the numbers of pygmy beetles, Atomaria linearis Steph., a sugar-beet pest. Crop rotation, and both insecticides, decreased damage by the pest and thereby increased establishment considerably, in the second and third years of the trial whereas herbicide had no effect. The effects of the insecticides on numbers of creatures caught in pitfall traps varied with species and with insecticide. For example, more Bembidion lampros Herbst., a carabid beetle, were trapped on plots treated with gamma-HCH than on untreated plots, whereas the effect was less marked on aldicarb-treated plots and was not observed in other carabid species with either insecticide.     

The effect of some invertebrate species on persistence of white clover in ryegrass swards

In two experiments in established swards of perennial ryegrass and white clover, plots were treated with pesticides to control slugs, leather-jackets, weevil larvae and lucerne flea as selectively as possible. Other plots were treated to control ail of these pests.
Chlorpyrifos application in early summer (to control weevil larvae) and methiocarb pellets (to control slugs) also gave partial control of leather-jackets. Other effects on non-target species were considered to be unimportant, as pest status could not be attributed to the species. A high level of control of lucerne flea by methiocarb pellets, noted previously, was confirmed.
At both sites combined treatment against insect pests and slugs produced large increases in clover content and yield over a 3-year period, in comparison with untreated plots, although clover tended to decline In alt plots. At one site, where the clover content of untreated plots reached 33% at one stage, specialist clover herbivores such as weevils and lucerne flea were more common. Treatments directed against weevils and slugs gave the highest clover yields, and leatherjacket control may also have contributed, particularly when the population reached 0.9 m ha⁻¹ in the final year. At the other site, where the clover content was low (ultimately 01.1–6%), leather-jacket populations reached 2.1 m ha⁻¹ and slug numbers were also relatively high. Control of these species contributed most to the relative increase in clover content and yield.     

Potential for biological control of Monilinia laxa in peach twigs

The antagonistic effect of four fungi (Aspergillus flavus, Epicoccum nigrum, Penicillium frequentans and Penicillium purpurogenum) against Monilinia laxa on peach twigs was assayed in two field experiments in central Spain in spring and autumn. Results were different in the two periods. In spring, E. nigrum, P. purpurogenum and P. frequentans significantly reduced the success of infection when introduced before inoculation with the pathogen but A. flavus caused only a transient delay in the development of symptoms. However, when inoculation preceded antagonist introduction, only the treatments with P. frequentans resulted in a lasting reduction of symptoms and those with P. purpurogenum merely delayed symptom development. In autumn, only the treatments with E. nigrum resulted in a reduction of M. laxa infection. The potential for practical use of these fungi is discussed.     

Slugs as a primary limitation to establishment of sod-seeded lucerne

The variable degree of success obtained with sod-seeded lucerne in the north-eastern United States had been attributed to slug and insect activity, although the evidence was circumstantial. Our aims were to examine the effects of a molluscicide (methiocarb) and an insecticide (carbofuran), and their interaction with level of vegetative cover on response of sod-seeded lucerne plants (establishment and damage) and slug numbers and to determine what relationship (if any) there was between slug numbers and plant response. Results are based on six field experiments seeded in mid-August and early September 1980 at Ithaca, NY. Removal of vegetation and application of pesticides reduced seedling losses and damage and generally reduced slug numbers, but response to the pesticides varied according to presence or absence of vegetative cover and whether the experimental site carried a ‘high’ or ‘low’ slug activity. As reflected by increased seedling numbers and reduced damage, the main response to molluscicide (and insecticide) occurred in the presence of cover at ‘low’ activity sites. However, at the site with a ‘high’ slug activity, slug numbers were reduced by the molluscicide only where cover had been removed. It was concluded that insects and slugs, particularly the latter, can seriously limit establishment of sod-seeded lucerne in the north-eastern United States.     

