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Amein T.,Box | Amein T.,Swedish University of Agricultural Sciences | Wright S.A.I.,University of Molise | Wikstrom M.,Jordbruksverket | And 10 more authors.
Journal of Plant Diseases and Protection | Year: 2011

Due to the lack of foliar fungicide use, the organic production of Brassica seeds free of Alternaria spp. is difficult. Therefore, effective seed treatments certified for use in organic farming are needed to eradicate or at least effectively reduce the seed-borne inoculum. We here report results of greenhouse and field experiments in which non-chemical seed treatments were tested for control of A. brassicicola on cabbage seeds naturally infested with the pathogen. In greenhouse experiments, significant improvements were obtained by seed treatment with some commercialised and experimental microbial biocontrol agents, an emulsion of thyme oil in water (0.1%) and by the tested physical seed treatments methods (i.e. hot water, aerated steam and electron seed treatment). Resistance inducers tended to increase the percentage of healthy plants, but the effects were statistically not significant. Generally the combination of physical treatments with the effective agents did not result in improved performance. Positive effects on crop establishment and yield by the same treatments were also observed in field tests. Overall the results indicate that several options for non-chemical control of A. brassicicola on Brassica seeds exist that are comparable in efficacy to the chemical standard Aatiram (active ingredient thiram) used in this study. © Eugen Ulmer KG, Stuttgart.


Koch E.,Institute for Biological Control | Schmitt A.,Institute for Biological Control | Stephan D.,Institute for Biological Control | Kromphardt C.,Institute for Strategies and Technology Assessment in Plant Protection | And 12 more authors.
European Journal of Plant Pathology | Year: 2010

The current study was initiated to evaluate the efficacy of physical methods (hot water, aerated steam, electron treatment) and agents of natural origin (resistance inducers, plant derived products, micro-organisms) as seed treatments of carrots for control of Alternaria dauci and A. radicina. Control of both Alternaria species by seed treatment with the resistance inducers was generally poor. Results were also not satisfactory with most of the formulated commercial micro-organism preparations. Based on the average of five field trials, one of these, BA 2552 (Pseudomonas chlororaphis), provided a low but significant increase in plant stand. Among the experimental micro-organisms, the best results were obtained with Pseudomonas sp. strain MF 416 and Clonostachys rosea strain IK726. A similar level of efficacy was provided by seed treatment with an emulsion (1%) of thyme oil in water. Good and consistent control was generally achieved with the physical methods aerated steam, hot water and electron treatment. Aerated steam treatment was, apart from the thiram-containing chemical standard, the best single treatment, and its performance may at least partially be due to extensive pre-testing, resulting in dosages optimally adapted to the respective seed lot. In some of the experiments the effect of the hot water treatment, which was tested at a fixed, not specifically adapted dosage, was significantly improved when combined with a Pseudomonas sp. MF 416 or C. rosea IK726 treatment. The results are discussed in relation to the outcome of experiments in which the same seed treatment methods and agents were tested in other seed-borne vegetable pathosystems. © 2010 KNPV.


Halter T.,University of Tübingen | Imkampe J.,University of Tübingen | Mazzotta S.,University of Tübingen | Mazzotta S.,Institute for Biological Control | And 19 more authors.
Current Biology | Year: 2014

Background Transmembrane leucine-rich repeat (LRR) receptors are commonly used innate immune receptors in plants and animals but can also sense endogenous signals to regulate development. BAK1 is a plant LRR-receptor-like kinase (RLK) that interacts with several ligand-binding LRR-RLKs to positively regulate their functions. BAK1 is involved in brassinosteroid-dependent growth and development, innate immunity, and cell-death control by interacting with the brassinosteroid receptor BRI1, immune receptors, such as FLS2 and EFR, and the small receptor kinase BIR1, respectively. Results Identification of in vivo BAK1 complex partners by LC/ESI-MS/MS uncovered two novel BAK1-interacting RLKs, BIR2 and BIR3. Phosphorylation studies revealed that BIR2 is unidirectionally phosphorylated by BAK1 and that the interaction between BAK1 and BIR2 is kinase-activity dependent. Functional analyses of bir2 mutants show differential impact on BAK1-regulated processes, such as hyperresponsiveness to pathogen-associated molecular patterns (PAMP), enhanced cell death, and resistance to bacterial pathogens, but have no effect on brassinosteroid- regulated growth. BIR2 interacts constitutively with BAK1, thereby preventing interaction with the ligand-binding LRR-RLK FLS2. PAMP perception leads to BIR2 release from the BAK1 complex and enables the recruitment of BAK1 into the FLS2 complex. Conclusions Our results provide evidence for a new regulatory mechanism for innate immune receptors with BIR2 acting as a negative regulator of PAMP-triggered immunity by limiting BAK1-receptor complex formation in the absence of ligands. © 2014 Elsevier Ltd.


