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scab conundrums

Posted by Shelah Horvitz 
scab conundrums
June 21, 2015 07:45PM
I am writing to learn about scab recommendations.

This past winter, my husband and I bought a 15-acre property, of which maybe 1/2 acre contained an existing orchard that had been neglected for a few years. This spring we bought and planted numerous trees, of which about 17 were cider apples, and expanded the orchard. The previous owners didn't tell us much about the property so we didn't know what problems we would have. In planting and spraying we have followed Michael Phillips's suggestions as closely as we can; I spray pretty much weekly with a combination of neem, beneficial bacteria, fish concentrate, and then when the nettles and horsetail came up, I added teas with them. Since I had no idea what kind of pest or disease pressure we would have, I haven't taken any particular precautions. I figured it would be best to find out what we're dealing with before targeting problems we may not have.

The one thing where we're really remiss is with the ramial wood chips. My husband and I have been looking for a wood chipper for, well, maybe six months. It's driving me crazy that we don't have one yet. We were hoping to get one used and affordable but it looks like we might have to bite the bullet and get one new and really expensive. But otherwise, we've been pretty much going by the book in how we're raising our trees.

This week I notice we suddenly have black spots all over our pear trees, most of which we inherited from the previous owners. We have a little bit of brown spots on some of our cider apples. I am new to orcharding but these spots look like the images on the web for pear and apple scab. It's been a cold spring. The damage on the pears might be fabrea leaf spot and not scab but either way it would be a fungal problem. So I looked through both of Michael Phillips's books to find out what to do about the damage. He mentioned micronized sulfur, which I don't have on hand.

I went to the local farmer's union and the only thing they had was a combination copper/sulfur dust, with poison warnings on the label. I was not keen on using it. My husband and I went up on ladders instead and removed and hauled away every single spotty leaf from our trees. I don't know if that was the right thing to do. It involved no poison but it also involved some pretty radical pruning during a time of year when we should not be pruning. Really, I don't know what to do.

By the way, about 500 yards away from our orchard, we have a wild orchard of apples which are as healthy as the day is long. Not a trace of scab. No curculio. No codling moth damage. No curler mites. We've got all these problems in the orchard. In the wild orchard, nirvana. They just need to be pruned.

I don't want to contaminate my nice nutritional sprayer with pesticides. Should I get a dedicated sulfur sprayer, one maybe that includes agitation to keep the sulfur in solution, and use the NuFilm with it? It's a considerable investment, a few hundred dollars for all this, especially considering I don't want to putting poisons on my apples at all. What I am reading on the forum is that spraying with sulfur is a necessary evil.

What's the consensus?

Shelah Horvitz
Savage Cider Orchards
Zone 4b in Weld, ME

Edited 1 time(s). Last edit at 06/21/2015 11:11PM by Michael Phillips.
Re: Comparing Holistic and Organic Programmes for Scab
June 21, 2015 10:29PM
Hello Shelah,
There are at least 2 very important factors you need to consider before going further in your thoughts for a scab management strategy...
1- What do you intend to do with the apples? Selling at the market? Making cider or juice? Some other sort of transformation?
2- What is your varietal selection like? Mostly scab resistant, or mostly scab sensitive?

So really, the question is what sort of percentage of clean apples do you need? For example, in my case, I mostly make cider with my apples, but unfortunately most of my old trees were inherited from a previous owner and are sensitive to scab. But I am happy if I get 25% of clean apples as this is plenty enough for the family consumption. The rest goes to the press and it doesn't matter if scabby. I can easily fulfill my needs of clean apples without making any spraying - hence I don't spray anything for scab. Some maintenance, pruning so the tree dries more quickly after rain, that's all.

On the other hand, if you do intend to sell apples at the market, then you probably need to have about 75% clean apples and yes you'll have to work hard and spray to get this - unless you mostly have scab resistant varieties.

You wrote:

By the way, about 500 yards away from our orchard, we have a wild orchard of apples which are as healthy as the day is long. Not a trace of scab. No curculio. No codling moth damage. No curler mites. We've got all these problems in the orchard. In the wild orchard, nirvana. They just need to be pruned.
Are these seedling trees? You might have a gold mine there! If you find one that has some bitterness in the taste and little acidity (i.e. somewhat bland), you might have a great bittersweer cider apple!!!


