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为有效控制桔小实蝇的危害,通过田间调查桔小实蝇数量动态和杨桃产量损失,研究了杨桃上桔小实蝇的防治指标。结果表明,杨桃产量损失率与桔小实蝇虫口密度、杨桃被害率之间具有显著相关性;建立了第一收获期至第四收获期桔小实蝇虫口密度、杨桃被害率与杨桃产量损失率回归方程。根据防治指标求解模型,将各回归方程系数和求解防治指标参数代入,得到一年四个收获期里不同产量水平下的桔小实蝇的防治指标。当以桔小实蝇虫口密度作为防治指标时,各收获期的防治指标分别为5.6、14.0、19.3和8.8头/瓶;经济允许密度为10.1、19.5、21.7和10.4头/瓶。当以杨桃被害率作为防治指标时,各收获期的防治指标分别为5.3%、8.9%、6.8%和7.5%;经济允许损失率为15.1%、15.3%、12.0%和9.8%。 相似文献
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对河北省26个主推玉米品种进行抗玉米粗缩病性鉴定,并对其发病率及病情指数与产量损失率的相关性进行了研究。结果表明:河北省目前玉米生产上主推品种中没有免疫和抗病品种,但感病后品种之间的病情严重度有显著差异,病情指数分布在35.37~80.05,产量损失率为15.55%~74.01%。以邢抗2号、费玉2号、费玉4号、沈玉17和农大108的病情严重度较轻,病情指数低于40,表现为感病,其他品种病情指数都在40以上表现为高感。产量损失率与病株率和病情指数呈显著相关,且产量损失率与病情指数的相关性(R=0.982)比产量损失率与病株率的相关性(R=0.756)更强。 相似文献
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Comparison of sandy soils suppressive or conducive to ectoparasitic nematode damage on sugarcane 总被引:1,自引:0,他引:1
ABSTRACT Two South African sandy soils, one suppressive and the other conducive to ectoparasitic nematode damage on monoculture sugarcane, were compared. Analysis of field transects indicated that the suppressive soil displayed a comparatively higher population of the weak ectoparasite Helicotylenchus dihystera, whose predominance among ectoparasitic nematodes is known to limit yield loss caused by more virulent phytonematodes. Soil type was identical at both sites (entisols), but the suppressive soil had a higher organic matter content and a lower pH, which correlated with H. dihystera population data. In contrast, microclimatic differences between the two field sites were unlikely to be responsible for the suppressive or conducive status of the soils, as shown in a greenhouse experiment. The two soils exhibited a bacterial community of the same size but with different genetic structures, as indicated by automated ribosomal intergenic spacer analysis (RISA). The number of culturable fluorescent pseudomonads was higher for the conducive soil, probably because extensive root damage caused by ectoparasitic nematodes favored proliferation of these bacteria. This study shows that apparently small differences in soil composition between fields located in the same climatic area and managed similarly can translate into contrasted nematode communities, ectoparasitic nematode damage levels, and sugarcane yields. 相似文献
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麦鞘毛眼水蝇为害损失与经济阈值的研究 总被引:1,自引:0,他引:1
1989—1990年在甘南藏族自治州合作地区选用青棵农家品种“肚里黄”为试验材料,根据麦鞘毛眼水蝇(IIydrellia chinensis Qi et Li)为害特点,应用田间自然种群与药剂处理相结合的方法,通过线性回归分析、相关分析及通径分析、对青稞不同受害程度与产量损失的关系进行了研究。结果表明:“肚里黄”品种旗叶叶鞘受害程度的大小对青稞千粒重产量的形成有明显的影响,而其它叶鞘的影响不明显;经回归分析,平均严重度(X_2)、为害指数(X_3)与产量损失率(Y)的关系式分别为:Y=4.1599 0.4962X_2和Y=5.4197 0.4718X_3;空壳率的上升是造成产量损失的直接因素;在自然条件下,其经济阈值的数学模型为: X=1/2.58977CN(10.8737CN C_1)(卵量) 据此,合作地区麦鞘毛眼水蝇的防治指标为拔节后期单株卵量4.2粒。 相似文献
