Betrachtung möglicher Auswirkungen des Klimawandels auf Schadpilze im Obstbau am Beispiel von Fruchtfäuleerregern an Äpfeln

Whereas the rise in temperature during the past 30–40 years has already had clear impacts on the phenology of fruit trees and pathogenic insects, there is a lack of such correlations for fungal pathogens. An examination of fruit rots indicates that pathogenic fungi react differentially to climate change due to their complex infection biology. The appearance of the black rot fungus Diplodia seriata in Northwestern Europe is best explained by rising temperatures during the vegetation period. An increase in fruit rot caused by Nectria galligena is anticipated when milder and more humid winter months favour canker formation on twigs and branches, thereby increasing inoculum for fruit infections. An increasing importance of Neofabraea alba and Glomerella cingulata and/or G.??acutata as storage rots of apples in Northern Germany cannot be safely correlated with the climate change at present. Research on fungi is currently being expanded at the OVB Jork in order to ensure a faster identification of new pathogens and a more thorough investigation of relevant features of their infection biology.     

Moderne Apfelz��chtung: Genetische Verarmung und Tendenzen zur Inzucht

The apple varieties used in the modern commercial apple cultivation are nearly all genetically based on six relatively disease susceptible ??ancestorvarieties??: Golden Delicious, Cox Orange, Jonathan, McIntosh, Red Delicious and James Grieve. This applies to varieties bred after 1920 until today, including the new scab resistant varieties. The following article shows the dimension of the genetical narrowing and problems concerning the vitality of modern apple varieties. The author has compared the healthiness of old and new apple varieties in his trialorchard under no fungicide-spray conditions. As a conclusion out of his observations he calls to bethink an overall??not just reduced on scab resistance??term of vitality, as well as to use also the genetical potential of old apple varieties.     

苹果轮纹病药剂筛选与药剂配方

为解决苹果枝干轮纹病有效防治药剂缺乏的问题,1998—1999年在富士苹果枝干轮纹病树上开展其病害的药剂配方、浓度、防治次数、时期筛选及病斑不同刮治程度试验,2000—2002年在富士苹果枝干轮纹病树上开展果实轮纹病防治试验,结果表明,5波美度石硫合剂∶硅石粉剂=100∶4或100∶6对苹果枝干轮纹病具有显著的增效作用;1年2次施药效果显著;第1次施药前应采取轻刮,以后防治直接用药;多菌灵与波尔多液交替、多菌灵与石硫合剂∶硅石粉剂交替使用采收期与贮藏期防治果实轮纹病效果均突出;套袋果实轮纹病防效达100%。     

Strain Variation in Pear Blister Canker Virus

Williams’ Bon Chretien pear trees inoculated with blister canker virus varied in symptom expression. Plants propagated from buds of mildly affected trees showed only slight symptoms while those raised from severely affected trees developed severe canker. Tests indicated that mildly affected plants contained a virus which protected them against the effects of a more virulent strain.

Williams’ Bon Chretien trees developed symptoms when infected with virus from any one of three sources ; Doyenne du Comice and Laxton’s Superb developed symptoms when inoculated with two of the virus sources, but not with the third. Infected Beurre Hardy, Conference and Fondante d’Automne trees were symptomless and latent infection was detected in a symptomless Quince C plant. Inoculation of apple and quince varieties indicated no relationship between pear blister canker and other virus diseases of pear, quince or apple.     

陕西渭北地区盛果期苹果树腐烂病调查研究

通过对陕西渭北3县区苹果树腐烂病调查研究,结果表明:陕西渭北地区13 a生红富士苹果树腐烂病发病株率平均达56.14%,平均单株病疤数最低1.3个;中干剪锯伤口部位与主枝基部夹角处病疤百分率合计达56.8%以上;主枝基部开张角度与基部发生腐烂病率之间存在着极显著的负相关性,此结果反应出陕西渭北地区盛果期苹果树腐烂病流行早、发病重的现实及其危害特点.增强树势、尽量减少中干剪锯伤口量、开张主枝角度、重视对剪锯伤口和主枝基部的保护等是防治腐烂病的重要措施.     

