Viruses infecting almond trees in the region of Valencia (Spain) 1

In the last 10 years, more than a thousand almond trees have been analysed by the DAS-ELISA method in the Valencia region. The most frequent virus infecting unselected almond trees was prune dwarf ilarvirus (PDV) (62%), followed by prunus necrotic ringspot ilarvirus (PNRSV) (36%), apple mosaic ilarvirus (ApMV) (14%) and apple chlorotic leafspot trichovirus (ACLSV) (2%). Infection levels of selected trees were 26% for PDV, 15% for PRSV, 0% for ApMV and 5% for ACLSV.     

胡瓜钝绥螨对柑桔害螨控制效果探讨

柑桔红蜘蛛、锈壁虱是柑桔园中的主要害虫，常规的防治方法主要依赖于化学防治，利用胡瓜钝绥螨(Amblyseius cucumersis)，通过人工释放手段进行生防，释放后3个月生防效果调查，平均“黑果率”控制在2．70%～3．63％内，害螨控制率达89．6%～92．7％，年降低农药使用次数40％～60％。     

Ecological data on predators ofParlatoria pergandii on sour orange trees in southern Greece

The present study was carried out in southern Greece during 1993-1995 on sour orange trees infested with the diaspididParlatoria pergandii Comstock. The activity of the natural enemies of the scale, the composition of their population during the year as well as their relation with hymenopterous parasitoids of coccinellids, were studied.P. pergandii was parasitized by a hymenopterous endoparasite of the genusEncarsia and the extent of parasitization ranged between 5.2% and 14.1%. The observed predators were the coccinelidsChilocoms bipustulatus Linnaeus andRhyzobius lophanthae Blaisdell and the nitidulidCybocephalus fodori Endrödy-Younga. The predominant predator wasR. lophanthae (84.3% of the larvae and 73.3% of the adults), which was active throughout the whole year in all of its developmental stages. Second most abundant was the predatorC. bipustulatus (15.7% of the larvae and 20% of the adults) and third the predator C.fodori (6.7% of the adults). Larvae ofC. bipustulatus were observed to be parasitized by the hymenopterous parasitoidsHomalotylus flaminius Dalman (Encyrtidae) andTetrastichus coccinellae Kurdjumov (Eulophidae). The parasitization percentage increased gradually from 4% in mid June to 94% around the end of September. Laboratory tests confirmed that the above mentioned parasitoids cannot infest larvae or nymphs ofR. lophanthae.     

川东地区柑橘矢尖盾蚧发生规律调查研究

采用系统调查方法研究了川东地区柑橘矢尖盾蚧的发生消长规律。明确了此虫在该地区一般1年发生3代,少数年份发生2代。第1、2代各龄若虫的发生均呈明显的双峰型。害虫主要在树冠的东、西方位和树的中、下层及内膛越冬。幼蚧始见后20d为第1次施药防治的关键时期。     

Varietal influence of orange trees on armoured scale insect fecundity (Hemiptera: Diaspididae)

Abstract

We studied the influence of two orange tree varieties on the fecundity of two hemipteran diaspidid scale insect species: Cornuaspis beckii (Newman) and Parlatoria pergandii Comstock. Samples of females were taken at 7 – 40 day intervals from two orange orchards [Citrus sinensis (L.) Osbeck], one of the Navel Lane Late cultivar and the other of the Valencia Late cultivar. Different categories for the egg stage were considered: preoviposited, oviposited and hatched eggs. Average fecundity in C. beckii was significantly higher than that of P. pergandii. Significant differences between the two orange varieties were evident for some egg categories, with a higher fecundity in Navel Lane Late than in Valencia Late. The temporal pattern of fecundity in relation to accumulated temperature was studied by two methods: (i) comparing the parameter r of a logistic function that related egg-days to accumulated degree-days, and (ii) comparing the parameters b and c of a sinusoidal function that relates the variation egg-days/degree-days to accumulated degree-days. The comparison of such parameters (indicators of changes in the temporal patterns of fecundity) did not show significant differences between orange varieties. Our results suggest that some type of physiological difference between Navel Lane Late and Valencia varieties could be responsible for the differential fecundity of diaspines. Nevertheless, currently we cannot recommend changes in the management of diaspine in citrus orchards.     