Jolicoeur Orchard
Zone 4 in Quebec
Author, The New Cider Maker's Handbook
Re: scab conundrums
June 22, 2015 03:30PM
How one grows tree fruit begins with understanding the big picture:
    Chemical fungicides break the fungal connection in the soil which is key to a strong immune response by the tree. Treat symptoms forever and you grow less meaningful fruit as regards our own health.

    Organic mineral fungicides in moderation (applied only when truly necessary) can be appropriate for orchards in transition, long periods of limited photosynthesis, and those diseases that overwinter in the buds and in twig cankers. That said, such biological compromise should be understood as just that. Conventional organic growers applying copper, sulfur, and lime sulfur 5 or 12 or even 20 or more times a season do not have the same degree of natural advantage at work in overly-sedated trees.

    Competitive colonization and fatty acid nutrition and immune stimulants are a whole other way of thinking. The holistic approach is all about boosting natural advantage to the fullest. Investing in broad mineralization, fungal foods like those ramial wood chips, and definite work every fall to abet leaf decomposition and heal twig cankers sets the stage for plausible disease resistance in any fruit variety.
Learning to "dance with scab and company" means intimately understanding where particular diseases come from, infection timing, and preemptive actions that can counter high pressure scenarios. Every season is a new opportunity to learn. Every season is a new opportunity to dance. Hang in there!

Lost Nation Orchard
Zone 4b in New Hampshire

Edited 1 time(s). Last edit at 06/23/2015 03:11PM by Michael Phillips.
Re: Comparing Holistic and Organic Programmes for Scab
June 22, 2015 03:48PM
First, I want to thank you for responding, and responding so quickly. As my husband said, "Wow, both your heroes (Joliceur and Phillips) responded on your very first post!" I am very honored to hear from you and Mr. Phillips. You are both so generous with your advice and your time. If there is a resurgence of holistic apple growing and fine cider brewing in the English-speaking world, you two are largely responsible.

That said, let me address the points you made.

When we came to our property, we originally had in mind the idea of subsistence farming. And we asked the land, "What do you *want* to grow?" We noticed that despite off-the-charts deer pressure — the previous owners treated the deer as pets and fed them apples and produce from the orchard, in the middle of the orchard, so that the trees were nibbled to stubs — when you got to a height beyond the deer's reach, especially in the wild orchard, the trees were in great shape. Despite the fact that most of our dozen or so wild apple trees are so shaded by pines and firs that they don't blossom, the one or two that have light are loaded with little apples. I was reading your book early this spring, and was gladdened to learn about the possibilities of wild seedlings. These trees — not so young, maybe 30 years old — were planted by the deer, so I consider them to be gifts from the deer, which is as cool as it gets. We don't know yet if these apples are good for cider. But we think the odds are high, which is why I named the orchard "savage cider", because I think there is a good chance that some of the apples that go into our cider will be feral, apples who have survived the law of tooth and fang. Ferocious apples.

I have no intention of trying to sell our apples at market. I am growing the kinds of apples I can't buy at market, because the point of growing these apples is to have the ingredients to make interesting cider. When I decided to make cider, I was thinking of how alcohol is a recession-proof industry, how really fine cider is rare and hard to find, and how I love a good, complex, bitter cider more than beer, more than wine. We will always be a small operation, but I want the quality to always be our foremost consideration. That is why I am trying to make our apples as healthy and disease-free as possible. I know scab is OK for cider, but I want to at least shoot for apples as close to perfect as I can. That said, there is the time constraint. I work as a software engineer in Boston, four hours away. I come up every weekend. So I cannot be there to do the intensive monitoring and spraying it would take to have a perfect crop. Someday when the economy goes south and I become unemployable because I am in a field that favors the very young, I will then be in Maine full-time and will be able to spend more time with my trees. But right now, I can only expect what can be achieved with weekly care.

You asked what kind of apples we're growing. Well, the trees we inherited were a Cortland and a Honeycrisp. We planted one each of Ashmead's Kernel, Bramtot, Canadian Strawberry, Cox Orange Pippin, Dabinette, Ellis Bitter, Grimes Golden, Harrison, Kingston Black, Whitney Crab, and Yarlington Mill — mostly English bittersweets. Of these, the Bramtot and Grimes Golden are doing the best, while the Canadian Strawberry and Kingston Black are in trouble. So, scab-resistant? Some of them.