Biology of Some Predatory Insects and Mites Associated With the Fruit Tree Red Spider Mite (Metatetranychus Ulmi (Koch)) in South-Eastern England: I. The Biology of Blepharidopterus Angulatus (Fall.) (Hemiptera-Heteroptera,Miridae)

Fungicide programmes, designed to control both scab and mildew, have been compared for phytotoxicity in several seasons on apple and pear varieties. Dodine acetate was found to cause russeting of the fruits of several apple and pear varieties. In one year, frost at a spraying time seemed to interact with dodine acetate application to produce unusual russet on Sunset apples. Crops of Conference and of Doyenne du Cornice pears were reduced in some years when dodine was applied.

The fungicide based on nitrated octylphenols, DNOPC, caused no undesirable effects on the apple varieties, but tended to reduce cropping on pears; the effects of the unesterified mixture, DNOP, were more serious.

Both dodine acetate and DNOPC caused reductions of fruit bud formation on Cornice, an effect already reported for organomercurial fungicides on Conference and for didecyldimethylammonium bromide (DDAB) on both varieties. It is suggested that freedom from this effect should be a criterion to be satisfied in the evaluation of any new pesticide for pears.     

苹果种质资源对苹果树腐烂病抗性评价

为全面了解苹果种质资源对苹果树腐烂病的抗性情况,利用2个不同来源的苹果腐烂病菌株,连续2 a对204份苹果种质资源进行了枝条离体接种鉴定。结果表明,接种后不同的种质资源的发病率和严重度均表现出丰富的多样性。西洋苹果资源（Malus domestica Borkh.）中发病率较低-极低的品种和类型所占的比例较高（16.6...     

Genetic transformation of Citrus sinensis cv. Hamlin with hrpN gene from Erwinia amylovora and evaluation of the transgenic lines for resistance to citrus canker

Transgenic Citrus sinensis (L.) Osb. cv. Hamlin plants expressing the hrpN gene were obtained by Agrobacterium tumefaciens (Smith and Towns) Conn-mediated transformation. hrpN encodes a harpin protein, which elicits the hypersensitive response and systemic acquired resistance in plants. The gene construct consisted of gst1, a pathogen-inducible promoter, a signal peptide for protein secretion to the apoplast, the selection genes nptII or aacC1 and the Nos terminator. The function of gst1 in citrus was evaluated in transgenic C. sinensis cv. Valencia harboring the reporter gene uidA (gus) driven by this promoter. Histochemical analysis for gus revealed that gst1 is activated in citrus leaves by both wounding and inoculation with Xanthomonas axonopodis Starr and Garces pv. citri (Hasse) Vauterin et al. Genetic transformation was confirmed by Southern blot hybridization in eight cv. Hamlin acclimatized plants. RT-PCR confirmed hrpN gene expression in seven cv. Hamlin transgenic lines before pathogen inoculation. Some hrpN transgenic lines showed severe leaf curling and abnormal growth. Six hrpN transgenic lines were propagated and evaluated for susceptibility to X. axonopodis pv. citri. RT-PCR confirmed gene expression in all six hrpN transgenic lines after pathogen inoculation. Several of the hrpN transgenic lines showed reduction in susceptibility to citrus canker as compared with non-transgenic plants. One hrpN transgenic line exhibited normal vegetative development and displayed very high resistance to the pathogen, estimated as up to 79% reduction in disease severity. This is the first report of genetic transformation of citrus using a pathogen-inducible promoter and the hrpN gene. Further evaluations of the transgenic plants under field conditions are planned. Nevertheless, the evidence to date suggests that the hrpN gene reduces the susceptibility of citrus plants to the canker disease.     

Root storage of nitrogen applied in autumn and its remobilization to new growth in spring of persimmon trees (Diospyros kaki cv. Fuyu)

This study was conducted to understand the effect of N supply in autumn on its uptake and distribution in tree parts and the utilization of reserve N the following year in persimmon trees (Diospyros kaki cv. Fuyu). The treated trees received 22.5-g N each for two successive years as a 3.5% urea solution from September 18 at 5-day intervals. Trees absorbed about 30% on average of the N applied in autumn. Sixty four to 83% of the N absorbed in autumn was in perennial parts, and 65–72% of that was in roots. Total N in perennial parts of the tree fertilized with N increased by over 4.28 g while leaf N changed little during senescence, indicating that the reserve N was constituted mostly by the N absorbed in autumn. Total N in the new growth was about the same as the amount of N declined in spring from perennial parts, indicating that there was little contribution by soil N to sustain new growth. Total dry weights of new growth the following year in a with-N tree were greater by over 34 g than those in a without-N tree.     

