Modelling the effects of alcohol ethoxylates on diffusion of pesticides in the cuticular wax of Chenopodium album leaves

Cuticular waxes represent the first and, in most cases, the limiting barrier for foliar uptake of pesticides from solution. Sorption of pesticides in reconstituted cuticular wax (wax/water partition coefficients) of Chenopodium album L. and in isolated cuticular membranes (cuticle/water partition coefficients) of Prunus laurocerasus L. was determined. Diffusion coefficients of pesticides in reconstituted cuticular wax of C. album leaves were size-dependent, increasing with increasing molar volume. In the presence of alcohol ethoxylates, diffusion coefficients were enhanced by up to two orders of magnitude, and size selectivity was significantly decreased. The accelerating effect and the decrease in size selectivity were attributed to plasticisation of the cuticular wax by the alcohol ethoxylates increasing the fluidity in the wax. A free volume model adopted from polymer science was successfully applied to predict diffusion coefficients of pesticides on the basis of the transport properties of the wax (size selectivity and crystallinity), the molar volume of the diffusing compound and the accelerator concentration in the wax.     

Occurrence of Prunus necrotic ringspot virus on nectarine (Prunus persica) in India

This paper presents the results of the first survey for Prunus necrotic ringspot virus (PNRSV) on nectarine ( Prunus persica ) in India, where stone fruits are grown on a commercial scale. Using basic diagnostic techniques such as ELISA and RT-PCR, the occurrence of Prunus necrotic ringspot virus is reported for the first time on nectarine ( Prunus persica ) in India.     

8个乡土树种抗逆性对比研究

在半干旱地区内蒙古中部3个不同造林立地类型对当地的8个乡土树种进行亚区造林对比试验,调查了被试树种在自然状态条件下的生长特征,应用PV技术测定了其水分生理指标,测定了抗寒及抗春季干旱风的等级,运用综合指标(成活、保存率、抗旱水分生理、耐寒性等)分析各树种的抗逆性和对不同立地条件的适应能力。结果表明:柄扁桃、桃叶卫矛、荆条和山杏(对照)抗逆性强,毛樱桃、山桃抗逆性较强,酸枣(山西种源)、欧李(山西栽培种)为中等,臭椿较差。     

Hosts and symptoms of Plum pox virus: woody species other than fruit and ornamental species of Prunus

The presence of Plum pox virus (PPV) in woody hosts other than in fruit and ornamental Prunus species was evaluated. PPV symptoms, and their variability and intensity, are described in leaves and fruits of Prunus cerasifera , Prunus spinosa , Ligustrum vulgare and Euonymus europaea . Juglans regia is not confirmed as a new host of PPV.     

Peach red marbling and peach sooty ringspot, two new virus-like degenerative diseases of Prunus

More than 600 Prunus samples were examined by using a nonradioactive digoxigenin-labelled RNA probe specific for hop stunt viroid (HSVd). Prunus salicina and Prunus armeniaca appeared to be better hosts than Prunus persica . The weak viroid concentration in flowers and young leaves of peach trees growing in the field did not permit its detection in such samples. The diagnosis was more reliable (about 85%) with bark and leaves aged 4 months and more, from regrowths of GF 305 peach seedlings inoculated and kept in the greenhouse. Detection of HSVd in leaves and bark of apricot and Japanese plum plants aged 3 months or more also proved reliable (about 80% and 90%, respectively). HSVd could be transmitted in apricot, peach and plum nucleic acid preparations to GF 305 peach seedlings by repeated stem slashing, and to cherries ( Prunus avium and Prunus serrulata ) by approach grafting with an infected P. salicina source. The viroid was eliminated from 18% of the clones obtained after thermotherapy.
In the course of this study, 25 selected Prunus accessions suspected to be infected by unusual diseases were analysed by hybridization with a HSVd-specific probe and by indexing on GF 305 peach seedlings in the greenhouse. Fifteen of these accessions were found to be infected by HSVd, 19 induced reddish marbling, and four induced small blackish spots on the leaves aged about 4 months. Repeated assays showed that these foliar symptoms were not caused by the viroid. Peach red marbling (PRMa) has not been associated with any known virus and seems to be caused by an infectious agent not yet described. That could also be the case with the agent of peach sooty ringspot (PSRS). PRMa and PSRS symptoms were reproduced by grafting and indexing, and their causal agents eliminated by thermotherapy in a significant fraction of the treated plants. They behave like viral agents and can infect the different Prunus species studied.     

