I am here at my mother-in-law’s for a week, she is in Yuba City near Sacramento and her 5 year old Asian pears have fireblight for the first time. I am rapidly reading everything here, I guess the first step is to prune all of this off and disinfect the shears each time?
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Is it worth spraying anything at this point? We went to Sutter Orchard supply and they recommended pruning 6 inches below the damage. They mentioned copper and a fungicide spray as prevention. But were neutral about spraying now
Your photo is of the “Touchdown Jesus,” an erstwhile landmark between Cincinnati and Dayton, OH, along I-75, that was totally destroyed by lightning twelve years ago on the night of 14 Jun 2010. Local firefighters risked eternal damnation, trying to extinguish the blaze.
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Yes, prune 8" - 12" behind the strike. Fire Blight is bacterial, so spraying a fungicide won’t be effective. Copper is a bacterial and fungicide preventative, so spraying copper now would not be effective. The only thing you may want to consider at this point is spraying Streptomyacin, an antibiotic. Some strains of fire blight are now resistant to Streptomyacin though. Either bag and dispose of your prunings or burn them.
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Here are the late Prof. Steiner’s blight cutting instructions on his Ugly Stub Method, and they are without equal: Through a process I call “ugly stub” cutting, cuts are still made 8 to 12 inches below visible symptoms, but always into 2-year or older wood (high carbohydrates) and then leaving a 4- to 5- inch naked stub above the next leaf, spur or branch. Although small cankers will still form around a significant number of these cuts, the ugly stubs can be easily recognized during the
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dormant pruning operation and removed at that time. A number of growers adopting this practice on a regular basis routinely spray paint the ugly stub bright orange so that they can be more easily located during the winter. This procedure is an important step in that it removes sources of inoculum in the orchard quickly which reduces the rate at which secondary infections occur and it has longer term effects in that fewer cankers are left in the orchard to fuel next year’s epidemic. It also has the very practical advantage of being much faster in that the tedious job of sterilizing tools between cuts is not necessary so long as the only consideration at the time is the removal of infected shoots. This last caution is important because such cutting forays should never be combined with routine summer pruning efforts.
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I once wrote something on fire blight for a master gardening assignment. I’ll include the relevant information here:
Regarding Fire Blight, this is a disease caused by the bacterium Erwinia amylovora. It spreads most commonly through infecting open flower blossoms.
Unfortunately once infected, the plant will harbor the pathogen indefinitely. The bacterium will not go away on its own. Hence prevention is the best treatment.
Avoid applying Nitrogen fertilizers and pruning that encourages shoot formation.
Avoid irrigating trees in bloom, and generally avoid overly wet conditions particularly when the temperature is 75 - 85 deg F.
Choose tolerant varieties if possible. Late-blooming trees are more heavily damaged by fire blight.
Chemical control may be attempted with potentially mixed results. Copper products can be applied to reduce new infections on open blossoms, but will not control an existing infection if it has already reached the wood. Apply at four- to five-day intervals during periods of high humidity and until late bloom is over.
For active management of an infection, infected wood should be pruned out. This can be done in summer or in winter, not when the bacteria is actively spreading, or in early spring as soon as infections appear. Use clean shears and consider disinfecting shears in 10% bleach solution in between cuts to prevent further spread. The location of the cut is critical to remove the infected tissue.
To locate the correct cutting site, find the lower edge of the visible infection in the branch, trace that infected branch back to its point of attachment, and cut at the next branch juncture down without harming the branch collar. This will remove the infected branch and the branch to which it is attached.
| | /
| | /____ affected branch
| | /
| |/ <--- cut here
| |
Here, in this poorly drawn example, the affected branch in red would require a cut at the next node down.
On the trunk or another location where pruning is not possible, scraping the bark down to the cambium layer may help prevent the spread. Remove discolored tissue and an additional 6 inches more beyond the boundaries of the infected tissue to prevent the spread (the bacteria spreads through the bark). This procedure is best done in winter when trees are dormant and bacteria aren’t active in the tree.
tl;dr if you do prune out the infection, make sure that conditions are DRY, otherwise you are making it easier for the bacteria to spread and multiply by creating fresh wounds for them to enter through.
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What @hambone mentioned about spraying the cut immediately after pruning makes a lot of sense to me as well. Welcome to the forum!
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I have driven by it many times.
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Thanks everyone! I tried to follow your instructions and I will come back in the winter to prune off the ugly stubs. When is the best time to do this pruning here in the Sacramento valley?
@disc4tw I don’t know if you were welcoming me to the forum but I have been around for a few years. I keep moving and leaving fruit trees behind (CO>CA>and now Portland, Oregon with a very small yard). But I come here for the friendly advice whenever I am staying in Yuba CIty for a few days.
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Found this on my Gold Rush today…
I have seen 3 other apple trees and 4 or 5 pears start out like this and eventually die here.
GR is supposed to be resistent… I whacked it back… we will see…
Arg…
You’d be surprised then, Andy, to learn that my use of “SOAP SHIELD” Flowable Liquid Copper ‘fungicide’ from GardensAlive --in combination with cutting just 6-8 inches ‘inward’ from blighted branch tips on the Keiffer Pear section of a multivar tree, Halted an early-fruit-period (mid-May) Blight Infection 3 years ago.
I had nothing to Lose in trying Copper–but it worked.
I may have been fortunate that my tree ‘caught’ a less-bacteriacide-resistant strain of the Blight.,
Zone 10A, Foothills of south-east San Fernando Valley (Los Angeles)
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Not really. You cut away the infected area and used the copper to control reinfestation, that’s certainly reasonable. My prior statement implies use of copper after infestation would be futile, and you’re correct in pointing out that would not be accurate.
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