Control of fire blight (Erwinia amylovora) by a novel strain 49M of Pseudomonas graminis from the phyllosphere of apple (Malus spp.)

My experience is once blight is in the orchard in a given year it will continue to re-infect until the temperatures get hot enough to roast it out. We had a really bad early spring wave, the worst in ten or more years here, and there have continued to be lots of small outbreaks since then. It is mainly the thin small shoots getting hit, not the vigorous ones. They have less vigor and less resistance.

@hambone thanks for that list, I may have seen it before but can’t remember. In looking through it is accurate on two varieties I didn’t have in the last wave: both Suncrisp and Ginger Gold are getting a lot of hits now. So far neither is getting major strikes just lots of small shoot strikes.


Scott- That list of factors was all mine, I edited post to reflect.

My pears are sailing through this bad blight year with just a single small strike vs hundreds of strikes in the surrounding apples. 2024: more pears; fewer apples.

I clipped a chart from some email from Washingon State University that discussed FB management for their area. .

Non-Antibiotic Products

In summary analysis of eight Washington trials Alum (potassium aluminum sulfate), Blossom Protect (A. pullulans) and several copper products (Previsto, Mastercop, Instill) provided good disease suppression of 70% to 73% similar to antibiotic checks (DuPont et al. 2023) (Figure 9). Several essential oil, copper, peracetic acid-peroxide and biological products (Serenade Opti, Cueva, Oxidate 5.0, Jet Ag, Thyme Guard, Thymox and Cinnerate) provided intermediate disease suppression between 45% to 62% significantly better than the water-treated control.

figure showing releative efficacy of non antibiotic materials.

Interesting to compare their recommendations where a lot of FB bacteria has developed resistance to strep against the recommendations I see for FB management from universities in the east. I noticed that lime sulfur is popular in organic programs in Washington.

Best information I have seen on FB is in the WSU link below: