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1.
BACKGROUND: Myclobutanil, a demethylation inhibitor (DMI) fungicide, is an important fungicide for controlling apple scab and powdery mildew. Overuse of this fungicide has led to establishment of scab isolates with reduced sensitivity to this fungicide in several countries. Experiments were conducted to determine the sensitivity of the causal agent of apple scab, Venturia inaequalis (Cooke) Winter, to myclobutanil in the UK, in order to assess whether there is a relationship between fungal insensitivity and the number of DMI applications, and establishing whether fungal sensitivity varied greatly within an orchard. RESULTS: Reduced sensitivity of V. inaequalis to myclobutanil was positively related linearly to the number of DMI applications. ED50 values ranged from 0.028 to 1.017 mg L?1 (average = 0.292) for the baseline population, whereas isolates from two other orchards had much greater ED50 values, ranging from 0.085 to 5.213 mg L?1 (average = 1.852). There was significant variation in fungal sensitivity to myclobutanil among fungal isolates from different locations within a single orchard. CONCLUSIONS: Spatial spread of insensitive isolates of V. inaequalis to myclobutanil is likely to be limited in distance. Conidia may be an important source of primary inoculum. Myclobutanil should still be effective for most field isolates, but its use should be strategically integrated with other groups of fungicides. Copyright © 2009 Society of Chemical Industry 相似文献
2.
A greenhouse experiment was conducted to study the role of plant growth regulators, a chelating agent, and plant growth‐promoting bacteria in lead (Pb) phytoextraction and their subsequent effect on the weed plant, Parthenium hysterophorus. Gibberellic acid (GA3) and indole‐3‐acetic acid (IAA) were used as the foliar spray. Ethylenediamine tetra acetic acid (EDTA) was applied in split doses. Bacillus and Rhizobium strains were used as a single culture and as co‐cultures. The accumulation of Pb in different parts of the plant was analyzed by using an atomic absorption spectrophotometer. The amount of lead translocation and accumulation in the stems and leaves was significantly higher in the hormonal and EDTA treatments, while the microbial treatments showed no significant difference in the amount of Pb translocation into the stems and leaves, when compared to the control. The EDTA increased the amount of translocation into the shoots, but the dry biomass declined and subsequently reduced the total Pb phytoextraction. The GA3 treatment showed the maximum total Pb accumulation, along with a higher dry biomass. The microbial co‐inoculated plants showed a significant increase in their dry biomass but the Pb accumulation did not increase like with the GA3 and IAA treatments. These findings encourage the use of the GA3 application for Pb phytoextraction by P. hysterophorus. One important feature of this weed plant is its unpalatable nature to herbivores, which could help in reducing the entrance of Pb into the food chain. Gibberellic acid is environmentally friendly compared to EDTA; therefore, more investigation of GA3 and P. hysterophorus is required. 相似文献
3.
Yared Tesfai Tewoldemedhin Mark Mazzola Lizel Mostert Adéle McLeod 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(4):637-651
Cylindrocarpon species are known to be a component of the pathogen/pest complex that incites apple replant disease. In South Africa, no
information is available on apple associated Cylindrocarpon species and their pathogenicity. Therefore, these aspects were investigated. Among the isolates recovered from apple roots
in South Africa, four species (C. destructans, C. liriodendri, C. macrodidymum and C. pauciseptatum) were identified using β-tubulin gene sequencing and phylogenetic analysis. This is the first report of C. liriodendri, C. macrodidymum and C. pauciseptatum on apple trees. Cylindrocarpon macrodidymum was the most prevalent. Isolates within each of the four species were pathogenic towards apple seedlings, but varied in their
virulence. With a single exception, all isolates were able to induce lesion development on seedling roots. Only 57% of the
isolates, which represented all four species, were able to cause a significant reduction in seedling weight and/or height.