东北地区主要树种的分布与Thornthwaite指标的关系

根据树种的分布资料和气象资料,采用桑斯威特(Thornthwaite)方法计算东北地区50种主要树种的潜在可能蒸散(PE)和湿润指数(IM),利用半峰宽法计算热量指数PE的最适范围,并构建Thornthwaite气候指标与树种分布的地理三维要素(纬度、经度和海拔高度)的回归模型,分析东北地区主要树种水热分布规律。综合潜在可能蒸散(PE)和湿润指数(IM)两个气候指标,将东北地区主要树种划分为寒温湿润型,寒温潮湿型,中温耐旱型,中温湿润型,中温潮湿型,暖温耐旱型、暖温湿润型和暖温潮湿型等8个水热指标类群,并论述了东北地区主要树种的水热分布格局。     

Interactions between citrus viroids affect symptom expression and field performance of clementine trees grafted on trifoliate orange

ABSTRACT Citrus exocortis viroid (CEVd), Citrus bent leaf viroid (CBLVd), a noncachexia variant of Hop stunt viroid (HSVd), Citrus viroid III (CVd-III), and Citrus viroid IV (CVd-IV) were co-inoculated as two-, three-, four-, and five-viroid mixtures to Clementine trees grafted on trifoliate orange to evaluate their effect on symptom expression, tree growth, and fruit yield. Most trees infected with CEVd-containing viroid mixtures developed exocortis scaling symptoms, as did CEVd alone, whereas most trees infected with HSVd- or CVd-IV-containing mixtures developed bark-cracking symptoms. Trees infected with mixtures containing both CEVd and CVd-IV revealed the existence of antagonism between these two viroids in terms of the expected bark-scaling and cracking symptoms. Synergistic interactions also were identified in trees infected with certain viroid combinations that, in spite of lacking CEVd, expressed exocortis-like scaling symptoms. Viroid interactions also affected the expected response of trees in terms of vegetative growth and fruit yield. Trees infected with viroid combinations containing CEVd or CVd-III were smaller and produced less fruit than trees infected with mixtures not containing these viroids. Viroid interactions on scion circumference and cumulative fruit yield, in terms of additivity of their effects, were statistically confirmed using a factorial analysis of variance model with two mean estimation approaches. In single-viroid infections, CEVd, CVd-III, and, to a lesser extent, CBLVd consistently and significantly reduced tree size and fruit yield. Conversely, HSVd and CVd-IV slightly increased fruit yield and reduced scion circumference. Rare and not consistent significant interactions were detected with the five-, four-, and three-viroid combinations. Antagonistic interactions between CEVd and CVd-III or CBLVd and CVd-III were revealed over the years with consistent significance. The antagonistic interaction between CEVd and CVd-IV was highly significant over the years when additional viroids were present; however, this antagonism appeared much later in the case of an exclusive interaction. HSVd and CVd-IV showed a consistent and significant synergistic interaction on yield only when both viroids were exclusively present. These results demonstrate antagonistic or synergistic relationships between citrus viroids depending on the viroid mixtures present in the host.     

Residues of acephate,amitraz, chlorpyrifos and formetanate hydrochloride on and in fruits after low-volume applications to orange trees

Acephate, amitraz, chlorpyrifos and formetanate hydrochloride were applied to orange trees. Test plots were treated at the maximum dose rates currently permitted in California in order to determine the consequent residues on and in the fruits. Applications were made with a low-volume airblast sprayer and used 0.94 klitres of spray per hectare. Fruit samples were collected at or near the legally prescribed California fruit-harvest waiting intervals. All residues were below the US tolerances for whole fruit. Analytical procedures for the gas chromatographic analysis of intact amitraz and formetanate and of 2,4-xylidine residues, without the necessity for derivative formation, are presented.     

