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1.
为明确大豆食心虫Leguminivora glycinivorella幼虫结茧次数及其相关因子以及结茧次数对其低温环境适应性的影响,通过人工剥茧扰动间隔持续观察法测定大豆食心虫越冬幼虫结茧次数,分析结茧次数与体重、茧重的关系,同时测定不同结茧次数虫体的过冷却点、结冰点及虫体海藻糖含量和虫茧蛋白氨基酸组成,并在自然环境条件下检测其越冬存活率。结果显示,大豆食心虫越冬幼虫有很强的结茧能力,其平均结茧次数为9.86次。幼虫体重影响其结茧次数,结茧次数与其体重呈显著负相关(y=14.8231-0.5456x,R~2=0.9223);性别对其结茧次数无显著影响。虫茧蛋白由16种氨基酸组成,各氨基酸组分含量与结茧次数均呈直线负相关。随着结茧次数增加,越冬幼虫过冷却点和冰点值均有所升高,结茧1次的过冷却点平均值为-18.19℃,显著低于结茧3次和5次的过冷却点;越冬幼虫体内海藻糖相对含量随结茧次数增加呈下降趋势;幼虫越冬存活率与结茧次数呈显著负相关,结茧1次、结茧2次和结茧3次的越冬存活率分别为66.05%、36.05%和13.60%,三者之间差异显著。表明大豆食心虫越冬幼虫随着结茧次数的增加其对低温环境适应性显著降低。  相似文献   

2.
梨小食心虫过冷却点及结冰点测定   总被引：1，自引：0，他引：1  
梨小食心虫Grapholita molesta(Busck)是世界性的果树害虫,以老熟幼虫越冬。由于果树新品种的选育以及气候变暖等原因,梨小食心虫寄主植物的适生区扩大。为了明确梨小食心虫的耐寒能力,即是否可以随着寄主植物种植范围的扩大而向寒冷地区发生迁移,本试验对不同虫态、不同龄期幼虫、不同性别的蛹与成虫以及来源于不同环境下的幼虫的过冷却点和结冰点进行测定,进而为判断梨小食心虫是否可以顺利越冬提供理论依据。结果表明:(1)梨小食心虫不同发育阶段的过冷却点及结冰点差异显著,结冰点和过冷却点表现为幼虫蛹成虫;(2)不同龄期幼虫的过冷却点及结冰点差异显著。5龄幼虫的过冷却点(-12.47±0.27)℃与结冰点(-8.21±0.41)℃最低,4龄幼虫的过冷却点(-9.23±0.38)℃与结冰点(-5.06±0.37)℃最高;(3)雌雄成虫与蛹的过冷却点及结冰点差异不显著;(4)不同环境下幼虫的过冷却点及结冰点差异显著,外采幼虫的过冷却点(-24.42±0.69)℃和结冰点(-10.21±0.71)℃最低,室内幼虫经冷驯化后过冷却点降低。因此,在越冬过程中梨小食心虫老熟幼虫的抗寒能力较强,提前经历低温环境可提高其抗寒能力。  相似文献   

3.
桃蛀螟越冬老熟幼虫过冷却点测定   总被引：2，自引：1，他引：1  
通过对桃蛀螟(Dichocrocis punctiferalis Guenée)越冬老熟幼虫和蛹过冷却点的测定,初步明确了寄主植物、幼虫体重、性别等因素对其越冬幼虫和蛹抗寒性的影响。取食玉米、高粱和向日葵不同寄主植物的桃蛀螟越冬幼虫的过冷却点差异不显著;幼虫体重与其过冷却点没有显著相关性;幼虫进入越冬状态越早,过冷却点越低;雌、雄越冬幼虫的过冷却点没有显著差异;蛹与越冬幼虫的过冷却点无显著差异;采自不同地区玉米植株上的5个地理种群的越冬幼虫过冷却点差异不显著。  相似文献   

4.
二化螟不同年龄段越冬幼虫的耐寒性比较   总被引：1，自引：1，他引：0  
为比较二化螟越冬幼虫种群内耐寒性的差异,根据体重将二化螟越冬幼虫分为高、中、低三个年龄段,于2008年1月至3月测定了各年龄段越冬幼虫的过冷却点和结冰点,并分析了其耐寒性的生理生化机制.结果表明:在1、2和3月的三次测定中,高龄幼虫的过冷却点在2月最高,为-9.81℃,中龄幼虫的过冷却点逐渐升高,2月份为-13.35 ℃,而低龄幼虫在2月最低,为-15.64℃,且显著低于高龄幼虫;同一月份,低龄越冬幼虫的含水量和甘油含量最高,中龄越冬幼虫次之,而高龄越冬幼虫最低,且差异显著.  相似文献   

