Apple Alert: Blossom Blight Infection: May 1-5
For any trees still in bloom (including rat tail bloom) there are numerous blossom blight infections predicted by the NEWA fire blight forecasting system from May 1-5. Models indicate that all conditions with the exception of a wetting event will be satisfied. Thus, any extended dew periods or even a fungicide/insecticide application that does not contain an antibiotic could trigger an infection. More specific infection events by region are:
Henderson County (Edneyville Area): High/Extreme: May 3, 4, 5
Henderson County (Flat Rock Area): High: May 2; High/Extreme: May 3, 4, 5
Polk County: Infection/Extreme: May 1, 2, 3, 4, 5
Brushy Mountains (Moravian Falls): High: May 2; High/Extreme: May 3, 4, 5
Morganton: Infection/Extreme: 5/2; High/Extreme: May 2, 3, 4, 5
- High Risk: If there are open blossoms in your block, a high risk of a blossom blight infection event means that 2 of 3 requirements (see Bloom Disease Update )are satisfied for blossom blight to occur. A preventative streptomycin or other bactericide application should be considered prior to a wetting period (dew or precipitation).
- Extreme Risk: If there are open blossoms in your block, an extreme risk of a blossom blight infection event means that 3 of 3 requirements (see Bloom Disease Update) are satisfied for blossom blight to occur. A preventative streptomycin or alternative bactericide application should be made prior to a wetting period (dew or precipitation).
If you are using the NEWA forecasting system, and plug in that you made a strep spray prior to the first scheduled infection event this week (e.g. on May 1), you might see another blossom blight infection warning come up for this week. I advise you to make a judgement call with that. With no rain, all OPEN blossoms will be protected with strep for at least three days, if not longer. If you still have some unopened flowers, you may want to consider another strep spray if NEWA calls for it.
For a list of registered products for blossom blight control, please refer to the NC State University Fire Blight fact sheet or to the 2018 Integrated Orchard Management Guide for Commercial Apples in the Southeast.
Once again, I stress this is not the time to skip a strep spray if there are open blossoms!