Incidence and control of dogwood borer (Lepidoptera: Sesiidae) and American plum borer (Lepidoptera: Pyralidae) infesting burrknots on clonal apple rootstocks in New York

Surveys were conducted in the major apple growing regions of New York state to determine the incidence of borers infesting burrknots on clonal apple rootstocks. Dogwood borer, Synanthedon scitula (Harris), was generally prevalent throughout the state, but American plum borer, Euzophera semifuneralis (Walker), was limited to western New York apple orchards near infested stone fruit trees. Insecticides evaluated in the field for efficacy against both borers were chlorpyrifos, endosulfan, indoxacarb plus oil, methoxyfenozide, fenpropathrin, and kaolin clay. Also, white latex paint was tested alone and mixed with chlorpyrifos. One application of chlorpyrifos applied at the petal fall developmental stage was equivalent to chlorpyrifos applied at petal fall and again in mid-July, and it provided season-long control of dogwood borer and American plum borer. One application of chlorpyrifos applied any time between the half-inch green developmental stage and petal fall, or after harvest the previous season, controlled both overwintered and summer brood larvae of dogwood borer. Multiple applications of fenpropathrin, indoxacarb plus oil, and endosulfan applied during the dogwood borer flight period controlled the summer brood.     

Discrimination by male dogwood borer, Synanthedon scitula (Lepidoptera: Sesiidae), among traps baited with commercially available pheromone lures

The response of male dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae), to four commercially available pheromone lures and to pheromone source concentration was evaluated in field trapping studies in commercial apple orchards in Virginia and West Virginia Male peachtree borer, Synanthedon exitiosa (Say), lesser peachtree borer, Synanthedon pictipes (Grote & Robinson), and lilac borer, Podosesia syringae (Harris), were also captured in traps baited with all lures tested. Among the lures used, the Scenturion dogwood borer lure was the most attractive to and selective for dogwood borer. Male dogwood borer showed a concentration-dependent response to traps baited with different source concentrations of the pheromone from Scenturion. Chemical analyses revealed that all lures contained principally (Z,Z)-3,13-octadecadien-1-ol acetate (ODDA) but that a significantly higher percentage of (Z,E) plus (E,Z)-3,13-ODDA was present in the Scenturion lure, compared with the others. Weekly collections of fresh male and female dogwood borer pupal exuviae from April until October in 2002 and 2003 suggested that traps baited with Scenturion lures significantly underestimated the size of populations in commercial apple orchards.     

Recommendations on minimum experimental plot size and succession of aphidophaga in West Virginia, USA, apple orchards

Five apple orchards in West Virginia, USA, were managed with five different pest management practices ranging from unsprayed to conventional insecticides. Data were collected on aphid, predaceous insect, and spider abundance every 2 weeks from May to July along one or two randomly selected, 15 consecutive tree transects. A total of 892 individual predaceous insects was observed: 32% wereAphidoletes aphidimyza, 21% wereCoccinella septempunctata and the rest were from 13 other taxa. The most important aphid predator seemed to beC. septempunctata. Of the 32 sample transects with predators, 72 % showed an edge effect in which either the standard error or mean of predator abundance differed from the edge towards the center of the orchard. This edge effect extended a mean of 7 trees (30 m) into the orchard. Only 39% of the 33 transects that had spiders showed an edge effect, extending into the orchard a mean of 8 trees (33 m). However, 75% of the transects with more than one spider per tree had an edge effect of 10 trees (43 m). We recommend a minimum border of seven trees before sampling for aphid predators and 10 trees before sampling for spiders. A recommended experimental plot size, for semi-dwarf, free-standing apple orchards, to eliminate edge effects is 1.25 ha for aphidophaga, 1.5 ha for spiders; a minimum plot size of 0.6 ha for aphidophaga and 0.75 ha for spiders would minimize edge effects.     