5.
对草地螟幼虫过冷却点和冰点测定的结果表明,光照、温度、幼虫滞育的深度以及虫体含水量均可以影响草地螟幼虫的抗寒能力。长光照(16 h)条件下发育成的非滞育幼虫过冷却点、冰点均显著低于短光照(10 h)发育而成的滞育幼虫;无论是非滞育幼虫还是滞育幼虫,经低温处理后抗寒能力都会上升。经4℃处理1 d的非滞育幼虫冰点为-2.28℃,而处理25 d的则降低到-4.76℃,过冷却点可从-13.97℃降低到-21.47℃;经4℃处理25、35 d的滞育幼虫,其过冷却点分别为-25.82、-26.79℃,冰点分别为-5.59-、9.13℃。滞育幼虫的过冷却点、冰点与其体重不相关,但与其体内的含水量显著相关。  相似文献   

6.
为探究大豆疫霉Phytophthora sojae卵孢子在黑龙江省土壤中的越冬存活率及其与所处土壤深度和媒介的相关性,以增强型绿色荧光蛋白为报告基因,将培养基及病残体中的大豆疫霉卵孢子分别接种到试验田框栽土壤表层下不同深处,检测其卵孢子的越冬存活率,同时在框栽中定量播种不含任何已知抗疫霉根腐病基因的大豆品种Sloan(rps),苗期调查其发病率。结果表明,大豆疫霉卵孢子在黑龙江省土壤中的适生性较强,可在5~15 cm深度土壤中安全越冬,越冬存活率高达81.67%~96.33%。卵孢子越冬存活率与其所处的越冬媒介关系不大,而与土壤深度有关。在5~15 cm范围内,随着土壤深度的增加,卵孢子越冬存活率增加。处于深层土壤中的卵孢子更容易打破休眠,进入萌发前的萌动状态。各处理间卵孢子越冬存活率的显著性差异并未在发病率上表现出来,说明除了土壤深度外,还有其它因素影响发病率。  相似文献   

7.
二点委夜蛾越冬虫态及其在越冬场所的空间分布调查初报   总被引：2，自引：0，他引：2  
为了明确二点委夜蛾越冬虫态及其空间分布,为二点委夜蛾的预测预报提供科学依据,通过对模拟大田自然环境观测区和大田环境下不同类型作物田二点委夜蛾越冬情况的系统调查,明确了二点委夜蛾是以休眠的老熟幼虫结一土茧或叶茧越冬,在空间分布上主要是在地表,占越冬幼虫的77％以上,部分叶茧在覆盖物中越冬.棉田、花生田、豆田、药材田、杂草地等多种田块的残留秸秆枝叶覆盖地为其越冬场所.棉田、豆田、杂草地的越冬存活率研究表明,棉田越冬存活率相对较大,秸秆覆盖厚度对存活率影响不显著.  相似文献   

8.
东北地区亚洲玉米螟越冬幼虫抗寒性时间动态   总被引：3，自引：2，他引：1  
为检测东北地区亚洲玉米螟Ostrinia furnacalis滞育幼虫在越冬期间生理指标的变化情况以及各地理种群间抗寒能力的差异,采用热电偶法于2013年11月—2014年4月对北至黑龙江省黑河市、南到辽宁省瓦房店市的12个地理种群滞育幼虫的过冷却点、冰点、虫体含水量和脂肪含量进行了测定。结果表明,不同地理种群亚洲玉米螟过冷却点在-5~-25℃、冰点在-2.5~-15℃范围内,随着环境温度的变化,过冷却点呈先下降后上升的趋势,最低点出现在1、2月且随地理纬度的升高而降低。不同种群的虫体含水量在50%~70%之间,时序上呈先下降后上升的趋势,与环境温度、过冷却点变化趋势一致;最高含水量出现在4月,最低含水量随着地理纬度的降低而升高。不同种群的虫体脂肪含量在45%~70%之间,时序上呈先上升后下降的趋势;最高脂肪含量随着地理纬度的降低而降低。幼虫最低过冷却点、最低冰点与虫体最低含水量和最高脂肪含量均显著相关,相关系数分别为0.733、-0.736、0.643和-0.636。表明亚洲玉米螟滞育幼虫的抗寒性存在明显的地理分化,高纬度地区种群抗寒力强于低纬度地区种群,幼虫减少体内含水量、增加脂肪积累是提高其抗寒能力的重要生理变化。  相似文献   