Weathering and the field efficacy of pelletized rodenticide baits in orchards

Commercially available US rodenticide bait formulations were tested in the field and laboratory to examine their weather resistance and the influence of moisture on efficacy and acceptability to voles (Microtus spp.). Baits containing one of several anticoagulant compounds or zinc phosphide (Zn₃P₂) were mechanically broadcast in orchard plots. Precipitation (7·62 mm) fell within 48 hours after application. There was not a marked difference in control between the multiple-feeding anticoagulants and the single-feeding anticoagulants or zinc phosphide. Laboratory tests showed that moist pellets of three rodenticide formulations were as effective and acceptable to pine voles (M. pinetorum) as dry pellets. No direct relationship was found to show that wet weather or moisture resistance of the given rodenticide formulations tested affected field control or laboratory mortality. Toxicity and concentration of the active ingredient in formulations used were important to efficacy.     

物理伤害诱导白木香应激反应的生理特征

为了分析物理伤害诱导白木香应激反应特征,本研究以3年生普通白木香与易结香白木香品系为对象,采用机械打孔处理,分析其受伤害前后的激素含量、抗氧化性酶活性、酚类与萜类防御物质以及萜类前体物质乙酰辅酶A含量的变化特征,比较两类白木香受物理伤害后的应激反应特征。结果表明：机械损伤后,普通白木香与易结香白木香茉莉酸、水杨酸、乙烯含量都显著增加。除抗坏血酸氧化酶外,其他5种抗氧化性酶活性显著增强。防御物质总酚、总萜含量在普通白木香中分别增加了15.31%和9.04%,在易结香白木香中分别增加了24.63%和15.08%。乙酰辅酶A在两类白木香中也显著增加。其中,易结香白木香中茉莉酸、乙烯前体含量变化显著高于普通白木香。且易结香白木香的超氧化物歧化酶、过氧化氢酶、过氧化物酶活性变化分别是普通白木香的1.63、1.60、1.55倍。易结香白木香的总酚和总萜增量显著大于普通白木香。易结香白木香中乙酰辅酶A的增量是普通白木香的1.74倍。综上所述,白木香在受到机械损伤后应激反应物质都得到了增加,并且多数指标在易结香白木香品系中显著高于普通白木香,表明在物理伤害诱导下易结香白木香应激反应强于普通白木香。茉莉酸、乙烯、超氧化物歧化酶、过氧化氢酶、过氧化物酶、总酚、总萜以及乙酰辅酶A等应激反应的特征物质在两类白木香中表现出显著差异,可作为快速判断易结香白木香品系的有效生理指标。     

镁营养对苦瓜生长发育及生理代谢的影响

采用砂培的方式,以‘翠玉’苦瓜（Momordica charantia）品种为试验材料,研究不同镁素浓度（0、20、40、80、160 mg/L）处理下对苦瓜生长特性（叶片和根系形态、光合色素含量、碳氮代谢、生物量积累）和生理响应（渗透调节、膜伤害和抗氧化）的影响。结果表明：镁浓度为20~80 mg/L时可以降低苦瓜叶片膜伤害,增加叶片中可溶性糖、可溶性蛋白质、光合色素和谷胱甘肽（GSH）含量,增强叶片抗氧化酶活性,包括超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和单脱氢抗坏血酸还原酶（DHAR）,降低叶片丙二醛（MDA）、脯氨酸（Pro）、过氧化氢（H₂O₂）含量和超氧阴离子（O₂^-）的产生速率及细胞膜透性,促进根系活力、光合作用和生物量积累。其中,40 mg/L镁处理对苦瓜的生长发育增效最明显,而缺镁（0 mg/L）和过量镁（160 mg/L）胁迫下,苦瓜叶片产生膜脂过氧化伤害、主根变短、侧根减少,苦瓜地上部和地下部生长均受到明显抑制,缺镁比镁过量的抑制作用更强。综上所述,缺镁和过量镁抑制苦瓜生长,而适量增施镁可有效提高苦瓜的生理活性,增强苦瓜抗逆性,促进苦瓜生长,40 mg/L为苦瓜栽培最适宜施镁浓度。     