On an outbreak of the citrus flat-headed borer,Agrilus auriventris E. Saunders in Nagasaki Prefecture

The process of an outbreak of the citrus flat-headed borer, Agrilus auriventris in Nagasaki Prefecture was described with some ecological considerations on causative factors. This outbreak which showed a typical “Gradation”, initiated around 1958, and terminated in 1963. The peak year was seen in 1961. At first attack by the borer was restricted to old and weak trees, but it was also found in young and healthy trees in the peak year. Some environmental conditions in orchards were examined in relation to the intensity of infestation by the borer. Soil management and drought seemed to have remarkable correlations with the borer's infestations. Probably, this outbreak was caused by the weakening of citrus tree by gummosis and abnormal defoliation, aging of orchard trees, and drought in the summer of 1959∼1960. Interrelation between these causes and processes are shown schematically in Fig. 12.     

Flower strips increase the control of rosy apple aphids after parasitoid releases in an apple orchard

Mass releases of two parasitoid species, Aphidius matricariae and Ephedrus cerasicola, may provide an alternative measure to pesticides to control the rosy apple aphid Dysaphis plantaginea in organic apple orchards. As an exploratory study, we tested if the presence of flower strips between apple tree rows could improve the action of three early parasitoid releases––and of other naturally present aphid enemies––on the control of aphid colonies and the number of aphids per tree. Apple trees located at various distances from parasitoid release points were monitored in plots with and without flower strips in an organic apple orchard over two years, along the season of aphid infestation (March to July). Our case study demonstrated that the presence of flowering plant mixes in the alleyways of the apple orchard reduced the presence of D. plantaginea by 33.4%, compared to plots without flower strips, at the infestation peak date. We also showed a negative effect of increasing the distance to parasitoid release points on aphid control. However, our results at the infestation peak date suggest that the presence of flower strips could marginally compensate for the detrimental effect of increasing distance to the release point, probably by improving the persistence and dispersal capacities of natural enemies. Despite high variations in aphid population dynamics between years, we conclude that combining flower strips with early parasitoid releases in apple orchards is promising for biological control of the rosy apple aphid, although the method merits to be further refined.     

洛川苹果园土壤水分变化特征

全面掌握洛川果园的土壤水分环境特征,不仅可为苹果的园址选择、砧穗组合和改进土壤水分管理措施提供理论依据,而且对我国苹果产区果园提质增效具有借鉴价值.采用定点土壤水分连续监测法,对洛川苹果园的总体土壤水分环境以及不同生长年限、不同立地类型和乔、矮化果园的土壤水分分异特征进行分析.结果表明： 苹果树根际区 (0～200 cm)土壤水分普遍亏欠,且0～60 cm土层的水分亏欠小于60～200 cm土层;生长季0～60 cm土层贮水量与降水量的变化一致,土壤相对含水量大多<60%,季节性旱象严重;果园剖面土壤含水量变异系数随土壤深度加深而递减;随果园生长年限的增大,土壤剖面贮水量下降;在栽培密度一致的条件下,矮化果园5 m土层土壤含水量均高于乔化果园,而栽培密度大的矮化果园的土壤贮水量低于栽培密度小的乔化果园;塬地成龄果园的土壤水分含量最高,川地次之,台地相对较低.密度对果园土壤水分含量有很大影响,在栽培密度一致的条件下,采用矮化栽培能减少土壤水分消耗,显著提高果园土壤含水量;挖株降低栽培密度是维持苹果园土壤水分平衡、实现可持续发展的有效途径.     

Rootstock genotype and orchard replant position rather than soil fumigation or compost amendment determine tree growth and rhizosphere bacterial community composition in an apple replant soil

Apple replant disease (ARD) is a complex soilborne disease syndrome that often causes problems when renovating old orchard sites. Soil fumigants sometimes control ARD, but biological and cultural alternatives are needed. In this study the growth of two widely used clonal apple (Malus domestica) rootstocks (M7 and M26) were compared to three new rootstocks from the Cornell-Geneva series (CG16, CG30 and CG210 (a.k.a. CG6210)) in an orchard site with a history of ARD, in Ithaca, NY. Trees were planted in two distinguishable positions – the previous tree rows versus the old inter-row grass lanes. Additionally, we compared the effects of compost amendment and fumigation with dichloropropene plus chloropicrin on tree growth on each replant rootstock. Rhizosphere bacteria and actinobacteria were assessed using PCR-DGGE for the rootstocks M7, M26, CG30 and CG210. Tree growth on the rootstocks M7, M26 and CG16 was suppressed in the old tree rows relative to grass lanes, while trees on CG30 and CG210 rootstocks grew equally well in both positions. The species composition of rhizosphere bacteria and actinobacteria differed significantly between the planting positions and between the rootstocks M7 and M26 compared to CG30 and CG210. In contrast, the preplant compost or fumigation soil treatments had no effect on tree growth and little impact on rhizosphere bacterial community composition. Abbreviations: ARD – apple replant disease; DGGE – denaturing gradient gel electrophoresis; PCR – polymerase chain reaction.     