9.
草地贪夜蛾室内种群抗寒能力测定   总被引：4，自引：0，他引：4  
为明确草地贪夜蛾的过冷却点和结冰点,为判断草地贪夜蛾抗寒能力提供依据,本研究利用过冷却点测定仪对草地贪夜蛾不同虫态的过冷却点和结冰点进行了测定,并对其频次分布进行了分析。结果表明:草地贪夜蛾的过冷却点(df=834,F=430.26,P0.01)和结冰点(df=834,F=891.71,P0.01)在各虫态之间存在极显著差异,其中卵的过冷却点和结冰点最低,分别为(-25.45±0.25)℃和(-24.70±0.25)℃,显著低于其他虫态。6龄幼虫的过冷却点和结冰点最高,分别为(-7.35±0.14)℃和(-2.07±0.11)℃;过冷却点由低到高顺序为:卵1龄幼虫3日龄蛹2龄幼虫1日龄成虫3龄幼虫4龄幼虫5龄幼虫预蛹6龄幼虫。结冰点的变化趋势和过冷却点相似,由低到高的顺序为:卵1龄幼虫2龄幼虫3日龄蛹3龄幼虫1日龄成虫4龄幼虫预蛹5龄幼虫6龄幼虫;幼虫期,过冷却点和结冰点随龄期增加而逐渐升高。同一虫态个体间的过冷却点和结冰点频次分布存在不同程度的变异。雌雄成虫过冷却点之间没有显著差异,雌成虫结冰点显著低于雄成虫。本研究结果初步表明草地贪夜蛾具有较强的抗寒能力,该结论为草地贪夜蛾越冬区划分和监测预警提供了科学依据。  相似文献   

10.
梨小食心虫滞育过程中几种代谢酶活力的相关变化   总被引：2，自引：2，他引：0  
梨小食心虫Grapholita molesta是一种重要的蛀果害虫,以老熟幼虫滞育越冬。为明确梨小食心虫滞育幼虫对低温的生理适应性,用3,5-二硝基水杨酸比色法、双试剂法及代谢酶活力测试盒分别测定了梨小食心虫幼虫体内海藻糖酶（trehalase,TRE）、山梨醇脱氢酶（sorbitol dehydrogen-ase,SDH）及己糖激酶（hexokinase,HK）、丙酮酸激酶（pyruvate kinase,PK）和碱性磷酸酶（alkalinephosphatase,ALP）的活力变化。在低温条件下,滞育幼虫体内各酶活力明显不同,TRE活力在滞育初期显著提高,而后随滞育时间的延长而逐渐降低;SDH活力总体变化较为平缓,变化量较小;HK、PK和ALP活力在滞育前期均显著降低,且随后一直保持在较低水平。滞育期间,5种代谢酶的活力均与滞育发育及温度有关;通过相关代谢酶的调节,梨小食心虫的代谢速率维持在较低水平,提高了虫体的耐寒能力,从而顺利完成滞育。  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.
Plant Viruses Transmitted by Whiteflies   总被引：18，自引：0，他引：18  
One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.  相似文献   

13.
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   

14.
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   

15.
Broad bean mottle virus (BBMV) was transmitted from infected to healthy faba-bean plants by the curculionid weevilsApion radiolus Kirby,Hypera variabilis Herbst,Pachytychius strumarius Gyll,Smicronyx cyaneus Gyll, andSitona lineatus L. The latter appeared to be an efficient vector: acquisition and inoculation occurred at the first bite, the rate of transmission was c. 41%, and virus retention lasted for at least seven days.S. lineatus transmitted the virus from faba bean to lentil and pea, but not to the three genotypes of chickpea tested. This is the first report on the generaHypera, Pachytychius, andSmicronyx as virus vectors, and onA. radiolus, H. variabilis, P. strumarius, andS. cyaneus as vectors of BBMV.Out of 351 samples of food legumes with symptoms suggestive of virus infection, 16, 11, 19, and 17% of the samples of chickpea, lentil, pea, and common bean, respectively, were found infected when tested for BBMV in DAS-ELISA. This is the first report on the natural occurrence of BBMV in chickpea, lentil, pea, and common bean. The virus should be regarded as a food-legume virus rather than a faba-bean virus solely, and is considered an actual threat to food legume improvement programmes.  相似文献   

