高温处理西花蓟马若虫对其雌成虫寿命、繁殖力及后代发育的影响

温度是影响昆虫生长发育的重要生态因素之一,高温逆境作为一种绿色防控手段可以有效控制温室害虫种群发展。为了探究高温处理西花蓟马若虫对其种群发展的影响,本试验用41℃和43℃两个温度分别处理西花蓟马初孵若虫2、6、12、24和36h后,观察并记录其雌成虫寿命、繁殖力及后代发育指标的变化情况。结果表明,随着处理时间的延长,两个高温处理后西花蓟马雌成虫寿命,子代若虫总数、成虫总数和总存活率(若虫发育到成虫的存活率)均显著下降,后代雌雄性比呈总体下降趋势。41℃处理后,性比从2.30∶1降低到2.13∶1;43℃处理后从2.25∶1降低到2.07∶1,均明显低于对照的2.69∶1。另外,两性生殖种群相比于孤雌生殖种群更易遭受高温处理的影响。     

苦参碱及吡虫啉对南方小花蝽的影响

为评价植物源杀虫剂和化学杀虫剂对南方小花蝽的影响,在室内条件下采用浸渍法比较了苦参碱及吡虫啉对西花蓟马的毒力,并分别利用两种杀虫剂对西花蓟马2龄若虫的LC50剂量作用于南方小花蝽,探究其对南方小花蝽捕食作用、雌成虫寿命和产卵量的影响.结果显示,苦参碱和吡虫啉对西花蓟马2龄若虫的LC5o值分别为24.811 mg/L和13.911 mg/L,两种药剂处理后南方小花蝽对西花蓟马的功能反应符合HollingⅡ圆盘方程,但其瞬时攻击率降低,苦参碱处理的瞬时攻击率高于吡虫啉处理;药剂处理后南方小花蝽雌成虫寿命及产卵量均下降,雌成虫寿命由22.0 d分别缩至19.0d及11.0d,其平均日产卵量由3.92粒/雌分别下降至2.25粒/雌及0.91粒/雌.研究表明苦参碱对南方小花蝽的影响小于吡虫啉.     

3种环境友好型药剂对西花蓟马的室内毒力与田间防效

测定了3种杀虫剂对西花蓟马的室内毒力和田间防效。室内生物测定结果表明,多杀菌素、甲氨基阿维菌素苯甲酸盐、阿维菌素对西花蓟马成虫的LC50值为0.050～2.887mg/L,对西花蓟马若虫的LC50值为0.040～0.457mg/L;田间药效试验表明,田间防治西花蓟马时推荐使用剂量(防效>80%)分别为:2.5%多杀菌素悬浮剂30～60g/667m2,1%甲氨基阿维菌素苯甲酸盐乳油30～60g/667m2,1.8%阿维菌素乳油不可低于75g/667m2。     

两种自然变温刺激对棕榈蓟马种群生命表参数及抗药性的影响

为明确高温对棕榈蓟马Thrips palmi种群生长发育及其种群抗药性的影响,利用年龄-龄期两性生命表方法,比较了15～25℃(室内)和14～45℃(室外)变温刺激后棕榈蓟马的生命表参数,并采用微虫笼法测定了这2种自然变温饲养条件下棕榈蓟马种群对阿维菌素和噻虫嗪2种杀虫剂的敏感性。结果表明,14～45℃变温刺激后的室外棕榈蓟马种群发育速度较15～25℃变温刺激后的室内棕榈蓟马种群显著加快,前者平均世代周期为14.33 d,后者为19.09 d;14～45℃变温刺激后的室外棕榈蓟马种群净生殖率和内禀增长率分别为26.83和0.21,均显著低于15～25℃变温刺激后的室内棕榈蓟马种群的79.33和0.23;14～45℃变温刺激后的室外棕榈蓟马种群单雌产卵量为46.01粒,也显著低于15～25℃变温刺激后的室内棕榈蓟马种群的135.98粒;14～45℃变温刺激下,室外棕榈蓟马种群雌成虫和2龄若虫对2种杀虫剂的抗药性显著提高,且雌成虫比2龄若虫的抗药性强。表明波动高温刺激不仅抑制了棕榈蓟马的种群发展,也提高了种群对常规药剂阿维菌素和噻虫嗪的抗性。     