That said, our healthiest apples are two Gravensteins. I don't know if they will make good hard cider. I've read the warnings about early apples and tart apples. We'll see. But there's a story about the Gravensteins. Before my husband and I married a few years ago — he's a Bergener from Norway — he drove me down by the Hardanger Fjord, which you may know is a fabulous apple-growing region. It's a place of mountain crofts, light so clear it hurts your eyes, 21 hours of sunlight in the summer, almost daily rain, grass so green it's almost fluorescent. Mile upon mile of happy sheep lounging in pastures. Houses with sod roofs and trees growing out of them. And fields of Gravensteins. You try the apple juice there and it's a revelation. We get Gravenstein apple juice here from California, and it's very good, but because of the terroir in Hardanger, the apples are so flavorful and sprightly that the juice there is well, like you've never had apple juice before. In Maine, we have colder winters, less rain, and far fewer light hours to the day. We can't reproduce their growing conditions. Still, we'll see what quality of apple we can achieve. Now, you may be interested in how they grow these marvelous apples in Norway. They're dwarves, coppiced, in tight rows. An apple orchard in Hardanger doesn't look too different from a wine vineyard in Sonoma, except everything is impossibly green.

So we'll see how we do with our terroir here. We're growing mostly standards because of the deer pressure, and a lot of our time is taken up with the effort to put up a metal eight-foot deer fence. It will take us the rest of the summer. I suspect that the English apples may not do too well. We have a bunch of young rootstocks growing, and some Mainer friends eager to show us local wild trees from which we can take scion wood. I'll have to learn how to graft. I am interested in John Bunker's heritage apple project and if we find any wonderful new varieties from our local wild trees, we will certainly share them.

We would both like to thank you for essentially setting our minds at ease about the scab. I don't want to be spraying copper or sulfur and if I don't have to, I don't want to. I want my apples to be organic or as close to organic as I can get. I don't expect any kind of yield for several years, but in the interim I will be buying apples from other growers and learning how to brew cider. I have been giving your book a close reading and I cannot wait to get to the Cider Days in Franklin to see and taste what other people have achieved.

Surely, right now at least, this is great fun.

Shelah Horvitz
Savage Cider Orchards
Zone 4b, Weld, ME
Re: scab conundrums
June 23, 2015 12:03PM
Shelah, we agree wholeheartedly with what Claude and Michael have written, and with what you have concluded - if you don’t need a high percentage of blemish-free fruit, then don’t even think about spraying copper/sulphur/lime sulphur. We are running about 20 acres of organic orchard, and it is our sole source of income – we must produce a high percentage of blemish free fruit to remain in business. As an alternative to the copper/sulphur approach, we have tried sprays of compost tea, neem, fish emulsion, etc. over the years, but have not been able to achieve adequate control of scab. This had more to do with our inconsistencies/failings than it had to do with the theory of holistic scab management. We recently emailed Michael with the following, which he thought would be a good addition to this discussion:

We still haven’t graduated to a holistic scab management regime, although that is our ultimate aim. It is just that we have been in survival mode and chasing our tail these past few years. A reduction in orchard size and increased help from Wwoofers should help to change all that in the next season or two……..

So what we have been doing isn’t really very sophisticated. We simply spray just before (i.e. 6 to 12 hours) each forecast rain event, some years this can be as often as every 5 to 7 days in spring (although this certainly wasn’t the case last spring). But the wettable sulphur rate is fairly low, at 3 ½ kg/ha. What you have rightly described as “the continuous sulphur bath approach” – not good! They do give out Black Spot (a.k.a apple scab!) warnings for the Adelaide Hills growers, but that is too far away to be of any use to us.

In spring we usually have two or three rainfall events which are responsible for most of the Black Spot infection – the worst seem to be in the 10 to 14 days after petal fall. We think we have a fairly good feel of which are the crucial wetting events. Because we have mild winters and Black Spot can survive on twigs and buds, we don’t really have a starting point so the degree day calculations, etc. are not all that useful for us (or so we think in our ignorance!).