Poor anchorage and growth of spur ‘Red Delicious’ apple trees with deep crown roots

Spur ‘Red Delicious’ apple Malus domestica (Bork.) trees on MM 111 and seedlings that had been blown over by high winds had greater depth to first root and had thinner trunks than adjacent undamaged trees.     

The Effect of Some Apple Viruses on the Growth of Malus Species and Varieties

The inoculation of 40 varieties of ornamental crab apple with viruses commonly carried latently in commercial apple varieties and rootstocks killed 10 of the varieties and impaired the growth of 27 others ; only 3 were unaffected. The ornamental crabs showed varying sensitivity to chlorotic leaf spot, and platycarpa dwarf viruses. The main symptoms were line and spot patterns and distortion of the leaves, tip die-back, bark necrosis and stunting.

Viruses latent in some commercial apple rootstocks appear to be the main reason for the incompatibility between these stocks and the ornamental crabs. It is assumed that the same viruses also affect the compatibility of commercial apple varieties worked on ornamental crab seedlings.     

苹果斑点病菌和霉心病菌的相互关系

通过对苹果斑点病菌（Ａｌｔｅｒｎａｒｉａｍａｌｉ）和霉心病菌（Ａｌｔｅｒｎａｒｉａａｌｔｅｒｎａｔａ）在形态学、生物学和致病性方面的比较，发现斑点病菌和霉心病菌在形态特征上相似，但在分生孢子大小、喙胞长短方面存在显著差异；在营养介质上斑点病菌喜好红星叶和果实煎汁，霉心病菌则不喜好红星叶煎汁；两种病菌的菌丝生长和孢子萌发对温度、湿度、ｐＨ值的要求相似；两者在致病性方面有差异，班点病菌是霉心病的病原菌之一。     

Influence of temperature and bark injuries on the development of Phytophthora cactorum and P. Citrophthora on peach trees

The effect of temperature and bark injuries on the occurrence of crown rot of peach trees caused by P. cactorum and P. citrophthora were examined in field and laboratory. Lesions developed at 35 °C (the complete range of temperatures tested) but maximum development occurred at 20–25 °C. Greatest growth of these fungi on cornmeal agar (CMA) also occurred between 15 and 30 °C. Both pathogens could infect injured trees up to 20 days after wounding, but could not infect uninjured plants or plants wounded 40 and 30 days before inoculation, respectively. This study showed that temperature is a critical factor for the development of Phytophthora crown rot of peach trees. In addition, crown rot developed from recent wounds inoculated with agar plugs of Phytophthora.     

Urban London plane tree dieback linked to fungi in the Botryosphaeriaceae

Since the first report of the stain canker agent Ceratocystis platani in 2001 in Geneva, dieback of London plane trees (Platanus × acerifolia) has focused greater attention and an epidemiological monitoring has been implemented, as part of a compelling state directive for stain canker management. Genetic identification was carried out in order to ascertain the presence or absence of C. platani. We report here observations recorded between 2011 and 2013, of samplings from a total of 6 plane trees in 4 locations. Identification of bacteria and fungi was performed by sequencing of the rDNA ITS region for fungi, and of the 16S rRNA gene for bacteria. Fungi belonging to the Botryosphaeriaceae species occurred in almost every sampling, whereas Ceratocystis platani was only isolated in 2 trees. The 4 botryosphaeriaceous species, Diplodia mutila, Dothiorella sp., Diplodia seratia and Neofusicoccum parvum, could be responsible for the observed plane cankers, while other fungi could participate in the dieback symptoms. Since these species have been reported as canker agents on other tree species in Europe, artificial infections were carried out with pure cultures of Dothiorella sp., Diplodia mutila and Neofusicoccum parvum on young plane trees. Only Neofusicoccum parvum managed to provoke cork canker symptoms after a few months, but D. mutila and N. parvum were found in internal necrotic tissues. This is the first report of Dothiorella sp., Diplodia mutila and Neofusicoccum parvum associated with plane tree dieback in Switzerland and the first report of pathogenicity of Neofusicoccum parvum in plane trees. This survey showed that most cases of plane tree dieback in the Geneva region were not caused by C. platani and that other fungi could be responsible for similar symptoms.     

