草地贪夜蛾CRAL_TRIO结构域基因家族的基因组鉴定及其表达特征分析

为明确重大入侵性害虫草地贪夜蛾Spodoptera frugiperda CRAL_TRIO结构域基因的功能,利用同源比对法鉴定该害虫基因组中的CRAL_TRIO结构域基因,利用系统进化树和基因染色体定位探究其进化关系,使用数字基因表达谱分析其在不同发育阶段的表达情况,并采用反转录PCR技术分析19个CRAL_TRIO结构域基因在雌雄成虫不同组织中的表达特征。结果显示,从草地贪夜蛾基因组中鉴定到46个CRAL_TRIO结构域基因,所编码的氨基酸序列存在典型CRAL_TRIO结构域,且该结构域中有8个保守的氨基酸位点。系统进化树和基因染色体定位分析表明,多数草地贪夜蛾CRAL_TRIO结构域基因通过基因复制进化而来。基因表达谱分析发现,草地贪夜蛾CRAL_TRIO结构域基因在不同发育阶段的表达可聚为2组,其中一组在幼虫前期高表达,另一组在6龄幼虫期、蛹期和成虫期高表达。挑选验证的CRAL_TRIO结构域基因大部分在触角和脑中高表达,有2个基因在触角中特异性表达,部分在复眼中具有较高的表达量,表明这些CRAL_TRIO结构域基因在草地贪夜蛾嗅觉和视觉行为调控中起重要作用。     

草地贪夜蛾Bt抗性相关lncRNA的预测及分析

为明确长链非编码RNA（long non-coding RNA,lncRNA）在草地贪夜蛾Spodoptera frugiperda对Bt产生抗性中的作用,采用生物信息学预测草地贪夜蛾的lncRNA基因,并对其进行特征分析、差异表达分析、靶标基因预测以及功能富集分析。结果显示,草地贪夜蛾46个RNA-Seq数据中共有2 033个lncRNA基因,对应2 034条lncRNA转录本;与蛋白质编码基因相比,草地贪夜蛾lncRNA的外显子数量更少,转录本长度更短。草地贪夜蛾Bt抗性品系和敏感品系之间共有266个差异表达的lncRNA,其中128个上调表达,138个下调表达;在lncRNA靶标中,顺式调控和反式调控的靶标基因分别为2 129个和1 955个;靶标基因分子功能主要集中于有毒物质结合、水解酶和丝氨酸类蛋白活性等。10个差异表达的lncRNA靶向碱性磷酸酶、氨肽酶N、ABC转运蛋白、丝裂原活化蛋白激酶以及钙黏蛋白等抗性相关基因,表明lncRNA可能参与了草地贪夜蛾对Bt抗性的形成。     

基于CRISPR/Cas9系统分析草地贪夜蛾Wnt1基因的生物学功能

为明确草地贪夜蛾Spodoptera frugiperda中Wnt1基因的生物学功能,采用实时荧光定量PCR(real-time quantitative PCR,qPCR)技术检测草地贪夜蛾胚胎发育期Wnt1基因的表达谱,利用CRISPR/Cas9系统对Wnt1基因进行定向敲除,并通过qPCR技术检测草地贪夜蛾Wnt1基因缺失突变体中与昆虫发育相关基因的表达水平。结果显示,Wnt1基因在草地贪夜蛾整个胚胎发育期均有表达,在胚胎发育早期（6 h）表达水平最高。将SfWnt1-sgRNA和Cas9蛋白混合注入草地贪夜蛾卵中,胚胎死亡率明显升高,同时获得了Wnt1基因缺失的草地贪夜蛾突变体。突变率与注射浓度相关,注射浓度越高,突变率越高;当SfWnt1-sgRNA和Cas9蛋白混合后终浓度均为300 ng/μL时,注射的724粒卵中获得体节缺陷突变体52头,附肢缺陷突变体64头,组织特化突变体20头;SfWnt1-sg RNA和Cas9蛋白混合后终浓度均为100 ng/μL时,注射的413粒卵中最终获得体节缺陷突变体14头,附肢缺陷突变体22头,组织特化突变体7头;这些突变体均无法存活至化...     

