Occurrence of Phytophthora Root and Stem Rot of Kiwifruit in Turkey

Vine decline of kiwifruit was observed in an orchard in Bart?n province of Turkey. Affected vines exhibited poor terminal growth, leaf discoloration and various degrees of dieback, including complete vine death. Symptoms were observed in the field on roots, crowns and stems. Two Phytophthora species were isolated from decayed cortical roots and lower stems of kiwifruits. They were identified as Phytophthora cryptogea and Phytophthora megasperma by their morphological characteristics and the analysis of sequences of the internal transcribed spacer (ITS) region of the rDNA. Pathogenicity of the isolates was tested by stem inoculation on kiwifruit seedlings. After 4 weeks, cankers developed in the plants inoculated with P. cryptogea, while no cankers formed in those inoculated with P. megasperma and in control plants. This is the first report of P. cryptogea causing root and stem rot of kiwifruit in Turkey.     

Relationships between management practices and ground‐active invertebrate biodiversity in New Zealand kiwifruit orchards

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In vitro breeding – shortcut to Pseudomonas syringae pv. actinidiae (Psa) tolerant kiwifruit

Pseudomonas syringae pv. actinidiae (Psa) causes the bacterial canker disease on kiwifruit vines. The disease outbreak has been reported in several countries worldwide, including New Zealand. Here, we briefly reviewed the current situation of Psa infection of kiwifruit vines in New Zealand, the effects of Psa on the New Zealand’s kiwifruit industry, and the disease control and breeding programmes undertaken in response to the outbreak of Psa in New Zealand. Then the methodology of an alternative breeding approach or in vitro breeding, which is a non-GM approach to obtain useful plant tissue culture-derived genetic variation in crop plants, was discussed. As a specific example of potential application of in vitro breeding, a novel plant breeding project idea based on the elemental defence mechanism is to generate Cu/Zn tolerant kiwifruit varieties that exhibit improved Psa tolerance.     

粮食上木霉菌的分离鉴定及其生防效果

【背景】粮食在生长和收储期极易受到病原真菌或产毒真菌的污染,造成严重的损失。众多实践证明木霉属(Trichoderma)可以有效防治植物病原真菌。【目的】鉴定和筛选能有效抑制粮食常见危害真菌的木霉生防菌株,开发生防菌剂,保障粮食生产安全。【方法】从粮食上分离筛选出35株木霉,通过多基因系统发育分析和形态学观察方法进行菌种鉴定,利用平板对峙试验筛选出对粮食常见危害真菌有抑制作用的菌株。【结果】35株木霉分属于8个种,分别为非洲哈茨木霉(Trichodermaafroharzianum)、类棘孢木霉(Trichodermaasperelloides)、 Trichoderma amoenum、近深绿木霉(Trichoderma paratroviride)、Trichoderma obovatum、长枝木霉(Trichoderma longibrachiatum)、东方木霉(Trichodermaorientale)和深绿木霉(Trichodermaatroviride)。对峙试验结果表明,这8种木霉对于粮食上分离到的10种危害真菌均具有较好的抑制效果。非洲哈茨木霉(T.afroharzi...     

Rhizosphere mycoflora of wheat after foliar application of chlorocholine chloride,urea and 4-chloro-2-methylphenoxyacetic acid

A single-step spraying of wheat during shooting under field conditions with solutions of CCC (chlorocholine chloride), CCC and urea, CCC and Aminex (ammonium salt of 4-chloro-2-methylphenoxyacetic acid), or CCC, urea and Aminex caused changes both in numbers and composition of the rhizosphere mycoflora. The numbers both in the rhizosphere of differently treated plants and in the free soil decreased during vegetation. A more pronounced effect in the number of fungi was demonstrated in plants treated only with CCC. The difference was more considerable during first 10 days after the spray. As far as the relative occurrence of individual genera in the rhizosphere soil is concerned, fungi of the generaPenicillium Link ex Fr.,Fusarium Link ex Fr.,Verticillium Nees andTrichoderma Pers were most influenced after the treatment with the used agents.     