16.
Isolates of an unidentified Rhizoctonia sp. (UR isolates) were obtained from creeping bentgrass and Kentucky bluegrass with reddish brown sheath and foliar rots. Because the UR isolates anastomosed with isolates of three varieties of Waitea circinata (var. oryzae, var. zeae, and var. circinata), colony morphology, hyphal growth rate at different temperatures, pathogenicity, sequence analysis of the internal transcribed spacers (ITS) region of ribosomal RNA genes (rDNA) were compared. The colony color of mature UR isolates was distinct from isolates of the other three varieties of W. circinata. In pathogenicity tests on creeping bentgrass, the severity of the disease caused by UR isolates was significantly higher than that caused by the three varieties of W. circinata. Sequence similarities of the rDNA-ITS region between UR isolates and between isolates within each variety were high (97–100%), but they were lower among isolates from UR and the varieties of W. circinata (88–94%). In a phylogenetic tree based on the rDNA-ITS sequences, UR isolates formed a cluster separate from each of the clusters formed by the three varieties of W. circinata. These results indicate that the UR isolates clearly differ from the three varieties of W. circinata. We therefore propose that the UR isolates be classified as new Rhizoctonia sp. that are closely related to W. circinata and that the disease on creeping bentgrass should be called Waitea reddish-brown patch disease (Sekikasshoku-hagusare-byo in Japanese).  相似文献   

17.
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   

18.
Corynebacterium fascians, which causes leafy gall, has been shown to be responsible for the unusual symptoms recently found in lilies. The symptoms are described and the different bacterial isolates compared by biochemical, serological and pathogenicity experiments. No evidence could be found for the existence of specialized strains even though considerable variation in virulence could be demonstrated. Although the role of variation in susceptibility of the different lily cultivars should not be underestimated, it would appear that high inoculum levels ofC. fascians in the soil may be largely responsible for these outbreaks.Also included in this study are the results of biochemical, serological and pathogenicity experiments ofC. fascians which has been isolated fromKalanchoe, Euphorbia, Brodiaea, Hebe andVerbascum.Samenvatting Reeds een aantal jaren was in lelies een woekering in stengelbollen bekend, die echter sporadisch voorkwam en economisch van weinig betekenis was. Tijdens de zomer van 1977 echter trad de ziekte op één enkel perceel zo ernstig op dat zeer aanzienlijke oogstderving het gevolg was. Behalve de stengelbol kan ook de hoofdbol misvormd zijn. Bovendien kunnen misvormde stengelbollen lange spruiten vormen, zgn. sabeltandvorming. Soms is het wortelstelsel gereduceerd; in de kas zijn verdikte stengels waargenomen. De ziekte staat nu bekend onder de naam woekerziekte.Door de PD te Wageningen en het LBO te Lisse werd de bacterieCorynebacterium fascians (Tilford) Dows. uit het zieke materiaal geïsoleerd. In gezamenlijk onderzoek werd nagegaan of de bacterie de veroorzaker is van bovengenoemde symptomen en of hier sprake is van een op lelie gespecialiseerde stam.Biochemische en serologische vergelijkingen tussen isolaten vanC. fascians uit lelie,Kalanchoe, Euphorbia, Brodiaeea, Hebe enVerbascum laten zien dat er zeer weinig verschillen bestaan. Alle isolaten reageren op een standaard antiserum met titers variërend tussen 1: 640–1: 5120.Een oriënterende inoculatieproef werd uitgevoerd op het LBO in 1977. Daarna werden op de PD 10 van de 25 isolaten uit lelie en 8 uit andere waardplanten getoetst op lelie, chrysant en lathyrus. Uit de inoculatieproeven blijkt, dat de bacterie de veroorzaker is van de waargenomen symptomen. Tussen de isolaten blijkt een groot verschil in pathogeniteit te bestaan (12–100% aantasting), zonder dat dit aan herkomst gebonden is. Het voorkomen van op lelie of andere waardplanten gespecialiseerde stammen is daarom niet aan te nemen.In hoeverre de hevige aantasting een gevolg is van een opbouw van de bacterie-populatie door een te nauwe vruchtwisseling en mechanische rooimethoden moet worden nagegaan.  相似文献   

19.
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   

20.
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.  相似文献   

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