基于Holdridge分类系统的东北地区主要树种的水热分布类群

根据东北地区树种分布资料和233个气象站资料,利用Holdridge生命地带分类系统计算了东北地区50种主要树种的Holdridge生命地带分类系统的年生物温度(BT)、可能蒸散(APE)、年降水量(PREC)和可能蒸散率(PER)。构建了Holdridge指标与树种分布的纬度、经度和海拔高度的回归模型,定量的分析了东北地区树种分布的气候规律。综合年生物温度(BT)和可能蒸散率(PER)两个气候指标将50种主要树种划分为8个水热指标类群,分别为寒温耐旱型、寒温湿润型,寒温潮湿型,中温耐旱型,中温湿润型,中温潮湿型,暖温耐旱型和暖温湿润型。     

桃蛀螟幼虫在板栗上的空间分布型研究

通过对不同板栗园桃蛀螟Dichocrocis punctiferalis Guenee幼虫的调查,用昆虫分布型的4种常用理论公式分别进行配合适度的χ2检验,再用6种空间分布型聚集度指标、Taylor幂法则及Iwao回归法对桃蛀螟幼虫的空间分布型进行测定。结果表明:桃蛀螟幼虫种群在板栗园中全部呈聚集分布,而且均符合负二项分布,其聚集原因是由该虫习性与环境因素共同造成的。此外,还利用了分布型参数确定了桃蛀螟幼虫的理论抽样数。     

Spatial and temporal distribution of trunk-injected (14) C-imidacloprid in Fraxinus trees

BACKGROUND: Since the discovery of Agrilus planipennis Fairmaire (emerald ash borer) in 2002, researchers have tested several methods of chemical control. Soil drench or trunk injection products containing imidacloprid are commonly used to control adults. However, efficacy can be highly variable and may be due to uneven translocation of systemic insecticides. The purpose of this study was to determine whether sectored xylem anatomy might influence imidacloprid distribution in tree crowns. RESULTS: Imidacloprid equivalent concentrations were higher in leaves from branches in the plane of the injection point (0°) than in leaves from branches on the opposite side of the injection point (180°). Leaves from branches 90° to the right of injection points had higher imidacloprid equivalent concentrations than leaves from branches 90° to the left of injection points. Leaves and shoots had higher imidacloprid equivalent concentrations than roots and trunk cores, indicating that imidacloprid moves primarily through the xylem. CONCLUSION: Imidacloprid equivalent concentration in leaves varied over time and in relation to injection points. It is concluded that ash trees have sectored ‘zigzag’ xylem architecture patterns consistent with sectored flow distribution. This could lead to variable distribution of imidacloprid in tree crowns and therefore to variable control of A. planipennis. Copyright © 2012 Society of Chemical Industry     

东北地区主要树种分布与气候的关系

根据东北地区树种分布资料和气象资料,计算了东北地区50种主要树种的Kira温暖指数(WI)、温暖指数的全范围和最适范围以及徐文铎提出的湿度指数(HI)。建立了东北地区气候因子与树种地理分布的回归模型,并对气候因素与树种地理分布的相关关系进行了分析。综合50种主要树种的水热指标值,将其划分为寒温湿润型,寒温潮湿型,中温耐旱型,中温湿润型,中温潮湿型,暖温耐旱型和暖温湿润型7个Kira水热指标分布类群,论述了东北地区主要树种沿热量和水分梯度的分布格局。     

Detection of mistletoe infected trees using UAV high spatial resolution images

Journal of Plant Diseases and Protection - Remote detection of aerial parasitic plants in forests is imperative in precision forestry, as it can help to manage tree stands and to monitor forest...     

油茶茶枝蠊蛾的生物学特性及防治

本文主要叙述了为害高产无性系油茶茶枝蠊蛾的一些生物学特性,并提出了有效的防治方法。     

苹果矮砧密植栽培模式下桃小食心虫发生规律

为掌握苹果矮砧密植栽培模式下桃小食心虫的发生规律,为其有效测报及防治提供理论依据,采用悬挂不同高度性信息素诱捕器的诱捕监测方法,对矮砧密植栽培模式下果实套袋和不套袋苹果园桃小食心虫的空间发生动态进行了研究。结果表明:泰安地区桃小食心虫成虫发生期为5月中下旬-10月上旬,其中,6月-9月是桃小食心虫发生盛期,此间共出现两次高峰。苹果矮砧密植栽培模式下,距离地面0~2.5m处均可监测到桃小食心虫雄成虫;果实不套袋苹果园在树体不同高度桃小食心虫的发生数量均显著高于果实套袋苹果园(P0.01);果实不套袋苹果园距地面1.5m处的桃小食心虫诱捕量显著高于其他高度(P0.01),而果实套袋苹果园2.0m处诱捕量显著高于其他高度(P0.01);桃小食心虫发生动态趋势、成虫发蛾高峰期和持续时间在果实套袋和不套袋两种条件下差异不明显。试验结果进一步明确了苹果矮砧密植栽培模式下桃小食心虫的空间分布动态规律,可为提升应用昆虫信息素预测预报的精准性与诱捕防治的全面性提供参考。     

油茶高产无性系碧蛾蜡蝉的生物学特性及防治

碧蛾蜡蝉为害嫁接油茶春梢和夏梢,在江西一年发生一代,5月初孵化,以若虫、成虫为害,以卵越冬,混交林较纯林发生重。40%速扑杀乳油、40%杀扑磷乳油、80%敌敌畏乳油、50%吡虫啉可湿性粉剂、20%啶虫脒可溶性粉剂、1%甲氨基阿维菌素苯甲酸盐乳油对其均有较好防效。     

水稻橙叶病分子检测及其在华南地区的发生与分布研究

对华南地区水稻橙叶病(rice orange leaf disease)进行病原菌分子检测和病情发生与分布调查。结果表明,该病是一种由电光叶蝉(Inazuma dorsalis)和黑尾叶蝉(Nephotettix cinticeps)传播的植原体(Phytoplasma)引起的病害,早期感病植株在分蘖期全株叶片表现为橙黄色,不久干枯死亡,对水稻生产造成严重为害。电镜下观察,病株幼叶叶脉筛管细胞中存在大量植原体。巢式PCR可从来源于水稻病株及介体电光叶蝉和黑尾叶蝉DNA抽提物中获得单一扩增产物,PCR产物核苷酸序列与文献报道的水稻橙叶植原体16S r DNA序列(Gen Bank登录号:KR061356)同一率均为99.8%以上。2015年广东各主要稻区及海南中部和广西东南部均有该病发生与分布。     

龟纹瓢虫对桑蓟马的捕食作用及两者在桑树上的分布

为了明确桑蓟马Pseudodendrothrips mori和龟纹瓢虫Propylea japonica在桑树上不同部位的分布情况, 及龟纹瓢虫对桑蓟马的捕食作用和防治潜力,本试验采用五点取样法, 使用叶片采集法对桑树上的桑蓟马和龟纹瓢虫分布进行了调查, 在室内开展了龟纹瓢虫2龄、3龄幼虫对桑蓟马2龄若虫和成虫的捕食能力试验。结果表明, 桑蓟马在桑叶背面的种群数量更高, 主要分布在第2至第5叶位上。龟纹瓢虫对桑蓟马若虫和成虫的捕食作用符合Holling Ⅱ型功能反应模型。龟纹瓢虫3龄幼虫对桑蓟马的控制能力大于2龄幼虫, 2龄幼虫对桑蓟马2龄若虫和成虫的最大理论捕食量分别为91.74头和55.56头, 3龄幼虫分别为344.83头和196.08头。搜寻效应随猎物密度升高而下降, 龟纹瓢虫对桑蓟马的捕食数量受自身密度的影响。龟纹瓢虫在室内对桑蓟马的2龄若虫和成虫具有较强的捕食潜力, 且其在田间具有分布, 可以作为桑蓟马生物防治的潜在材料。     

Persistence and distribution of three benzimidazole fungicides in pear trees sprayed for the control ofventuria pirina

The persistence and distribution in leaves and fruits of benomyl, carbendazim and methylthiophanate were investigated, following fungicide spray treatments in pear orchards. Chemical analysis and bioassays showed that basal leaves sprayed more than once with benomyl, contained 50 ppm of methyl benzimidazole carbamate (MBC) 4 days after the last spray. Seven months later. 8 ppm MBC was detected in the basal leaves, just before normal abscission. In apical leaves, the fungicide levels were lower than in the basal ones. Analyses of basal leaves showed that the residue level of MBC, 5 and 7 months after the last treatment with benomyl. carbendazim or methylthiophanate, was very similar in all treatments. Bound MBC was not detected in the leaves and only low concentrations of 2-amino benzimidazole (2-AB) were detected. There was no translocation of these fungicides from treated leaves to new young leaves. Chemical analysis of pear fruits from an orchard sprayed with benomyl revealed that 3 weeks after the last spray treatment, the residue level of MBC was 0.4 ppm. About 85% of the fungicide was found in the peel, and only 15% in the pulp. The more infected fruits consistently contained a lower concentration of MBC than the less infected fruits.