The greatest seedling growth reductions were caused by two isolates of C. destructans, and one isolate each of C. liriodendri and C. macrodidymum. A quantitative real-time polymerase chain reaction (qPCR) method was developed for simultaneous detection of all four Cylindrocarpon species. qPCR analyses of Cylindrocarpon from the roots of inoculated seedlings showed that the amount of Cylindrocarpon DNA in roots was not correlated to seedling growth reductions (weight and height) or root rot. The qPCR method is, however,
very useful for the rapid identification of apple associated Cylindrocarpon species in roots. The technique may also hold potential for being indicative of Cylindrocarpon disease potential if rhizosphere soil rather than roots are used. 相似文献
4.
Dynamics of post‐harvest pathogens Neofabraea spp. and Cadophora spp. in plant residues in Dutch apple and pear orchards 
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下载免费PDF全文 J. Köhl M. Wenneker B. H. Groenenboom‐de Haas R. Anbergen H. M. Goossen‐van de Geijn C. H. Lombaers‐van der Plas F. A. M. F. Pinto P. Kastelein 《Plant pathology》2018,67(6):1264-1277
Post‐harvest diseases of apple and pear cause significant losses. Neofabraea spp. and Cadophora spp. infect fruits during the growing season and remain quiescent until disease symptoms occur after several months in storage. Epidemiological knowledge of these diseases is limited. TaqMan PCR assays were developed for quantification of N. alba, N. perennans, C. malorum and C. luteo‐olivacea in environmental samples. Various host tissues, dead weeds and grasses, soil and applied composts were collected in 10 apple and 10 pear orchards in May 2012. Neofabraea alba was detected in 73% of samples from apple orchards and 48% from pear orchards. Neofabraea perennans was present in a few samples. Cadophora luteo‐olivacea was detected in 99% of samples from apple orchards and 93% from pear orchards, whilst C. malorum was not detected in any sample. In apple orchards, highest concentrations of N. alba were found in apple leaf litter, cankers and mummies, and of C. luteo‐olivacea in apple leaf litter, mummies and dead weeds. In pear orchards, N. alba and C. luteo‐olivacea were found in highest concentrations in pear leaf litter and in dead weeds. Substrate colonization varied considerably between orchards. The temporal dynamics of pathogens was followed in four apple orchards and four pear orchards. In apple orchards the colonization by pathogens decreased from April until August and increased from September until December. This pattern was less pronounced in pear. Knowledge on population dynamics is essential for the development of preventative measures to reduce risks of fruit infections during the growing season. 相似文献
5.
M. P. Dobrowolski B. L. Shearer I. J. Colquhoun P. A. O’Brien G. E. StJ. Hardy 《Plant pathology》2008,57(5):928-936
To test the hypothesis that resistance in Phytophthora cinnamomi to control by the fungicide phosphite (phosphonate) would arise in sites with prolonged use of phosphite, 30 P. cinnamomi isolates were collected from a range of sites with different phosphite‐use histories, including phosphite‐treated and untreated avocado orchards, and phosphite‐treated and untreated native vegetation sites. The colonizing ability of these isolates was tested by different inoculation methods against a range of host tissues, treated and untreated with phosphite, including mycelial stem inoculation on clonally propagated Leucadendron sp., mycelial root inoculation of lupin seedlings and zoospore inoculation of Eucalyptus sieberi cotyledons. Isolates from avocado orchards with a long history of phosphite use were, on average, more extensive colonizers of the phosphite‐treated Leucadendron sp., lupin seedling roots and Eucalyptus sieberi cotyledons. These isolates did not colonize untreated plant tissue (Leucadendron sp.) more extensively than isolates from sites with no history of phosphite use and no isolates were resistant to control by phosphite. Analysis of all isolates with microsatellite markers revealed the majority were from a single clonal lineage. Selection for decreased sensitivity to phosphite in planta has taken place within asexual clonal lineages of P. cinnamomi in sites with prolonged use of phosphite. 相似文献
6.