Hegazi E.M.,Alexandria University | Konstantopoulou M.A.,Greek National Center For Scientific Research | Herz A.,Institute for Biological Control | Khafagi W.E.,Egyptian Plant Protection Res Institute | And 5 more authors.
Insect Science | Year: 2011

Prays oleae Bern, (OM) and Palpita unionalis Hüb., (JM) are two of the most important pests in olive groves in Egypt. A 3-year monitoring study using sex pheromone traps in semi-arid and arid olive groves was performed. In the semi-arid grove, flight pattern of the OM was the same as in other Mediterranean countries, but in dates concordating plant phenology. The moth completes three generations annually: the first flight is in March to April, the second is in May to June and the third occurs in August to October. In the arid olive grove, an interesting flight pattern was observed. First flight was always very close or overlapped with the second one with no male catches during August to October. However, eggs were present most of the season, indicating unusually high female presence and oviposition activity of the OM during the absence of males in the traps. Generally, moth densities were significantly lower in low fruiting years than in higher ones and were also lower in the arid olive grove than in the semi-arid one. In contrast, JM males were present all season, exhibiting six to seven and three to four overlapping flight peaks in arid and semi-arid olive groves, respectively. Moth densities were significantly higher in the arid olive grove than those in the semi-arid one. This study shows that trapping location and fruit bearing year are characteristics that strongly affect the grove-specific information needed to estimate correctly adult emergence and thus the timing of control measures. © 2011 The Authors Journal compilation © Institute of Zoology, Chinese Academy of Sciences.


Hegazi E.M.,Alexandria University | Konstantopoulou M.A.,Greek National Center For Scientific Research | Khafagi W.E.,Egyptian Plant Protection Res Institute | Schlyter F.,Swedish University of Agricultural Sciences | And 4 more authors.
Phytoparasitica | Year: 2012

Jasmine moth (JM), Palpita unionalis (Hübner) (Lepidoptera: Pyralidae) is a very important pest in the commercial, densely planted olive orchards in Egypt. In years of its highest population density, it can destroy a significant part of the crop. The objectives of this study were to determine the male flight trend and egg laying trend of the JM in three large plots of different olive varieties (two varieties/plot) in two successive fruiting seasons. Differences in male flight trend and egg laying trend of JM were observed among the different varieties ('Sennara', 'Toffahi', 'Shamy'). In 2003, more males were captured in traps placed in the Sennara/Toffahi plot than in the two Shamy/Toffahi plots. Egg densities were higher on Toffahi trees grown between Sennara trees than on Toffahi trees grown between Shamy ones. In 2004, in the plot where Toffahi and Sennara were grown together, JM females laid more eggs than in the olive plot where Toffahi rows alternated with Shamy rows. The results suggest that the Shamy variety discouraged gravid females from ovipositing, compared with Toffahi or Sennara varieties. In conclusion, olive variety, cropping system (mixed culture) and trapping season are among those characteristics that affect this pest. © 2012 Springer Science + Business Media B.V.


Moharam M.H.A.,Sohag University | Leclerque A.,Institute for Biological Control | Koch E.,Institute for Biological Control
Phytoparasitica | Year: 2012

Despite the economic importance of covered kernel smut of sorghum (Sporisorium sorghi) in many African states and other parts of the world, only limited information is available on laboratory cultivation methods for this fungus and techniques for its diagnosis in plant tissue. The current paper describes laboratory and greenhouse experiments performed with field material of S. sorghi. When intact sori were kept at 5°C, 80% of the spores germinated even after 24 months of storage. Spore germination on agar medium and production of mycelial dry weight in still culture were highest between 20° and 35°C, with a peak at 30°C. Both showed a steady increase from pH 4. 5 to pH 7. 5, followed by a decline at pH 8. 5 and 9. 5. In shake culture in different broth media the addition of 0. 3% peptone from soybean caused an increase in fungal growth compared with the media alone. Of the media tested, mycelial production was highest in malt dextrose broth supplemented with peptone. When cultivated on different agar media, the morphology of single spore isolates differed both among isolates and depending on the agar medium. In greenhouse experiments, five short, early maturing sorghum breeding accessions proved to be partially or fully resistant to covered kernel smut. Among the plant materials tested, cv. 'Dorado' appeared to be the one best suited for greenhouse experiments with covered kernel smut. By microscopy of hand-cut sections stained with trypan-blue, hyphae of S. sorghi were seen in apical buds and in nodes of young sorghum plants. Diagnostic PCR amplified a 903 bp element comprising the internal region of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) encoding gene and enabled the detection of S. sorghi in both nodes and apical buds of infected sorghum seedlings. Both techniques, i. e., microscopy and diagnostic PCR, have the potential to be used in studies for the identification of effective sorghum seed treatments already at the seedling stage. © 2012 Springer Science + Business Media B.V.


