There are no chemicals for the control of fireblight registered in the UK. Monitoring and forecasting are therefore a vital part of fireblight prevention and control, which is based on early detection of symptoms and removal of affected tissue to prevent spread.
- Because fireblight in the UK is sporadic, monitoring is best linked to weather, to identify risk periods when symptoms may be present, and field information.
- Monitoring should also include nearby hawthorns and susceptible ornamentals.
- Various fireblight-forecasting systems have been devised worldwide e.g., Maryblyte (USA), but the most reliable system for the UK is Billing’s Integrated System 1995 (BIS95).
- This system can be used manually from weather data collected daily from a reputable meteorological station. The BIS95 system has also been incorporated into ADEM.
- ADEM is a PC-based system giving warnings of several diseases – apple scab, apple mildew and canker as well as fireblight. Weather data is recorded on a logger and downloaded to the PC
- The BIS95 model in ADEM mainly concerns the effects of weather on infection of apple and pear by fireblight bacteria. When assessing risks, the first concern is the effects of weather on infection. However, because infection depends on other factors such as the availability and susceptibility of host tissues, inoculum level, presence of alternative hosts etc., risk days identified by ADEM are potential infection days, not necessarily days of actual infection.
- It is therefore, vital that the BIS95 system is used in conjunction with field information and not alone. Its use is therefore quite different to that of scab and mildew models in ADEM.
- When run, the model scans weather data and identifies potential infection risk days for blossom blight and shoot blight where young green tissue is infected. In this phase, the model assumes that neither host tissue susceptibility nor inoculum are limiting factors. Thus the model indicates days when weather was favourable for infection.
- For each potential infection day, the model also indicates the earliest date when early blight symptoms might be seen. This information is graphically displayed.
- The date when symptoms might be seen is used to time field searches in at risk orchards, to spot infection as soon as possible to limit spread.
- In addition to standard weather data, records should also be kept of host phenology and unusual weather, i.e., storms, wind and hail, which might cause damage to young shoots etc. and increase the fireblight risk.
- BIS can also be used to time sprays during blossom if treatment were available.