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1.
为了解绒柏Chamaecyparis pisifera精油和日本扁柏Chamaecyparis obtuse精油对蚊虫的生物活性,通过浸渍法测试了两种植物精油对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus 4龄幼虫及蛹的毒杀活性,采用人体局部涂肤法测试其对白纹伊蚊成蚊的驱避活性,并利用气相色谱-质谱联用仪（GC-MS）定性分析了精油的化学成分。结果表明,绒柏精油和日本扁柏精油对白纹伊蚊4龄幼虫/蛹的24 h LC50分别为47.66/152.33和73.11/205.06 μg/mL,对致倦库蚊4龄幼虫/蛹的24 h LC50分别为31.74/107.61和63.94/131.42 μg/mL。以1.5和2.0 μL/cm2剂量涂抹人体皮肤,绒柏精油、日本扁柏精油驱避白纹伊蚊的完全保护时间分别是3.24 h和0.78 h、5.45 h和1.86 h。经GC-MS分析鉴定出绒柏精油中含α-蒎烯（29.89%）、17-norkaur-15-ene（9.96%）、Δ-3-蒈烯（9.79%）等16种成分,日本扁柏精油含Δ-3-蒈烯（35.33%）、α-蒎烯（25.60%）、β-月桂烯（12.86%）等22种成分。可见,绒柏精油和日本扁柏精油对白纹伊蚊和致倦库蚊4龄幼虫及蛹有较强的毒杀活性,而且绒柏精油对白纹伊蚊还有很强的驱避活性,具有研发为环保型蚊虫防控剂的潜力。  相似文献   

2.
为了明确芳香植物对茶尺蠖Ectropisobliqua的驱避、拒食作用和获得应用于茶园茶尺蠖"推-拉"策略的植物材料,利用"Y"型嗅觉仪室内测定其成虫对芳香植物气味的趋性反应,并采用叶碟法测定芳香植物提取液对其幼虫的拒食作用及营养干扰效果。丁香罗勒、迷迭香、柠檬桉和芸香植株挥发物及甲醇提取液对茶尺蠖雌、雄成虫有显著的驱避效果。猫薄荷、迷迭香和鼠尾草的2 00 mg/mL甲醇提取液对茶尺蠖3龄幼虫表现出显著拒食活性,24 h后的选择性拒食率分别为93.85%、86.00%和77.32%,非选择性拒食率分别为85.77%、87.00%和88.05%。其中,迷迭香处理的幼虫生长率最低,仅为0.12 mg/天,对幼虫的相对取食量、食物利用率和食物转化率等营养指标有影响。研究表明,10种芳香植物中迷迭香具有显著的行为调控功能,是构建茶尺蠖"推-拉"策略的理想材料。  相似文献   

3.
野胡萝卜果实精油对蚊幼虫的毒杀活性   总被引：2，自引：0，他引：2  
采用浸液法研究了野胡萝卜Daucus carota果实精油对白纹伊蚊Aedes albopictus和致倦库蚊Culexpipiens quinquefasciatus幼虫的毒杀活性;利用气相色谱-质谱联用（GC-MS）对精油的主要成分进行了定性、定量分析。结果发现,野胡萝卜果实精油毒杀白纹伊蚊和致倦库蚊4龄幼虫的24h LC50值分别为67.87μg.mL-1和34.12μg.mL-1;精油中共含有34种化合物,相对含量最高的是α-蒎烯（54.72%）,其次为β-红没药烯（11.35%）和β-细辛脑（10.14%）;对6种活性化合物进行定量分析,含量最高的是α-蒎烯（577.46mg.mL-1）,其次是月桂烯（80.26mg.mL-1）、柠檬烯（28.95mg.mL-1）、β-石竹烯（24.38mg.mL-1）、β-蒎烯（11.59mg.mL-1）和γ-萜品烯（2.33mg.mL-1）。研究结果表明,野胡萝卜果实精油对蚊幼虫的毒杀效果强于以往文献报道的多种植物精油,是开发高效环保蚊虫杀幼剂的好材料。  相似文献   