吊罗山石碌含笑群落木本植物种间联结性研究

石碌含笑（Michelia shiluensis）是海南特有树种和国家Ⅱ级濒危保护植物,野外仅见分布于吊罗山、鹦哥岭、五指山等海南中南部山区。吊罗山是石碌含笑最集中的自然分布区,开展吊罗山石碌含笑群落木本植物种间联结性研究,有助于了解该树种在群落中的地位与作用,为制定合理的就地保护措施提供参考。本研究基于2×2列联表,综合运用χ²检验、Pearson相关系数检验和Spearman秩相关系数检验对吊罗山石碌含笑与群落内其他伴生种的种间关系进行了探讨分析。结果表明：石碌含笑种群与灌木层的正关联比乔木层多;石碌含笑与群落内绝大多数植物的种间联结不显著,种间关系表现出总体比较松散的趋势,种群间相互独立的趋势明显,乔木层和灌木层总体上与石碌含笑正关联物种多于负关联物种数,表明群落的发展朝着有益于石碌含笑种群发育的趋势。研究结果对制定合理的就地保护措施和恢复计划具有参考价值。     

中国辣椒(Capsicum chinense)对象耳豆根结线虫的抗性鉴定及机理研究

根结线虫(Meloidogyne spp.)是一类高度专化性的杂食性植物病原线虫.目前,世界上已报道的根结线虫种类有98种,我国危害农作物最为严重的根结线虫有6种,包括南方根结线虫(M.incognita)、北方根结线虫(M.hapla)、爪哇根结线虫(M.javanica)、花生根结线虫(M.arenaria)、拟禾...     

桃蚜取食对抗、感蚜辣椒品种水杨酸、茉莉酸信号途径的影响

为了明确水杨酸及茉莉酸信号途径在辣椒抗蚜性中的重要作用,本研究在获得遗传稳定的抗、感蚜参照辣椒品种的基础上,系统开展了桃蚜为害前后抗、感蚜参照辣椒品种叶组织中水杨酸、茉莉酸含量及相关基因表达量的差异分析。结果表明,桃蚜为害后,水杨酸含量在抗蚜辣椒品种‘猪大肠’（ZDC）和感蚜辣椒品种‘大羊角椒’（DYJJ）中均比为害前显著提高,而茉莉酸含量在ZDC中显著提高,在DYJJ中则先显著降低之后又恢复到为害前水平。水杨酸信号途径相关基因PR1、EDS5、PAD4的表达量在ZDC、DYJJ被桃蚜为害后均能够显著诱导,并且桃蚜为害早期PR1和EDS5基因在ZDC中的表达量显著高于DYJJ。ZDC被桃蚜为害后,茉莉酸信号途径基因LOX2、AOC的表达量比为害前先显著提高,之后又逐渐降低至为害前水平,而这2个基因在DYJJ中的表达被显著抑制,并且也显著低于ZDC中的表达水平。研究结果表明,抗蚜辣椒品种可以同时激活水杨酸、茉莉酸信号途径抵御桃蚜为害,而感蚜辣椒品种激活水杨酸途径、显著抑制茉莉酸途径则有利于桃蚜为害。本研究从以上2个防御信号途径初步揭示了辣椒的抗蚜性分子机理。     

不同基质配比下米老排组培苗移植效果

为探讨基质配比对组培苗移植效果的影响,以黄心土和泥炭土为基质,按照体积比设置5种基质配比处理,即T₁（100%黄心土）、T₂（80%黄心土+20%泥炭土）、T₃（60%黄心土+40%泥炭土）、T₄（40%黄心土+60%泥炭土）和T₅（20%黄心土+80%泥炭土）,分析不同基质处理对米老排组培苗移植成活率、生长量和苗木质量指数的影响效应。结果表明：T₁和T₃处理有利于提高米老排组培苗移植后成活率,移植1个月的苗木成活率以T₁最高（83.33%）,T₃次之（81.11%）;随着泥炭土比例的增加,米老排组培苗的株高、叶片数、地径均呈先增加后降低的变化规律,并在T₃时达到峰值,移植6个月的株高、叶数与地径分别为30.93 cm、8.1片和5.04 mm,均极显著高于其他4个处理（P<0.01）,分别是T₁的2.11、1.82和1.67倍;6个月的苗木地上干重和地下干重大小均为：T₃>T₄>T₅>T₂>T₁,T₃的地上干重和地下干重分别为T₁的8.51和5.56倍;T₃的苗木质量指数达到了1.13,显著高于T₅、T₂和T₁（P<0.05）。60%黄心土+40%泥炭的混合基质是米老排组培苗移植的理想育苗基质。     