菊酯类药剂对草地贪夜蛾的毒力及对钠离子通道的诱导特性

为明确菊酯类药剂对草地贪夜蛾Spodoptera frugiperda的防治效果,采用点滴法在室内测定高效氯氟氰菊酯、高效氯氰菊酯、联苯菊酯、溴氰菊酯和茚虫威原药对草地贪夜蛾3龄幼虫的毒力,利用实时荧光定量PCR技术测定3龄幼虫在这5种药剂诱导不同时间下其体内钠离子通道基因片段的表达量变化。结果显示,高效氯氟氰菊酯、溴氰菊酯、联苯菊酯、茚虫威和高效氯氰菊酯这5种药剂处理草地贪夜蛾3龄幼虫24 h后的LD50值分别为74.911、83.280、152.662、179.372、567.250 mg/L;处理48 h后的LD50值分别为18.946、67.874、120.888、132.790、461.635 mg/L;同时发现草地贪夜蛾3龄幼虫钠离子通道基因的表达均呈现不被诱导或诱导下调现象,表明草地贪夜蛾幼虫可通过降低靶标基因的表达量进而减少药剂对其的毒性。表明供试4种拟除虫菊酯类药剂和1种氯虫苯甲酰胺类药剂可作为草地贪夜蛾田间应急防控药剂施用。     

草地贪夜蛾取食诱导玉米叶片转录组分析

为阐明玉米响应草地贪夜蛾Spodoptera frugiperda取食胁迫防御反应的分子机制,利用RNAseq技术对草地贪夜蛾取食的玉米叶片进行转录组测序分析,并对抗虫代谢产物生物合成途径中的基因进行筛选鉴定。结果显示,与未接虫对照相比,草地贪夜蛾取食18 h导致玉米叶片中有1 645个基因差异表达(log2|处理/对照|1且FDR0.05),其中上调表达基因有1 352个,下调表达基因有293个。茉莉酸、水杨酸、乙烯等植物激素生物合成与信号转导途径相关基因大多上调表达,其中44个茉莉酸途径相关基因全部上调表达,说明该途径在玉米响应草地贪夜蛾取食诱导的防御反应中发挥着核心作用,其它激素生物合成与信号转导途径发挥协同作用。玉米重要抗虫次生代谢物苯并噁唑嗪酮类生物合成相关基因中有9个基因上调表达;15个萜烯挥发物生物合成相关差异表达基因中有14个上调表达,包括8个萜烯合成酶基因和1个CYP基因CYP92C5。表明草地贪夜蛾取食会诱导玉米复杂的植物激素途径和基因调控机制,激活以次级抗虫代谢物合成为主的防御反应。     

草地贪夜蛾核型多角体病毒对草地贪夜蛾的毒力及其侵染特征

为明确草地贪夜蛾核型多角体病毒（Spodoptera frugiperda multiple nucleopolyhedrovirus,SfMNPV）对草地贪夜蛾Spodoptera frugiperda 的毒力及其体内外侵染特性,于室内测定SfMNPV对草地贪夜蛾的毒力,采用苏木精-伊红（hematoxylin-eosin,HE）染色分析SfMNPV侵染后草地贪夜蛾的组织病理学特征,通过实时荧光定量PCR（real-time fluorescence quantitative PCR,qPCR）技术分析SfMNPV在草地贪夜蛾体内和Sf9细胞系中的复制特征。结果表明,SfMNPV对草地贪夜蛾2龄幼虫的LC₅₀和LT₅₀分别为7.39×10⁵ OBs/mL和3.82 d;SfMNPV可侵染草地贪夜蛾幼虫的真皮、气管、脂肪体和中肠等组织,未侵染肌肉组织;SfMNPV侵染96 h后草地贪夜蛾体内SfMNPV基因组拷贝数最大,为3.91×10⁶ 拷贝数/ng,SfMNPV侵染96 h后Sf9细胞培养上清液中SfMNPV基因组拷贝数最大,为2.08×10⁷ 拷贝数/mL。     