Mulberry twigs were inserted into the soil as bait to detect Rosellinia necatrix at an early stage of tree infection in the orchard. R. necatrix was frequently trapped on twigs near the trunk base at soil depths of 6–20 cm within 10–20 days in May–July, suggesting that
the incubation period was dependent on soil temperature. Subsequently, we inserted twig in the soil around healthy-looking
trees in naturally infested orchards. R. necatrix was trapped from 80.0% of Japanese pear and 75.0% of apple trees that later proved to be infected. This bait twig method
facilitated quicker diagnosis of white root rot on Japanese pear and apple at early stages of infection and can be used to
detect recurrence of the fungus after fungicide treatment. 相似文献
7.
Xiangming Xu Nick Harvey Anthony Roberts Dez Barbara 《European journal of plant pathology / European Foundation for Plant Pathology》2013,135(1):97-104
Apple scab, caused by Venturia inaequalis, is one of the most important apple diseases worldwide. To investigate between- and within-orchard fungal variability, 212 isolates were sampled from two mixed orchards, one of 10?years of age and the other of 45?years of age, in the UK and genotyped with AFLP and SSR markers. Populations of isolates from the two orchards did not differ significantly in terms of allele frequencies at the screened AFLP and SSR loci. However, groups of isolates from individual cultivars differed significantly within each orchard and there were also significant differences between groups of isolates from individual trees of the same cultivar in the same orchard. These differences were less pronounced in the younger mixed orchard than in the older one. The existence of tree-to-tree fungal variability indicates a possible role for conidia as a source of primary inoculum. Non-random mating may be one of the factors causing the significant differences among fungal populations from different cultivars. These results suggest that apparently ??susceptible?? cultivars have different background genetic resistance factors, which can be exploited for disease management in mixtures. 相似文献
8.
Genetic population structure and fungicide resistance of Botrytis cinerea in pear orchards in the Western Cape of South Africa 下载免费PDF全文
下载免费PDF全文 Botrytis cinerea isolates from pear blossoms (Pyrus communis) in South Africa were collected from four orchards in two production areas in the Western Cape. The cryptic species status based on vegetative‐incompatibility alleles of the Bc‐hch gene indicated that all the isolates belonged to B. cinerea. A microsatellite analysis of B. cinerea populations was performed to assess the genetic population structure. Total gene diversity (H) was high, with a mean of 0.69 across all populations. Some genotype flow was evident between orchards as indicated by the spread of microsatellite multilocus genotypes, in agreement with the moderate, but significant population differentiation among orchards (mean φPT = 0.118, P = 0.001). Index of association analyses (IA and r?d) suggest that the populations reproduce mostly asexually, even though mating type distribution did not differ significantly from a 1:1 ratio, suggesting frequency‐dependent selection. Isolates resistant to benomyl were evident in one orchard only. This orchard was also significantly differentiated from all other populations, suggesting infrequent localized selection for benomyl resistance. Overall, the findings of this study highlight the dangers of a mixed reproduction system, and stress the importance of regularly monitoring fungicide resistance levels towards developing more efficient management practices. 相似文献
9.
陕西省新老苹果产区果园土壤硝态氮累积特性研究 总被引：1，自引：0，他引：1
以陕西省新、老果区（分别为洛川及礼泉）为研究对象，调查了两县各15个成龄果园的施肥现状，计算了果园氮素表观平衡，并测定了这15个果园的0~200 cm土壤剖面硝态氮含量，分析了树龄、施氮量与土壤剖面硝态氮累积量的关系。结果表明：新、老果区苹果园均过量施用氮肥，平均施氮量分别高达1 287±244 kg·hm-2（洛川）和1 193±300 kg·hm-2（礼泉），导致土壤中盈余了大量的氮素。新、老果区土壤0~200 cm硝态氮累积量分别达2 724 kg·hm-2和5 226 kg·hm-2, 老果区土壤剖面硝态氮累积量显著高于新果区。相关分析表明，果园土壤剖面累积的硝态氮与树龄和施氮量呈正相关，与树龄的相关系数为0.641，与洛川、礼泉果园施氮量的相关系数分别为0.402和0.306。因此，建议研究区域采取措施控制果园施氮量，减少果园土壤硝态氮累积带来的资源浪费及环境污染。 相似文献
10.
