Esteburg Fruit Research and Advisory Center

Jork, Germany

Esteburg Fruit Research and Advisory Center

Jork, Germany
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Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Weber R.W.S.,University of Aarhus | Entrop A.-P.,Esteburg Fruit Research and Advisory Center
European Journal of Plant Pathology | Year: 2017

In a four-year survey of strawberry nursery plants, 340 Botrytis isolates were collected and examined for fungicide resistance. High percentages of isolates with resistance to members of all fungicide classes registered on strawberries in Germany were found, i.e. trifloxystrobin (90.3%), boscalid (53.8%), cyprodinil (41.5%), fludioxonil (28.2%) and fenhexamid (15.6%). Of these isolates, 10.3% possessed multiple resistance to all compounds. At 5.0%, resistance to the recently registered fungicide fluopyram was low. Dutch nursery material harboured significantly higher proportions of isolates with resistance to any or all fungicides than plants produced in Germany. These data point to nursery plants as a possible route of introducing fungicide-resistant Botrytis strains into commercial strawberry fields. © 2017 Koninklijke Nederlandse Planteziektenkundige Vereniging

Maxin P.,University of Aarhus | Williams M.,University of Aarhus | Weber R.W.S.,Esteburg Fruit Research and Advisory Center
Erwerbs-Obstbau | Year: 2014

In the Lower Elbe region of Northern Germany and in other Northern European fruit production areas, about 80 % of all storage rots of apples are caused by Neofabraea alba and N. perennans. Other pathogens include Colletotrichum acutatum, Monilinia fructigena, Phaci-diopycnis washingtonensis, Neonectria galligena, Botrytis cinerea, Penicillium expansum and Fusarium avenaceum. Hot-water treatments of freshly harvested fruits for 3 min at 50-52 °C gave high efficacies against most of these storage rots except F. avenaceum. Substantial evidence supported a heat shock-induced antimicrobial response rather than a direct killing of fungal inoculum as the principal mode of action of hot-water treatments in apples. Shorter exposures for < 30 s at 55-60 °C also provided good control of fungal storage rots and thereby offer new possibilities for this technology in Northern European fruit production. These possibilities include the integration of a hot-water unit into existing grading lines and the option to treat fruits at different time points, e.g. at harvest, after short-term storage and/or after long-term storage. © 2014 Springer-Verlag Berlin Heidelberg.

Maxin P.,University of Aarhus | Weber R.W.S.,Esteburg Fruit Research and Advisory Center
Journal of Plant Diseases and Protection | Year: 2011

Phacidiopycnis washingtonensis, cause of rubbery rot of apples during long-term storage, was first observed in Denmark in April 2010 on fruits of the 2009 harvest. Hot-water treatments were examined as a possible way to control P. washingtonensis. The effective temperature causing a 50% mortality of infectious spores (conidia) after a 3-min submersion in water was 40.2°C. A significant reduction of rubbery rot was achieved by dipping artificially infected fruit in a water bath at 47-52°C for 3 min. Using naturally infected apples, P. washingtonensis as well as the widespread storage-rot pathogen Neofabraea perennans were effectively controlled by a post-harvest dip at 50°C for 3 min or by a rinse at 55°C for 20 s, followed by cold storage in controlled-atmosphere conditions. In contrast, a treatment of freshly harvested fruits with 1-methylcyclopropene (1-MCP) instead of hot water failed to control P. washingtonensis.