黏虫咽侧体抑制神经肽基因克隆与成虫期表达模式分析

为明确黏虫咽侧体抑制神经肽基因(allatostatin,AST)在调控黏虫Mythimna separata(Walker)保幼激素(juvenile hormone,JH)中的功能,采用RT-PCR和RACE技术克隆获得的黏虫AST基因cDNA全长序列902bp,开放阅读框378bp,编码125个氨基酸。蛋白分子量为14.33kD,等电点为9.25,具有C型AST典型的PISCF序列。进化树分析表明,黏虫AST氨基酸序列与一点黏虫、草地贪夜蛾、棉铃虫氨基酸序列相似性高达80%以上。实时荧光定量PCR结果表明AST在成虫期的表达有明显组织和时间特异性。AST在飞行肌中表达量最高,头部其次,卵巢最低;黏虫头部AST表达量在7日龄最高,飞行肌中AST基因的表达量在1日龄最高。本研究对进一步揭示黏虫AST基因对JH调控作用,明确黏虫JH调控迁飞和生殖的相关的分子调控机制具有重要意义。     

黄淮海夏玉米区草地贪夜蛾为害籽粒玉米的产量损失与防治阈值

为确定我国草地贪夜蛾 Spodoptera frugiperda重点防范区——黄淮海夏玉米区该虫为害籽粒玉米的防治阈值,于2020—2021年分别在籽粒玉米小喇叭口期（6~8叶）、大喇叭口期（8~10叶）和抽雄吐丝期 （12~14叶）,通过人工接草地贪夜蛾2龄幼虫进行田间试验,分析不同虫口密度和为害株率下玉米的产量损失,并确定相应防治阈值。结果显示,草地贪夜蛾2龄幼虫密度为2~12头/株时,小喇叭口期、大喇叭口期和抽雄吐丝期的玉米产量损失率分别为16.78%~31.91%、 10.45%~25.14%和15.71%~29.17%,在3个玉米生育期对草地贪夜蛾的防治阈值分别为2龄幼虫55~67头/百株、 97~118头/百株和59~71头/百株;当草地贪夜蛾2龄幼虫为害株率为5%~60%时,小喇叭口期、大喇叭口期和抽雄吐丝期的玉米产量损失率分别为8.81%~22.43%、 4.83%~17.75%和8.16%~20.43%,在3个玉米生育期对草地贪夜蛾的防治阈值为害株率分别为4.24%~5.22%、 7.61%~9.49%和4.46%~5.55%。表明黄淮海夏玉米区草地贪夜蛾在不同生育期为害籽粒玉米的产量损失和防治阈值不同。     

Sensitivity to iprodione and boscalid of Sclerotinia sclerotiorum isolates collected from rapeseed in China

Baseline sensitivity of Sclerotinia sclerotiorum, causal agent of stem rot of rapeseed, to a dicarboximide fungicide iprodione was determined using 50 isolates (historic population) collected in 2001 from the rapeseed fields without a previous history of dicarboximide usage. The 50% effective concentration (EC₅₀) values to iprodione of these wild-type isolates ranged from 0.163 to 0.734 μg/ml with a mean of 0.428 μg/ml. In 2007 and 2008, 111 isolates (current population) were collected from rapeseed fields with 4–5 years of iprodione application. The EC₅₀ values of these 111 isolates ranged from 0.117 to 0.634 μg/ml. The historic and current populations were not significantly (P > 0.05) different in sensitivity to iprodione. The EC₅₀ values of these 161 isolates to a carboxamide fungicide boscalid ranged from 0.002 to 0.391 μg/ml with a mean of 0.042 μg/ml. In the laboratory, three iprodione-resistant (IR) isolates HA17-IR, SZ31-IR, and SZ45-IR were induced from wild-type isolates HA17, SZ31, and SZ45, respectively. The EC₅₀ values of the IR isolates were 200-fold higher than those of the original wild-type parents. The IR isolates showed an increase in osmotic sensitivity. The IR isolate HA17-IR lost its ability to produce sclerotia, and showed a significantly lower virulence on rapeseed leaves than its parent isolate HA17. In contrast, the IR isolate SZ31-IR had a significantly higher virulence than its wild-type parent SZ31. PCR assays showed that the partial two-component histidine kinase (os-1) gene, which is the putative target gene of iprodione, was deleted in the low virulent IR isolate HA17-IR. DNA sequence analysis showed that each of the other two IR isolates SZ31-IR and SZ45-IR had two point mutations in their partial os-1 genes. These results indicate that the mutations in os-1 gene may be associated with dicarboximide sensitivity, sclerotial development, and virulence in S. sclerotiorum.     

