运用自组织人工神经网络模型判别柑桔溃疡病始见期

 1984-1990年运用T.Kohonen自组织人工神经网络模型系统观察甜橙新梢萌芽(始花)的时期及有关天气资料,建立了柑桔溃疡病始见期预测的计算机智能专家系统。经1991年春梢及幼果的柑桔溃疡病斑始见期验证,预测准确,历史回验,符合率达100%。     

从柑桔叶潜蛾的蔓延分布与为害看植物检疫工作的重要性

柑桔叶潜蛾Phyllocnistis citrella Stainton(英文名Citrus leaf-miner)是柑桔新梢的主要害虫。属鳞翅目、叶潜蛾科。别名鬼画符、绘图虫。它以幼虫为害柑桔新梢嫩叶,偶尔也为害嫩果。幼虫刚孵化,即由卵壳底面潜入叶表皮细胞层潜食为害,造成银白色弯曲隧道,被害叶卷曲硬化,不仅影响光合作用中光能的利用,而且随着隧道的薄膜表皮破裂,伤口又有利于柑桔溃疡病(Citrus canker)Xanthomonas Citri细菌的入侵和蔓延。在华南地区,一年中以夏秋两季抽梢期发生最盛,常猖獗成灾,尤以苗圃幼树、叶嫩汁多的品种以及偏施氮肥的果     

柑桔溃疡病综合防治研究

1985—1989年研究结果表明:14%胶氨铜水剂是目前防治柑桔溃疡病较理想的杀菌剂,效果略超过常规农药波尔多液;溃疡病药剂防治适期是春、夏、秋梢的梢长分别为4—5、6—7、5—6cm 时,以及果实横径为0.8—1.0、1.8—2.0、2.8～3.0cm 时。重病园用单一防治措施无法奏效,综合防治可有效地降低发病程度,提高果实产量、品质及增加经济效益。     

柑桔溃疡病综合防治研究

1985-1989年研究结果表明:14%胶氨铜水剂是目前防治柑桔溃疡病较理想的杀菌剂,效果略超过常规农药波尔多液;溃疡病药剂防治适期是春、夏、秋梢的梢长分别为4-5、6-7、5-6cm时,以及果实横径为0.8-1.0、1.8-2.0、2.8~3.0cm时。重病园用单一防治措施无法奏效,综合防治可有效地降低发病程度,提高果实产量、品质及增加经济效益。     

根除柑桔溃疡病初报

柑桔溃疡病 Xanthomonas citri(Hasse)Dowson 是细菌性病害。泸县的柑桔溃疡病经西南农大植保系噬菌体测定为病毒力极强的亚洲型(CBCD-A)。病菌侵染寄主植物的各个地上部分,主要在叶片、嫩梢和未成熟果实上形成难看的病斑。引起落叶、枯枝、果实脱落,直接影响柑桔品质和产量,因此,此病为国内外     

柑橘溃疡病田间消长规律及药剂防治技术

多年田间系统观察表明 ,柑橘溃疡病的消长 ,在春梢期 ,主要影响因子为气温。 4月下旬平均气温 2 0℃持续 1 0～ 1 5d ,田间始病 ;平均气温 2 5℃连续 3d ,田间进入病情激增期。在夏、秋梢期 ,主要影响因子为湿度和降雨。相对湿度低于 70 % ,不利于发病 ;持续阴雨或短时大雨极有利于流行。溃疡病的药剂防治应掌握在春梢展叶后 7d用药 ,夏、秋梢则萌芽后即用药。药剂品种以可杀得和百菌清最理想 ,喷药次数以 3次为好。     

如何做好柑桔溃疡病的防治工作

柑桔溃疡病是一种世界性的病害,也是我区柑桔产区重要病害之一,为国内外植物检疫对象。可潜伏在病叶、病枝梢和病果等病部组织内越冬,又能随果、苗调运而进行远距离传播。又颇耐干燥,在室内玻片上可存活121天;其抗寒能力极强,且耐低温,冻结24小时后并不影响其生活力,实属一种顽固性病害。如蕲春县八里湖果园场于1984年从宜昌地区柑桔研究所调入了124株甜橙桔苗,1986年,发现这批桔苗带有溃疡病,为了杜绝病害再     

不同柑桔品种对柑桔溃疡病抗病能力的测定

柑桔溃疡病为国内外检疫对象,危害柑桔苗木、幼树和成年树的叶片、果实、树梢等,引起落叶、落果、枯梢、削弱树势,是柑橘的重要病害.不同的柑桔品种对该病的抗病性差异程度较大,为了明确不同种类的柑桔品种对该病的抗病性,我们进行了柑桔不同品种对其抗性能力的测定.     

AR模型在柑桔溃疡病测报中的应用

 柑桔溃疡病发生程度的预测是进行该病治理的重要依据。本研究用自回归方法对2004年3月12日~2005年4月13日期间调查的病情原始数据进行标准化、平稳化处理以及模型的参数估计和拟合检验,所得AR (14)模型可以精确预测溃疡病发生趋势。     

柑桔秋梢潜叶蛾和蚜虫的防治

柑桔秋梢潜叶蛾和蚜虫的防治莫禹诗（广东省农科院植保所，５１０６４０）柑桔夏秋季新梢常被柑桔潜叶蛾和蚜虫严重为害，潜叶蛾为害造成的伤口易引起溃疡病的发生，蚜虫排出的蜜露会导致烟霉病，这对柑桔产量和质量影响极大。现将两大害虫防治方法述后。柑桔潜叶蛾在浙江...     