The effect of groundcover and herbicide treatment on twospotted spider mite density and dispersal in southern Oregon pear orchards

A total of 49 groundcover plant species representing 47 genera in 22 families were identified from a survey of 5 pear orchards. Density of twospotted spider mite (Tetranychus urticae Koch) inhabiting these plants was estimated visually several times during the field season. Plants were ranked in 1 of 3 categories depending on mite densities found on these plants during the summer. T. urticae was found to be highly abundant (category 3) on 26 species, at lower densities on 10 species (category 2), and was rarely or never found on the remaining 12 species (category 1). Dispersal of mites from groundcover plants into trees was found to be highly variable within and between orchards. Within orchard dispersal appeared to be related to the distribution and abundance of category 3 host plants in the orchard. Variability between orchards may also be affected by groundcover management techniques and levels of acaricide resistance in T. urticae. The use of herbicides to control groundcover plants significantly increased the dispersal of T. urticae into the orchard trees.     

Tylenchulus semipenetrans Alters the Microbial Community in the Citrus Rhizosphere

Infection of citrus seedlings by Tylenchulus semipenetrans was shown to reduce subsequent infection of roots by Phytophthora nicotianae and to increase plant growth compared to plants infected by only the fungus. Hypothetical mechanisms by which the nematode suppresses fungal development include nutrient competition, direct antibiosis, or alteration of the microbial community in the rhizosphere to favor microorganisms antagonistic to P. nicotianae. A test of the last hypothesis was conducted via surveys of five sites in each of three citrus orchards infested with both organisms. A total of 180 2-cm-long fibrous root segments, half with a female T. semipenetrans egg mass on the root surface and half without, were obtained from each orchard site. The samples were macerated in water, and fungi and bacteria in the suspensions were isolated, quantified, and identified. No differences were detected in the numbers of microorganism species isolated from nematode-infected and uninfected root segments. However, nematode-infected root segments had significantly more propagules of bacteria at all orchard sites. Bacillus megaterium and Burkholderia cepacia were the dominant bacterial species recovered. Bacteria belonging to the genera Arthrobacter and Stenotrophomonas were encountered less frequently. The fungus community was dominated by Fusarium solani, but Trichoderma, Verticillum, Phythophthora, and Penicillium spp. also were recovered. All isolated bacteria equally inhibited the growth of P. nicotianae in vitro. Experiments using selected bacteria, T. semipenetrans, and P. nicotianae, alone or in combination, were conducted in both the laboratory and greenhouse. Root and stem fresh weights of P. nicotianae-infected plants treated with T. semipenetrans, B. cepacia, or B. megaterium were greater than for plants treated only with the fungus. Phytophthora nicotianae protein in roots of fungus-infected plants was reduced by nematodes (P ≤ 0.001), either alone or in combination with either bacterium. However, treatment with bacteria did not affect P. nicotianae development in roots. The results suggest different mechanisms by which T. semipenetrans, B. cepacia, and B. megaterium may mitigate virulence of P. nicotianae.     

Seasonal abundance and spatial distribution of larval and adult thrips (Thysanoptera) on weed host plants in mango orchards in Penang,Malaysia

The spatial distribution of larval and adult thrips (Thysanoptera) was studied on mango panicles, Mangifera indica L., on Penang Island, Malaysia, during two consecutive mango flowering seasons from December 2008 to March 2009 and from August to September 2009. Larval and adult thrips were sampled from mango panicles using the carbon dioxide (CO₂) collection technique weekly in treated and untreated orchards. Seasonal abundance and dispersion pattern of thrips were investigated on weed host plants in the treated orchard between June 2008 and March 2009. Spatiotemporal dynamics of larvae and adults was analyzed using Taylor’s Power Law (TPL), Lloyd’s Index (LI), and Green’s Index (GI). Thrips hawaiiensis (Morgan) was the dominant thrips species recovered from mango panicles and weeds in the treated orchard, whereas Scirtothrips dorsalis (Hood) was the most abundant species captured in the untreated orchard. Thrips adults and larvae analyzed via dispersion indices were found to be aggregated in mango panicles in both orchards. The value of the aggregation index (b) of TPL for the total number of adult thrips was significantly higher in the treated orchard than in the untreated orchard, whereas slopes of TPL for the total number of larval thrips did not differ significantly between treated and untreated orchards. All adult thrips species were distributed regularly on the weed plants; however, their larvae were aggregated. It is concluded that pesticide treatment caused adult thrips to become more aggregated on mango panicles, hiding in flower parts that were less exposed to the chemicals.     