枯草芽孢杆菌LF17与甲基硫菌灵协同防治苹果树腐烂病的效果研究

通过室内测定枯草芽孢杆菌LF17与3种化学药剂对苹果树腐烂病菌(Valsa mali)的毒力,而后将菌株LF17的菌悬液与化学药剂进行复配,探讨复配剂对苹果树腐烂病菌的室内毒力及其田间防治效果。结果表明:枯草芽孢杆菌LF17与甲基硫菌灵生物相容性最好;LF17的菌悬液与甲基硫菌灵复配剂(浓度为1.36×10⁷ cfu/mL+1.0271μg/mL,按体积比5∶5配制)对苹果树腐烂病菌的抑菌率为81.36%、毒性比率为1.66、表现为增效作用,离体枝条的防治效果为74.05%,显著高于2个单剂的防治效果,且复配剂中甲基硫菌灵的使用量减少约60%。     

覆玉米秸对苹果枝干轮纹病的影响

通过对苹果园pH值,可溶性盐含量,腐殖质的含量,P、N含量等的分析,研究覆玉米秸对苹果枝干轮纹病的影响。结果表明:覆玉米秸可以降低土壤pH值、可溶性盐的含量,提高土壤腐殖质的含量,这些均有利提高苹果树对枝干轮纹病的抗性;而覆玉米秸降低P、N含量,还引起一些火灾、鼠害、病害,这些均加重了苹果枝干轮纹病的发生。     

Keine effektive Kontrolle des norddeutschen Heidelbeer-Triebsterbens durch Fungizidbehandlungen

Trials with the fungicides Cuprozin WP (active ingredient copper hydroxide), Malvin WG (captan), Switch (cyprodinil and fludioxonil) and Signum (pyraclostrobin and boscalid) were conducted in two young blueberry orchards (variety ‘Duke’) severely affected by twig dieback. Treatments were sprayed twice during leaf fall in autumn 2011 or once during budding in spring 2012. No treatment had any effect against twig dieback. This result confirms earlier indications of winter frost damage of xylem tissue as the primary cause of these symptoms in Northern Germany. A colonisation of dead twigs by Godronia cassandrae was therefore probably the consequence, rather than cause, of dieback.     

Relationships among mineral nutrition,ethylene and post-harvest physiology in apples on six rootstocks

The relationships among several mineral elements of August-sampled leaf October-harvested fruit, maturity and post-harvest quality factors of ‘Starkspur Golden Delicious’ apple trees grown on Seedling, Malling (M) 1, Malling Merton (MM) 106, M 7, Oregon Apple Rootstock (OAR 1) or M 26 in a high-density orchard during 1980–1982 were evaluated. Positive correlations were found between leaf N, K and P and fruit N, K and P, respectively, in most rootstocks. Leaf Ca did not correlate with fruit Ca; thus leaf analysis cannot be recommended for estimates of fruit Ca. Both leaf and fruit N positively correlated with fruit green color and negatively with fruit soluble solids in all rootstocks. Fruit Ca and fruit P were both negatively correlated with fruit soluble solids at harvest and after 6 months of 0°C storage for all rootstocks. The ratio of fruit $\text{N}\text{Ca}$ was positively correlated with internal ethylene in MM 106, M 7 and OAR 1, while fruit $\text{K}\text{Ca}$ ratio was positively correlated with titratable acidity in all rootstocks. Fruit Ca showed negative correlations with bitterpit, storage rot and field internal ethylene, but positive correlation with firmness. Yield was positively correlated with leaf and fruit N, Ca and Cu but slightly negatively correlated with B of those tissues. Higher yield was associated with lower leaf K concentrations. Fruit green color was negatively correlated with soluble solids and titratable acidity. Fruit dry matter was highly positively correlated with soluble solids and titratable acidity in MM 106, OAR 1 and M 26. Soluble solids at harvest were strongly predicted by pre-harvest dry matter.     

The Effect of Some Latent Virus Infections on the Growth and Cropping of Apples

SUMMARY

Seedlings of Newton Wonder apple multiplied vegetatively on Malus sikkimensis rootstocks and inoculated with a mixture of chlorotic leaf spot, scaly bark and dwarf viruses showed varying degrees of sensitivity to these infections. Although none of the seedlings showed clearly recognizable virus symptoms, many showed a very significant reduction in vigour; the girth differences between the infected and control trees were still increasing three years after inoculation.

The infected trees showed signs of nitrogen deficiency, which were confirmed by foliar analysis ; leaf nitrogen as percentage of dry weight was 10% lower than that of the controls. Four years after inoculation 43% of the infected trees had cropped, compared with 58% of the controls.

The results suggest that some selection of varieties and rootstocks for virus tolerance has taken place and that the evaluation of new seedlings on their own roots may not be a true indication of their performance on infected rootstocks.