Extrafloral nectar in an apple ecosystem to enhance biological control

A common goal of conservation biological control is to enhance biodiversity and increase abundance and effectiveness of predators and parasitoids. Although many studies report an increase in abundance of natural enemies, it has been difficult to document increases in rates of biological control. To enhance parasitism of the tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae), alternate food was provided by interplanting peaches bearing extrafloral nectaries into apple (Malus spp.) orchards. Laboratory studies showed that the presence of nectar increased longevity and parasitism rates by Goniozus floridanus (Bethylidae), the dominant parasitoid of tufted apple bud moth in West Virginia. In orchard studies, we found the total number of hymenopteran parasitoids was higher on peach (Prunus spp.) trees than on adjacent apple trees. Abundance of parasitic Hymenoptera also was significantly higher on the side of traps facing away from rather than toward peach trees, indicating attraction to peach trees. However, total parasitism rates of tufted apple bud moth were not affected by the presence of peach extrafloral nectar in any field studies. Insect injury to fruit at harvest showed that fruit from orchards with interplanted peach trees had less injury from San Jose scale, Quadraspidiotus perniciosus (Comstock) and stink bugs (Pentatomidae) than fruit from an apple monoculture. Although interplanting with peach trees did not produce the hypothesized result of increased biological control, the experiment did have beneficial results for pest management. These results demonstrate the importance of collecting data on variables beyond the targeted species when evaluating habitat manipulation experiments to fully assess the impact on the ecosystem.     

渭北旱塬矮砧密植苹果园土壤矿质氮积累与空间分布特征

随着苹果矮砧密植栽培模式的迅速发展,揭示矮砧密植苹果园土壤矿质氮的积累与分布特征对果园科学施肥具有重要意义.本研究以不同树龄(6a、9a、12a)的矮砧密植苹果园为对象,在树下、株间、行间以及树干与行间的中间点位置采集土样,分析土壤硝态氮、铵态氮和矿质氮的积累与分布特征.结果 表明:O～ 300 cm土层土壤硝态氮累积...     

Conservation biological control of rosy apple aphid, Dysaphis plantaginea (Passerini), in eastern North America

Because of the potentially serious damage rosy apple aphid, Dysaphis plantaginea (Passerini) (Homoptera: Aphididae), can cause to apple fruit and branch development, prophylactic insecticides are often used for control. If biological control could be relied on, the amount of pesticide applied in orchards could be reduced. This study examined biological control of rosy apple aphid in eastern West Virginia and the potential for enhancement through conservation biological control, in particular, the effect of interplanting extrafloral nectar-bearing peach trees. By 20 d after first bloom, only 2% of fundatrices initially present survived to form colonies based on regression of data from 687 colonies. Exclusion studies showed that many of the early colonies were probably destroyed by predation; the major predator responsible seemed to be adult Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Mortality before apple bloom was most important in controlling rosy apple aphid population growth but by itself is not sufficiently reliable to prevent economic injury. Interplanting of extrafloral nectar-bearing trees did not increase biological control, and interplanting with 50% trees with extrafloral nectar glands reduced biological control. The number of leaf curl colonies in the 50% interplanted orchards was lower than in monoculture orchards, suggesting a preference of alate oviparae for more diverse habitats, supporting the resource concentration hypothesis but not at a level sufficient to prevent injury. Predation and parasitism after the formation of leaf curl colonies was not adequate to control rosy apple aphid populations.     

