ISHS Acta Horticulturae 347: II International Symposium on Integrated Fruit Production
AN IMPROVED APPLE SCAB WARNING SYSTEM: CONSIDERATION OF THE BIOLOGICAL PARAMETERS, ASCOSPORE PRESENCE AND LEAF GROWTH, IN ADDITION TO MICROCLIMATIC FACTORS |
| Authors: | M. Bühler, C. Gessler, J. Boos |
| DOI: | 10.17660/ActaHortic.1993.347.12 |
| Abstract:
The current apple scab warning system in Integrated Production (IP) is based on the prediction of Mills infection periods calculated by monitoring the micro-climatic factors (duration of leaf wetness and temperature). An improved warning system should also consider the parameters "ascospore release" and "availability of susceptible tissue". In 1991 and in 1992 field trials were made to check the applicability and the limitations of an improved warning system as well as the applicability of an intervention threshold in secondary season. In 1991 only four fungicide treatments were made compared to eight treatments with the current warning system. With both strategies the final scab incidence at harvest was below 1% (fruits and leaves) and 6% (shoots). In 1992 at the same site only three fungicide applications were made compared with eight with the IP strategy. At the end of July scab incidence with both strategies was 0% (fruits), below 1.5% (leaves) and 5% (shoots). At another site the new system enabled one of eight fungicide treatments to be saved. Scab incidence was higher at this site (1–5% scabbed fruit and leaves and 30–36% scabbed shoots at the beginning of August), but no significant difference in scab incidence between the conventional and the improved apple scab warning system was noticed. | |
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