4.
为筛选出对小菜蛾幼虫取食和卵孵化行为均有生物活性的精油用于小菜蛾防控。本研究测试了7种精油对小菜蛾2龄幼虫取食和卵孵化行为的影响。结果表明,石菖蒲精油对小菜蛾2龄幼虫取食的抑制作用最强。经石菖蒲精油10μL/mL、100μL/mL浓度处理,2龄幼虫取食面积均显著低于对照,表现出了较高的拒食作用。经植物精油200μL/mL浓度处理,香茅精油、柠檬精油、陈皮精油、石菖蒲精油、甜橙精油、洋甘菊精油、橘子精油对小菜蛾卵孵化行为均起到了抑制作用,其中石菖蒲精油与橘子精油的抑制作用最强,抑制率达到100%。可见,石菖蒲精油对小菜蛾2龄幼虫取食及卵孵化行为均有抑制作用,可用于小菜蛾的绿色防控之中。  相似文献   

5.
对印楝素A和印楝素B的生物活性进行了研究。在3μg/mL的剂量下处理后24 h,印楝素A和印楝素B对小菜蛾3龄幼虫的拒食率分别为85.3%和80.4%;在5μg/mL的剂量下处理后24 h,对棉铃虫3龄幼虫的拒食率分别为94.9%和80.2%。处理后72 h,印楝素A和印楝素B对斜纹夜蛾3龄幼虫的LC50分别为1.0μg/mL和3.3μg/mL。印楝素A和印楝素B在3μg/mL的剂量下处理后72 h,小菜蛾3龄幼虫的死亡率分别为90.42%和84.11%;在5μg/mL的剂量下处理后72 h,棉铃虫3龄幼虫的死亡率分别为99.1%和100.0%;在0.5μg/mL的剂量下处理后72 h,斜纹夜蛾4龄幼虫体重降低率分别为57.5%和72.73%;在0.8μg/mL的剂量下处理后72 h,棉铃虫3龄幼虫体重降低率分别为84.1%和80.9%。  相似文献   

6.
为筛选新型绿色植物源杀螨剂,采用水蒸气蒸馏法提取7种植物精油,通过Potter喷雾法、熏蒸法、药膜法测定精油对苹果全爪螨Panonychus ulmi (Koch)的触杀、熏蒸、驱避活性,筛选出生物活性较强的薄荷精油,并通过气相色谱-质谱联用仪技术(GC-MS)对薄荷精油进行了化学成分的鉴定和分析。结果表明：薄荷精油喷雾触杀12、24、48 h后的LC50分别为2.13、0.83、0.77 g/L,熏蒸12、24、48 h后的LC50分别为382.86、73.89、16.08μL/L,说明薄荷精油对苹果全爪螨具有较强的触杀和熏蒸活性。最后,驱避处理24h后,薄荷精油对苹果全爪螨的驱避活性较强,驱避率为77.82%,驱避等级为Ⅳ级。薄荷精油经GC-MS分析,共鉴定出34种化学成分,所检测出的化学成分占精油总含量的99.67%,其主要成分为薄荷醇(32.16%)、D-柠檬烯(16.44%)、4-异丙基甲苯(11.32%)、3-蒈烯(10.27%)、丙二酸二乙酯(9.57%)、薄荷酮(3.91%)。由此可见,薄荷精油对苹果全爪螨有较强的生物活性,为...  相似文献   

7.
为筛选环保型植物源灭蚊剂,从福建柏Fokienia hodginsii叶中提取精油,采用浸液法测试了该精油对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus IV龄幼虫和蛹的毒杀作用,采用密闭圆筒法研究了该精油对2种蚊虫成蚊的熏蒸活性,并用气相色谱-质谱联用法对其化学成分进行了检测。结果表明:福建柏精油对白纹伊蚊IV龄幼虫和蛹的LC50值分别为53.21和144.34μg/mL,对致倦库蚊分别为55.85和147.68μg/mL;在4.36μg/cm3熏蒸剂量下,该精油对白纹伊蚊和致倦库蚊成蚊的KT50值分别为14.63和14.90 min,24 h校正死亡率均为90.00%。从福建柏精油中共检测出16种主要化学成分:其中相对含量最高的为α-蒎烯(α-pinene),为29.25%;其次是马鞭烯醇(bicyclo[2.2.1]hept-3-en-2-ol)10.88%和氧化石竹烯(caryophyllene oxide)9.64%等。研究结果表明,福建柏精油对2种供试蚊虫具有显著的杀虫活性。  相似文献   