警惕果树重大害虫——苹楔天牛

苹楔天牛Saperda candida Fabricius(鞘翅目Coleoptera:天牛科Cerambycidae)原产北美,主要危害果树,300多年来被认为是原产地果园最具毁灭性的害虫。2008年该害虫首次传入欧洲(德国费马恩岛),因而受到许多国家的重视。该害虫的寄主植物苹果、梨、李、山楂等果树在我国种植非常广泛,具有十分重要的经济价值。该天牛会随着寄主植物的引进、调运进行远距离传播,我国应加强对该害虫的检疫。文章就其形态特征、危害特点、生物学特性及潜在风险作一阐述。     

Effectiveness of odor-baited trap trees for plum curculio (Coleoptera: Curculionidae) monitoring in commercial apple orchards in the northeast

The plum curculio, Conotrachelus nenuphar (Herbst), is a key pest of pome and stone fruit in eastern and central North America. For effective management of this insect pest in commercial apple (Malus spp.) orchards in the northeastern United States and Canada, one of the greatest challenges has been to determine the need for and timing of insecticide applications that will protect apple fruit from injury by adults. In a 2004-2005 study, we assessed the efficacy and economic viability of a reduced-risk integrated pest management strategy involving an odor-baited trap tree approach to determine need for and timing of insecticide use against plum curculio based on appearance of fresh egg-laying scars. Evaluations took place in commercial apple orchards in seven northeastern U.S. states. More specifically, we compared the trap-tree approach with three calendar-driven whole-block sprays and with heat-unit accumulation models that predict how long insecticide should be applied to orchard trees to prevent injury by plum curculio late in the season. Trap tree plots received a whole-plot insecticide spray by the time of petal fall, and succeeding sprays (if needed) were applied to peripheral-row trees only, depending on a threshold of one fresh plum curculio egg-laying scar out of 25 fruit sampled from a single trap tree. In both years, level of plum curculio injury to fruit sampled from perimeter-row, the most interior-row trees and whole-plot injury in trap tree plots did not differ significantly from that recorded in plots subject to conventional management or in plots managed using the heat-unit accumulation approach. The amount of insecticide used in trap tree plots was reduced at least by 43% compared with plots managed with the conventional approach. Advantages and potential pitfalls of the bio-based trap tree approach to plum curculio monitoring in apple orchards are discussed.     

Rootstock genotype succession influences apple replant disease and root-zone microbial community composition in an orchard soil

Apple replant disease (ARD) is a soil-borne disease complex that affects young apple trees in replanted orchards, resulting in stunted growth and reduced yields. Newly developed rootstock genotypes with tolerance to ARD may help to control this disease. We determined the effects of rootstock genotype rotations during orchard renovation, by investigating root-zone soil microbial consortia and the relative severity of ARD on seven rootstock genotypes (M.9, M.26, G.30, G.41, G.65, G.935, and CG.6210) planted in soil where trees on four of those same rootstocks (M.9, M.26, G.30 and CG.6210) had grown for the previous 15 years. Rootstock genotyping indicated that genetic distances among rootstocks were loosely correlated with their differential responses to ARD. Root-zone fungal and bacterial community composition, assessed by DNA fingerprinting (T-RFLP), differed between M.26 and CG.6210. Soil bacterial communities were influenced most by which rootstock had grown in the soil previously, while fungal communities were influenced more by the current replanted rootstock. In a clone library of bacteria from M.26 and CG.6210 root-zone soil, β-Proteobacteria was the most abundant phylum (25% of sequences). Sequences representing the Burkholderia cepacia complex were obtained only from CG.6210 soil. Rootstock genotypes that were grown in the orchard soil previously affected subsequent ARD severity, but replanting with the same or closely related rootstocks did not necessarily exacerbate this disease problem. Our results suggest that genotype-specific interactions with soil microbial consortia are linked with apple rootstock tolerance or susceptibility to ARD.     