Survey of Prunus necrotic ringspot virus in Rose and Its Variability in Rose and Prunus spp

ABSTRACT A survey for viruses in rose propagated in Europe resulted in detection of only Prunus necrotic ringspot virus (PNRSV) among seven viruses screened. Four percent of cut-flower roses from different sources were infected with PNRSV. Progression of the disease under greenhouse conditions was very slow, which should make this virus easy to eradicate through sanitary selection. Comparison of the partial coat protein gene sequences for three representative rose isolates indicated that they do not form a distinct phylogenetic group and show close relations to Prunus spp. isolates. However, a comparison of the reactivity of monoclonal antibodies raised against these isolates showed that the most prevalent PNRSV serotype in rose was different from the most prevalent serotype in Prunus spp. All of the 27 rose isolates tested infected P. persica seedlings, whereas three of the four PNRSV isolates tested from Prunus spp. were poorly infectious in Rosa indica plants. These data suggest adaptation of PNRSV isolates from Prunus spp., but not from rose, to their host plants. The test methodologies developed here to evaluate PNRSV pathogenicity in Prunus spp. and rose could also help to screen for resistant genotypes.     

黄土丘陵沟壑区不同人工林地土壤肥力变化研究

通过对吴起县不同纯林及其交互效应混交林地的土壤调查、样品测定和室内分析,了解不同人工林地土壤肥力变化情况.结果表明0～20 cm表层土壤养分变化较大.其中,山杏×沙棘混交林地和山杏纯林地利于改善土壤有机质水平,分别达到20.79 g/kg和13.93 g/kg;山杏×小叶杨混交林地和小叶杨纯林地碱解氮含量增幅较大,分别为61.55 mg/kg和61.11 mg/kg;山杏×小叶杨混交林地有效磷含量相对较高,为5.43 mg/kg;山杏纯林地、山杏×小叶杨混交林地和小叶杨纯林地速效钾变化较为明显,分别为126.94,125.61和119.28 mg/kg.混交林地比纯林地更利于改善土壤肥力,建议种植山杏×沙棘混交林.     

Phytoplasma transmission by in vitro graft inoculation as a basis for a preliminary screening method for resistance in fruit trees

In vitro grafting was tested as a technique for inoculating Prunus rootstock Prunus marianna GF 8-1 with European stone fruit yellows (ESFY) phytoplasmas and apple rootstock Malus pumila MM106 with apple proliferation (AP) phytoplasmas. In vitro shoot cultures of ESFY-infected Prunus marianna GF 8-1 and AP-infected Malus pumila MM106 were used as graft inoculum to transmit the phytoplasmas to the respective healthy rootstock. Phytoplasma transmission was assessed after a graft contact of 1, 2 or 3 months. Healthy autografts were used as controls to monitor parameters of in vitro grafting. Successful graft union formation ranged from 58 to 79% irrespective of the plant species and the sanitary state of the graft. Pathogen-specific polymerase chain reaction (PCR) was used to test the inoculated rootstocks for the presence of ESFY and AP phytoplasmas, respectively. The rate of ESFY phytoplasma transmission in successful Prunus -grafts increased from 69 to 94% with the time of contact. AP phytoplasma transmission to Malus occurred in 80 to 97% of successful grafts. To our knowledge this is the first report of phytoplasma transmission by grafting in vitro . The results provide a good basis for the establishment of a preliminary in vitro screening method for phytoplasma resistance in Prunus and Malus .     

Mapping the spread of apricot chlorotic leaf roll (ACLR) in southern France and implication of Cacopsylla pruni as a vector of European stone fruit yellows (ESFY) phytoplasmas

An epidemiological study on European stone fruit yellows (ESFY) phytoplasmas infecting Prunus fruit trees was carried out from 1994 to 2000 in Languedoc-Roussillon (southern France). The spread of the disease was monitored for 7 years by visual observation of symptoms and by PCR detection of the phytoplasma in an experimental orchard planted with apricot hybrid seedlings. This indicated that aerial vectors were responsible for disease spread, and that transmission rates were low at the beginning of the spread. Seventy thousand homopteran insects were captured within and in the surroundings of highly ESFY-infected apricot orchards, of which about 10 000 were used in PCR and nested-PCR assays with universal ribosomal and ESFY-specific nonribosomal primers to detect ESFY phytoplasmas. The other insects were confined in cages for trials of transmission to test plants. ESFY phytoplasmas could not be detected by PCR in any of the leafhopper species captured but could be detected in the psyllid Cacopsylla pruni caught on Prunus domestica and Prunus cerasifera rootstock suckers of apricot trees and on Prunus spinosa . Nested PCR revealed ESFY phytoplasmas in one individual of the deltocephalid Synophropsis lauri captured on an apricot tree. Transmission trials confirmed the role of Cacopsylla pruni as the ESFY phytoplasma vector in France. When apricot seedlings were used as bait plants from April to November during two consecutive years, no natural transmission could be demonstrated. However, one out of 50 apricot seedlings left for the whole year in the orchard became infected. An early spring ESFY infection is in agreement with both the natural transmission results and the life cycle of Cacopsylla pruni .     