Phenotypic and genetic characterization of Pseudomonas syringae strains associated with the recent citrus bacterial blast and bacterial black pit epidemics in Tunisia 下载免费PDF全文
下载免费PDF全文 E. Abdellatif M. Kałużna J. D. Janse P. Sobiczewski F. Helali J. R. Lamichhane A. Rhouma 《Plant pathology》2017,66(7):1081-1093
In the spring of 2012, symptoms of a disease resembling citrus blast and citrus black pit were observed in some orchards in Tunisia. The epidemic spread rapidly in the following years. Twenty‐four commercial citrus orchards from four Tunisian regions showing characteristic symptoms of bacterial diseases were surveyed during a 3‐year study. Eighty‐eight Pseudomonas‐like bacterial isolates were successfully obtained from the northeast and west of Tunisia. No isolates were recovered from the central region. Overall, 46 isolates were identified as Pseudomonas syringae pv. syringae and most of them showed similar phenotypic and genetic profiles. The virulence of three selected isolates differed from one plant cultivar to another as well as from the type of plant organ used for the inoculation. In a bioassay test, all isolates produced syringomycin, which was confirmed by molecular detection based on the syrB and syrD genes. Only EC122 possessed syrD but not syrB. DNA fingerprints, based on repetitive sequence‐based polymerase chain reaction (rep‐PCR) and PCR melting profile (PCR MP), were used to determine the potential genetic diversity among strains. Clustering of PCR MP fingerprinting data matched with rep‐PCR fingerprinting data. The generated distribution tree showed that Tunisian isolates were closely related to the citrus reference strain LMG5496. In contrast, EC112, isolated from citrus, and the almond isolate EC122 were distantly related to the type strain LMG1247T isolated from lilac. Such studies have not been reported until now for P. syringae from citrus. 相似文献
11.
在苹果园果树行间种植覆盖作物——白花草木樨Melilotus albus Desr.是果园土壤管理制度中的一项措施。它影响到苹果树上捕食性天敌群落的组成。种植覆盖作物后,一些天敌,如拟长毛钝绥螨Amblyseius pseudolongispinosus Xin et Lian和中华草蛉Chrysopa sinica Tjeder等在苹果树上捕食性天敌群落中的个体数量相对百分比有所增加;而另一些,如小花蝽Orius minutus(Linnaeus)、塔六点蓟马Scolothrips takahashii Priesaer和瓢虫类(Coccinellidae)等天敌有所减少;还有一些天敌,由于发生数量较少,不易与免耕法对照区进行比较。当使用广谱性化学杀虫剂进行树上喷雾时,覆盖作物对于受到化学杀虫剂干扰的苹果树上小花蝽O.minutus(Linnaeus)种群的恢复与建立有着促进作用。 相似文献
12.
Conidial germination and differentiation, the so‐called prepenetration processes, of the barley powdery mildew fungus (Blumeria graminis f.sp. hordei) are triggered in vitro by very‐long‐chain aldehydes, minor constituents of barley leaf wax. However, until now it has not been demonstrated that these cuticle‐derived molecules also play a significant role in the initiation and promotion of the fungal prepenetration processes in vivo, on the surface of a living plant leaf. In the maize (Zea mays) wax mutant glossy11, which is completely devoid of cuticular very‐long‐chain aldehydes, germination and appressorial differentiation of B. graminis were strongly impeded. Spraying the mutant leaf surface with aldehyde‐containing wild‐type wax or pure n‐hexacosanal (C26‐aldehyde) fully restored fungal prepenetration, whereas maize wild‐type leaf surfaces coated with n‐docosanoic acid exhibited reduced conidial germination rates of 23%, and only 5% of the conidia differentiated infection structures. In vitro studies were performed to further corroborate the extensive prevention of fungal germination and differentiation in response to artificial surfaces coated with aldehyde‐deficient maize wax. Because of its phenotype affecting the B. graminis prepenetration processes, the glossy11 mutation of maize may become a valuable molecular target and genetic tool that could provide a means of developing basal powdery mildew resistance in the globally important crops wheat and barley. 相似文献
13.
