泰安市核桃园主要病虫害发生情况及其化学防治用药流程

为明确山东省泰安市核桃园主要病虫害的发生情况及其化学防治的用药流程，于2017—2018年采用田间调查法进行主要病虫害的调查，于2019年采用常规喷雾法对不同防治对象进行化学防治，研究不同用药时间及用药次数下3种农药对核桃的保果效果及对主要病虫害的防治效果，确定用药流程。结果表明，2017年泰安市核桃园主要病虫害以核桃细菌性黑斑病、核桃炭疽病和核桃举肢蛾Atrijuglans aristata为主，造成的病虫果率达83.25%。5月中旬至6月下旬，以核桃细菌性黑斑病和核桃举肢蛾单独发生为主；7月上旬至8月上旬，以核桃细菌性黑斑病和核桃炭疽病单独发生为主；8月中旬至下旬，以核桃炭疽病单独发生和核桃炭疽病+核桃细菌性黑斑病共同发生为主。2018年3种病虫害造成核桃的总体落果率为79.84%，共出现2次落果高峰，即在6月下旬以核桃举肢蛾造成的落果和在8月下旬以核桃炭疽病单独发生和核桃炭疽病+核桃细菌性黑斑病共同发生造成的落果。针对以上3种主要病虫害，在核桃生长期应至少喷药6次，其总体的保果效果和防治效果分别达到96.58%和93.70%，分别显著高于喷药4次的83.72%和70.56%，与喷药8次处理差异不显著。在实际生产中，建议对核桃细菌性黑斑病自5月上旬至8月上旬，每15~20 d用药1次，至少用药6次；对核桃炭疽病自6月下旬至8月上旬，每15~20 d用药1次，至少用药4次；对核桃举肢蛾在5月下旬和7月下旬各用药1次。     

梨小食心虫在桃树和核桃间转移规律初步研究

为了掌握梨小食心虫Grapholita molesta在新疆和田县桃园和核桃园间的转移为害和种群动态变化规律, 以期确定核桃园内梨小食心虫的最佳防治时间, 同时在桃园和核桃园设立监测点, 通过对梨小食心虫在桃园和核桃园间的发生动态监测以及在核桃园内产卵情况和蛀果率调查, 明确了梨小食心虫在桃园和核桃园间的转移规律。研究发现梨小食心虫在和田县桃园1年发生5代, 越冬代成虫于3月下旬开始出现, 各代高峰期分别在4月上旬、5月中旬、6月下旬至7月上旬、7月下旬至8月上旬、9月上旬, 以第1代和第2代发生为害严重, 具有世代重叠现象。梨小食心虫在核桃园1年发生2代, 成虫产卵于核桃果实和叶片, 主要以幼虫为害果实。于6月下旬开始从桃园向核桃园转移, 8月下旬又从核桃园转移至桃园, 具有明显的寄主转移规律。7月初为核桃园内梨小食心虫的防治关键期。     

基于功能性状评价7种核桃砧木幼苗水分利用效率

为筛选高效用水核桃砧木,测定了干旱条件下7种核桃砧木幼苗的长期水分利用效率(WUEL)及其水分利用相关功能性状,分析WUEL与各功能性状的相关性,采用隶属函数法、主成分分析法和聚类分析法对7种核桃砧木幼苗的水分利用效率进行综合评价.结果表明:7种核桃砧木幼苗的WUEL存在显著的种间差异(P<0.001),其中鸡爪绵和香...     

树干注药后吡虫啉在核桃组织中的分布动态研究

采用高效液相色谱(HPLC)测定了吡虫啉经树干注药后在核桃树体中的分布动态。结果表明,树干注药后吡虫啉在核桃树体内具有较好的传导、分布性能,其在不同组织中的含量差异较大,含量由大到小顺序为:叶片＞果皮＞果仁。吡虫啉在核桃树体内残留期较长,注药后60 d时,药剂在核桃叶片、果皮和果仁中的含量分别为0.256、0.178 和0.046 mg/kg;注药后80 d时,吡虫啉在叶片、果皮和果仁中的含量均小于0.05 mg/kg。根据吡虫啉在核桃果仁中的残留量变化动态及国外相关最大允许残留限量标准,建议在利用吡虫啉树干注药防治核桃害虫时,注药时间距核桃采收期应大于60 d。     