This coming season, we will endeavour to treat a section of the orchard “properly”, and do the full holistic programme – including better weed control. We think tree health (and therefore immune function) in our orchard has been compromised by competition from large tussock forming grasses (phalaris and cocksfoot) at times of high nutrient demand, including Black Spot infection times. We do believe that controlling the tussocks and then introducing understorey herbs, using mulches, ramial wood chips and foliar sprays of neem, fish, etc. will result in healthier trees, zero sulphur/copper requirement and better tasting fruit. So we must do it!!

The whole point is that Michael has actually done it. In recent years he has been able to achieve what most people considered impossible (and many still do) - control of scab using solely holistic practices.

Kalangadoo Orchard
On the “other side” in South Australia
Re: scab conundrums
June 24, 2015 10:07PM
I don't know if I've just been dumbassed lucky or what ....... When I started following Michaels direction I went in head first . There was some wish to do things healthier but fear may have been on top of the list . I was watching my dad give way to pesticide poisoning , just after finding Michaels website the hose popped on my sprayer and I took that full in the face ( mask on ) . That was the last time I used chemicals . My timing is off some of the time , I remember putting surround on in Aug. once because I was going to be away for a time . Don't do that unless your willing to polish your apples by hand surround really does not wash off to easy . But I had no codling moth that year !

I did get hit with scab one year the biggest infection was about the size of a pencil eraser but most was pencil dot size . My neighbour was wiped out . Michael did offer to send me some which I respectfully decline .

Codling moth ; ( maybe this should be elsewhere but I'm offering my results ) I've come down from over 10% to last year though there were 13 in the trap no damage was found
by our local authority . ( SIR was formed in BC to irradicate CM ) We are 7 weeks into the " season " I'm sitting with 0 in the trap and have not found any damage .

Shelah , a thought on your chipper have you looked at renting . I took out 50 of my 3/4 size trees so I could replant . I chipped everything that was to small to use for fire wood . Renting a machine for the day $160. ( that was a big one does 6" material )
Re: scab conundrums
June 25, 2015 04:40AM
David, perhaps if we start consistently doing what Michael and yourself have been doing, we will become "dumbassed lucky" too!

Kalangadoo Orchard
On the “other side” in South Australia

Edited 1 time(s). Last edit at 06/25/2015 04:44AM by Michelle & Chris McColl.
Re: scab conundrums
June 27, 2015 01:20PM
Today I see that some of the trees have been attacked by scab so badly I doubt they will survive our -20 degree winter. But I notice a pattern: the trees hit the worst are near the pines. Upslope of the orchard, about 30 feet before the apple trees start, we have two white pines each about 100 feet tall. The trees with the worst scab are the ones closest to the pines. It's also a little drier there, being on top of the slope, but it's a very gentle grade, maybe 15 degrees. Between the trees we have a mixture mostly of different kinds of clover and meadow flowers like coltsfoot and dandelion. Below the pines, we have some bare patches and crab grass and not as much clover.

About 50 feet away from the pines and away from the orchard, still upslope, the grass is lush. So the issue is not rain and drying out: that's where the compost pile is.

The scabby trees are in full sun and are not being shaded by anything. They are not close enough to the pines that they are being dripped upon by the pines. There is no appreciable drop of pine needles in the vicinity of these apple trees.

I am wondering, are the pines sucking up all the available nutrients nearby, so that the nearby trees are getting scab because they're undernourished and can't fight off the pathogen? Or are the pines putting out some kind of poison to reduce competition? If they were doing that, the apple trees towards the back should be suffering, because there are many conifers there too, although they are downslope of the apples. Our most distant apple, closest to the confers at back, is not doing great but it's OK. More to the point, the plums back there, also by conifers, are going great guns.

If the pines are just starving out the nearby scabby apple trees, should I give the scabby trees some compost or use compost tea, or some other nutrient or nutrients? Should I move the scabby apple trees? Would it kill them to move them now? They're young trees, planted this spring.

It's going to rain tonight and all day tomorrow, and most of next week.

Thanks for all your good help and expertise.