不同温度下4株白僵菌对西花蓟马的致病力

本文测定了4株白僵菌在18、22、26、30、34 ℃ 5个温度下对西花蓟马成虫和若虫的毒力, 结果表明：白僵菌JMS、HS、MBb、RSB 4个菌株在这5个温度下对西花蓟马成虫均具有很高的致病力,绝大多数西花蓟马在5 d左右死亡,致死率均在97％以上,多数为99％～100％,致死中时为1.4～3.2 d,白僵菌RSB菌株对西花蓟马成虫的致死中时最短,在30 ℃下,仅为1.4 d。在各温度下供试菌种对西花蓟马若虫的致病力明显低于对西花蓟马成虫的致病力,其致死率一般在90％～99％,致死中时也相对较长。     

宁夏设施辣椒上西花蓟马的生长发育和繁殖研究

在宁夏设施蔬菜大棚内的盆栽辣椒上接虫,对西花蓟马各虫态的发育历期、存活率、成虫产卵量及成虫寿命进行了统计分析。西花蓟马各虫态发育历期研究结果表明,卵期4.96 d,1龄若虫2.78 d,2龄若虫3.41 d,"蛹"期3.76d,成虫产卵前期3.15 d,产卵期17 d,世代周期18.06 d。各虫态存活率统计结果表明,1龄若虫53.72%,2龄若虫69.70%,"蛹"为71.43%,世代存活率为26.74%;成虫寿命27.35 d,每雌产卵量为46.32粒。根据该研究结果及宁夏气象条件,理论上可预测西花蓟马在宁夏设施蔬菜中年发生15~18代,下代发生量可为本代雌虫数量的12倍左右,为准确预测宁夏设施蔬菜中西花蓟马的发生趋势并及时做好有效防控措施提供参考。     

温度对西花蓟马、花蓟马存活和繁殖的影响

在室内研究了19、22、25、28和31℃条件下两种蓟马在辣椒上的存活率、成虫寿命、繁殖力及生命参数,以揭示温度对入侵害虫西花蓟马Frankliniella occidentalis和本地害虫花蓟马Frankliniellaintonsa的影响。结果显示,在19～31℃范围内两种蓟马雌、雄成虫寿命均随温度的升高而缩短,内禀增长率随温度的升高而增大,西花蓟马和花蓟马皆是在31℃时最高,分别为0.1347和0.1822。两种蓟马的种群趋势指数及净增殖率与温度之间呈曲线关系。在相同温度条件下,西花蓟马在各温度下的存活率高于花蓟马,但内禀增长率低于花蓟马。西花蓟马的繁殖力、种群趋势指数及净增值率在22℃时最高,花蓟马在25℃时最高。两种蓟马对温度的适应能力不同,22℃是西花蓟马的最适温度,而25℃更适合于花蓟马。     

不同温度下巴氏新小绥螨对西花蓟马初孵若虫的捕食功能

为明确巴氏新小绥螨[Neoseiulus barkeri(Hughes)]对西花蓟马[Frankliniella occidentalis(Pergande)]初孵若虫的捕食效应,在相对湿度RH 85%±5%,5个温度梯度16、20、24、28、32℃,光照L∥D=16h∥8h条件下选取西花蓟马的初孵若虫进行捕食功能反应。结果表明:巴氏新小绥螨对西花蓟马初孵若虫的捕食功能反应属于HollingⅡ型方程。在16~28℃温度范围内,巴氏新小绥螨对西花蓟马初孵若虫的攻击系数、捕食能力、最大日捕食量均随温度升高而增加,处理时间则缩短,28℃时日捕食量最高达14.471 8头,处理时间最短为0.069 1d。温度达到32℃时,捕食量下降。当西花蓟马初孵若虫的种群密度一定时,巴氏新小绥螨的平均捕食量随其自身密度的增加而降低。说明猎物密度固定时巴氏新小绥螨存在明显的相互干扰作用。     