山东省核桃主要病害及其综合防治

核桃为山东省重要的经济林树种之一,近年病害发生严重。经对山东济南、泰安、临沂、济宁、莱芜等地核桃园病害发生情况的调查和对病原分离鉴定,初步明确了目前山东核桃的主要病害为炭疽病、褐色顶端坏死病、溃疡病、枯梢病和白粉病等。针对主要病害发生规律,本文提出了对核桃主要病害的综合防治办法。     

滴灌施肥条件下核桃树早衰叶片矿质元素含量分析

通过对滴灌及地面畦灌核桃树叶片矿质元素含f对比分析表明:滴灌成龄核桃树早衰叶片除磷、钙、铁含量较地面灌正常叶高111.1%、9.6%、11.1%外,其他矿质元素均不同程度低于地面灌正常叶片的含量,其中微量元素含量表现尤为明显;核桃树叶片早衰主要是由于叶片中钾、铁、锰、锌缺少所致;滴灌及滴灌施肥对核桃树中微量元素的吸收有...     

核桃枝枯病病原菌鉴定及其生物学特性

In May 2018,a new shoot dieback disease was found in several walnut orchards in Rizhao,Shandong Province.The fungal pathogen was obtained on PDA plate from diseased walnut shoots using a tissue isolation method.The purified fungal isolates formed white to grey colonies on PDA plate and three single spore isolates SDWa1-SDWa3 were obtained.Based on morphological characteristics and analysis of rDNA internal transcribed spacer (ITS),calmodulin (CAL),translation elongation factor 1-α (TEF1) and β-tubulin (TUB) sequences,the fungal isolates were identified as Diaporthe nobilis,a new pathogen on walnut.The test of Koch's rule confirmed that D.nobilis was the pathogen of walnut shoot dieback.To determine optimal growing conditions for the pathogen,its biological characteristics test was conducted.The results showed that the optimal growth temperature and pH value were at 25℃ and pH 5-9,respectively.The optimum carbon source was glucose,and favourable nitrogen source was peptone.     

核桃枝枯病病原菌鉴定及其生物学特性

In May 2018,a new shoot dieback disease was found in several walnut orchards in Rizhao,Shandong Province.The fungal pathogen was obtained on PDA plate from diseased walnut shoots using a tissue isolation method.The purified fungal isolates formed white to grey colonies on PDA plate and three single spore isolates SDWa1-SDWa3 were obtained.Based on morphological characteristics and analysis of rDNA internal transcribed spacer (ITS),calmodulin (CAL),translation elongation factor 1-α (TEF1) and β-tubulin (TUB) sequences,the fungal isolates were identified as Diaporthe nobilis,a new pathogen on walnut.The test of Koch's rule confirmed that D.nobilis was the pathogen of walnut shoot dieback.To determine optimal growing conditions for the pathogen,its biological characteristics test was conducted.The results showed that the optimal growth temperature and pH value were at 25℃ and pH 5-9,respectively.The optimum carbon source was glucose,and favourable nitrogen source was peptone.     

甘肃陇南市核桃病害调查及重要病害综合防治

[目的]为明确甘肃陇南地区核桃病害种类及重要病害的病原、为害特点、发生规律及综合防治策略[方法]通过采用踏查和五点取样对8县1区核桃主产区进行调查.[结果]发现为害核桃的病害8种,其中黑斑病、炭疽病、褐斑病和膏药病4种发生程度为重度.并对引起4种重要病害的病原、为害特点、发生规律及综合防控技术做了阐述.[结论]以期实现...     