Koch E.,Institute for Biological Control | Enders M.,Institute for Biological Control | Ullrich C.,Institute for Biological Control | Molitor D.,Center De Recherche Public Gabriel Lippmann | Berkelmann-Lohnertz B.,Geisenheim Research Center
Journal of Plant Diseases and Protection | Year: 2013

The paper describes in vitro and in vivo experiments with extracts from Primula root and Hedera helix aimed at characterizing their effect on Phyllosticta ampelicida (teleomorph: Guignardia bidwellii), the causal agent of black rot disease of grapevine. In pre-tests, collodion membranes placed over water agar were determined to be better suited for spore germination and appressoria formation than cellophane sheets. On collodion membranes placed over water agar amended with different agents, the fungicide Polyram® WG (metiram) inhibited germination of the conidia of P. ampelicida completely. Inhibition by the extract from Primula root was similarly high and stronger than by the extract from H. helix. Primula root extract also inhibited conidial germination on grape leaves. In greenhouse tests, protective application of the extracts of H. helix and Primula root at concentrations of 1.0 and 0.5% reliably provided control of black rot with efficacy > 90%, which was in the same range as protection provided by the saponin-containing reference extracts from Sapindus mukorossi, Chenopodium quinoa and Quillaja spec. In further tests, protective and curative activity (i.e. application of treatments 24 h before or 24 h after pathogen inoculation) was compared. The agents tested were extracts from Primula root and H. helix, Polyram® WG, the resistance inducer BION® 50 WG (acibenzolar-S-methyl) and Frutogard®, a product containing an extract from brown algae and phosphonate. When applied protectively, all treatments reduced the disease severity. The efficacy of primula root extract was similar to that of Polyram® WG, which provided complete control. Curative application caused a much lower reduction in disease, which was most pronounced for the Frutogard® treatment. © Eugen Ulmer KG, Stuttgart.


Wunderle J.,Institute for Biological Control | Leclerque A.,Institute for Biological Control | Schaffrath U.,RWTH Aachen | Slusarenko A.,RWTH Aachen | Koch E.,Institute for Biological Control
European Journal of Plant Pathology | Year: 2012

Loose smut fungi of barley and wheat (Ustilago nuda and U. tritici, respectively) colonize the plant without causing obvious disease symptoms before heading. The availability of diagnostic methods to detect and follow the growth of these pathogens in the plant would therefore be highly advantageous for both resistance breeding and the development of effective seed treatments. Using seed lots of barley and wheat highly infected with loose smut, we studied the early establishment of the loose smut pathogens in the plant by fluorescence microscopy. In hand-cut sections stained with the fluorochrome Blankophor®, fungal hyphae were observed to invade the shoot apical meristem and leaf primordia during the first days after the onset of germination. At the first node stage the ear and leaf primordia were generally extensively colonized. Hyphae of U. nuda were also regularly observed in high density in the nodes. A protocol was developed for the specific amplification of U. nuda and U. tritici DNA extracted from infected plant tissue. PCR screening of U nuda in seedlings from infected and healthy seed lots was compared to ELISA, microscopy and ultimately head infection of mature plants derived from tillers of the tested seedlings. The results indicated that a prediction of loose smut infection by real-time PCR is possible at the second leaf stage, and that the assay is equally suited for use with spring and winter varieties of barley and wheat. © 2012 KNPV.


Scherf A.,Institute for Biological Control
Communications in agricultural and applied biological sciences | Year: 2010

In organic cucumber production infection with downy mildew (Pseudoperonospora cubensis) is a major problem. Plant extracts from Glycyrrhiza glabra L. (licorice), a plant belonging to the family Fabaceae, and Salvia officinalis (sage) as well as cultures of the bacterium Aneurinibacillus migulanus were investigated for efficacy of disease control under commercial growing conditions. Contrary to bioassays, where sage extract and the microorganism showed highest activity, in the trials of 2008 G. glabra extract was more effective than sage extract or A. migulanus against P. cubensis. Parameters such as concentrations of the preparations or application intervals could have been the reason for this. In the following year's trial (2009) the concentration of these agents was therefore increased somewhat and plants were either treated in seven day application intervals or in ten day application intervals. In the semi-commercial trials of 2009 all alternative biological agents showed good efficacies up to around 80% against infection with downy mildew. The application interval seemed to have a marginal effect only. Again, the licorice extract tended to be the best agent.


Schuster C.,Institute for Biological Control
Communications in agricultural and applied biological sciences | Year: 2010

In previous investigations an ethanolic plant extract from Glycyrrhiza glabra (2.5% w/v) showed 100% efficacy against late blight (Phytophthora infestans) on detached tomato leaves. Based on these findings, the objective of this work was to investigate the effect of this extract against different important plant pathogenic fungi. Tests were carried out on potted plants. Against P. infestans, efficacies of 75% and 58% were achieved on tomato and potato plants with 5% extract concentration, respectively. Against another Oomycete, Pseudoperonospora cubensis, on cucumber, application of a 2.5% extract led to an efficacy of above 90%. The EC50-value was calculated to be 0.5% In a trial on beans against bean rust (Uromyces appendiculatus), G. glabra extract (5% concentration) showed 92% efficacy. In contrast, against powdery mildew on cucumber (Podosphaera xanthii), no disease reduction was found. Overall, the results indicate a high potential for the extract of G. glabra to control a number of important plant pathogens.

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