Maxin P.,University of Aarhus | Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Lindhard Pedersen H.,University of Aarhus | Williams M.,University of Aarhus
European Journal of Horticultural Science | Year: 2012

The efficacy of hot-water dipping against apple storage rots caused by Neonectria galligena, Botrytis cinerea and Penicillium expansum was examined. Pure spore suspensions as well as artificially inoculated 'Elstar' apples were incubated for 3 min in a water bath heated to specific temperatures in the range of 32 °C to 70 °C, followed by incubation at 2 °C (fruit) or 20 °C (spores). Whereas there were striking interspecific differences in the dipping temperatures survived by spores, storage rots caused by all three species were significantly reduced by dipping temperatures around 50 °C. Temperatures above 52 °C caused serious heat scald on the fruit surface and gave rise to increasing levels of fruit rot in the case of N. galligena and P. expansum. Very similar temperature-response curves of blue mould development were observed in apples inoculated with P. expansum before or after hot-water dipping, except for the highest temperature tested (70 °C). It is concluded that the major effect of hot-water dipping against these fruit rots is mediated by heat-induced acquired resistance of fruit rather than heat-mediated spore mortality. These results suggest possible applications for hot-water dipping of apples at harvest, after short-term cold storage or after the opening of controlled- atmosphere storage rooms in order to improve fruit quality during subsequent storage periods. © Verlag Eugen Ulmer KG, Stuttgart.

Maxin P.,University of Aarhus | Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Pedersen H.L.,University of Aarhus | Williams M.,University of Aarhus
Postharvest Biology and Technology | Year: 2012

Hot-water rinsing (3 or 4. min) and dipping (15, 20 or 25. s) at a range of incubation temperatures was applied to apples (cv. 'Ingrid Marie' and 'Pinova') naturally infected with a range of North West European storage-rot fungi. Significant reductions in the incidence of fruit rot were achieved by incubation periods of 3. min at 50-54. °C (dipping) and 20 or 25. s at 55. °C (rinsing), followed by up to 100. d cold-storage at 2. °C and 14. d at 18. °C. Pathogens controlled in this way were . Neofabraea alba, . N. perennans, . Monilinia fructigena, . Colletotrichum acutatum, . Phacidiopycnis washingtonensis and . Cladosporium spp. . Neonectria galligena was reliably controlled by dipping but not rinsing. No effects of either heat treatment on . Gibberella avenacea and . Botrytis cinerea were apparent. Following rinsing at 65. °C for 20. s, the incidence of . P. washingtonensis, . Penicillium expansum, . Mucor spp. and . Phoma exigua was higher than in untreated control fruit or in apples rinsed at lower temperatures, and was associated with heat damage. The relative contributions of heat effects on inoculum viability and activation of defence responses of apple fruit are discussed. Hot-water rinsing has several advantages over hot-water dipping related to the efficient processing of fruit either directly after harvest or after long-term storage. © 2012 Elsevier B.V.

A review of apple canker caused by Neonectria ditissima is presented for Northwestern Europe with a focus on the Lower Elbe region (Northern Germany). Whereas conidia released by rainsplash are produced mainly from spring to autumn, the liberation of wind-borne ascospores peaks in autumn and/or early spring. Infection occurs via natural as well as pruning-induced wounds, some of which are present throughout the year. Autumnal leaf scars are the most frequent entry point for N. ditissima. Wounds on tree trunks, especially bark cracks in the crotch regions, are potentially even more serious because cankers on trunks and leader shoots commonly cause the total loss of a tree. Surface moisture is a prerequisite for leaf scar infections but possibly not for an entry through other wounds. Irrespective of the entry route, successful infection of a wound requires a mass inoculum of at least 50-100 conidia or ascospores. Infections of trees originating in nurseries may enter a state of latency from which they can break out up to 3 years after the trees have been explanted into the production orchard. Streaks of brown wood discolourations can be caused both by systemic colonisation of the xylem by N. ditissima and by winter frost damage. Apple varieties may show pronounced differences in their sensitivity to canker. For highly susceptible varieties, this disease can be a major production-limiting factor. Flower infections by N. ditissima commonly lead to a pre-harvest rot at the blossom end of the fruit, whereas infections of the growing fruit before harvest lead to a storage rot. Rigorous pruning is an essential canker control measure. Chemical control during the growing season is achieved by apple scab fungicides such as dithianone, captan or dodine. At leaf fall and in winter, copper fungicides are indispensible for controlling canker on highly susceptible varieties in Northern Germany. © 2014 Springer-Verlag Berlin Heidelberg.

Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Zabel D.,Esteburg Fruit Research and Advisory Center
European Journal of Horticultural Science | Year: 2011

A milky discolouration of red-pigmented apple varieties such as 'Redprince' and 'Elstar' from Northern Germany was due to the abnormal development of air spaces in hypodermal tissues. This physiological condition was identified as scarf skin, which is well-known in the United States but is reported here for the first time from Europe. White haze, caused by a superficial colonisation of the apple cuticle by mycelial yeasts, was also observed in Northern Germany, and two Til-letiopsis spp. were isolated and characterised. The occurrence of scarf skin and white haze in Northern Germany is discussed with reference to other fruit producing regions. © Verlag Eugen Ulmer KG, Stuttgart.

Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Hahn M.,University of Kaiserslautern
Journal of Plant Diseases and Protection | Year: 2011

A simple test based on the germination of conidia of Botrytis on agar media augmented with various fungicides has been developed. Average concentrations causing a 50% reduction of germ-tube growth (EC50) of highly sensitive isolates were determined on 1% malt extract agar (thiophanate-methyl 0.090 ppm; iprodione 0.566 ppm; fludioxonil 0.026 ppm; fenhexamid 0.144 ppm), 1% malt extract agar with 100 ppm salicyl hydroxamic acid (QoI fungicides, viz. trifloxystrobin 0.009 ppm; pyraclostrobin 0.013 ppm; azoxystrobin 0.087 ppm), 0.5% yeast extract agar (boscalid 0.069 ppm) and 0.5% sucrose agar (cyprodinil 0.053 ppm). In order to detect different levels of resistance against these various fungicides, two discriminatory concentrations were identified for each compound. A routine assay method was developed in which drops of a conidial suspension harvested directly from diseased plant material or sporulating cultures were incubated on each of 20 different agar media. Because of a very short time-span of 24-48 h between sample collection and evaluation of results, field-specific information on the occurrence, frequency and types of resistance of Botrytis against common botryticides in soft-fruit production may be generated prior to the main fungicide spray season at blossom time. © Eugen Ulmer KG, Stuttgart.

Weber R.W.S.,Esteburg Fruit Research and Advisory Center
Plant Disease | Year: 2011

During the vegetation period 2010, 353 isolates of Botrytis cinerea from 23 Northern German strawberry, raspberry, highbush blueberry, and redcurrant fields were examined for sensitivity to the benzimidazole derivative thiophanate-methyl and the dicarboximide iprodione, as well as five fungicides currently used against gray mold in Germany. Of all isolates, 40.5% were highly resistant to thiophanate-methyl, 64.0% to iprodione, 45.0% to fenhexamid, 76.8% to trifloxystrobin, 21.5% to boscalid, and 14.7% to cyprodinil. No high resistance to fludioxonil was observed but medium resistance was recorded to fludioxonil as well as cyprodinil (41.1 and 27.2% of all isolates, respectively). In all, 63 isolates were sensitive to all five of the currently registered botryticides whereas 43, 81, 94, 49, and 23 isolates were medium or highly resistant to one, two, three, four, and five fungicides, respectively. Isolates resistant to five fungicides in vitro were capable of causing fruit rot on wounded apple pretreated with any one of the three commercially available products containing fenhexamid, pyraclostrobin plus boscalid, or cyprodinil plus fludioxonil. These results question the sustainability of the current gray mold control strategy relying exclusively on fungicides with specific, single-site modes of action. © 2011 The American Phytopathological Society.

Leroch M.,University of Kaiserslautern | Plesken C.,University of Kaiserslautern | Weber R.W.S.,Esteburg Fruit Research and Advisory Center | Kauff F.,University of Kaiserslautern | And 2 more authors.
Applied and Environmental Microbiology | Year: 2013

The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations, which are differentially distributed according to their host preference and adaptation to chemical treatments. © 2013, American Society for Microbiology.

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