科尔沁沙地复叶槭等3个阔叶树种的光合特性及其水分利用效率

在自然条件下,利用LI-6400型便携式光合作用测定系统测定了科尔沁沙地3个阔叶树种复叶槭、紫叶矮樱和紫叶稠李的光合参数,研究各树种水分利用效率特征。结果表明:复叶槭、紫叶矮樱和紫叶稠李的净光合速率日变化呈双峰型,最大峰值出现在8:00~10:00,分别为12.22、11.70和7.24μmol.m-2.s-1。通过比较3个树种的蒸腾速率,得出紫叶矮樱和紫叶稠李的蒸腾速率日均值较低,分别为5.10和4.95mmol.m-2.s-1,而复叶槭蒸腾速率日均值最高,为6.21mmol.m-2.s-1;对于水分利用效率而言,3个树种的日均值由高到低分别为紫叶矮樱(1.08μmol CO2mmol-1H2O)>复叶槭(0.78μmol CO2mmol-1H2O)>紫叶稠李(0.69μmol CO2mmol-1H2O),说明紫叶矮樱对干旱环境适应能力更强。最后,通过净光合速率与各影响因子的相关分析得出,3个阔叶树种净光合速率与其胞间CO2浓度相关系数最大,分别为r复叶槭=-0.954、r紫叶矮樱=-0.968和r紫叶稠李=-0.970,说明胞间CO2浓度是影响树种净光合速率最主要的影响因子。     

PM 4/35(1): Soil test for virus–vector nematodes in the framework of EPPO Standard PM 4 Schemes for the production of healthy plants for planting of fruit crops,grapevine, Populus and Salix

Specific scope

This standard describes the sampling and testing of soil in which propagation and certified stocks of the following crops are to be planted: PM 4/8 (Vitis spp.), PM 4/9 (Ribes spp.), PM 4/10 (Rubus spp.), PM 4/11 (Fragaria x ananassa), PM 4/16 (Humulus lupulus), PM 4/29 (Prunus avium, Prunus cerasus and their rootstocks), PM 4/30 (Prunus armeniaca, Prunus domestica, Prunus dulcis, Prunus persica, Prunus salicina and their rootstocks), PM 4/17 (Olea europea), PM 4/32 (Sambuscus spp.), PM 4/33 (Populus spp. and Salix spp.).

Specific approval and amendment

First approved in 2009‐09.

     

宁夏贺兰山自然保护区蒙古扁桃群落物种多样性

通过野外实地调查40个蒙古扁桃样地,得到野生维管束植物133种(包括种下等级),隶属于91属39科。区系分析表明,宁夏贺兰山自然保护区蒙古扁桃群落具有温带性质,且以北温带成分优势,占总属数的35.16%。生活型谱中地面芽植物占总种数的近半,表明蒙古扁桃群落生境寒冷而干旱。物种多样性指数测度结果表明:1)草本层的多样性高于灌木层;2)北段海拔1700~1800 m处多样性最高,则在中段2000~2100 m处多样性最高;3)北段阴坡的多样性最低,中段则相反,阴坡和半阴坡的多样性比阳坡和半阳坡的高;4)坡度20°以下坡上的群落多样性高于20°以上坡的多样性,且20°以上的坡,随坡度增加而多样性减少。     

Epidemiology of sharka disease in France

Plum pox virus was first detected in France in the 1960s. Both PPV-D and PPV-M strains are present but epidemics related to the PPV-M strain detected in the late 1980s are the most problematic. The two PPV strains have unequal distributions in peach and apricot orchards and different prevalences. More than 20 different aphid species have been identified as vectors of PPV but most of them do not colonize Prunus species. Thus, aphids involved in the spread of PPV in orchards are essentially visiting aphids. The main sources of inoculum for the vectors are leaves and fruits of infected stone-fruit trees. Spontaneous, wild and ornamental Prunus species such as Prunus dulcis , P. spinosa or P. pissardii are susceptible to PPV isolates found in France but their role as a reservoir in sharka epidemics is probably negligible. The disease spreads rapidly in orchards but the rate of progression may vary according to the identity of the PPV strain and the Prunus species. Analysis of spatial patterns of disease has shown that secondary spread by aphids frequently occurs over short distances in the orchards (aggregated patterns) but also that dissemination at longer distances (of several hundred metres) is a common event.     

