河南省假禾谷镰刀菌对咯菌腈的敏感性

由假禾谷镰刀菌Fusarium pseudograminearum引起的小麦茎基腐病已成为重要的土传病害,并且影响小麦的品质和产量。为了明确中国河南省假禾谷镰刀菌对咯菌腈的敏感性,采用菌丝生长速率法测定了咯菌腈对2019年从河南省6个地市分离的105株假禾谷镰刀菌F. pseudograminearum 的敏感性,通过最小显著差异法(LSD)和SPSS聚类方法对测定结果进行了分析,并测定了假禾谷镰刀菌对多菌灵和戊唑醇的敏感性,分析了咯菌腈与这两种杀菌剂毒力的相关性。结果表明:咯菌腈对供试菌株的最低抑制浓度(MIC)为0.2400 μg/mL。敏感性频率分布图显示,EC₅₀值范围在0.0027~0.0470 μg/mL,敏感性差异达17.41倍;敏感性频率分布为连续单峰曲线,平均EC₅₀值为(0.0263 ± 0.0101) μg/mL,可作为假禾谷镰刀菌对咯菌腈的敏感性基线。方差分析结果显示,不同县市的小麦假禾谷镰刀菌对咯菌腈的敏感性差异较大,EC₅₀值变化范围为0.0150~0.0335 μg/mL,其中咯菌腈对郑州中牟的敏感性最低和最高菌株的EC₅₀值相差16.78倍。聚类分析结果显示,河南省小麦茎基腐病菌菌株对咯菌腈敏感性差异与菌株的地理来源无明显关联性。多菌灵和戊唑醇对病菌的平均EC₅₀值分别为 (0.7881 ± 0.3153) μg/mL和(0.0886 ± 0.1453) μg/mL。病菌对咯菌腈与其对多菌灵和戊唑醇的敏感性之间无明显相关性。温室防效结果显示,用咯菌腈悬浮种衣剂对小麦进行拌种处理,2020年 (咯菌腈有效成分为75.0 μg/g)对小麦茎基腐病的防治效果可达58.00%,2021年 (咯菌腈有效成分为50.0 μg/g)的防治效果可达到63.69%。本研究结果可为咯菌腈在小麦茎基腐病防治中的合理使用提供依据,为病原菌对药剂的敏感性监测提供参考。     

中国河南省小麦纹枯病菌对咯菌腈的敏感性

为明确河南省小麦纹枯病菌对咯菌腈的敏感性,采用菌丝生长速率法测定了咯菌腈对2013年从河南省15个地市分离的98株病菌的毒力。结果表明:咯菌腈对供试小麦纹枯病菌菌株的EC50值在0.009~0.079 μg/mL之间,平均EC50值为(0.025 ±0.012)μg/mL;98个菌株对咯菌腈的敏感性分布呈连续单峰曲线,未出现敏感性下降的亚群体,可将(0.025 ±0.012)μg/mL作为小麦纹枯病菌对咯菌腈的敏感性基线;方差分析(LSD法)及SPSS聚类结果均显示,同一地市内的菌株对咯菌腈的敏感性差异较大,EC50最大值和最小值之比在1.0~4.1之间,而不同地区菌株间对咯菌腈敏感性差异不明显,咯菌腈EC50平均值变化范围在0.015~0.060 μg/mL之间,后者是前者的4倍;小麦纹枯病菌对咯菌腈的敏感性与其对噻呋酰胺、苯醚甲环唑、井冈霉素、丙环唑及戊唑醇的敏感性之间无明显相关性。本研究结果可为河南省小麦纹枯病防控杀菌剂的合理使用提供理论依据。     

马铃薯早疫病菌对咯菌腈的敏感基线及其对不同药剂的交互抗性

采用菌丝生长速率法测定了河北省马铃薯主产区的122株早疫病菌Alternaria alternata对咯菌腈的敏感性,并测定了紫外诱导的15个抗咯菌腈突变菌株及其3个敏感亲本菌株对咯菌腈、异菌脲、腐霉利、苯醚甲环唑、吡唑醚菌酯的敏感性。田间马铃薯早疫病菌群体对咯菌腈保持高度敏感,122株早疫病菌对咯菌腈的EC₅₀值在0.0025~0.0857 μg/mL之间,平均值为0.0404±0.0171 μg/mL,相差34.87倍,呈近似正态分布,可作为早疫病菌对咯菌腈的敏感基线。此外,咯菌腈与吡唑醚菌酯和苯醚甲环唑之间无交互抗性关系,而与异菌脲和腐霉利之间存在正交互抗性关系。在田间药效试验中,50%咯菌腈WP施药量为105、115 g/hm²时,对马铃薯早疫病防效达80%以上,显著高于常规药剂80%代森锰锌WP 1 350 g/hm²和25%丙环唑EC 37.5 g/hm²的防效。表明咯菌腈可作为吡唑醚菌酯和苯醚甲环唑的替代药剂用于马铃薯早疫病的防治。     