巩留野核桃林土壤的形成及其特征特性

本文研究了我国唯一的野核桃自然保护区的野核桃林土壤的形成条件、形成过程、剖面特片及理化特性。野核桃在巩留凯特明山前峡谷的繁衍生息，并发育着野核桃林土壤，是特殊的地质历史条件和小气候等综合作用的结果，野核桃土壤在长期特定的生物、气候条件下，其腐殖化过程和钙积化过程明显，粘化过程较弱。土壤剖面含硅铝高，但分异明显，具有特色。ＡＳ和Ａ１层质地适中，土体温润，结构良好，富含有机质和养分，春肥力较高，林木自     

Identification of a genetic lineage within Xanthomonas arboricola pv. juglandis as the causal agent of vertical oozing canker of Persian (English) walnut in France

A new bacterial disease of Persian (English) walnut (Juglans regia) has been observed in France. This disease, called vertical oozing canker (VOC), is characterized by vertical cankers on trunks and branches of affected walnut trees with oozing exudates. To determine the aetiology of the disease, a study was carried out in 79 walnut orchards and nurseries located in southeastern and southwestern France. Bacterial analysis from diseased samples yielded 36 strains identified as Xanthomonas arboricola and 32 strains identified as Brenneria nigrifluens on the basis of biochemical tests. The causal agent of VOC was identified as X. arboricola by pathogenicity tests on walnut. Fluorescent amplified fragment length polymorphism (F‐AFLP) was carried out on 36 strains of X. arboricola collected in this study, 24 strains of X. arboricola pv. juglandis isolated from walnut blight symptoms and one strain of X. arboricola pv. corylina included as an outgroup. Based on cluster analysis of F‐AFLP data, most X. arboricola strains responsible for main VOC outbreaks showed a high degree of similarity, forming a cluster clearly separate from strains of X. arboricola pv. juglandis isolated from walnut blight symptoms. It is suggested that VOC is caused by a distinct genetic lineage within the pathovar juglandis of X. arboricola that is also able to cause classical bacterial blight symptoms on walnut leaves and fruits.     

Comprehensive diversity assessment of walnut-associated xanthomonads reveal the occurrence of distinct Xanthomonas arboricola lineages and of a new species (Xanthomonas euroxanthea) within the same tree

Xanthomonas arboricola pv. juglandis (Xaj) is the aetiological agent of walnut diseases causing economic losses on walnut production worldwide. This phytopathogen is spread around the world where walnuts are produced and has a considerable genetic diversity. Using a comprehensive sampling methodology, focusing on factors that could influence the diversity of walnut-colonizing Xaj in Portugal, this work provides new insights on xanthomonad populations on walnut. Genetic diversity was assessed by multilocus sequence analysis (MLSA) and dot blot hybridization patterns on 131 Xanthomonas isolates obtained from 64 walnut trees considering epidemiological metadata such as year of isolation, distinct bioclimatic regions, production regimes, and host-related features. The results showed that the majority of isolates were split into 17 lineages of Xaj, while the other isolates clustered in four MLSA groups that did not include Xaj strains. These four groups were represented by three lineages of X. arboricola, and 11 lineages of Xanthomonas spp., including strains assigned to the recently proposed new species Xanthomonas euroxanthea. Furthermore, distinct Xaj, X. arboricola, and Xanthomonas spp. were isolated from the same walnut tree, suggesting possible genetic admixture within the same host. Phylogenetic analysis through geoBurst revealed the high diversity of these Xanthomonas spp. populations. Assessment of type III effector genes gave the indication that some Xanthomonas spp. strains were nonpathogenic on walnut, with the exception for X. euroxanthea CPBF 424. Altogether, these findings add to the thorough characterization of walnut-associated xanthomonads in Portugal, providing a comprehensive snapshot of the current diversity that could contribute to risk assessment analysis and improve phytosanitary control.     

Functional analysis of walnut polyphenol oxidase gene (JrPPO1) in transgenic tobacco plants and PPO induction in response to walnut bacterial blight

