2026 Disease Update: Fire Blight Infection April 14-15

Thanks to the unpredictable nature of hot days, many in the region experienced severe thunderstorms and significant rainfall late yesterday, Tuesday, April 14. This was not in the forecast. There was no warning that thunderstorms might occur. Those who experienced this weather were in bloom, and possibly in full bloom. Unfortunately, this was a significant fire blight infection event. 

If you did not spray strep before yesterday's storm(s): It is NOT too late. Spray Today. We are in a window of time when streptomycin should still work to protect the blossoms. Streptomycin is partially systemic and should penetrate the nectaries; this penetration is enhanced when tank-mixed with an adjuvant, such as Regulaid. Bacteria should be killed.

If you want to add more oomph to your tank mix, given that we are in the middle of a severe fire blight period: Include FungOUT. This is citric acid, and when added to your spray mix will lower the pH of the tank. Erwinia amylovora dislikes an acidic environment, and this, in theory, should enhance streptomycin's control.

Disclaimer: I have not tested this hypothesis yet. I'm doing it this year, as we speak, to know for certain. Research from Oregon State (Ken Johnson) showed that when acidifying antibiotic sprays (either streptomycin or oxytetracycline), the antibiotic was more effective at controlling blossom blight than the antibiotic alone. I’ve also heard anecdotal reports that growers who tank-mixed strep and FungOUT last year saw much less fire blight in those orchards than in orchards where FungOUT was not included. So use this product at your own discretion.

Additional Options: Including plant defense elicitors (Actigard) and Apogee/Kudos will also help address potential aftermath in the following weeks. Consider incorporating these into your spray tank today. Yes, it will be expensive. But it's more expensive to lose orchards to fire blight.

Looking at the forecast through the weekend: Even if you spray strep today, you may need another strep spray later in the week (~April 18) because the hot weather will encourage any additional blossoms to open, and the temps will favor the bacterial load to skyrocket once again. Please be vigilant…and stay alert. I have a feeling we are not out of the woods yet with the unpredictable weather.

For more information, please refer to the article from April 13, 2026.