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| Authors: | C. Jacquart-Romon, D. Payen, J.P. Paulin |
Abstract:
Billing's system l has not been devised to be used as a spray warning system.
Nevertheless, it could provide suitable basis for such a system, as soon as reliable weather forecasts of suitable meteorological data are available.
A tentative computerized system is proposed, based on the analysis of climatic data and inoculum potential during 3 distinct consecutive periods :
- climatic data are computerized daily, to provide informations on the climatic potential of the disease (PD 9 days, rank of incubation periods, infection days…). Some of these informations are general for all 3 periods, others are specific for each of them.
- forecast for climatic factors considered to be of importance for each period can be included daily, and their consequences for the potential of disease are calculated,
- then, the climatic risk is rated (from 1 to 6).
- the local inoculum is estimated according to the past history of the disease in the surroundings, and rated (from 1 to 5).
- a combination of these ratings for these 3 periods allows a graded warning (no action, observation and pruning out of symptoms, spray) which remains to be adjusted to local conditions (varieties, growing conditions, vicinity of inoculum sources).
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