黄土高原苹果园土壤水分及水分生产力模拟

以长武地区为例,采用WinEPIC模型模拟1980—2018年间黄土高原旱作苹果园地深剖面土壤水分和水分生产力变化动态,以期为该区苹果产业的可持续发展提供科学依据。结果表明: 长武地区苹果园年均产量为26.37 t·hm^-2,年均蒸散量为673.66 mm,年均水分生产力为4.07 kg·m^-3,成龄果树水分胁迫天数主要受降雨量影响,果树生长后期年均胁迫天数为46.46 d,深层土壤含水量最早于9龄果树开始接近凋萎湿度。长武地区苹果整个生长周期内供水量是对果园产量影响最大的因素,深层土壤有效水含量降低是制约果树生长中后期产量提高的最主要因素,在降水不足的年份果树会利用更深层土壤水分。当深层土壤可利用水分较少时,过多的降水并未被果树利用,而是转化为浅层土壤水分蒸发。对于成龄果树在年供水量低于500 mm或高于700 mm时都会造成产量的下降。针对不同生长时期的果园,在不同的降雨年份应该调整果园水分管理策略,可以通过补充灌溉、拦蓄集聚雨水、覆盖、修剪枝条等管理措施,降低果树非生产性耗水及自身奢侈性耗水,延缓深层土壤干层的出现时间,在保证果树生长的同时避免水资源的浪费。     

Effects of soil fumigation on the growth of apple and cherry rootstocks on land previously cropped with apples

Apple and cherry rootstocks were planted into land on which apple trees had previously been grown and which pot tests had shown to be subject to apple replant disease. Prior to planting the land was either left unfumigated or zones of progressively increasing area (0.052 m², 0.839 m³, 3.356 m²) centred on the proposed planting holes were fumigated with chloropicrin. Fumigation greatly increased the growth of the apple rootstocks but not of the cherry rootstocks. In the first year after planting the effects of the two larger fumigated areas were identical but in later years apple rootstock growth was directly related to the size of the fumigated area. This indicated that the replant disease does not simply affect tree establishment as was previously thought to be the case. The implications of this are discussed.     

Size of orchard trees as a factor affecting behavioural control of apple maggot flies (Dipt., Tephritidae) by traps

Over a 3-year period (1997–1999), we examined the influence of tree size on effectiveness of traps for behaviourally controlling apple maggot flies, Rhagoletis pomonella (Walsh), in small blocks of trees in Massachusetts commercial apple orchards. Traps were red spheres coated with Tangletrap and baited with an attractive synthetic host fruit odour (butyl hexanoate). Traps were placed 6 m apart on perimeter apple trees of each block and were designed to intercept apple maggot flies immigrating into blocks from unmanaged host trees. Based on captures of adults by unbaited red spheres placed near the centre of each block to monitor degree of adult penetration into the interior and on percentages of fruit injured by apple maggot, traps surrounding blocks of small trees (1.5 m canopy diameter) planted at high density were more effective in controlling apple maggot flies (relative to control obtained by insecticide sprays used in comparison blocks) than were traps surrounding blocks of large trees (3.7 m canopy diameter) planted at low density, with traps surrounding blocks of medium-size trees (2.5 m canopy diameter) planted at medium density generally providing an intermediate level of control.     

Bacterial Blister Bark of Apple Trees in Italy

At the beginning of spring 1996, raised, brown areas along the bark of trunk and twigs were observed on young apple trees in Piedmont (northern Italy). In many cases the epidermis flaked off. Longitudinal cracks accompanied by necrosis of the tissues beneath the bark were also observed. In one orchard the disease caused the death of 2500 trees. Biochemical, nutritional and pathogenicity tests, as well as the comparison of whole-cell protein profiles of the isolates with type-strains, indicated that Pseudomonas syringae pv. syringae was the causal agent of the disease. Bacterial blister bark remains a threat for apple cultivation also in Italy, especially in orchards planted in sandy soils.     