Jürgen Köhl Belia Groenenboom-de Haas Helen Goossen-van de Geijn Adrianus Speksnijder Pieter Kastelein Sybren de Hoog Bert Gerrits van den Ende 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):151-162
Stemphylium vesicarium (teleomorph: Pleospora herbarum) is the causal agent of brown spot disease in pear. The species is also able to cause disease in asparagus, onion and other
crops. Saprophytic growth of the fungus on plant debris is common. The objective of this study was to investigate whether
isolates of S. vesicarium from different hosts can be pathogenic to pear. More than hundred isolates of Stemphylium spp. were obtained from infected pear fruits, dead pear leaves, dead grass leaves present in pear orchard lawns as well as
from necrotic leaf parts of asparagus and onion. Only isolates originating from pear orchards, including isolates from dead
grass leaves, were pathogenic on pear leaves or fruits in bioassays. Non-pathogenic isolates were also present in pear orchards.
Stemphylium vesicarium from asparagus or onion, with one exception, were not pathogenic to pear. Analysis of the genetic variation between isolates
using Amplified Fragment Length Polymorphism (AFLP) showed significant concordance with host plants. Isolates from asparagus
or onion belonged to clusters separate from the cluster with isolates from pear or grass leaves collected in pear orchards.
Multilocus sequencing of a subset of isolates showed that such isolates were similar to S. vesicarium. 相似文献
14.
Soleño J Anguiano L de D'Angelo AP Cichón L Fernández D Montagna C 《Pest management science》2008,64(9):964-970
BACKGROUND: Azinphos‐methyl is the main insecticide used to control codling moth on apple and pears in Northern Patagonia. The aim of this study was to evaluate the toxicological and biochemical response of diapausing larvae of codling moth in orchards subjected to different insecticide selection pressure. RESULTS: Dose–mortality assays with azinphos‐methyl in diapausing larvae of Cydia pomonella L. showed significant differences between the LD95 from a population collected in one untreated orchard (2.52 µg moth?1) compared with that in a laboratory‐susceptible population (0.33 µg moth?1). Toxicity to azinphos‐methyl in field populations of diapausing larvae collected during 2003–2005 was evaluated by topical application of a discriminating dose (2.5 µg moth?1) that was obtained from larvae collected in the untreated orchard (field reference strain). Significantly lower mortality (37.71–84.21%) was observed in three out of eight field populations compared with that in the field reference strain. Most of the field populations showed higher esterase activity than that determined in both the laboratory susceptible and the field reference strains. Moreover, there was a high association between esterase activity and mortality (R2 = 0.64) among the field populations. On the other hand, a poor correlation was observed between glutathione S‐transferase activity and mortality (R2 = 0.33) among larvae collected from different orchards. CONCLUSIONS: All the field populations evaluated exhibited some degree of azinphos‐methyl tolerance in relation to the laboratory susceptible strain. Biochemical results demonstrated that esterases are at least one of the principal mechanisms involved in tolerance to this insecticide. Copyright © 2008 Society of Chemical Industry 相似文献
15.
J. Nykyri X. Fang F. Dorati R. Bakr M. Pasanen O. Niemi E. T. Palva R. W. Jackson M. Pirhonen 《Plant pathology》2014,63(4):747-757
Bacterial soft rot is a globally significant plant disease that causes major losses in the production of many popular crops, such as potato. Little is known about the dispersal and ecology of soft‐rot enterobacteria, and few animals have been identified as vectors for these pathogens. This study investigates whether soil‐living and bacterial‐feeding nematodes could act as vectors for the dispersal of soft‐rot enterobacteria to plants. Soft‐rot enterobacteria associated with nematodes were quantified and visualized through bacterial enumeration, GFP‐tagging, and confocal and electron scanning microscopy. Soft‐rot enterobacteria were able to withstand nematode grazing, colonize the gut of Caenorhabditis elegans and subsequently disperse to plant material while remaining virulent. Two nematode species were also isolated from a rotten potato sample obtained from a potato storage facility in Finland. Furthermore, one of these isolates (Pristionchus sp. FIN‐1) was shown to be able to disperse soft‐rot enterobacteria to plant material. The interaction of nematodes and soft‐rot enterobacteria seems to be more mutualistic rather than pathogenic, but more research is needed to explain how soft‐rot enterobacteria remain viable inside nematodes. 相似文献
16.