广州输入性花卉蓟马的种类组成及种群动态分析

西花蓟马Frankliniella occidentalis(Pergande)是一种世界性的入侵害虫,近年来传入我国并迅速扩散蔓延,持续监测广州市输入性花卉中蓟马的种类组成及种群动态,对西花蓟马的早期监测预警具有重要的意义。2011年4月-2013年7月对广州市岭南花卉市场玫瑰、百合、康乃馨三种输入性花卉的蓟马种类及种群动态进行系统调查,利用用气相色谱-质谱联用仪(GC-MS)对蓟马若虫的表皮碳氢化合物进行分析。结果表明:广州地区输入性花卉上蓟马包括西花蓟马F.occidentalis、烟蓟马Thrips tabaci、花蓟马F.intonsa、黄蓟马T.flavidulus 4种,其中西花蓟马是蓟马优势种,而康乃馨是携带西花蓟马的主要花卉品种。西花蓟马在康乃馨上常年发生,成虫种群消长呈单峰型,高峰期在6-8月,冬季最少。此外,康乃馨上蓟马若虫的各色谱峰保留值与西花蓟马若虫的基本一致,比例为83.33%。     

入侵种西花蓟马与本地种花蓟马生长发育的比较研究

研究了在不同恒温条件下西花蓟马(Frankliniella occidentalis)、花蓟马(Frankliniella ibtonsa)取食辣椒时各虫态的发育历期和存活率.并计算了其发育起点温度和有效积温.结果表明.西花蓟马、花蓟马各虫态的发育历期均随温度的升高而缩短;发育历期与温度之间的关系为直线关系:在各温度条件下各虫态的存活率均较高.西花蓟马卵、1龄若虫、2龄若虫、预蛹、蛹的发育起点温度分别为12.47、7.05、13.35、12.67、13.74℃,其有效积温分别为43.13、46.09、64.26、15.57、29.70℃,成虫未成熟期的发育起点温度为12.18℃,有效积温为199.07℃;花蓟马卵、1龄若虫、2龄若虫、预蛹、蛹的发育起点温度分别为12.92、10.36、12.84、11.88、13.19℃,其有效积温分别为44.82、26.15、40.16、15.03、22.83℃.成虫未成熟期的发育起点温度为12.03℃,有效积温为154.85℃.     

Survey of Bacterial and Fungal Seedborne Diseases in Imported and Domestic Potato Seed Tubers

Potato seed tubers are imported to Israel from northern Europe and planted in spring; tubers harvested early from the spring crop are used as seed for the autumn crop. Although only seed lots registered as certified are imported, a previous survey (1984–1994) indicated that most imported lots were affected by latent or active infections caused byErwinia carotovora,Streptomyces scabies, Rhizoctonia solani, Fusarium spp. andSpongospora subterranae. The survey was extended until 1998, and included additional pathogens:Ralstonia solanacearum,Helminthosporium solani, Colletotrichum coccodes andVerticillium dahliae. Most of these pathogens were also monitored in domestic seed tubers, and are reported for the first time. Brown rot was not observed in any of the imported lots. Blackleg and soft rot caused byErwinia spp. were detected in most of the imported lots; however, less than 7% of the lots were contaminated at high levels, while approximately 65% were contaminated at moderate levels. Common scab was detected in most of the imported lots; 51% of the imported lots were contaminated at moderate or high levels, whereas only 6.5% of the domestic seed lots were contaminated at these levels. Black scurf was detected in most of the imported lots; on average, 47.3%, 44.2% and 1.4% of the lots were contaminated at low, moderate and high levels, respectively, and only 7.1% were disease-free. In contrast, most of the domestic lots were either disease-free (45.4%) or had a low disease incidence (37.3%). Only 16.7% of the lots were moderately infected and 0.2% were highly contaminated. Silver scurf was observed in most of the imported lots during all years of the survey, with no differences among the producing countries; on average, 22.7%, 66.1% and 7.5% of the lots were contaminated at low, moderate and high levels, respectively, and only 3.7% were disease-free. Most of the domestic lots (76%) were disease-free and only 6.6% were infected at moderate or high levels. Black dot was observed in a considerable portion of the shipments from Holland during all years of the survey, particularly in 1998, when 34% of the lots were infected. The shipments from France and Germany were infected at low levels, except in 1998, when 19% and 11% of the lots, respectively, arrived infected. In shipments from Scotland and Ireland low incidences of the disease were observed in 1994 and 1995. In the domestic lots, black dot incidence was low (<2.4%) except in 1996, when 11% of the lots were infected.V. dahliae was monitored only in domestic seed tubers. The incidence of disease-free lots was 56–64%, whereas in 20–30% of the lots the level of infection was <5%, and in 6–16% of the lots the level was >5%. The survey findings demonstrate transmission of seedborne pathogens; most of these pathogens can become established in the soil and eventually cause severe outbreaks of disease in potatoes grown in Israel. http://www.phytoparasitica.org posting May 16, 1999.     