葡萄白腐病菌对抑霉唑的敏感基线及其与不同杀菌剂的交互抗性

为明确山东省胶东地区葡萄白腐病菌Coniella diplodiella对抑霉唑的敏感性及抑霉唑与常规杀菌剂之间的交互抗性,采用菌丝生长速率法测定葡萄白腐病菌对抑霉唑等杀菌剂的敏感性,并通过分析抑霉唑与戊唑醇、吡唑醚菌酯、福美双、多菌灵、代森锰锌毒力的相关性,判断抑霉唑与各药剂之间是否存在交互抗性。结果表明,供试69株葡萄白腐病菌菌株对抑霉唑的EC₅₀在0.13~55.53 μg/mL之间,最高值与最低值相差427.15倍;其频数分布图呈多峰曲线,第一主峰内EC₅₀平均值为6.34 μg/mL,可作为胶东地区葡萄白腐病菌对抑霉唑的敏感基线。与敏感基线相比,田间已出现抑霉唑低抗菌株,占检测总株数的8.70%,未检测到中、高抗菌株。选择3个抗性菌株连续继代培养10代后,其对抑霉唑的敏感性明显提高,说明其抗药性不能稳定遗传。抑霉唑EC₅₀对数值与戊唑醇、吡唑醚菌酯、福美双、多菌灵、代森锰锌的EC₅₀对数值之间的相关系数分别为0.799、-0.143、-0.089、-0.268和0.159,说明抑霉唑与戊唑醇存在一定的交互抗性,但与其他4种药剂之间不存在交互抗性。表明抑霉唑可用于胶东地区田间葡萄白腐病的有效防控。     

辽宁省不同地区番茄灰霉病菌对咯菌腈的敏感性

为明确辽宁省不同地区间番茄灰霉病菌对咯菌腈的敏感性是否存在差异,以及咯菌腈与其他杀菌剂之间是否存在交互抗性,采用菌丝生长速率法测定番茄灰霉病菌对咯菌腈、腐霉利、多菌灵的敏感性。结果表明,从辽宁省6个不同地区分离的番茄灰霉病菌菌株对咯菌腈的平均EC50差异不显著,番茄灰霉病菌菌株对咯菌腈的敏感性频率呈正态分布,咯菌腈对不同地区共117株番茄灰霉病菌的EC50平均值为(0.007 3±0.004 5)μg/mL,且咯菌腈与腐霉利和多菌灵之间均不存在交互抗药性。     

湖北省小麦赤霉病菌对多菌灵、戊唑醇和咪鲜胺的敏感性

对2014年采自中国湖北省7个县、市的206株小麦赤霉病菌样品进行单孢分离与鉴定,并采用菌丝生长速率法随机测定了其中100株菌株对多菌灵、戊唑醇和咪鲜胺的敏感性,建立了其敏感基线。结果表明:多菌灵、戊唑醇和咪鲜胺对湖北省小麦赤霉病菌的EC50值范围分别为0.115~0.705、0.006~1.356和0.002~0.370 μg/mL,平均值分别为0.248、0.181和0.040 μg/mL;供试100株小麦赤霉病菌对3种药剂的敏感性频率均呈单峰拟正态分布,因此可将所得各EC50平均值分别作为湖北省小麦赤霉病菌对3种药剂的敏感基线参考值。以各药剂EC50平均值的10倍作为敏感性鉴别浓度,对2015及2016年湖北省小麦赤霉病菌的敏感性进行了监测,在该鉴别浓度下,多菌灵、戊唑醇和咪鲜胺对2015年小麦赤霉病菌的平均抑制率分别为100%、85.14%和82.35%,对2016年小麦赤霉病菌的平均抑制率分别为100%、76.67%和73.62%。研究表明,虽然戊唑醇和咪鲜胺对2016年小麦赤霉病菌的抑制率略有下降,但整体而言,湖北省小麦赤霉病菌对多菌灵、戊唑醇及咪鲜胺仍具有较高的敏感性。     