Effect of fungi–termite interaction on the chlorophyll content of three rice varieties grown on ultisol soil of Ikenne,south-west Nigeria

The effect of fungi–termite interaction on three rice varieties was conducted in a screen house at the Africa Rice Center (AfricaRice) Ibadan, Nigeria. Of the 10 fungi species (Fusarium verticilloides, Trichoderma sp., Aspergillus niger, Aspergillus flavus, Macrophoma sp., Neurospora sp., Botryodiplodia theobromae, Penicillum sp., Rhizopus sp. and Sclerotium rolfsii) isolated from termites, soil and rice plants, F. verticilloides, Trichoderma sp. and B. theobromae were used for the interaction study. Each fungus was inoculated singly and in combinations with termite into the root of each rice variety in potted soil. Leaf samples were taken to measure the chlorophyll content which is a major parameter to estimate effect of termite–fungi interaction. The chlorophyll content of the inoculated rice plants was significantly reduced when compared with the control. Fungi interaction with termite had significant reduction on the chlorophyll content. The synergistic relationship between the fungi and the termite was discussed.     

Allelochemicals and their transformations in the Ageratum conyzoides intercropped citrus orchard soils

Intercropping Ageratum conyzoides in citrus orchards may effectively suppress weeds and control other pests. Investigations showed that the inhibition of major weeds and soil pathogenic fungi in citrus orchards was significantly correlated with the allelochemicals released into the soil by intercropped A. conyzoides. Three flavones, ageratochromene, and its two dimers were isolated and identified from the A. conyzoides intercropped citrus orchard soil. These allelochemicals had different biological actions on major weeds and soil pathogenic fungi in the citrus orchard. Three flavones and ageratochromene could significantly inhibit the growth of weeds Bidens pilosa, Digitaria sanguinalis and Cyperus difformis, and spores germination of soil pathogenic fungi Phytophthora citrophthora, Pythium aphanidermatum and Fusarium solani. However, two dimers of ageratochromene had no inhibitory actions on them. The presence of these allelochemicals in soils suggests that they may be able to make a major contribution to control some weeds and diseases in citrus orchards. Further studies revealed that dynamic transformation between ageratochromene and its two dimers in the A. conyzoides intercropped citrus orchard soil was reversible, that is, ageratochromene released from ground A. conyzoides plants was transformed into its dimers, and the dimers can be remonomerized in the soils. However, this dynamic transformation did not occur in the soil with low organic matter and fertility. The dimerization was not correlated with microorganisms in the soil, but the biodegradation of both ageratochromene and its two dimers may have occurred, particularly in the soil with low organic matter and fertility. Our results strongly suggest that the reversible transformation between ageratochromene and its dimers in the A. conyzoides intercropped citrus orchard soil can be an important mechanism maintaining bioactive allelochemicals at an effective concentration, thus, sustaining the inhibition of weeds and pathogenic fungi in soil.     

Bacterial blight of kiwifruit

Bacterial blight of kiwifruit (Actinidia deliciosa) is caused by Pseudomonas viridiflava. Symptoms are rot of floral buds and flowers, and spots on leaves. Buds and flowers nearest the ground are most likely to be affected. Isolations made from healthy buds, flowers and leaves suggest that the pathogen is an epiphyte on vines throughout the year. Disease incidence fluctuates between seasons, and varies between orchards. A relationship between disease incidence and rainfall in spring is indicated.     

Evidence for host-specificity of culturable fungal root endophytes from the carnivorous plant Pinguicula vulgaris (Common Butterwort)

The unique mode of nutrition by carnivorous plants makes the facilitation of nutrient acquisition by mycorrhizal fungi seem unlikely. However, previously we have reported that the carnivorous plant Drosera rotundifolia can host at least eight species of fungal root endophyte. Although the function of these fungi remains unknown, their ubiquitous presence suggests that they may give plants a competitive advantage in both stressful and nutrient poor environments. The aim of this study was to examine the species of fungal endophyte colonising the roots of Pinguicula vulgaris and to compare them with the species isolated from D. rotundifolia found growing in the same location. Trichoderma spp. were isolated from every plant, whilst four other species were isolated once from single plants (Neonectria sp., Leohumicola spp., Cladosporium macrocarpum and Volutella ciliata). Although Trichoderma were isolated from both carnivorous plants, all of the other fungal endophytes were found colonising either P. vulgaris or D. rotundifolia. This observation may indicate a degree of host-specificity for these fungal species, despite the two host plants having very similar ecological strategies for living in a very nutrient poor and abiotically stressful environment.     

