The dreaded F word (Fireblight) is showing up in our orchards


#122

Just to give a guess at what they mean:
If bacteria is present in the bark, even far away from the symptomatic area, then the very act of pruning itself is likely driving the bacteria into the cambium.

So therefore sterilizing is ineffective because it is not cross-contamination from a previous cut, re-infection occurs from the pruning cut itself.

I do not know if that is the correct interpretation, but that’s the only interpretation I can come up with that seems logical and consistent with what they’re saying.


#123

Scott and others have advised to wait til dormant season to prune out blight unless you see small oozing droplets on the blighted twigs. I hope I can detect oozing if it’s there. If I see it I will prune away a foot or two of branch and leave a four inch stub.


#124

Firebligt susceptible cultivars become slightly fireblight tolerant when grafted to ultradwarfing rootstocks. They do get fireblight from time to time but the fireblight doesn’t aggressively spread lower in the limbs, oftentimes drying out a couple of inches from the tips and not progressing any further. I was able to enjoy fruits from my Bartlett pear that was grafted to ultradwarfing rootstock. I forgot the ultradwarfing rootstock that came with it.


#125

I’m waging war on FB this year. I lost 4 supposedly FB resistant trees on geneva rootstock last year. I pruned out strikes dutifully but to no avail. I have concluded that apples are simply not possible in my area with out antibiotic sprays. I can count on one hand the number of apple trees I see driving around my town. I suspect there is a very good reason for that. I’m doing my bloom sprays and hopefully that will help. Goldrush survived but cut back to 4 ft . King david had strikes but had the least serious damage.


#126

Barry,
Copper is more effective than antibiotic spray prior to bloom.


#127

I’ve always done copper at 1/4 inch green but I think the FB pressure is too high for it to help much. My goldrush is in full bloom and king David is just getting started. It was so bad last year the Bradford pears looked 50% black foliage. Of course they came through fine and are looking great this spring.


#128

Which trees did you lose? For me, Goldrush was hit hard but survived. Unknown heirloom one a few strikes, but nothing severe. Unknown heirloom two no strikes. Pink lady hit pretty hard. Liberty no strikes, Enterprise no strikes.

The worst for me last year, by far, was Goldrush. Very strange.


#129

@barry
I’m going to be very honest about the problem your having with fireblight and then you can decide if you agree. Those varities such as king David are fireblight magnets and I would graft those over to something easier to grow eg. Nova easygrow, liberty etc. . To be perfectly honest I think the apples such as king David are the worse trees for getting fireblight of any type I know of but some self proclaimed experts will disagree. I live in an extremely high fireblight area and apples such as honeycrisp have not had a single strike that I recall and other trees were killed completely including the roots. It might be worth your time to read through this thread http://www.growingfruit.org/t/disease-resistant-apples/7340


#130

Thanks for the suggestions clark.

Here’s the final tally:
Ark black on g41: dead
Liberty on g41 dead
Williams pride on g890: dead
Priscilla on g41: dead
Goldrush on g30: ok but cut back to 4ft
King david on g222: had strikes last year like the rest but seems fine.
Fugi on m7: dead

You may be correct that KD is a magnet, but it had no more strikes than the others and came through ok. I do plan to graft it over however. I suspect there is a lot of stochasticity to which trees get hit such that reports like mine have little value on their own.

I think doing the ugly stub was a problem. When I pruned them off in dormant season it was clear that those stubs were a home base from which FB ran the tree. Perhaps in my area with long growing season need to prune out stubs as soon as FB slows down in midsummer rather than wait til dormant. Live and learn.


#131

@barry
I prune the fireblight off as soon as I see it. In my area it’s so bad if you leave it the entire tree dies. Kieffer pears get hit hard at times and on those years it’s all I can do to stay ahead of it. If your area is like that you may not be able to grow many apples and pears. I’ve eliminated it in my orchard and the neighbor who was spreading it the worst lost every pear tree ( around 30). I have one neighboring tree that still has it which is a Granny Smith that has lived with it the last several years in the trunk. Not sure why it hasn’t died but it’s producing very little for them. Older trees stop getting hit when growth slows down. We have some really old trees without a single strike.