广东省辣椒疫霉菌对嘧菌酯的敏感性

从广东省各地采集了54个辣椒疫霉菌株,分别测定了菌丝生长和游动孢子囊形成对嘧菌酯的敏感性。结果表明,嘧菌酯对辣椒疫霉的菌丝生长具有很强的抑制作用,EC₅₀范围为0.1428～1.9509μg/mL,平均为0.9649μg/mL;对游动孢子囊形成的抑制作用更强,EC₅₀范围为0.0010～0.0844μg/mL平均为0.0239μg/mL。正态分析表明,辣椒疫病菌54个菌株菌丝生长对嘧菌酯的敏感性符合正态分布,而孢子萌发则在高浓度区具有拖尾现象,表明自然界中已存在个别具有一定耐药性的辣椒疫霉种群。     

黄淮麦区假禾谷镰刀菌对3种杀菌剂敏感性测定

以假禾谷镰刀菌Fusarium pseudograminearum为主要病原菌引起的小麦茎基腐病已经成为黄淮麦区的主要小麦病害之一,对小麦生产安全带来严重威胁。为了解假禾谷镰刀菌对氰烯菌酯、戊唑醇和咯菌腈3种杀菌剂的敏感性,采用菌丝生长速率法对采自河南、河北、山东的108株假禾谷镰刀菌进行了室内毒力测定。试验结果表明：氰烯菌酯对假禾谷镰刀菌的EC₅₀为0.088～0.929μg/mL,EC₅₀均值为(0.471±0.181)μg/mL;敏感性分布为连续单峰曲线,经Shapiro-Wilk正态性检验符合正态分布(W=0.988,P=0.437>0.05),所以将所有菌株的EC₅₀平均值0.471μg/mL定为假禾谷镰刀菌对氰烯菌酯的敏感基线;戊唑醇对供试菌株的EC₅₀为0.015～0.961μg/mL,EC₅₀均值为(0.384±0.219)μg/mL,敏感性分布不符合连续单峰的正态分布;咯菌腈对供试菌株的EC₅₀为0.029～0.354μg/mL,E...     

辽宁省稻瘟病菌对稻瘟灵的抗性监测及其对稻瘟病的田间防治效果

为明确辽宁省水稻稻瘟病菌Magnaporthe oryzae对稻瘟灵的抗性水平及变化动态,本研究于2017—2019年自辽宁省6个市的6个稻区采集并分离获得187株稻瘟病菌,利用菌丝生长速率法测定这187株稻瘟病菌菌株对稻瘟灵的敏感性及抗性,并采用茎叶喷雾法测定稻瘟灵对水稻稻瘟病的田间防治效果以及该药剂与其它药剂的交互抗性。结果表明：供试187株稻瘟病菌菌株对稻瘟灵的EC₅₀范围为0.94~34.96 μg/mL,左侧正态分布峰内EC₅₀平均值为5.05 μg/mL,稻瘟病菌对稻瘟灵的敏感性分布频率不符合正态分布,表明菌群中已经出现对稻瘟灵敏感性下降的亚群体。187株稻瘟病菌菌株对稻瘟灵的平均抗性倍数为3.70,抗性菌株出现频率为55.61%,平均抗性指数为0.40,抗性水平呈逐年增加趋势。2017—2019年稻瘟灵对水稻叶瘟病的防治效果分别为82.97%、78.86%和81.36%,对水稻穗颈瘟的防治效果分别为79.81%、77.68%和80.20%,说明在现有防控手段下未产生高水平抗性群体。稻瘟灵与肟菌酯、戊唑醇之间无交互抗性。与不同药剂轮换使用的前提下,稻瘟灵仍可作为主要药剂防治稻瘟病。     