8.
20种植物提取物对几种昆虫的拒食作用   总被引：15，自引：1，他引：15       下载免费PDF全文
对20种植物的杀虫活性进行了初步筛选,并对有效植物中的活性成分进行了初步分离。结果表明:水仙Narcissus tazetta var. chinensis和乌桕Sapium sebiferum两种植物的提取液对菜粉蝶Pieris rapae 5龄幼虫有较强的生物活性。对供饲叶碟24 h后的拒食率分别为95.22%和87.12%;48 h后的拒食率分别为89.64%和79.85%;7 d后的校正死亡率分别为72.56%和54.62%。水仙鳞茎甲醇提取液(简称NTME)对小菜蛾Plutella xylostella、大豆毒蛾Dasychira locuples和枇杷黄毛虫Melanographia flexilineata Hempson也有非常强的拒食活性。水仙鳞茎中的活性成分主要存在于乙酸乙酯相中,浓度为3.0 mg/mL时,对小菜蛾3龄幼虫24 h和48 h后的拒食率分别为94.89%和89.78%。  相似文献   

9.
植物精油对三种鳞翅目害虫的杀虫活性   总被引：15，自引：1，他引：15  
测试了27种植物精油对粘虫、棉铃虫和小菜蛾的杀虫活性。结果表明:①用100倍精油丙酮液处理的小麦叶碟饲喂粘虫3龄幼虫48h后,砂地柏果实、玳玳花、甜橙果皮和姜根4种精油对试虫的拒食率均达80％以上;砂地柏果实、玳玳花、甜橙果皮等7种精油对粘虫4龄幼虫历期和蛹重均产生一定的影响,尤以砂地柏果实、玳玳花、甜橙果皮精油致幼虫死亡率最高,砂地柏果实和甜橙果皮精油对蛹重影响最为明显;②以含1％精油的人工饲料饲喂棉铃虫3龄幼虫9天后,山苍子果实、甜橙果皮精油处理组幼虫重量均仅为对照的20％左右,且各精油对幼虫历期、蛹重和化蛹率均有一定的影响;③八角茴香果实精油对小菜蛾的拒食活性达59.1％以上。  相似文献   

10.
进行了21种茼蒿素类似物对小菜蛾2龄幼虫的拒食活性筛选,对8号、12号和20号化合物进行了拒食活性测定,研究了20号化合物对菜粉蝶幼虫体壁及血细胞的影响,并进行了20号化合物对菜粉蝶幼虫的田间小区试验.21种茼蒿素类似物中,20号、16号、12号和8号等化合物的拒食活性较好.8号、12号和20号化合物对小菜蛾4龄幼虫处理后24h的非选择性AFC50分别为549.03、405.97和205.06μg/mL;选择性AFC50分别为432.57、114.34和72.32μg/mL.处理后24h,12号与20号化合物对菜粉蝶4龄幼虫的选择性AFC50分别为398.88和280.54μg/mL,20号化合物对菜粉蝶2龄幼虫非选择性AFC50为112.76μg/mL.20号化合物对菜粉蝶4龄幼虫血细胞数量、体壁及体壁中几丁质有明显的抑制作用.药后第3、5和7天,400μg/mL的20号化合物对菜粉蝶幼虫的防治效果分别为28.60%、54.93%和58.21%.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
The phytopathogens Xanthomonas oryzae pathovar (pv.) oryzae and Xanthomonas axonopodis pv. citri each contain several avrBs3/pthA family genes. Structural features of these genes important for avirulence and/or virulence functions include a central region of multiple direct repeats and three nuclear localization signals (NLSs) and an acidic activation domain (AAD) at the 3′ end. To identify other regions critical to function in the 3′ ends of these genes, we constructed several chimeras using apl1 and apl2 from X. axonopodis pv. citri and avrXa10 and avrXa7 from X. oryzae pv. oryzae and evaluated their functions by inoculation to citrus and rice. The apl1 and avrXa7 genes are major virulence determinants in citrus and rice, respectively, while the contributions of apl2 and avrXa10 to virulence are negligible or not measurable. Constructs that contained a 417 bp HincII-SphI fragment from the 3′ end of apl1 in combination with the repeats from avrXa7, avrXa10, and apl1 caused a canker phenotype on citrus. Interchange of the HincII-SphI fragment between avrXa7 and avrXa10 abolishes avrXa7 avirulence function and reduces its virulence but it does not affect avrXa10 avirulence function in rice. avrXa7 caused a hypersensitive response (HR) in citrus and replacement of it's 3′ end with that of apl1 resulted in loss of canker and induction of HR. Thus, the HincII-SphI fragment of the avrBs3/pthA gene family is important for avirulence and virulence functions in two different plant species, Oryza sativa and Citrus natsudaidai HAYATA.  相似文献   