海南野生鹧鸪茶资源调查与鉴定评价

鹧鸪茶是具有海南地方和民族特色的代茶饮料植物和药用植物,已开发成为广受欢迎的特色旅游产品,但大规模的人为无序开发对野生资源造成了极大的破坏。通过对海南野生鹧鸪茶进行资源调查、收集保存和保护利用等研究,结果表明：在海南全省10个市县共13个调查地点中,仅2个地点的野生鹧鸪茶基本未受到人工影响,其余地点的野生植株长势较弱,人为破坏较严重,部分生境已受到人工开垦的影响;先后收集保存285份鹧鸪茶种质资源,并在异地建设种质资源圃安全保存;对收集保存的285份资源进行5个描述性状和6个数值性状的植物学鉴定评价,其中描述性状的多样性指数的变化范围为0.69~1.74,数值性状的多样性指数的变化范围为1.93~2.11,说明收集保存的鹧鸪茶种质具有丰富的遗传多样性。本研究可为人工培育优良鹧鸪茶无性品系提供了资源基础和评价数据。     

Sensory-cue enhancement of the bird repellency of methiocarb

Methiocarb can be an effective, non-lethal repellent to bird pests in numerous agricultural situations world-wide. It elicits a conditioned aversion response (based on an internal physiological reaction) which birds presumably associate with a treated food crop and then avoid. However, in developing countries its cost is often prohibitive. Studies on Quelea quelea also indicate that repellency occurs at levels lower than birds can discriminate by taste. The cost of using methiocarb can be reduced by incorporating inexpensive sensory cues that birds associate with its soporific effects. In the laboratory, methiocarb/sensory-cue combinations applied to heads of sorghum significantly enhanced the repellent response to quelea. Likewise, field tests in Africa and the Philippines comparing a 1% methiocarb treatment with a 0·5% methiocarb/1·0% wattle tannin formulation applied to ripening sorghum, millet, and wheat resulted in equivalent protection and significantly less damage when compared with untreated heads. The results have practical implications to farmers, particularly in developing countries, for protecting their crops economically.     

The effect of pesticide application on the establishment of white clover in a newly-sown ryegrass/white clover sward

In plots of perennial ryegrass and white clover, regular treatment with chlorpyrifos and methiocarb more than trebled the clover content of the sward, compared with untreated plots, in just over 2 years from sowing. Chlorpyrifos alone accounted for most of the effect, which was attributed mainly to the control of Sitona lepidus. Combined treatment increased total herbage dry matter yield by 4·24 t ha⁻¹ during this period but had little effect on grass-only plots. Methiocarb appeared to have contributed by assisting earlier establishment of clover, but otherwise had little effect until slugs, which were initially uncommon, became more abundant in the later stages of the experiment. The effect of slug control was most noticeable in a cultivar of low cyanogenic potential. This factor did not influence the effect of chlorpyrifos.     

不同比例红蓝光及光照强度对金线莲生理及叶绿素荧光特性的影响

为探讨LED光源在金线莲工厂化栽培中的应用,利用研发的具有不同比例红（R）、蓝光（B）的LED灯作为光源,以白色荧光灯为对照（CK）,设置以下5个试验处理,T₁：R/B(3/7), PPFD 20 μmol/(m²·s);T₂：R/B(7/3), PPFD 20 μmol/(m²·s);T₃：R/B(3/7), PPFD 30 μmol/(m²·s);T₄：R/B(7/3), PPFD 30 μmol/(m²·s);T₅：R/B(7/3), PPFD 50 μmol/(m²·s),研究不同比例红蓝光源及其光照强度对金线莲的生长、光合作用、叶绿素荧光反应和生理特性的影响。结果表明：与对照处理相比,T₄、T₅处理的金线莲株高、茎粗、植株干鲜重显著提高;T₅处理的金线莲叶片净光合速率显著高于其他处理,而T₁、T₃处理间差异不显著,但显著高于T₂、T₄处理。不同比例红蓝光处理下金线莲叶片的叶绿素含量显著高于对照处理,在相同的光照强度下,R/B(7/3)处理的金线莲叶片叶绿素含量大于R/B(3/7)处理。不同比例红蓝光源处理的金线莲叶片最大光化学效率、光系统II活性均显著高于对照处理;红光比例减少,蓝光比例增加,可降低金线莲叶片最大光化学效率、光系统II活性,同时光系统II实际光化学效率和光合电子传递效率也随之降低。T₂处理可有效提高金线莲叶片SOD和CAT活性,但POD活性降低;T₄处理下金线莲叶片POD和CAT活性降低,SOD活性升高;与对照相比,T₁处理的金线莲叶片MDA含量显著增加,较对照提高19.4%,而T₅处理与对照差异不显著。综合各处理金线莲生长来看,T₅处理R/B(7/3), PPFD 50 μmol/(m²·s)的金线莲生长最好,保持较高的光合速率及生理活性。     

不同品系昆虫病原线虫对蜂巢小甲虫的致病力研究

为明确市售昆虫病原线虫制剂对蜂巢小甲虫（Aethina tumida）幼虫和蛹的致病力,为该害虫的防治提供新的技术措施,室内采用浸渍法、土壤法测定了5种不同品系昆虫病原线虫对蜂巢小甲虫末龄老熟幼虫和蛹的致病力,采用土壤法测定了小卷蛾斯氏线虫（Steinernema carpocapsae All）不同施用时间、不同施用剂量对蜂巢小甲虫幼虫致病力的影响。浸渍法生物测定结果表明,5种不同品系昆虫病原线虫对蜂巢小甲虫幼虫的致病力差异很大,其中小卷蛾斯氏线虫All侵染4 d、12 d后,蜂巢小甲虫幼虫的校正死亡率分别为67.50%±0.05%和72.36%±3.14%,均显著高于其他品系。土壤法生物测定结果表明,昆虫病原线虫对蜂巢小甲虫幼虫具有明显的致死作用,其中小卷蛾斯氏线虫All对蜂巢小甲虫幼虫的侵染效果达100%,显著高于其他线虫品系。蜂巢小甲虫幼虫入土后,按不同时间顺序施用小卷蛾斯氏线虫All,结果表明14 d前施用均能取得良好的防治效果。侵染期线虫小卷蛾斯氏线虫All与蜂巢小甲虫幼虫数量之比大于213∶1时,防治效果最佳。因此小卷蛾斯氏线虫All具有防治蜂巢小甲虫的潜力,可在发生蜂巢小甲虫危害的蜂场推荐使用。     

Alternate-row treatment with the repellent methiocarb to protect cherry orchards from birds

An alternate-row treatment of the bird repellent methiocarb (CA chemical name 3, 5-dimethyl-4-(methylthio)phenyl methylcarbamate; Mesurol® was evaluated for protecting entire cherry orchards from damage by European starlings, American robins, house finches, common grackles and other birds. Half of each orchard was randomly selected for treatment with methiocarb (1·7 kg/ha) applied to trees in every other row. The other half of each orchard was used as a control. Estimated loss of cherries to birds at the time of damage assessment was significantly lower in the six partially sprayed blocks (6·5%) than in the six unsprayed, control blocks (8·8%) (P = 0·03). However, the level of bird damage and the magnitude of the reduction were insufficient to provide a favourable benefit:cost ratio: there was a return of only $0·80 in cherries saved for every $1·00 spent on application and chemical costs. The overall lower damage in the partially sprayed blocks appeared to result primarily from reduced feeding by birds in the sprayed trees, which averaged 4·6% loss compared with 8·4% loss for unsprayed trees within the same block (P = 0·22). That this difference was not statistically significant indicates that birds had to sample a substantial number of berries before discriminating between sprayed and unsprayed fruit. It is not clear how birds detected berries sprayed with the repellent. Suggestions for evaluating other partial treatments of bird repellents in cherry orchards are discussed.