Polyphosphate kinase is essential for swarming motility, tolerance to environmental stresses, and virulence in Pseudomonas syringae pv. tabaci 6605

Polyphosphate kinase (PPK), encoded by the ppk gene, is a principal enzyme responsible for synthesis of inorganic polyphosphate (poly P) from ATP in many Gram-negative bacteria. In order to elucidate the functions of poly P in Pseudomonas syringae pv. tabaci 6605, an in-frame deletion mutant of the ppk gene (ppk) was constructed. The ppk mutant did not accumulate poly P, whereas the wild-type strain accumulated a large quantity. The mutant had reduced swarming motility, even though it retains swimming motility like the parental strain. The mutant exhibited increased sensitivity to prolonged incubation and environmental stresses, such as heat shock and oxidative stress and reduced exopolysaccharide (EPS) production compared to the wild-type. Northern blot analysis revealed that expression of the rpoS gene, encoding the stationary phase sigma factor RpoS, was reduced in ppk in the logarithmic phase, indicating that rpoS is regulated by the ppk gene. The poly P deficient mutant had significantly reduced ability to cause disease in its host tobacco plant and in planta growth of the mutant was also significantly reduced in host tobacco leaves as compared to the wild-type strain. Thus, our results suggest that poly P plays an important role in the virulence of P. syringae pv. tabaci 6605.     

豌豆蚜防控的关键RNAi靶标基因筛选与分析

为筛选防控豌豆蚜Acyrthosiphon pisum的关键RNA干扰(RNA interference,RNAi)靶标基因,通过构建精氨酸激酶(arginine kinase,AK)、超氧化物歧化酶(superoxide dismutase,SOD)和几丁质合成酶(chitin synthase,CHS)这3个与豌豆蚜生长发育相关基因的dsRNA,于室内检测ds AK、ds SOD和ds CHS处理后对其致死效果,并比较4种dsRNA递送方式对其致死效果的影响,筛选获得防治效果明显的dsRNA及其递送方式。结果显示,处理48～168 h后,不同基因dsRNA处理组豌豆蚜的死亡率比阴性对照组高2.19倍～4.39倍,其中ds AK处理组豌豆蚜的死亡率为27.7%～91.1%,显著高于ds SOD、ds CHS处理组及阴性对照组。使用ds AK通过人工饲喂法和叶片注射饲喂法处理豌豆蚜,48 h即可出现显著致死效果。ds AK通过人工饲喂方法处理72 h后,豌豆蚜AK基因表达量比空白对照组降低43.2%,同时可抑制豌豆蚜的生长发育,使其体长比阴性对照组减少了5.9%。表明ds AK对豌豆蚜...     

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.     

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.     

Nematicidal Activity of Chrysanthemum coronarium

Organic amendments and green manure are potential alternatives to the harmful chemical control means currently used against plant-parasitic nematodes. In this work, Chrysanthemum coronarium was applied to the soil as a green manure to control the root-knot nematodes Meloidogyne incognita and M. javanica. Chrysanthemum coronarium significantly reduced nematode infection of tomato roots and improved plant-top fresh weight, both in the greenhouse and in microplots. Other green manures, derived from Anthemis pseudocotula, wild chickpea (Cicer pinnatifidum), Geranium spp. and wheat, were not as effective as C. coronarium. Chrysanthemum coronarium, retained its nematicidal activity even when applied as a dried material. Only mature C. coronarium plants, in their flowering stage, exhibited nematode control activity, but the green plant parts were more effective than the flowers. An aqueous extract of C. coronarium exhibited in vitro, nematostatic activity towards M. incognita and M. javanica second-stage juveniles and inhibited their hatching from eggs and egg-masses; its nematostatic activity was expressed also against other phytonematode species such as Heterodera avenae and Pratylenchus mediterraneus, but did not affect the beneficial entomopathogenic nematode Steinernema feltiae.     