The use of PCR melting profile for typing of <Emphasis Type="Italic">Pseudomonas syringae</Emphasis> isolates from stone fruit trees

Of thirty fluorescent Pseudomonas isolates originating from symptomatic tissues of sweet (Prunus avium) and sour cherry (Prunus cerasus), plum (Prunus domestica), peach (Prunus persica) and apricot (Prunus armeniaca), 23 were identified as P. syringae using LOPAT tests. Further characterization of those isolates by GATTa and L-lactate utilization tests showed that 10 of them belonged to race 1, six to race 2 of P. syringae pv. morsprunorum (Psm) and six other isolates were identified as pathovar syringae (Pss). One isolate (791) was determined as atypical. Phenotypic determination and genetic analysis of studied isolates for toxin production revealed that isolates of Pss produced syringomycin, 3 Psm race 1 produced coronatine and 6 Psm race 2 produced yersiniabactin. Genetic diversity of all isolates was evaluated with the PCR melting profile (PCR MP) method. A dendrogram constructed with PCR MP patterns showed positive correlation with phenotypically distinguished pathovars. Isolates of Psm races 1 and 2 formed distinct, tight clusters, whereas Pss isolates were more heterogeneous. Isolate 791 was placed within Pss isolates. Bacteria identified as Pss caused more severe symptoms on immature cherry fruits compared to Psm, which corresponded to determined pathovars and races.     

First detection and complete genome characterization of a Cherry (C) strain isolate of plum pox virus from sour cherry (Prunus cerasus) in Germany

Journal of Plant Diseases and Protection - An isolate of plum pox virus (PPV) was detected in sour cherry (Prunus cerasus) in the Eastern region of Germany. Symptoms observed on infected sour...     

山杏幼苗水分生理生态特性及凋萎湿度的研究

对山杏幼苗进行 3种施水量的水分培养和干旱处理。结果表明 :随施水量的减少 ,叶片的净光合速率、蒸腾速率、气孔导度和水分利用效率等指标都随之下降 ,叶片温度提高。 40 9.2和 1 89.2 mm施水量对山杏幼苗各项指标的影响呈显著差异 ,而 40 9.2和 32 1 .2 mm之间与 32 1 .2和 1 89.2 mm之间均无差异。随土壤干旱的加剧 ,山杏幼苗叶片的蒸腾速率和水势与土壤含水量呈规律性变化 ;当干旱持续 39天时 ,1 .44%的土壤含水量可视为山杏幼苗的凋萎湿度     

布朗李叶枯病菌生物学特性研究

对布朗李叶枯病菌(Macrophoma kawatsukai Hara)生物学特性研究表明,该菌最适生长和产孢的培养基为布朗李果汁。菌丝生长和产孢的最佳碳源分别为蔗糖、麦芽糖和果糖;氮源分别为酪氨酸、谷氨酰胺、天门冬酰胺和半胱氨酸。菌丝生长最适温度25℃,最适pH5～7;分生孢子形成最适温度25～30℃,最适pH8,饱和湿度有利于产孢,阳光照射形成分生孢子器最多,紫外光照射对分生孢子器形成有一定的抑制作用。孢子萌发最适温度为20～30℃,最适pH6～9,相对湿度为90%～100%,以在水滴中萌发最好。布朗李杆煎汁和布朗李果汁对孢子萌发有促进作用。     

Viruses and viroids of stone fruits in Syria

Field surveys were carried out in the main stone fruit-growing areas of Syria to evaluate the sanitary status of mother blocks, varietal collections and commercial orchards. The presence of virus and virus-like diseases was checked by enzyme-linked immunosorbent assay (ELISA), sap transmission to herbaceous hosts, testing on the woody indicators Prunus persica cv. GF 305 and Prunus serrulata cv. Kwanzan and dot-blot hybridization tests. A total of 1337 samples was tested by ELISA (444 apricot, 283 peach, 246 cherry, 222 almond and 142 plum). The overall mean infection rate was 13%, and the percentage infection level of single species was: peach 24%, cherry 16%, almond 13.5%, apricot 6%, plum 5%. The following viruses and viroids were detected: PNRSV, PDV, ACLSV, PPV, ApMV, PLMVd and HSVd ¹ .     

Location of Prunus Necrotic Ringspot Ilarvirus Within Pollen Grains of Infected Nectarine Trees: Evidence from RT-PCR, Dot-blot and in situ Hybridisation

Prunus necrotic ringspot Ilarvirus (PNRSV) is a pollen and seed-borne ilarvirus affecting most Prunus spp. The location of the virus in infected nectarine pollen grains was investigated by molecular hybridisation, RT-PCR and in situ hybridisation. The first two approaches revealed an internal location of the virus. In situ hybridisation demonstrated the virus in the bicellular pollen grain, where it was present in the cytoplasm of the vegetative cell but not in the generative cell. This result seems to indicate that the sperm cells, formed by the mitosis of the generative cell, are not involved in virus transmission to seed. Other possible mechanisms are discussed.