Epidemiology and simulation of population development of Sitobion avenae in winter wheat

The epidemiology ofSitobion avenae and its natural enemies in winter wheat was studied in 1975, 1976 and 1977. Immigration was important until the end of flowering. The alate immigrants had apterous offspring. These became the driving force in population growth. Their offspring were mostly alatae which usually left the field. A model of the epidemic was developed. Quantitative relations between the aphids and their environment were obtained from literature or established in laboratory trials. The model simulated population development and population composition from the beginning of June till the population peak at the end of June or early in July. Because quantitative data on relations between aphids and their natural enemies and pathogens are scarce, and since the knowledge on wing formation is still limited, the population collapse could not be predicted. In the future, prognosis over a period of three weeks seems possible.Samenvatting De toenemende betekenis van graanbladluizen (vooralSitobion avenae) gepaard gaande met een sterke toename van het gebruik van insecticiden op granen maakte verbetering van de prognose over het schadelijk optreden wenselijk. Door gedetailleerde tellingen in het veld (Fig. 1–7) werden gegevens verkregen over het verloop van de epidemie en het optreden van natuurlijke vijanden in 1975, 1976 en 1977.Een immigratieperiode tot in de bloei kon worden vastgesteld. Daarna lijkt de aantrekkelijkheid van het gewas voor alate luizen te verminderen. De alate immigranten krijgen aptere nakomelingen. Deze vormen de stuwende kracht van de populatiegroei. De nakomelingen van apteren zijn merendeels alaat. Zij verlaten het gewas.Een model van de populatieontwikkeling gedurende de epidemie werd opgesteld. De relatiediagrammen Fig. 9 en 10 laten groei en ontwikkeling vanS. avenae en een predator (Syrphus corollae) zien. Kwantificering van de betrekkingen werd mogelijk door literatuurgegevens en laboratoriumexperimenten.Met het model kon de populatieontwikkeling vanS. avenae vanaf begin juni tot aan de populatiepiek in 1975, 1976 en 1977 vrij goed worden gesimuleerd (Fig. 12). Ook de populatieopbouw kon worden gesimuleerd (Fig. 14). De teruggang van de populatiedichtheid blijkt moeilijker te voorspellen door het ontbreken van gegevens over natuurlijke vijanden.Het lijkt waarschijnlijk dat in de toekomst met het model een prognose over de piek van de bladluispopulatie circa 3 weken tevoren mogelijk zal zijn.     

Diagnostics,genetic diversity and pathogenic variation of ascochyta blight of cool season food and feed legumes

Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.     

Bacterial induction of the accumulation of phaseollin,pisatin and rishitin and their antibacterial activity

Bean hypocotyls, pea pods and tomato fruits were tested for phaseollin, pisatin and rishitin production when challenged with the phytopathogenic bacteriaErwinia carotovora, Pseudomonas phaseolicola, P. pisi andP. solanacearum, and their isolated extracellular polysaccharides. All bacteria induced phytoalexin accumulation, whereas only phaseollin and pisatin, but not rishitin, were elicited by EPS. The inhibitory effect of these three phytoalexins on bacterial growth was studied in liquid medium; whereas phaseollin and pisatin strongly inhibited growth, only a slight inhibitory effect resulted from the presence of rishitin in the medium.Samenvatting Bonehypocotylen, erwtepeulen en tomatevruchten werden onderzocht op hun vermogen tot vorming van respectievelijk faseolline, pisatine en rishitine, na inoculatie met de fytopathogene bacteriënErwinia carotovora, Pseudomonas phaseolicola, P. pisi enP. solanacearum en na behandeling met oplossingen van hun extracellulaire polysacchariden (EPS). Alle bacteriesoorten induceerden fytoalexinevorming, terwijl hun EPS wel faseolline- en pisatine-, maar geen rishitinevorming induceerden. Faseolline en pisatine remden de groei van de bacteriën in vloeibaar medium sterk; rishitine daarentegen had slechts een geringe groeiremming tengevolge.     