Inactivation of soil-borne plant pathogens during small-scale composting of crop residues

Samples of heavily infested crop residues were incorporated in static compost heaps (2.5–4.6 m³) of the Indore type. Temperature increased to 50–70°C within 6 days depending on the type of crop residues used and the location within the heap. The heat phase (>40 °C) lasted 2–3 weeks and was followed by a c. 5-months maturation phase (<40 °c).=" among=" the=" 17=" pathogens=" tested,=">Olpidium brassicae and one of the four formae speciales ofFusarium oxysporum that were tested survived composting, but also their inoculum was greatly reduced.Survival during specific phases of composting was studied by incorporation and retrieval of samples at various stages of the process.F. oxysporum f. sp.melonis was completely inactivated andO. brassicae andPlasmodiophora brassicae were almost completely inactivated during the short heat phase. The three pathogens survived the long-lasting maturation phase without loss of viability. Heat evolved during composting was found to be the most important factor involved with sanitation of crop residues. The possible involvement of fungitoxic conversion products and microbial antagonism is discussed.     

浅黄恩蚜小蜂和丽蚜小蜂对温室白粉虱的寄生潜能分析

浅黄恩蚜小蜂Encarsia sophia GiraultDodd和丽蚜小蜂Encarsia formosa Gahan是防治粉虱类害虫的优势寄生蜂,通过生命表技术方法分析了2种寄生蜂对温室白粉虱Trialeurodes vaporariorum(Westwood)的防治潜能。结果表明,丽蚜小蜂在羽化第3天和第10天出现2次寄生高峰,占其总寄生量的13.7%和8.0%,在2次高峰之间逐日寄生粉虱数量比较平稳,单雌逐日平均产雌数保持在10.6~13.4头,10 d后寄生量呈明显的下降趋势;而浅黄恩蚜小蜂羽化10 d内逐日寄生粉虱量变化不大,单雌逐日产雌数稳定在4.2~5.4头,羽化14 d后寄生量呈明显下降趋势。丽蚜小蜂和浅黄恩蚜小蜂的R0、T、rm、λ值分别为171.5、18.0、0.2854、1.3303和61.6、16.2、0.2544、1.2897;粉虱若虫充足时,丽蚜小蜂平均单雌寄生若虫数是浅黄恩蚜小蜂的2.7倍,而后者平均单雌取食若虫数为60.6头,明显高于前者42.7头,总的来看,丽蚜小蜂通过寄生和取食杀死粉虱总量220.8头,明显高于浅黄恩蚜小蜂的127.9头。表明在应用寄生蜂防治温室白粉虱时,单独释放丽蚜小蜂比浅黄恩蚜小蜂显示出更好的防治潜能。     

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.     

Pathogenic fungi involved in root rot of peas in the Netherlands and their physiological specialization

Research on root rot pathogens of peas in the Netherlands has confirmed the prevalence ofFusarium solani, F. oxysporum, Pythium spp.,Mycosphaerella pinodes andPhoma medicaginis var.pinodella. Aphanomyces euteiches andThielaviopsis basicola were identified for the first time as pea pathogens in the Netherlands. Other pathogens such asRhizoctonia solani andCylindrocarpon destructans were also found on diseased parts of roots. F. solani existed in different degrees of pathogenicity, and was sometimes highly specific to pea, dwarf bean of field bean, depending on the cropping history of the field.A. euteiches was specific to peas, whereasT. basicola showed some degree of physiological specialization.