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Abo-Elyousr A.M.K.,Assiut University | Sallam M.A.A.,Assiut University | Hassan M.H.A.,Assiut University | Zeller W.,Institute For Biologischen Pflanzenschutz
Plant Pathology Journal | Year: 2010

The effect of Acibenzolar-S-methyl (ASM) and Rahnella aquatilis Ra39 against apple fire blight disease caused by Erwinia amylovora were tested as a possible alternative to streptomycin. In vitro studies, no inhibition effect against the pathogen was found when ASM was tested. Under greenhouse conditions, application of R. aquatilis Ra39 with the highly susceptible M26 rootstock resulted in a marked disease suppression. Application of ASM and strain Ra39 caused a high decrease of the disease, 82% and 58% respectively; this was correlated with a reduction of the growth of the pathogen within host plants up to 64% and 49.5% respectively. Further studies in the field under artificial infection condition during full bloom revealed that application of ASM and R. aquatilis Ra39 with Gala variety resulted in a control effect up to 21 and 29% respectively. In physiological studies, enhanced activities of PR-proteins (chitinase and β-1, 3-glucanase) were detected, which are well known as biochemical markers for systemic acquired resistance. Application of ASM to apple shoots caused the highest chitinase activity followed by strain Ra39. The enzyme activity was increased after 2, 4 and 6 days from application. In addition, ASM-treatment caused the higher β-1, 3-glucanase activity than strain Ra39. Maximum enzyme activity was recorded after 6 days from application and then decreased after 8 and 10 days from application. © The Korean Society of Plant Pathology.


Sallam N.M.,Assiut University | Abd Elrazik A.A.,Assiut University | Hassan M.,Assiut University | Koch E.,Institute For Biologischen Pflanzenschutz
Archives of Phytopathology and Plant Protection | Year: 2010

The APIZYM system of detection of enzymes was proven to be useful in the differentiation of 15 European and Egyptian isolates of S. cepivorum, the incitant of onion white rot. The tested isolates produced alkaline phosphatase, esterase (c4), esterase lipase (c8), leucine arylamidase, valinearylamidase, trypsine, α-chymatrypsin, acid phosphatase, naphthol-AS-B1-phosphohydrolase, ß-galactosidase, ß-glucutronidase, α-glucosidase, ß-glucosidase and N-acetyl-ß-glucosaminidase and did not produced lipase (c14), crystine arylamidase, trypsine, ß-glucutronidase, α-mannosidase and α-fucosidase. According to enzyme activity, isolates can be divided into four groups (G). The differences between groups were in the activity of the enzymes α-chymotrypsin and α-glucosidase. The tested European isolates and the Egyptian isolates No.6 of the pathogen were in G1 and G2; however the rest of the Egyptian isolates were in G3 and G4. © 2010 Taylor and Francis.


Kunz S.,University of Konstanz | Schmitt A.,Institute For Biologischen Pflanzenschutz | Haug P.,Fordergemeinschaft Okologischer Obstbau
Acta Horticulturae | Year: 2011

In organic fruit growing, effective control strategies are needed to prevent blossom infections by the fire blight pathogen Erwinia amylovora. In Germany, many potential control agents have been considered and more than 40 different preparations have been tested systematically in laboratory trials in vitro and on detached blossoms to select the products with highest efficacy. In eleven field trials conducted since 2004 according to EPPO guideline PP1/166(3) BlossomProtectTM and Myco-Sin® had the highest efficiencies (79 and 65%, respectively). In 2010 LX4630 was tested the first time and showed comparable efficiency to BlossomProtect. BlossomProtect contains blastospores of the yeast Aureobasidium pullulans. The blastospores are sensitive to fungicides including sulphur and lime sulphur that are used for apple scab control. In some cases, A. pullulans enhanced fruit russet depending on the number of applications and of the apple cultivar treated. Spray strategies in which BlossomProtect was used alternating with sulphur fungicides did not hamper the efficacy of BlossomProtect against fire blight. However, up to 8 applications had to be made during bloom to achieve fire blight and scab control. Applying BlossomProtect and wettable sulphur in a tank mixture reduced the total number of applications to four without reducing significantly the efficiency against fire blight. With a strategy to alternate BlossomProtect applications with sprays of a mixture of wettable sulphur and Myco-Sin®, the total number of applications during bloom could be reduced to four, with only a slight decline in fire blight control. In addition in this strategy the reduction of the number of applications of BlossomProtect from four to two reduced the risk of fruit russet.


Saucke H.,University of Kassel | Schultz B.,University of Kassel | Wedemeyer R.,University of Kassel | Liebig N.,Okoring Niedersachsen e. V. | And 2 more authors.
Gesunde Pflanzen | Year: 2011

The cabbage whitefly,Aleyrodes proletella, has developed to a key pest in brassica vegetable crops throughout Germany. In a 3-year project we investigated a biotechnical approach employing netting (0.8 × 0.8 mm meshsize) in combination with the native parasitoidEncarsia tricolor in an inoculative-inundative approach in organic Brussels sprouts under field conditions. In small scale plot experiments continuous netting from transplanting in May till October alone reduced whitefly larval densities by 77 % at peak infestation in all years. Remaining whitefly infestation under net was associated with the necessity of temporary net removal for the purpose of mechanical weeding, which caused primary whitefly infestation. Release of mass rearedE. tricolour under net at the first signs of larval infestation significantly increasedA. proletella-parasitation and reduced infestation compared to netted controls without release. Furthermore, at highest dosage in 2009,E. tricolor had a significant enhancing effect on raw yield and the quality level of marketable yield. Additional on-farm experiments without netting in 2008 and 2009 confirmed the control potential ofE. tricolor. Although the most important project mile stones have been achieved, namely (a)E. tricolour-establishment under net and in the open field, (b) enhanced parasitation corresponding with pest density decline and (c) a positive impact on yield and quality parameters, further research will be necessary. The focus should be on the initial infestation period, optimizing the timing, frequency and required dosage. © 2011 Springer-Verlag.

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