Tumours of Begonia and some other ornamentals,induced by Corynebacterium fascians

In 1975 many tumours were observed in plants ofBegonia Schwabenland grown in Aalsmeer. Submersion of the roots ofNicotiana megalosiphon seedlings in a homogenate of tumorous tissue, induced tumours after two weeks. Short periods of submergence yielded results similar to those obtained after longer periods. Tumour homogenates lost their infectivity after ten min at 50°C. Aphids transmitted the infectious agent.Treatment with propylene oxide did not inhibit infectivity completely. Filtration through a 450 nm filter removed the infectious agent.Tobacco tumor virus or a viroid could not be isolated. Cultures ofCorynebacterium fascians, isolated from tumours ofN. megalosiphon were highly infectious and induced tumours in healthyN. megalosiphon andBegonia. Tumorous tissue homogenates ofPelargonium zonale, Dahlia sp.,Gladiolus sp., andLilium sp. also caused tumours inN. megalosiphon, from whichC. fascians was isolated. It was not possible to produce tumours inN. megalosiphon with homogenates from roses with symptoms of bud proliferation.Samenvatting In 1975 werden vele tumoren waargenomen inBegonia Schwabenland op Aalsmeerse bedrijven (Fig. 1). De infectiositeit van tumorweefsel kon goed en snel worden vastgesteld door de wortels van zaailingen vanNicotiana megalosiphon in een homogenaat van tumorweefsel te dompelen. Tumoren ontstonden na twee weken, de eindbeoordeling geschiedde na een maand (Fig. 2). Ook verschillende andereNicotiana spp.,Melilotus officinalis (Fig. 3) enPisum odoratum (Fig. 4) werden aangetast.Bij de infectiositeitstoets gaven zeer korte dompeltijden even goede resultaten als langere (Tabel 1). Infectieus sap verloor zijn infectievermogen na 10 min verhitting bij 50°C. Bladluizen brachten de smetstof over. Propyleenoxide verminderde de infectiositeit wel, doch onderdrukte deze niet totaal. Bij filtratie door een 450 nm filter bleef het infectieuse agens op het filter achter. Het tumor-inducerende agens was ook aanwezig in die delen van planten met tumoren welke gezond leken en het ging voor een gering deel over met zaad (Tabel 2).Uit tumoren konden wij geen tabakstumorvirus of een viroïde isoleren. Culturen vanCorynebacterium fascians, geïsoleerd uit tumoren vanN. megalosiphon bleken zeer infectieus en veroorzaakten tumoren inN. megalosiphon enBegonia. Homogenaten van tumorweefsel vanPelargonium zonale, dahlia (Fig. 5), gladiool (Fig. 6) enLilium Mid Century Hybrid Enchantment (Fig. 7) veroorzaakten ook tumoren opN. megalosiphon, waaruitC. fascians werd geïsoleerd. Met sap van kroeskopzieke rozen konden wijN. megalosiphon niet besmetten.     

Evaluation of Natural Chemical Compounds Against Root-lesion and Root-knot Nematodes and Side-effects on the Infectivity of Arbuscular Mycorrhizal Fungi

The survival of two species of plant parasitic nematodes: the root-lesion nematode Pratylenchus brachyurus, and the root-knot nematode Meloidogyne javanica, was evaluated in saturated atmospheres of 12 natural chemical compounds. The infectivity of two isolates of arbuscular mycorrhizal fungi: Glomus mosseae and Glomus intraradices, under identical experimental conditions, was also determined. All the compounds tested exerted a highly significant control against M. javanica and among them, benzaldehyde, salicilaldehyde, borneol, p-anisaldehyde and cinnamaldehyde caused a mortality rate above 50% over P. brachyurus. The infectivity of G. intraradices was inhibited by cinnamaldehyde, salicilaldehyde, thymol, carvacrol, p-anisaldehyde, and benzaldehyde, while only cinnamaldehyde and thymol significantly inhibited mycorrhizal colonization by G. mosseae.     

Identification and pathogenicity of Pythium species causing damping-off of kidney bean

Five Pythium species (Pythium irregulare, P. mamillatum, P. myriotylum, P. spinosum and P. ultimum var. ultimum) were isolated from the hypocotyls and roots of kidney bean plants with damping-off from a commercial field and from experimental plots that have undergone either continuous cropping with kidney bean or rotational cropping with arable crops. In inoculation tests, all five Pythium species were pathogenic to kidney bean. This is the first report of damping-off of kidney bean caused by Pythium species; we named this disease damping-off of kidney bean. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession numbers AB291811, AB291944 and AB291945.     