Evidence that Bacterial Blight of Kiwifruit, Caused by a Pseudomonas sp., was Introduced into New Zealand From China

Strains of the bacterium, Pseudomonas sp., causing blight of kiwifruit, isolated from affected vines in New Zealand and in the People's Republic of China, were compared using DNA-DNA hybridization and repetitive-PCR (rep-PCR) and biolog. DNA of each strain was hybridized to DNA of reference strains representing P. viridiflava, P. savastanoi and the kiwifruit pathogen. Strains of the pathogen from New Zealand and China shared reassociation values exceeding 76%. Strains from both countries shared reassociation values of more than 66% (average 82%) with DNA of the type strain of P. savastanoi, and less than 51% with DNA of P. viridiflava (average 33.5%). A comparison by rep-PCR using the primers REP, ERIC and BOX showed that strains from New Zealand and China were indistinguishable. Comparison of endonuclease restriction patterns of strains from New Zealand showed that those gathered over a 20-year period from different growing regions were more diverse than strains gathered in one orchard in a single season. The ecological implications of these data and the source of the pathogen in New Zealand are discussed. It is concluded that the pathogen originated in China and was introduced into New Zealand in vegetative kiwifruit material, and not as was previously thought, in two small seed samples.     

猕猴桃园节肢动物群落重建及主要类群的生态位

为研究猕猴桃节肢动物群落重建过程和主要类群生态位移,本试验系统调查野生猕猴桃和人工栽植不同树龄(3年、9年、14年)猕猴桃园节肢动物群落,测定群落特征指标和主要类群的时空生态位。结果表明,群落包含3纲15目74科,约90种。不同桃园节肢动物群落的主要类群不同,各类群占群落总数的比例差异显著,野生猕猴桃园群落中各类群分布较均匀,栽植桃园群落中害虫比例较大。野生猕猴桃园和栽植猕猴桃园之间,群落的多样性指数、均匀度和优势度差异均极显著,群落稳定性表现为野生>9年>14年>3年。各类群的时空二维生态位也会随着栽植时间增长发生变化：蜘蛛和蝇类的生态位在不同树龄的猕猴桃园中都保持在较高水平;人工栽植初期,山楂叶螨和叶蝉占据的时空生态位较宽,成为优势类群,小薪甲与山楂叶螨生态位重叠较大,竞争激烈;随后,小薪甲和瘿蚊的时空二维生态位逐渐增大,到14年桃园中已经取代了山楂叶螨和叶蝉,成为主要害虫。总之,人工干扰的节肢动物群落重建是一个次级演替过程,与自然生态系统群落明显不同。     

Isolation and identification of endophytic and mycorrhizal fungi from seeds and roots of <Emphasis Type="Italic">Dendrobium</Emphasis> (Orchidaceae)

The seed germination of orchids under natural conditions requires association with mycorrhizal fungi. Dendrobium nobile and Dendrobium chrysanthum are threatened orchid species in China where they are considered medicinal plants. For conservation and application of Dendrobium using symbiosis technology, we isolated culturable endophytic and mycorrhizal fungi colonized in the protocorms and adult roots of two species plants and identified them by morphological and molecular analyses (5.8S and nrLSU). Of the 127 endophytic fungi isolated, 11 Rhizoctonia-like strains were identified as Tulasnellales (three strains from protocorms of D. nobile), Sebacinales (three strains from roots of D. nobile and two strains from protocorms of D. chrysanthum) and Cantharellales (three strains from roots of D. nobile), respectively. In addition, species of Xylaria, Fusarium, Trichoderma, Colletotrichum, Pestalotiopsis, and Phomopsis were the predominant non-mycorrhizal fungi isolated, and their probable ecological roles in the Dendrobium plants are discussed. These fungal resources will be of great importance for the large-scale cultivation of Dendrobium plants using symbiotic germination technology and for the screening of bioactive metabolites from them in the future.     