15.
During a survey conducted from 1998 to 2002, Fusarium proliferatum was found associated with young and adult palms belonging to the genera Chamaerops, Phoenix, Trachycarpus and Washingtonia showing symptoms of wilt and dieback. The fertility and toxicological profile of 36 strains representing different locations and hosts were studied. All of them except two, which were infertile, belonged to mating population D. Both mating types (MATD-1 and MATD-2) were isolated from the same host species, showing a high potential of genetic recombination in the field. Additionally, eight strains were fertile once crossed as female. Toxin analysis showed differences in the ability of strains to produce fumonisin B1, moniliformin, beauvericin, fusaric acid and fusaproliferin. Only 17 of them produced all the toxins analyzed. Pathogenicity tests were conducted on Phoenix dactylifera and P. canariensis using nine F. proliferatum Spanish strains and two reference strains from Saudi Arabia. Eight months after inoculation all strains caused disease, with palms showing lesions on the bases of leaves and development of wilt symptoms similar to those originally observed in affected plants. This is the first report on the occurrence of F. proliferatum on P. dactylifera in Spain and also the first report of this pathogen on C. humilis, P. canariensis, P. reclinata, T. fortunei, W. filifera and W. robusta.  相似文献   

16.
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.  相似文献   

17.
Barley yellow dwarf disease is one of the most important problems confronting cereal production in Iran. Barley yellow dwarf virus-PAV (BYDV-PAV) and Cereal yellow dwarf virus-RPV (CYDV-RPV) are the predominant viruses associated with the disease. One isolate of BYDV-PAV from wheat (PAV-IR) and one isolate of CYDV-RPV from barley (RPV-IR) were selected for molecular characterisations. A genome segment of each isolate was amplified by PCR. The PAV-IR fragment (1264 nt) covered a region containing partial genes for coat protein (CP), read through protein (RTP) and movement protein (MP). PAV-IR showed a high sequence identity to PAV isolates from USA, France and Japan (96–97%). In a phylogenetic analysis it was placed into PAV group I together with PAV isolates from barley and oats. The fragment of RPV-IR (719 nt) contained partial genes for CP, RTP and MP. The sequence information confirmed its identity as CYDV. However, RPV-IR showed 90–91% identity with both RPV and Cereal yellow dwarf virus-RPS (CYDV-RPS). Phylogenetic analyses suggested that it was more closely related to RPS. These data comprise the first attempt to characterise BYD-causing viruses in Iran and southwest Asia. The nucleotide sequence data reported appear in the EMBL, GenBank and DDBJ Nucleotide Sequence Databases under the accession numbers AY450425 and AY450454  相似文献   

18.
浅黄恩蚜小蜂和丽蚜小蜂对温室白粉虱的寄生潜能分析   总被引：1，自引：1，他引：0  
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。  相似文献   

19.
Tsror  Leah  Aharon  M.  Erlich  Orly 《Phytoparasitica》1999,27(3):215-226
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.  相似文献   

20.
Damping-off and stem rot disease-causing Sclerotium rolfsii has been reported as a destructive soil-borne pathogen of numerous crops, especially in the tropics and subtropics. Trials were conducted to test the efficacy of biocontrol agents alone or combined with Moringa oleifera leaf extracts for the control of the disease. In the laboratory, PDA was amended with Moringa leaf extract, and mycelial growth of S. rolfsii was measured. In the greenhouse and field, Trichoderma Kd 63, Trichoderma IITA 508 and Bacillus subtilis were evaluated as seed treatments, soil drench or sprinkle, separately or combined with Moringa leaf extracts. Percentage disease incidence, severity and control were recorded. In the laboratory, the higher the extract concentration the less the mycelial growth and no mycelial growth occurred on extract at 15 or 20 g leaves 10 ml−1 water. In the greenhouse, the highest disease control was observed at a Moringa extract concentration of 15 kg leaves 10 l−1 water (w/v). Seed treatments using Trichoderma Kd 63, and soil sprinkle using Trichoderma IITA 508 had a significantly (P = 0.05) higher effect on a disease incidence than Bacillus. Disease severity followed the same pattern. Moringa seed treatment combined with Trichoderma soil sprinkle resulted in significantly more than 94% and 70% disease control in the greenhouse and field, respectively, with significant yield increase in the field. This is the first report of Moringa leaf extract combined with Trichoderma as an integrated control for Sclerotium damping-off and stem rot of cowpea in the field.  相似文献   

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