吉林省西瓜蔓枯病菌对吡唑醚菌酯的抗性监测及抗性风险评估

为明确吉林省西瓜蔓枯病菌Stagonosporopsis citrulli对吡唑醚菌酯的敏感基线和抗性风险,采用菌丝生长速率法测定吉林省151株西瓜蔓枯病菌菌株对吡唑醚菌酯的敏感性及吡唑醚菌酯对西瓜蔓枯病菌的最低抑制浓度,并监测375株西瓜蔓枯病菌菌株对吡唑醚菌酯的抗性水平。结果表明,供试的151株菌株对吡唑醚菌酯的敏感性频率分布呈连续的单峰曲线,接近正态分布,敏感基线为1.800 μg/mL;吡唑醚菌酯的最低抑制浓度MIC为80.000 μg/mL。抗性水平监测结果显示,375株菌株对吡唑醚菌酯的抗性频率为0。室内药剂驯化获得的抗性突变菌株T-LH3-1和T-XZC5-1在连续转接培养8代后的EC₅₀分别为16.139 μg/mL和31.782 μg/mL,抗性倍数分别为15和51,均为中抗水平,抗药性可以稳定遗传。抗性突变体及其亲本菌株生物学性状结果显示,抗性突变体生物适合度与其亲本菌株差异不显著。交互抗性结果表明,吡唑醚菌酯与醚菌酯之间存在正交互抗性,与戊唑醇、异菌脲、多菌灵和肟菌酯之间不存在交互抗性,可以交替使用以达到延缓抗药性的产生。     

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.     

Combined effect of generally regarded as safe (GRAS) compounds andTrichoderma harzianum on the control of postharvest diseases of rambutan

Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of the rambutan postharvest diseases stem-end rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits(Nephelium lappaceum) against the three pathogens were compared: potassium metabisulphite (250 ppm) or cinnamaldehyde (30 ppm), each combined withTrichoderma harzianum (TrH 40). The application of TrH 40 and potassium metabisulphite effectively controlled the incidence and severity of the three postharvest diseases and maintained the overall quality and color of the fruit under low temperature storage at 13.5°C and 95% r.h. for 18 days. The greatest effect of this treatment was shown onG. microchlamydosporum. Cinnamaldehyde affected the growth and germination of TrH 40, whereas potassium metabisulphite did not. http://www.phytoparasitica.org posting Nov. 4, 2001.     

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.     

Effects of the saprophytic leaf mycoflora on growth and productivity of winter wheat

The effects of the saprophytic mycoflora and its interference with cereal aphids on growth and yield of winter and spring wheat was studied in field experiments in 1980, 1981 and 1982.Yields varied between 5000 and 8000 kg dry matter of kernels per ha. The effect of the saprophytic mycoflora on yield was determined in different treatments: A) no control measures against cereal aphids and saprophytic and necrotrophic fungi, B) no control of cereal aphids, control of saprophytic and necrotrophic fungi, C) control of cereal aphids and control of saprophytic and necrotrophic fungi, D) control of cereal aphids and stimulation of saprophytic mycoflora and E) control of cereal aphids, no control of saprophytic and necrotrophic fungi nor stimulation of saprophytic mycoflora.Considerable differences in top densities of saprophytic mycoflora (10 times as large in A and D as in B and C) were determined. The consequences of these differences for the growth and productivity of wheat were minor. A negative effect of saprophytic mycoflora on the yield could not be detected in 1981 and 1982, whereas a small positive significant effect was found in 1980. This stimulation may have been due to competition between necrotrophic fungal pathogens and saprophytic mycoflora. As a result of favourable weather conditions necrotrophic fungal pathogens were very numerous in 1980 and could form an important yield reducing factor. Yield levels may effect the importance of the necrotrophic and saprophytic mycoflora as yield reducing factors. Additionally, in the presence of aphid honeydew captafol was found to be relatively ineffective against saprophytic fungi.     

Detection of the phytotoxin coronatine by ELISA and localization in infected plant tissue

Several pathovars of Pseudomonas syringae produce the phytotoxin coronatine (COR)in vitro, and the availability of purified toxin has facilitated development of immunological detection methods. A modified, indirect competitive ELISA using the COR-specific monoclonal antibody 11B8 was developed to detect COR in various host plants infected by P. syringae. The estimated detection limit for COR was 50 pg per well, and COR could be reliably quantified from 5 to 40 ng ml⁻¹. The subcellular localization of COR within infected tomato tissue was investigated using the COR-specific antibody MAb 8H3G2. Immunofluorescence microscopy and immunogold labelling showed that COR was present inside tomato cells and was associated with chloroplasts and particles of proteinase inhibitor I. Localization studies indicated that COR is mobile in infected plant tissue and can be detected in healthy tissue adjacent to the bacterial lesions.