The effect of root pressurization on water relations, shoot growth, and leaf gas exchange of peach (Prunus persica) trees on rootstocks with differing growth potential and hydraulic conductance

It is well known that rootstocks can have an effect on the vegetative growth and development of the tree; however, there has been no clear explanation about the physiological mechanism involved in this phenomenon. Evidence indicates that the rootstock effects on tree vegetative growth may be related to hydraulic limitations of the rootstock. The objective of these experiments was to investigate the shoot growth, water potential, and gas exchange of peach trees on different rootstocks in response to manipulations of water relations of trees on rootstocks that differ in root hydraulic conductance. Tree water relations were manipulated by applying different amounts of pneumatic pressure on the root system and then relative shoot extension growth rate, tree transpiration rate, leaf water potential, leaf conductance, leaf transpiration, and net CO(2) exchange rate responses were measured. Root pressurization increased leaf water potential, relative shoot extension growth rate, leaf conductance, leaf transpiration, and net CO(2) exchange rates of trees on both vigorous and dwarfing rootstocks. There was a significant positive linear correlation between applied pneumatic pressure and tree transpiration rate and leaf water potential. Leaf conductance, transpiration rate, and net CO(2) exchange rate as well as relative shoot extension growth rates were also positively correlated with the applied pneumatic pressure on the root system. These relationships were consistent across both vigorous and size-controlling rootstocks, indicating that rootstock hydraulic limitation may be directly involved in the vegetative growth control of peach trees.     

Linking Soil Biotic and Abiotic Factors to Apple Replant Disease: a Greenhouse Approach

Apple replant disease (ARD) is a frequently occurring plant disease, which causes retarded growth and mortality of young apple trees in replanted orchards. The aetiology is not well understood, but soil‐borne micro‐organisms are often discussed as primary causal agents of the replant problem. A greenhouse study was conducted in Laimburg, Italy, with orchard soils from the region, with the aim of obtaining information about the influence of soil biotic and abiotic factors on the aetiology of the disease. Apple rootstocks (M9) were planted into soils cultivated with apple trees that were either fumigated with chloropicrin or not fumigated, as well as mixtures of fumigated and non‐fumigated soils. In addition, uncultivated soils (from the inter‐row, from a fallow plot and from a meadow) were taken as controls. Various parameters were measured after 62 days in a controlled pot assay. Soils fumigated with chloropicrin resulted in higher apple shoot growth and lower microbial biomass carbon than non‐fumigated soils. Uncultivated soils had generally the highest microbial biomass carbon and the highest ergosterol contents. No considerable differences between basal respiration, ergosterol content, pH, electrical conductivity, and most nutrient and metal contents were observed between fumigated and non‐fumigated soils. Denaturing gradient gel electrophoresis gels of DNA extracted from the soils revealed differences in the fungal, bacterial and actinobacterial communities of the different soils, indicating significant shifts in microbial community composition after chloropicrin treatment. This study indicates biotic factors in soil to be a causal agent of apple replant disease.     

渭北旱塬苹果园地产量和深层土壤水分效应模拟

为了研究实时气象条件下渭北旱塬不同生长年限苹果园地产量变化趋势和深层土壤水分变化规律,在模型适用性与模拟精度验证基础上,应用WinEPIC模型模拟研究了1962—2001年期间洛川旱塬苹果园地产量演变动态和深层土壤水分效应。结果表明：(1) 在模拟研究期间,洛川旱塬4—40年生苹果园产量整体上呈波动性下降趋势,初期产量逐渐增加,11—23年生达到最大值(平均为28.8 t/hm2),之后随降水量年际波动呈现出明显的波动性降低趋势。(2) 40年间苹果园地遭受的干旱胁迫日数呈波动性上升趋势,与年降水量波动趋势相反。(3) 1—15年生期间苹果园地平均年耗水量高于同期年降水量,导致苹果园地0—10 m土层土壤强烈干燥化,逐月土壤有效含水量波动性降低,1—10年生、11—20年生和21—40年生期间发生土壤干燥化并且程度逐渐加剧,但干燥化速率逐渐减缓,土壤干燥化速率分别为95.4 mm/a、12 mm/a和1.5 mm/a。(4) 随生长年限的延长,苹果园地0—10 m土层土壤湿度逐渐降低、土壤干层分布深度逐渐加大,在14年生时超过了10 m,20年生以后2—10 m 土层形成稳定的土壤干层。因此,基于土壤水分利用的苹果生长与果园利用的合理年限为20 a,最长不宜超过23 a。