Species presence and density of tetranychid and phytoseiid mites in unsprayed and sprayed apple orchards in Northern Israel

Species presence and density of mixed populations of phytophagous tetranychid and predacious phytoseiid mites were studied in sprayed and unsprayed apple orchards in northern Israel during three growing seasons. Two species of phytophagous tetranychids, namely,Tetranychus cinnabarinus Boisduval andT. Urticae Koch, and two species of predatory phytoseiid mites —Typhlodromus athiasae Porath and Swirski andAmblyseius swirskii Athias-Henriot — were found. Predator density was lower than herbivore density in sprayed commercial orchards, but the reverse was true in unsprayed orchards. Contribution from the Agricultural Research Organization. No. 2855-E, 1989 series.     

The involvement of ethylene and calcium in gray mold of pelargonium,ruscus, and rose plants

Leaves ofPelargonium domesticum andRuscus hypoglossum infected byBotrytis cinerea Pers., produced 12 and 1.5 nl ethylene/h/g, respectively, 34 days after inoculation; wounded or healthy leaves and phyloclades of them produced much lower amounts. When the fungus was grown on dead leaves it produced negligible amounts of the gas even when supplemented with methionine. Exogenous ethylene enhanced gray mold development in both hosts. Silver thiosulfate, aminooxyacetic acid (AOA) and aminoethoxyvinylglycine significantly inhibited disease development in pelargonium, and the latter two compounds inhibited ethylene production. AOA inhibited disease development and ethylene production in cut rose flowers; calcium ions inhibited disease development whereas the chelator EGTA [ethylene glycol bis-(β-aminoethyl ether)N,N,N′,N′-tetraacetic acid] enhanced it. Disease suppression by an excess of Ca²⁺ was correlated with repression of ethylene production by the flowers, whereas deficiency in Ca²⁺ increased disease severity. Publication of the Agricultural Research Organization. No. 2413-E, 1988 series.     

Fungi on roots and stem bases of asparagus in the Netherlands: species and pathogenicity

A survey was made to identify the most important soilborne fungal pathogens of asparagus crops in the Netherlands. Ten plants were selected from each of five fields with a young (1–4 y) first planting, five fields with an old (6–13 y) first planting and five fields with a young replanting. The analysis included fungi present in the stem base and the roots of plants with symptoms of foot and root rot or showing growth decline without specific disease symptoms. Isolates of each species were tested for pathogenicity to asparagus on aseptically grown plantlets on Knop's agar. Symptoms were caused byFusarium oxysporum, F. culmorum, Botrytis cinerea, Penicillium verrucosum var.cyclopium, Cylindrocarpon didymum, Phialophora malorum, Phoma terrestris andAcremonium strictum. F. oxysporum was by far the most common species and was isolated from 80% of the plants. Not all of its isolates were pathogenic to asparagus. Symptoms were caused by 67%, 78% and 93% of the isolates obtained from young first plantings, old first plantings and replantings, respectively.F. culmorum was isolated from 31% of the plants. Two other notorious pathogens of asparagus,F. moniliforme andF. proliferatum, did not occur in our samples.Species causing symptoms in the vitro test that were found on more than 5% of the plants were additionally tested for their pathogenicity in pot experiments.F. oxysporum f.sp.asparagi caused severe foot and root rot, significantly reduced root weights and killed most of the plants.F. culmorum caused lesions on the stem base often resulting in death of the plant.P. terrestris, a fungus only once reported as a pathogen of asparagus, caused an extensive root rot, mainly of secondary roots that became reddish. The fungus was isolated in only a few samples and is not to be regarded as an important pathogen in Dutch asparagus crops.P. malorum caused many small brown lesions on the stem base and incidentally also on the upper part of small main roots. This is the first report of its pathogenicity to asparagus. The fungus is one of the organisms inciting spear rust and it reduced crop quality rather than crop yield.P. verrucosum var.cyclopium andC. didymum did not cause symptoms in pot experiments.Because of its predominance on plants with foot and root rot and its high virulence,F. oxysporum f.sp.asparagi was considered to be the main soilborne pathogen of asparagus in the Netherlands.