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Development of strategies for fire blight control in organic fruit growing
Project
Project code: 2806OE336
Contract period: 01.01.2007
- 28.02.2009
Budget: 129,030 Euro
Purpose of research: Applied research
The fire blight pathogen Erwinia amylovora cause economic losses in pome fruit. To avoid fire blight epidemics, organic fruit-growing needs a strategy to prevent blossom infections. Since 2004 in this project 44 preparations have been tested in vitro and on detached blossoms. The experiments showed, that only preparations with a bacteriostatic effect in vitro were able to prevent blossom infections on detached apple blossoms in the laboratory. The results of the experiments on detached blossoms were confirmed in 11 field trials according to the EPPO-guideline PP1/166 (3). BlossomProtect was the most efficient control agent in the field trials with an efficiency of 78% in average, followed by the rock flour Myco-Sin (65%). Copper is a known bactericide and was used in our field trials with application rates between 90 and 200 g copper/ha. For an adequate efficiency 200g copper/ha was needed. However, copper applications during bloom increase the risk for fruit russet. After reports on the increase of fruit russett caused by BlossomProtect applications in 2004, from 2005 on field trials to evaluate the risk for fruit russet were included in this research project. The increase in fruit russet caused by BlossomProtect depends on the treated variety and on the number of applications. On varieties which are sensitive to fruit russett the number of BlossomProtect applications should be reduced to two. The efficiency of BlossomProtect depends on the propagation of the Aureobasidium pullulans blastospores wich are the active igredient in BlossomProtect. In organic fruit growing wettable sulfur and lime sulfur is used for apple scab control during bloom. These fungicides arrest the propagation of A. pullulans in vitro. In field trials the use of wettable sulfur or lime sulfur one day before or one day after BlossomProtect application had no effect on the efficiency of BlossomProtect against fire blight. If according to weather conditions more than two applications against fire blight are necessary, BlossomProtect should be alternated with Myco-Sin. Myco-Sin can be combined with wettable sulfur for scab control. This strategy reduces the number of applications during bloom.
Section overview
Subjects
- Arboriculture