怀集县柑橘溃疡病发生现状及其对柑橘产业的影响

通过对怀集县柑橘溃疡病发生面积、发生程度和空间分布调查,分析柑橘溃疡病对怀集县柑橘产业发展造成的影响,就柑橘溃疡病发生原因,提出相应地防控措施。     

The Effect of Irrigation Practices on the Spatio-temporal Increase of Asiatic Citrus Canker in Simulated Nursery Plots in Reunion Island

Asiatic citrus canker is a potentially severe disease of several citrus species and cultivars in many tropical and subtropical areas. In such areas, infected nursery plants constitute an important source of primary inoculum for newly established citrus groves. The influence of overhead, drip, and mist irrigation systems on the development of Asiatic citrus canker was studied in simulated, Mexican-lime nurseries in Reunion Island. Overhead irrigation exacerbated the increase of disease incidence and severity caused by a streptomycin-resistant strain of Xanthomonas axonopodis pv. citri. The temporal development of Asiatic citrus canker for overhead irrigated nursery plots was best described by an exponential model, because disease incidence in these plots did not come close to an asymptote during the experimental period. This can be explained by the continuous production of new growth, susceptible to infection by Xanthomonas axonopodis pv. citri, and splash dispersal of Xanthomonas axonopodis pv. citri associated with overhead irrigation. Based on spatial correlation and spatio-temporal analyses, aggregated disease patterns were found irrespective of the irrigation system. In overhead-irrigated plots, the spread of Xanthomonas axonopodis pv. citri lacked directionnality. Rainstorms of short duration and high intensity were apparently associated with disease increase in drip-irrigated plots. There is a need to improve cultivation practices in Reunion Island citrus nurseries to minimize Asiatic citrus canker incidence in nurseries and to minimize the introduction of Xanthomonas axonopodis pv. citri to new groves.     

Effect of temperature and leaf wetness duration on infection of sweet oranges by Asiatic citrus canker

Asiatic citrus canker, caused by Xanthomonas smithii ssp. citri , formerly X. axonopodis pv. citri , is one of the most serious phytosanitary problems in Brazilian citrus crops. Experiments were conducted under controlled conditions to assess the influence of temperature and leaf wetness duration on infection and subsequent symptom development of citrus canker in sweet orange cvs Hamlin, Natal, Pera and Valencia. The quantified variables were incubation period, disease incidence, disease severity, mean lesion density and mean lesion size at temperatures of 12, 15, 20, 25, 30, 35, 40 and 42°C, and leaf wetness durations of 0, 4, 8, 12, 16, 20 and 24 h. Symptoms did not develop at 42°C. A generalized beta function showed a good fit to the temperature data, severity being highest in the range 30–35°C. The relationship between citrus canker severity and leaf wetness duration was explained by a monomolecular model, with the greatest severity occurring at 24 h of leaf wetness, with 4 h of wetness being the minimum duration sufficient to cause 100% incidence at optimal temperatures of 25–35°C. Mean lesion density behaved similarly to disease severity in relation to temperature variation and leaf wetness duration. A combined monomolecular-beta generalized model fitted disease severity, mean lesion density or lesion size as a function of both temperature and duration of leaf wetness. The estimated minimum and maximum temperatures for the occurrence of disease were 12°C and 40°C, respectively.     

Over-expression of the Arabidopsis <Emphasis Type="BoldItalic">NPR1</Emphasis> gene in citrus increases resistance to citrus canker

Citrus canker, caused by the bacterial pathogen Xanthomonas citri subsp. citri (Xcc), is a serious leaf and fruit spotting disease affecting many important citrus cultivars including grapefruit and certain sweet oranges. Currently, efficacious and economical disease control measures for highly susceptible citrus cultivars are lacking. Development of commercial cultivars with greater field resistance to citrus canker is the optimum strategy for effective disease management. In this study, we generated transgenic ‘Duncan’ grapefruit (DG) and ‘Hamlin’ sweet orange (Ham) expressing the Arabidopsis NPR1 gene (AtNPR1), which is a key positive regulator of the long-lasting broad-spectrum resistance known as systemic acquired resistance (SAR). Our results indicate that over-expression of AtNPR1 in citrus increases resistance to citrus canker and that the resistance is related with the expression levels of AtNPR1 in the transgenic plants. The line (DG 42-2) with the highest expression level of AtNPR1 was also the most resistant, which developed significant fewer lesions accompanied by a ten-fold reduction in Xcc population. The lesions developed on DG 42-2 were smaller and darker than those on the control and lacked callus formation. These lesion phenotypes resemble those on canker resistant kumquats and canker susceptible citrus trees treated with SAR-inducing compounds. Therefore, over-expression of AtNPR1 in citrus is a promising approach for development of more resistant cultivars to citrus canker.     

柑橘溃疡病检疫与防治

细菌性溃疡病是严重危害世界柑橘产业的重大检疫性病害之一,柑橘溃疡病引起落叶、枯枝和落果,溃疡病斑导致果品质量降低,影响外贸出口。世界各国长期以来对病害采取严格苗木检疫、疫区病树铲除、零星病害药剂防控的综合治理措施;新近美国农业部推出"柑橘健康种植行动计划";2007年7月中国农业部正式启动"柑橘非疫区建设和维护"项目,总体目标在于防控柑橘溃疡病的发生和传播,确保柑橘产业的安全。     

Copper rate and spray interval for joint management of citrus canker and citrus black spot in orange orchards

European Journal of Plant Pathology - Citrus canker and citrus black spot are two of the most important diseases in the São Paulo (SP) citrus belt, Brazil. Canker control was based on an...