Seasonal occurrence of specialist and generalist insect predators of spider mites and their response to volatiles from spider-mite-infested plants in Japanese pear orchards

In two adjacent Japanese pear orchards (orchards 1 and 2), we studied the seasonal occurrence of the Kanzawa spider mite, Tetranychus kanzawai, and its predators. Also the response of these predators to the volatiles from kidney bean plants infested with T. kanzawai was investigated using trap boxes in orchard 1. The mite density in orchard 1 was unimodal, with one peak at the end of August. In this orchard, population development of the specialist insect predators, Scolothrips takahashii, Oligota kashmirica benefica and Stethorus japonicus, was almost synchronized with that of the spider mites. These predators disappeared when the density of their prey became very low in mid-September. Both S. takahashii and O. kashmirica benefica abruptly increased in number in orchard 2 when the spider mite population in orchard 1 decreased. These results suggested that some of the predators migrated from orchard 1 to orchard 2. In this period, predator-traps with T. kanzawai-infested bean plants attracted significantly more S. takahashii than traps with uninfested plants. Very few individuals of S. japonicus and O. kashimirica benefica were found in the traps, despite their abundance in orchard 1. The generalist insect predator, Orius sp., was attracted to the traps throughout the experimental period irrespective of the density of spider mites, although this predator was never observed inside the orchards.     

Significance of lytic enzymes from Trichoderma spp. in the biocontrol of fungal plant pathogens

The use of specific mycolytic soil microorganisms to control plant pathogens is an ecological approach to overcome the problems caused by standard chemical methods of plant protection. The ability to produce lytic enzymes is a widely distributed property of rhizosphere-competent fungi and bacteria. Due to the higher activity of Trichoderma spp. lytic enzymes as compared to the same class of enzymes from other microorganisms and plants, effort is being aimed at improving biocontrol agents and plants by introducing Trichoderma genes via genetic manipulations. An overview is presented of the data currently available on lytic enzymes from the mycoparasitic fungus Trichoderma. This revised version was published online in August 2006 with corrections to the Cover Date.     

Seasonal monitoring of Drosophila suzukii and its non-crop hosts in Wuhu,Eastern China

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a serious pest that prefers fresh fruits and is native to Southeast Asia. In our study, apple cider vinegar bait traps were used to capture and monitor the population dynamics of this native pest in Wuhu City, China, from May/June 2017 to May 2018. The research was conducted at 15 locations in two fruit orchards in Wuhu. Traps caught more adults in general in a Meiling blueberry orchard than in a Xicun mixed orchard, and the highest trap counts occurred near harvest time (October). Females had more mature eggs from September to November, and the number of mature eggs declined thereafter. We found several non-crop hosts, which can provide food and reproductive resources for D. suzukii and are common in forests and field margins. By comparing the number of captured adults in the Meiling and Xicun orchards, we found that blueberry was preferred by D. suzukii among the fruits in our search. Fruit ripening times differed among crops; therefore, fly populations moved between crop and non-crop habitats during the year or had varying population dynamics on different crops in different seasons. The D. suzukii population and the number of mature eggs decreased in summer and winter but increased in spring and autumn. Drosophila suzukii had higher survival rates with blueberry than those with other fruits, and D. suzukii could use four non-crop species growing around the orchards as host plants.     

Effects of nutrients and arbuscular mycorrhizal colonization on the growth of Salix gracilistyla seedlings in a nutrient-poor fluvial bar

A field survey and a pot culture experiment were conducted to examine the effects of nutrients (N and P) and arbuscular mycorrhizal (AM) fungi on the growth of Salix gracilistyla, a pioneer plant in riparian habitats. The plants growing in the field were colonized by AM and/or ectomycorrhizal fungi. However, the direct effect of AM colonization on seedling growth was not detected in the pot culture experiment. In contrast, N application significantly promoted plant growth, suggesting that the growth of S. gracilistyla seedlings is largely limited by the availability of N in the field.     

Root demography in kiwifruit (Actinidia deliciosa)

A rhizotron was used to study fine-root demography in mature vines of kiwifruit (Actinidia deliciosa). The vines were grown in a deep, well drained, silt loam and received normal orchard management. Roots were measured from 10 to 160cm depth at biweekly intervals for 2 years. After an initial phase of rapid colonisation of the repacked soil behind the rhizotron windows, the total length of visible roots per vine remained quite steady. This apparent stability of the total belied fast and sustained localized turnover of the fine roots at all soil depths. Fifty-one per cent of the roots survived ≤28d, 69% died at an age ≤56d and only 8% survived >252d. For each year, the cumulative length of roots grown was equivalent to about 2·75 times the maximum net length of roots visible. These may be the largest annual rates of root turnover yet reported. This has important ramifications for the carbon balance, mineral nutrition and water relations of the plant.