Walnut (Juglans regia) is economically important for both its wood and nut nutritional value, but it is susceptible to diseases such as walnut bacterial blight, caused by Xanthomonas arboricola pv. juglandis (Xaj). Walnuts contain many phenolic compounds, providing a good model on which to study polyphenol oxidase (PPO). We inoculated the detached walnut fruits of cultivars Ford, Chandler, Franquette, Robert Livermore, and Payne with Xaj and measured the induction of PPO activity in infected sites and adjacent to infected sites. Compared to infected and uninfected sites, PPO activity was induced significantly in areas adjacent to infected sites in all cultivars except Ford. Ford and Franquette, presenting the lowest and highest PPO activity, showed the largest and smallest mean diameter spots in response to Xaj, respectively. Polyacrylamide gel electrophoresis confirmed monophenol oxidase activity of walnut PPO in the assessed tissues. Then, we revealed the antipathogenic potential of walnut PPO through Agrobacterium tumefaciens-mediated walnut JrPPO1 gene transfer into tobacco (Nicotiana tabacum). Two transformed tobacco lines overexpressing the JrPPO1 gene were regenerated successfully and challenged with Pseudomonas syringae pv. tabaci. Transgenic lines showed significantly higher PPO activity and lower disease severity to the pathogen compared to the control. However, a significant difference in disease severity and PPO activity level was observed between the two transgenic lines. Our results demonstrate a potential defence-related role of PPO in transgenic tobacco and its induction in areas adjacent to infection sites in walnut cultivars treated with Xaj.     

Thousand cankers disease in Europe: an overview

Walnut (Juglans regia L.) is traditionally present in most European countries as an ornamental tree, and in Southern Europe in particular it is grown for both fruit and wood. Since the 1980s, to supply the increasing demand for walnut timber, large areas of southern and central Europe, from France to Hungary, have been planted with black walnut (Juglans nigra L.) to provide wood for furniture production. The fungus Geosmithia morbida and its vector Pityophthorus juglandis, causing the thousand cankers disease of walnut in the USA in the last 2 decades, were recently reported in Europe (in Italy) on both walnut species. Thousand cankers disease can have a high negative impact on the landscape and economy of many agricultural and forest areas. Following a detailed pest risk analysis performed by EPPO in 2015, both organisms were included in the EPPO A2 List of pests recommended for regulation as quarantine pests. The main biological, epidemiological and monitoring aspects of thousand cankers disease and its status in Europe are reported.     

Evaluation of root damage to English walnut caused by five Phytophthora species

The pathogenicity of five species of Phytophthora to English walnut was studied in a greenhouse experiment. Phytophthora cinnamomi was the most aggressive species, causing severe root rot and seedling mortality. The other species tested, P. cambivora , P. citricola , P. cactorum and P. cryptogea , did not induce visible crown symptoms on seedlings 2 months after inoculation. Some strains of P. cambivora and P. cactorum also caused taproot damage to seedlings. All except one of the tested isolates caused significant necrosis of fine roots and a significant reduction of root weight compared with noninoculated seedlings. Reduction of above-ground plant development was not statistically significant. While P. cinnamomi is well known as an aggressive primary pathogen of English walnut, the other species of Phytophthora may act as predisposing factors to walnut decline, affecting root system development and increasing host vulnerability to environmental stress.     

Diurnal variation of walnut tree volatiles and electrophysiological responses in Cydia pomonella (Lepidoptera: Tortricidae)

BACKGROUND: In recent years, many studies have been carried out on the behavioural and electrophysiological responses of Cydia pomonella (L.) to host volatile emissions, to find alternative attractants to the sex pheromone for pest monitoring. These studies have focused on apple and pear, and very little has been done on walnut. In the present work, the diurnal and seasonal variation in walnut volatile emissions and the electrophysiological response of C. pomonella have been studied. RESULTS: Ninety compounds were detected in walnut emissions, mainly monoterpenes and sesquiterpenes. The most abundant compound was β‐pinene, which, together with (Z)‐3‐hexenyl acetate, (E)‐β‐ocimene, limonene, germacrene D, 1,8‐cineole, sabinene, (E)‐β‐farnesene, (E)‐β‐caryophyllene, β‐myrcene and β‐phellandrene, constituted between 81.9 and 90.5% of the total chromatographic area. Differences between seasonal periods were significant for 39 compounds, and between daytimes for 14 compounds. Discernible and consistent EAD responses were detected to 11 walnut‐origin compounds, and confirmed with synthetics to seven of them. Except for alloocimene, pinocarvone and caryophyllene oxide, all these compounds are also emitted by apple. CONCLUSION: Walnut volatile emissions differ widely from apple ones, but both share many compounds that are EAD‐active in C. pomonella. However, among EAD‐active compounds there are three walnut‐specific ones, which should be further tested in behavioural assays. Copyright © 2008 Society of Chemical Industry     

Gibbsiella quercinecans and Brenneria roseae subsp. roseae associated to the canker disease of walnut trees in northwestern Iran

European Journal of Plant Pathology - A bacterial disease of walnut (Juglans regia) has been observed in northwestern Iran during the summer of 2018 with symptoms similar to the shallow bark canker...     