#132

Can someone please show me an example of a fireblight strike? I’ve never seen one. I do spray with copper here being in North Florida I’ve taken advice from many and decided it was only prudent in such a high humidity area. I have apple trees, Anna, Pink lady, and golden delicious. And a Stark delicious pear and a Bartlett. Both are just on their second year. All the apple as well.


#133

Sure this thread has pictures of fireblight http://www.growingfruit.org/t/late-season-fireblight/2548. Here is another picture from above on a pear I grafted last year. 37D84FA1-C6BA-4D9B-9745-39BB41005F03


#134

Wow. Looks to be easily identifiable. Thanks. From reading yours and other posts it seems it comes on quick. And it appears the remedy is cut the branch or Branch’s off and spray. Great to know.


#135

FB only attacks growing trees so your safe in the winter. Bacterial canker in stone fruit is still active during winter so diseases can be very different in terms of fighting them. The most dangerous time for FB is spring when there is a lot of growth. Copper kills bacteria so spray your trees with copper just prior to bloom to reduce FB bacteria numbers which will help a lot. There is not a point to spray antibiotic to control FB after they bloom because by that point if the bacteria is going to enter the blooms it’s done it already. My rule is I prune pome fruit like apples and pears in the winter and stone fruit like peaches after they start growing.


#136

I find FB strikes on different varieties to be very random. About 4 years ago it rained almost every day during bloom season and 4 of my trees bit the dust to FB and I had FB strikes on many other varieties. My Williams Pride came thru that period like a champ with no damage. I posted at that time Williams Pride to be one of my top 3 for FB resistance. Last year Williams Pride was about my only variety out of 45 to get FB shoot blight and was dead by the end of the summer, go figure.


#137

@Chris_in_GA
That’s hard to read when it’s like that. At my place it’s more straight forward if the tree is resistant long term it will likely live but if it’s not fireblight resistant long term it will likely die. Getting fruit takes practice but I do get plenty of fruit here. I graft non resistant types on resistant types to get hard to grow pear fruit but I know I’m on limited time every time I graft those type of pears.


#138

Don’t believe Apogee has been mentioned yet. It has been shown to significantly reduce the shoot blight phase of FB in Apples.

I spray it twice - once around petal fall and one more time several weeks later.

Also, it helps to use a model to time the strep sprays. NEWA has monitoring stations in many apple growing areas that send data to the Cougarblight FB model. Its a waste of time to spray Strep unless conditions require it, but its important to spray ahead of the rain or the wetting event.


#139

I prune it out right away, but last year pruned branches kept getting reinfected. So if a branch got cut back within 8-12 " of the trunk I tried ugly stub figuring if I pruned to the trunk it would reinfect at the trunk anyway. In hindsight its possible i could have saved them by cutting the entire tree way back to a stump as soon as FB slowed down in July, but it’s tough to pull the trigger on that. I think blueberry did something like that a few years ago.


#140

I planted 6 apple trees last Spring (April '17) and we had the worst, rainy, cool weather all summer long. At the tail end of the summer/early fall they put on a bunch of growth because the weather got a bit better, and that worried me.

I don’t know how I didn’t notice it earlier, but today I noticed my Blue Pearmain and one other tree (I think it was Keepsake) have fire blight. The Blue Pearmain has it the worst, and it’s infected in several areas, one being on the main trunk at the first scaffold (which is where I probably should have topped it when I put it in). It had a wound that was healed over when I got it, but I assumed it was from the cold/warm weather at the nursery. Now I wonder. Would the correct thing to do be to cut the main trunk under the FB below the first scaffold (it’s at least 24" off the ground) and spray with copper? Should I seal the wound after I make the cut?

This tree was large when I received it, it’s around an inch and a half in diameter at the trunk. I just want to try to salvage the tree if I can at this point. The other tree I think I can just remove the top, spray and be OK. I was planning on using copper (Kocide) when it warms up a bit (still snow and ice here in 4b). Am I on the right track?


#141

Cutting the leaders below the infection and spraying with copper may work.

I had a lot of leaders on young trees infected with FB a few years ago that I cut back. Some recovered but most did not, especially the trees that I had to cut low to the ground to remove the FB. Some of the smaller cankers on the leaders healed themselves with no surgery. If I was faced with the same problem again, I would remove the trees with the worst infection and replace them with new trees.