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香蕉束顶病在华南和西南各产区均有发生 ,是香蕉的重要病害之一。在海南省和广东、广西尤其常见而且严重 ,感病植株矮缩 ,不开花结蕾。即在出蕾期感病的植株果少而小 ,无商品价值 ,损失很大。1 症状本病最突出的症状是新长出的叶片一片比一片短而窄小 ,叶片硬直并成束丛生于假茎顶端 ,形成束顶的树冠和矮缩的植株。病叶边缘褪绿变黄、质硬而脆 ,很易折断。在病株的叶柄和假茎上有浓绿色条纹发生 ,称为“青筋”。这些绿色条纹是诊断本病特别是早期病株最可靠的重要特征 ,病株分蘖较多 ,球茎变红紫色 ,无光泽 ,大部分的根腐烂或变紫色 ,不发… 相似文献
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近年来 ,不少地方到外地病疫区调运香蕉种苗 ,带进香蕉花叶心腐病的病苗 ,致使在部分蕉区发病扩展蔓延 ,发病蕉园病株率高达 30 % ,严重威胁香蕉生产。1 危害症状发病初期香蕉叶片上出现褪绿的黄色不连续条纹或纺锤体状圈斑 ,随着叶片的老熟 ,条纹或圈斑逐渐变成黄褐色至紫黑色 ,最后成枯纹或枯斑。发病严重的则心叶黄化、腐烂 ,病株出现叶缘卷曲或皱缩。病株假茎 (叶鞘 )上呈现小水渍状斑点 ,以后变黄褐色 ,再变深熏烟色至血红色 ,病部随后坏死腐烂 ,心叶腐烂即心腐。抽蕾期发病的植株 ,果轴或花苞出现黄色条纹圈斑 ,果实出现黑斑点 ,发育… 相似文献
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香蕉假茎腐烂病简称茎腐病,主要危害香蕉假茎。近年来在广西浦北县香蕉生产区,蕉园受害日趋严重。被害植株叶片黄化,假茎变黑坏死、腐烂,发病严重园,香蕉叶片大面 相似文献
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香蕉枯萎病的两种症状类型 总被引：3，自引：0，他引：3
香蕉枯萎病是蕉类毁灭性病害,60—70年代在两广局部地区已有发生,近几年在广东中山等地为害龙牙蕉(过山香)、粉蕉严重,限制了这些优良蕉种的发展。1983年以来,在对该病的田间调查中,我们发现表现叶片黄化症状的蕉株,有部分表现叶片倒垂、有部分则表现假茎基部开裂。通过病原 相似文献
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9种杀线剂对香蕉根结线虫病的防效评价 总被引：6，自引：0，他引：6
对9种不同作用机理的杀线虫制剂进行了田间防效评价试验。结果表明,10%噻唑磷颗粒剂、35%威百亩水剂和98%棉隆微粒剂对根结线虫具有良好的防效,不仅能控制土壤中2龄幼虫数量,而且能非常有效地抑制根结的形成,同时具有速效性好、持效期长、残留毒性低等优点,可作为根结线虫防治的首选药剂;5%丁硫克百威颗粒剂和0.5%阿维菌素颗粒剂具有较好的防效,对土壤中2龄幼虫数量和作物根结的形成具有中等水平的控制能力,速效性好、同时具有一定的持效性;生防制剂5亿活孢子/g淡紫拟青霉颗粒剂和2.5亿孢子/g厚孢轮枝菌微粒剂在香蕉生长前期防效较差,而在生长中期的防效逐渐上升并保持稳定;2.5%二硫氰基甲烷可湿性粉剂的表现一般,但可在生长季节多次灌根使用,同时具有毒性低、使用方便的优点,是当前为数不多的、能在作物生长季节里施用的广谱型杀线虫制剂;50%氰氨化钙颗粒剂的表现最差,仅能一定程度地控制根结线虫数量,未能有效地抑制病害的发展,对2龄幼虫的控制能力不超过60 d,生长中后期的2龄幼虫数量和根结指数增长较快。 相似文献
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大棚番茄根腐病的发生与无公害防治 总被引：1，自引：0，他引：1
1症状表现 番茄的根腐病主要危害茎基部和根部,定植后即可发病.初发病时侧根和毛细根变褐(黑),根表面产生黑色小粒点或裂缝,根的表皮木栓化,又称"木栓病",严重的病根肿胀或变粗,随跟部病害的扩展,茎基部变成黑褐色以至腐烂,导致地上部分生长不良,下部叶片变黄干枯.发病初期病株中午萎蔫,早、晚可复原,但病情严重时不再复原,从茎基部枯烂严重,致全株枯死.因此,在生产上又习惯称为番茄"茎基腐病". 相似文献
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山药根结线虫病田间呈分散或条块状分布。该病主要发生在地下块茎部位 ,地上部一般没有明显的症状 ;发病严重者 ,地上部表现叶色淡、生长弱、植株繁茂性差。山药根结线虫病主要发生在 0～ 30cm的土层内 ,30cm以下的土层发病较少。高燥的沙土地块、连作地发病重。山药地下块茎感染根结线虫病后 ,在块茎的表皮上产生许多大小不等的近似馒头状的瘤状物 ,瘤状物相互连结 ,重叠形成更大的瘤状物 ,在瘤状物上产生少量粗短白根。发病部位的皮色比正常的皮色明显偏暗 ,即呈黄褐色。其内部组织的颜色无明显的变化。在块茎的细根上有小米粒大小的根结… 相似文献
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广东黄秋葵黄脉曲叶病样中检测到烟粉虱传双生病毒 总被引：6，自引：1，他引：5
黄秋葵是近几年来从日本和我国台湾引进的一种蔬菜作物。近期,广东的黄秋葵上发生了黄脉曲叶病。病株的典型症状表现为叶脉黄化,在叶片正面形成网络状,在叶背面叶脉肿大突起明显,病株幼叶小且向下卷曲,甚至整片幼叶黄化。植株早期被感染表现矮化。在发生黄脉曲叶病的黄秋葵田间,其病株率高达60%以上。用烟粉虱传双生病毒简并引物对随机采集的病样进行PCR检测,从这些病样中均能扩增出1条预期大小为570 bp的特异片段;基因克隆及测序分析结果表明,与该特异片段同源的均属双生病毒科菜豆金色花叶病毒属病毒DNA,其中与木尔坦棉花曲叶病毒（Cotton leaf curl Multan virus, CLCuMV）分离物G6相似性最高,为99%。这些研究结果表明,广东黄秋葵黄脉曲叶病中存在烟粉虱传双生病毒,该病害可能也是由CLCuMV侵染引起的。 相似文献
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小麦黄花叶病(WYNW)的研究 总被引：3，自引：0，他引：3
小麦黄花叶病的病状是黄色花叶。病株细胞内有1至数个内含体。病毒质粒为线状,稍弯曲,大小为13×100-600毫微米,存在于细胞质中。内含体呈风轮状。病毒仅感染小麦属(Triticum)10多种,能通过病根、病土及它们侵出液传染。介体为禾谷多粘霉(Polymyxa graminis),其寄主有小麦等28种禾本科植物。病土加灭菌土1000倍混合仍有致病性,病田表土致病性最强,深到31-40厘米处还会发病。田间3月中旬以后病株不再增加。予防本病以选育选育抗病品种为主,辅以轮作,增施肥料和迟播等。 相似文献
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Q. S. Novaes J. Freitas-Astua V. A. Yuki E. W. Kitajima L. E. A. Camargo J. A. M. Rezende † 《Plant pathology》2003,52(5):648-654
During the spring of 2001, approximately 10 000 yellow passion flower plants, from two orchards in the county of Livramento de Nossa Senhora, Bahia State, Brazil, exhibited intense yellow mosaic symptoms and drastic reduction of the leaf lamina and plant development. A large population of whiteflies ( Bemisia tabaci ) was also found colonizing the plants. All field samples collected tested positive for Passion fruit woodiness virus in DAS-ELISA. Five out of 20 passion flower plants inoculated with adult whiteflies collected from diseased plants in the field developed symptoms 20–30 days after inoculation. Two of these plants gave a positive reaction in TAS-ELISA using antiserum against a begomovirus. Degenerated PCR primers amplified viral DNA fragments from the DNA-A and DNA-B components of a begomovirus infecting these plants. The fragment corresponding to the core region of the coat protein (DNA-A) was cloned and sequenced. A phylogenetic analysis placed this begomovirus isolated from passion flower in the same clade of the New World begomoviruses as several other species from Brazil. Based on the symptoms induced by this virus alone, the disease was tentatively named passion flower little leaf mosaic. 相似文献
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Neither Cladosporium allii nor C . allii-cepae was detected in seed samples of 46 commercial cultivars of leek and nine of onion.
In glasshouse tests where flower inflorescences of onions and leeks were dusted with conidia of C. alliicepae and C. allii , respectively, few onion seeds and no leek seeds became contaminated. In field crops of leeks some spathes and inflorescences became diseased and gave 0 002% C. allii contaminated seeds. No infected onion seeds were obtained from naturally-infected plants in the field.
Conidia of both fungi survived for less than 6 weeks in sterile and non-sterile soil (during which time the temperature varied from -8 to +11 C); pseudothecial bodies survived longer.
Both pathogens survived for 3 months in debris of onion or leek on the surface of soil in pots under similar conditions. In debris buried at a depth of 7 cm in sterile or unsterile soil they survived for 2 months. Although C. allii survived only 1 month in debris on the soil surfaces following a leek crop, conidia of the fungus were trapped from the air above the area for at least 6 months and healthy leeks transplanted into this area developed the disease. No leaf blotch developed in leeks grown on land which had not previously borne that crop. 相似文献
In glasshouse tests where flower inflorescences of onions and leeks were dusted with conidia of C. alliicepae and C. allii , respectively, few onion seeds and no leek seeds became contaminated. In field crops of leeks some spathes and inflorescences became diseased and gave 0 002% C. allii contaminated seeds. No infected onion seeds were obtained from naturally-infected plants in the field.