The location of virus-like particles in the male gametophyte of birch, walnut and cherry naturally infected with cherry leaf roll virus and its relevance to vertical transmission of the virus

Virus-like particles (VLPs) in close-packed paracrystalline arrays were observed in cells forming the anther walls and in the sperm cell cytoplasm of immature pollen grains developing within cherry leaf roll virus (CLRV)-infected birch ( Betula pendula Roth.). VLPs within tubules, that were in some instances multiple and membrane bound, were also observed in anther cells and in pollen grains of CLRV-infected walnut ( Jugians regia L.). VLPs rarely coated the outer surfaces of developing grains. Washings from intact freshly collected pollen did not contain infective agents but pollen triturates were infectious after 12 months storage at-70°C. Purified CLRV (concentration 6·4 ng/ml) was readily detected by enzyme-linked immunosorbent assay (ELISA). CLRV-specific antigens (detected by ELISA) and VLPs (detected on grids coated with an antiserum prepared against CLRV) were readily removed by washing intact pollen grains from infected birch, walnut and cherry ( Prunus avium L. cv. F12/1). The antigen was less tenaciously held to the surfaces of anemophilous (birch and walnut) than entomophilous (cherry) pollen. Treatment of grains before ELISA testing with CLRV-specific γ globulin virtually eliminated the antigenicity of pollen washings whereas γ globulin from a pre-immune serum had no such effect. When anti-CLRV γ globulin-treated pollen grains were disrupted, CLRV-specific antigens were liberated. VLPs trapped on CLRV-antiserum coated grids to which pollen washings or extracts from disrupted grains had been applied were identified by decoration; a halo of antibody molecules enveloped VLPs treated with CLRV-antiserum but not those treated with antiserum prepared against poplar mosaic virus.     

8种杀菌剂对核桃炭疽病病原菌胶孢炭疽菌的室内毒力

由胶孢炭疽菌Colletotrichum gloeosporioides引起的核桃炭疽病是目前危害山东省核桃生产的主要病害。为筛选防治该病害的高效药剂,在确定了最适菌丝生长和分生孢子萌发温度的基础上,采用菌丝生长速率法和孢子萌发法,测定了8种常用杀菌剂对胶孢炭疽菌的毒力,评估了温度对咪鲜胺和戊唑醇毒力的影响,检测了17个胶孢炭疽菌菌株对咪鲜胺和戊唑醇的敏感性,同时评价了这2种杀菌剂的预防和治疗作用。结果显示:在胶孢炭疽菌菌丝生长和孢子萌发的最适温度28℃下,供试8种杀菌剂中,咪鲜胺、戊唑醇和三唑酮对供试菌株菌丝生长的抑制作用最强,平均EC50值分别为0.07、1.45和3.04 mg/L;异菌脲、代森锰锌和咪鲜胺对分生孢子萌发的抑制作用最强,平均EC50值分别为21.07、25.14和25.18 mg/L。咪鲜胺对菌丝生长的抑制作用受温度影响较小,而戊唑醇对菌丝生长的抑制作用随温度降低而增强;供试17个菌株对咪鲜胺和戊唑醇均有较高敏感性,平均EC50值分别为0.08 和 1.03 mg/L。建议在核桃炭疽病发病的不同时期,轮换使用咪鲜胺、戊唑醇、三唑酮、异菌脲和代森锰锌等杀菌剂,以有效控制该病害。     

除虫脲防治核桃举肢蛾的研究

1989～1991年,在河北省灵寿县,于核桃举肢蛾成虫羽化高峰期,用20％除虫脲5000倍药液防治两次,好果率达95％,对照不防治的树,核桃全部被害。除虫脲还能兼治核桃缀叶螟和刺蛾,对瓢虫的影响也较喷速灭杀丁小。