Phenotypic,molecular and pathogenic characterization of Phlyctema vagabunda,causal agent of olive leprosy 下载免费PDF全文
下载免费PDF全文 J. Romero M. C. Raya L. F. Roca C. Agustí‐Brisach J. Moral A. Trapero 《Plant pathology》2018,67(2):277-294
Olive leprosy, caused by the fungus Phlyctema vagabunda, is a classic fruit rot disease widespread in the Mediterranean basin. From 2009 to 2013, new disease symptoms consisting of small circular necrotic leaf lesions, coin branch canker and shoot dieback were observed in Spanish and Portuguese olive orchards showing intense defoliation. Phlyctema‐like anamorphs were consistently isolated from leaves and shoots with symptoms. Representative isolates from affected leaves, shoots and fruits were characterized based on morphology of colonies and conidia, optimum growth temperature and comparison of DNA sequence data from four regions: ITS, tub2, MIT and rpb2. In addition, pathogenicity tests were performed on apple and olive fruits, and on branches and leaves of olive trees. Maximum mycelial growth rate ranged between 0.54 and 0.73 mm per day. Conidia produced on inoculated apple fruits showed slight differences in morphology among the representative fungal isolates evaluated. Phylogenetic analysis clustered all of the Phlyctema‐like isolates in the same clade, identifying them as Phlyctema vagabunda. On fruits, influence of wounding, ripening and cultivar resistance was studied, with cv. Blanqueta being the most susceptible cultivar. On branches, a mycelial‐plug inoculation method reproduced olive leprosy symptoms and caused shoot dieback. On leaves, Koch's postulates were fulfilled and the pathogen caused characteristic necrotic spots and plant defoliation. This is the first time that the pathogenicity of P. vagabunda in olive leaves has been demonstrated. 相似文献
17.
为探究不同根型苜蓿在不同生长年限的抗旱性与内源激素间的关系,采用高效液相色谱法测定根茎型、直根型、根蘖型苜蓿播种当年及生长第2年在干旱胁迫后地上与地下部内源激素吲哚乙酸（IAA）、赤霉素（GA3）、玉米素（ZT）和脱落酸（ABA）含量。结果表明,随干旱胁迫加剧,播种当年及生长第2年,根茎型、直根型和根蘖型苜蓿地上、地下部IAA和ZT含量显著降低,相比CK,IAA的年均降幅分别为50.09%、36.52%、49.15%和58.17%、53.42%、56.62%,ZT的年均降幅分别为38.11%、52.57%、36.18%和43.86%、63.94%、54.17%。ABA含量显著升高,随生长年限延长增幅降低,种植当年及生长第2年的增幅分别处于62.50%～358.82%和19.70%～85.19%之间;而GA3含量在播种当年显著下降,生长第2年中、重度胁迫下达到峰值。相比CK,播种当年地上、地下部GA3/ABA、IAA/ABA、（IAA+GA3+ZT）/ABA比值及干质量随胁迫加剧呈下降趋势;生长第2年... 相似文献
18.
The relative importance of conidia and ascospores as primary inoculum of Venturia inaequalis in a southeast England orchard 下载免费PDF全文
下载免费PDF全文 Apple scab, caused by Venturia inaequalis, can lead to large losses of marketable fruit if left uncontrolled. The disease appears in orchards during spring as lesions on leaves. These primary lesions are caused by spores released at bud burst from overwintering sources; these spores can be sexually produced ascospores from the leaf litter or asexual conidia from mycelium in wood scab or within buds. The relative importance of conidia and ascospores as primary inoculum were investigated in an orchard in southeast England, UK. Potted trees not previously exposed to apple scab were placed next to (c. 1 m) orchard trees to trap air‐dispersed ascospores. Number and position of scab lesions were assessed on the leaves of shoots from both the potted trees (infection by airborne ascospores) and neighbouring orchard trees (infection by both ascospores and splash‐dispersed, overwintered conidia). The distribution and population similarity of scab lesions were compared in the two tree types by molecular analysis and through modelling of scab incidence and count data. Molecular analysis was inconclusive. Statistical modelling of results suggested that conidia may have contributed approximately 20–50% of the primary inoculum in early spring within this orchard: incidence was estimated to be reduced by 20% on potted trees, and lesion number by 50%. These results indicate that, although conidia are still a minority contributor to primary inoculum, their contribution in this orchard is sufficient to require current management to be reviewed. This might also be true of other orchards with a similar climate. 相似文献
19.