Conidia of both fungi survived for less than 6 weeks in sterile and non-sterile soil (during which time the temperature varied from -8 to +11 C); pseudothecial bodies survived longer.
Both pathogens survived for 3 months in debris of onion or leek on the surface of soil in pots under similar conditions. In debris buried at a depth of 7 cm in sterile or unsterile soil they survived for 2 months. Although C. allii survived only 1 month in debris on the soil surfaces following a leek crop, conidia of the fungus were trapped from the air above the area for at least 6 months and healthy leeks transplanted into this area developed the disease. No leaf blotch developed in leeks grown on land which had not previously borne that crop. 相似文献
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Cavity spot of carrot (CCS), one of the most important soilborne diseases of this crop worldwide, is characterized by small sunken elliptical lesions on the taproot caused by a complex of pathogens belonging to the genus Pythium , notably P. violae . In most soilborne diseases the soil is the source of inoculum for primary infections, with diseased plants then providing inoculum for secondary infections (both auto- and alloinfection). Using fragments of CCS lesions to infest soil, it was demonstrated that CCS lesions on carrot residues can cause primary infection of healthy roots. Using a novel soil infestation method, in which an artificially infected carrot root (the donor plant) was placed close to healthy roots (receptor plants) the formation of typical CCS lesions were induced more efficiently than the use of classical soil inoculum and showed that CCS can spread from root to root by alloinfection from transplanted diseased roots. The method also demonstrated the polycyclic nature of a CCS epidemic caused by P. violae in controlled conditions. Secondary infections caused symptoms and reduced root weight as early as two weeks after transplantation of the diseased carrot. This reproducible method may be used for delayed inoculation and for studying the effect of cropping factors and the efficacy of treatments against primary and secondary cavity spot infections. 相似文献
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Relationships Between Verticillium dahliae Inoculum Density and Wilt Incidence, Severity, and Growth of Cauliflower 总被引：1，自引：0，他引：1
ABSTRACT Microplot and field experiments were conducted to evaluate the effects of inoculum density on Verticillium wilt and cauliflower growth. Soil containing Verticillium dahliae microsclerotia was mixed with various proportions of fumigated soil to establish different inoculum densities (fumigated soil was used as the noninfested control). Seven inoculum density treatments replicated four times were established, and the treatments were arranged in a randomized complete block design. Soil was collected from each microplot immediately after soil infestation for V. dahliae assay by plating onto sodium polypectate agar (NP-10) selective medium using the Anderson sampler technique. Five-week-old cauliflower was transplanted into two beds within each 1.2- by 1.2-m microplot. At the same time, several extra plants were also transplanted at the edge of each bed for destructive sampling to examine the disease onset (vascular discoloration) after planting. Cauliflower plants were monitored for Verticillium wilt development. Stomatal resistance in two visually healthy upper and two lower, diseased leaves in each microplot was measured three times at weekly intervals after initial wilt symptoms occurred. At maturity, all plants were uprooted, washed free of soil, and wilt incidence and severity, plant height, number of leaves, and dry weights of leaves and roots were determined. The higher the inoculum density, the earlier was disease onset. A density of 4 microsclerotia per g of dry soil caused 16% wilt incidence, but about 10 microsclerotia per g of soil caused 50% wilt incidence. Both wilt incidence and severity increased with increasing inoculum density up to about 20 microsclerotia per g of soil, and additional inoculum did not result in significantly higher disease incidence and severity. A negative exponential model described the disease relationships to inoculum levels under both microplot and field conditions. Stomatal resistance of diseased leaves was significantly higher at higher inoculum densities; in healthy leaves, however, no treatment differences occurred. The height, number of leaves, and dry weights of leaves and roots of plants in the fumigated control were significantly higher than in infested treatments, but the effects of inoculum density treatments were variable between years. Timing of cauliflower infection, crop physiological processes related to hydraulic conductance, and wilt intensity (incidence and severity) were thus affected by the inoculum density. Verticillium wilt management methods used in cauliflower should reduce inoculum density to less than four micro-sclerotia per g of soil to produce crops with the fewest number of infected plants. 相似文献
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G. Tuitert 《European journal of plant pathology / European Foundation for Plant Pathology》1993,99(2):85-96
Horizontal dispersal of beet necrotic yellow vein virus (BNYVV) by means of viruliferous zoospores ofPolymyxa betae was studied in greenhouse experiments. BNYVV was not detected in roots of sugar beet plants grown in silver sand for 4 weeks at a root-free distance of 5 cm from eitherP. betae- and BNYVV-infected plants or BNYVV-infested soil. Spread of BNYVV from inoculum sources in the field was studied in the absence and presence of tillage practices. Active dispersal in combination with root growth from and towards point sources of inoculum contributed only little to horizontal dispersal of viruliferous inoculum and spread of disease during the season, as determined for one soil type, two different years and in the absence of tillage and tread. In the second beet crop after application of inoculum to whole field plots, more BNYVV-infected plants were detected at 2 m than at 8 m distance from the infested plots in the tillage direction. In the third year, disease incidence at 8 m was high and equivalent to that at 2 m. 相似文献