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Abstract The cereal cyst nematode, Heterodera avenae Wollenweber, 1924, occurs worldwide including India where it causes ‘molya’ disease of wheat and barley. Wheat yield losses due to the nematode were estimated during 1974-76 at a few villages in Mohindergarh district, Haryana, India, by applying dichloropropane-dichloropropene mixture and dibromochloropropane singly or in combination as soil f umigants. In light soil the cereal cyst nematode infestation at 4/5 eggs and larvae/g soil approximated the economic threshold level. However, depending on the initial population density of H. avenae and other field conditions, such as soil type, moisture, soil condition, chemical application method, chemical application time etc., the increase in yield of wheat cv. Kalyan Sona ranged from 8 to 49% at nematode infestation levels of about 6 to 13 eggs and larvae/g soil when treated with these nematicides. 相似文献
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为明确甘肃省党参根结线虫病的发生、分布及病原种类,在甘肃省党参主产区调查、统计田间根结线虫病发生情况,并通过形态学和分子生物学方法进行种类鉴定。结果表明,甘肃省6个党参主产区均有根结线虫病发生,病田率、病株率分别为40.7%、13.2%,病情指数为10.4。依据根结线虫各虫态的形态测量值和雌虫会阴花纹等特征,将危害党参的根结线虫初步鉴定为北方根结线虫Meloidogyne hapla Chitwood, 1949。rDNA-ITS区段和28S rDNA D2D3区段序列比对和系统发育树显示,6个根结线虫群体无核苷酸差异,与多个北方根结线虫聚为一支且有较高的置信度。利用特异性引物Mh-F/Mh-R扩增得到北方根结线虫的特异性片段,大小为462 bp。故综合形态学和分子生物学特征,将危害甘肃省党参的根结线虫鉴定为北方根结线虫。 相似文献
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Cs. BUDAI 《EPPO Bulletin》1994,24(2):511-514
Under Hungarian climatic conditions, root-knot nematodes, and other phytoparasitic nematodes, generally cause damage in certain plant growing areas. These pests are present in glasshouses throughout the country. In the field the nematodes occur in sandy soil in the vegetable-growing areas of southern and central Hungary. The following species of root-knot nematodes have so far been reported to occur in Hungary: Meloidogyne incognita, M. arenaria, M. hapla, M. javanica, M. incognita acrita, M. thamesi and M. naasi. There are 10 specific nematicides registered for nematode control in the country. These chemicals are mainly applied in glasshouses where their use produces most economic return. Nematoderesistant cultivars are only available in the case of tomato. The nematodes cause the heaviest damage on glasshouse cucumber. 相似文献
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通过形态学与分子生物学相结合的方法对引起甘肃省陇西县黄芩根结线虫病的病原种类进行了鉴定,并采用室内人工接种的方法测定其对黄芩的致病性。结果表明,从黄芩根系分离的根结线虫其形态特征及测量值与北方根结线虫Meloidogyne hapla基本一致。该线虫种群rDNA-ITS和28S rDNA D2/D3序列与NCBI数据库中的北方根结线虫序列相似性分别为99.60%和99.74% (rDNA-ITS: JX024147; 28S rDNA D2/D3: MW288147)。贝叶斯系统发育树显示,该线虫群体与其他北方根结线虫群体聚为一支,置信度在95%以上。利用北方根结线虫特异性引物Mh-F/Mh-R扩增并测序得到457 bp的特异性片段。因此,基于形态学结合rDNA-ITS、28S rDNA D2/D3序列和特异性片段长度,将黄芩根结线虫病病原鉴定为北方根结线虫M.hapla。接种该线虫后的黄芩生长缓慢,叶片黄化,40 d后须根上有明显的根结。经分离鉴定,致病群体为北方根结线虫。综上所述,甘肃省陇西县黄芩根结线虫病病原为北方根结线虫M.hapla,该线虫对黄芩具有较强的致病性,其繁殖系数为1.997。 相似文献
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象耳豆根结线虫的PCR鉴定和检测方法 总被引:5,自引:1,他引:5
象耳豆根结线虫是一种在中国具有潜在经济重要性的农作物病原物。为提供有助于控制象耳豆根结线虫传播扩散的方法,研制了该线虫的快速PCR鉴定和检测法。该方法PCR引物的扩增目标为rDNA-IGS2区域,其设计依据象耳豆根结线虫与南方、爪哇、花生和北方根结线虫在该区域核酸序列的差异。通过对6种近似根结线虫的不同地理群体及自然土壤线虫群体的测试,验证了设计的PCR引物针对象耳豆根结线虫的特异性和可靠性。本方法具有快速灵敏的特点,可用于象耳豆根结线虫单条线虫的直接鉴定以及混合土壤线虫群体中象耳豆根结线虫的检测。 相似文献
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近年来,随着我国荞麦面积的迅速增加,根结线虫病呈逐年加重趋势,严重影响了荞麦的产量与品质。本研究于2014年对西南10个地区17个乡镇秋播苦荞麦根结线虫的分布、发生种类以及危害程度进行了调查。结果表明,西南地区危害荞麦的根结线虫种类有南方根结线虫(Meloidogyne incognita)、爪哇根结线虫(M.javanica)和花生根结线虫(M.arenaria)3种,其中南方根结线虫为优势种群。田间根结线虫种群大多数为单一种群,23.5%的样品为南方根结线虫与爪哇根结线虫(或花生根结线虫)组成的混合种群。调查发现前作为烟草或马铃薯的地块,荞麦根结线虫发生危害严重,平均被害株率为6.0%~77.5%,病情指数为1.4~26.1,而前作为玉米的荞麦根结线虫则较轻,被害株率最高为16.0%,相应病情指数为2.3。 相似文献