Imre J. Holb 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(4):397-408
In a three-year Hungarian study, conidial density of Monilinia fructigena in the air determined from mid-May until harvest was related to brown rot disease progress in integrated and organic apple
orchards. Conidia of M. fructigena were first trapped in late May in both orchards in all years. Number of conidial density greatly increased after the appearance
of first infected fruit, from early July in the organic and from early August in the integrated orchard. Conidial number continuously
increased until harvest in both orchards. Final brown rot incidence reached 4.3–6.6% and 19.8–24.5% in the integrated and
organic orchards, respectively. Disease incidence showed a significant relationship with corresponding cumulative numbers
of trapped conidia both in integrated and organic orchards, and was described by separate three-parameter Gompertz functions
for the two orchards. Time series analyses, using autoregressive integrated moving average (ARIMA) models, revealed that the
temporal patterns of the number of airborne conidia was similar in all years in both integrated and organic orchards. Conidia
caught over a 24-h period showed distinct diurnal periodicity, with peak spore density occurring in the afternoon between
13.00 and 18.00. Percent viability of M. fructigena conidia ranged from 48.8 to 70.1% with lower viability in dry compared to wet days in both orchards and all years. Temperature
and relative humidity correlated best with mean hourly conidial catches in both integrated and organic apple orchards in each
year. Correlations between aerial spore density and wind speed were significant only in the organic orchard over the 3-year
period. Mean hourly rainfall was negatively but poorly correlated with mean hourly conidial catches. Results were compared
and discussed with previous observations. 相似文献
20.
BACKGROUND: Proquinazid is a new quinazolinone fungicide from DuPont registered in most European countries for powdery mildew control in cereals and vines. The aim of this paper is to present baseline sensitivity data in populations of Blumeria graminis f. sp. tritici EM Marchal and Erysiphe necator (Schw) Burr as well as results from cross‐resistance studies with other fungicides. RESULTS: Proquinazid exhibited a high intrinsic activity on B. graminis f. sp. tritici isolates at rates ranging from 0.000078 to 0.02 mg L?1. Erysiphe necator isolates were comparatively less sensitive to proquinazid, with EC50 values ranging from 0.001 to 0.3 mg L?1. Proquinazid controlled equally well B. graminis f. sp. tritici isolates sensitive and resistant or less sensitive to tebuconazole, fenpropimorph, fenpropidin, cyprodinil and kresoxim‐methyl. A positive correlation (r = 0.617) between quinoxyfen and proquinazid sensitivities was found among 51 B. graminis f. sp. tritici isolates. Quinoxyfen‐resistant B. graminis f. sp. tritici isolates were slightly less sensitive to proquinazid than the quinoxyfen‐sensitive isolates; however, proquinazid remained much more active than quinoxyfen on these isolates. A stronger sensitivity relationship (r = 0.874) between proquinazid and quinoxyfen was found among 65 E. necator isolates tested in a leaf disc assay. The sensitivity values for proquinazid were significantly lower than those for quinoxyfen, confirming the higher intrinsic activity of proquinazid on both pathogens. CONCLUSION: Given the history of resistance development in powdery mildew and the observed sensitivity relationship with quinoxyfen, specifically in E. necator, we conclude that the risk of resistance developing to proquinazid might be influenced by the use of quinoxyfen. Based on these results, the authors recommend that proquinazid and quinoxyfen be managed together for resistance management. Copyright © 2009 Society of Chemical Industry 相似文献