|Authors: ||S.C. Gouk, M. Spink, M.R. Laurenson|
|Keywords: ||Erwinia amylovora, weather, infection event|
Erwinia amylovora, the causal pathogen of fire blight, colonises stigmas of apple and pear flowers.
Under warm, wet conditions, infection can occur, leading to the development of blossom blight.
Conditions governing development of blossom and shoot blight described in an American predictive model, MARYBLYTTM, have been used in New Zealand to predict infection events.
The predictive criteria used for blossom blight are: (1) accumulation of at least 110 degree hours ≥ 18.3 °C from pink; (2) an average daily temperature of ≥ 15.6 °C; (3) a wetting event with 0.25 mm rain on the day, or 2.5 mm rain the day before or wetness of > 6 hours; (4) flowers must be open with petals intact.
All four conditions need to be fulfilled on the same day for an infection event to occur.
These predictions matched observed fire blight incidences.
FireWork, a fire blight predictive programme, implements these rules using software written in Delphi 4 for Windows 95 and Windows NT. The programme is driven by weather data stored in the Orchard 2000® weather database.
Throughout the principal horticultural regions of New Zealand, there are over 40 automatic weather stations.
Growers access these stations and use Orchard 2000® software for a range of orchard management decisions.
FireWork has been released for testing by a limited number of users in the 1998–99 season to obtain feedback on its features and ease of use.
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