Savage Cider Orchard
Zone 4b, Weld, ME

Edited 3 time(s). Last edit at 06/27/2015 01:31PM by Shelah Horvitz.
Re: scab conundrums
June 27, 2015 07:04PM
I doubt there is any direct connection (e.g., a poison) between the pines and the scabby trees. The only way that scab can get passed from one tree to the next is within the Malus family -- so basically from apple to apple. There are no alternate hosts. Which leads to wonder about varietal susceptibility. You haven't mentioned the varieties that are scabby and the ones that aren't -- well, sort of. But not with any specificity regarding location within the orchard or proximity to the old orchard and/or pines. IN my book, all apples are susceptible to scab at one level or another. Even some of the old scab immune varieties are not a resistant as they used to be (the Vf gene is breaking down). Excluding any locational susceptibility, then microclimate or nutrition is the only place to look. Are the trees that are scabby shaded so they stay wet longer (longer wetting/infection period)? Are the trees otherwise healthy (have you done a leaf or soil analysis?)? The pines would decrease the pH, but I doubt based on your description that the pH will vary much from one spot to another in the orchard. A lower pH could theoretically be beneficial as scab spores have a harder time germinating in a pH environment. As well, cobalt, which seems to have some role in limiting the success of spore germination is more available int he soil at lower pHs, but that is all theoretical at this point.

So, you have to have a local source for scab and it doesnt sound from your earlier posts that older trees were the source (healthier than the day is long!), unless I didn't that post. It is possibly they have had scab in the past and the overwintering inoculum on the ground is the source, so sanitation for next year would be a good place to start in fixing the problem. For now, you need to protect the rest of the developing foliage from any further primary and any future secondary infections. Unprotected, scab will run through the trees all season long -- then you have exacerbated your problem for next year by creating next's year's infection source. As painful as it might be, at this point using a few sprays of sulfur will protect those trees this season. Meanwhile you can work on cleaning up the orchard floor to reduce overwintering inoculum. Depending on how much you have to clean up -- you can rake and compost; others have used a leaf sucker to pick up the leaves and grind them through a pulverizer. After you've cleaned up the ground, a good pile of compost and ramial mulch will help to break down anything you missed and establish that fungal environment we all strive for. But for now you need to get your trees healthy and through the winter. Protect the foliage (sulfur), clean up the ground (rake and compost), prepare for next year (compost/mulch). Also, try to identify any surrounding confounding issues that you havent recognized -- there may be more to this puzzle than you realize.

Once you get things back on track and in balance, then a little scab isn't bad. But too much, as you've pointed out, can be detrimental to any meaningful fruit production,.

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: scab conundrums
June 27, 2015 07:41PM
OK! Thank you for the answer. I have started the sulfur and ordered the requisite materials so I can keep up the pressure.

Because growers are out there looking for what varieties to plant, I will write here which of my varieties have the worst scab.

Hands-down the worst is Dabinette. I will say my little M111 was weak to begin with, the only Dabinette left at the Fedco tree sale. It's been devastated by scab. We'll see if I can bring it back.

Second worst is Canadian Strawberry, but it also had been attacked first by leaf-curler mites so its resistance was down.

Every other one of my trees, including pear and plum, also has a small amount of scab but it's really the Dabinette that's in mortal danger.

Moving forward next year, I will want to balance out my apple varieties with a low-acid base apple, because except for one Cortland, I don't have any. I am thinking of Baldwin, especially because I understand it is disease- and insect-resistant. What other scab-resistant apples have cold-weather growers had success with? Would Liberty be a good choice? What about Pomme Grise?

Savage Cider Orchards
Zone 4b, Weld, ME

Edited 1 time(s). Last edit at 06/28/2015 07:50PM by Shelah Horvitz.
Re: scab conundrums
July 03, 2015 05:12AM
Now I have a question regarding how long you need to wait after a sulfur application before you can spray nutritional teas again.

Last weekend I dusted with a copper/sulfur mix because that was all I could find in the stores and the equipment/materials to spray micronized sulfur hadn't arrived yet (still hasn't). It rained three days during the week, but today I see almost all the trees look better. Dabinette has come back to life. The only one that looks unhappy is Gravenstein — I stumbled on that section in _The Apple Grower_ that says Gravenstein doesn't do well with copper only today, dammit.

Still, now I'm back at my orchard and I could be useful. Since there's still sulfur dust residue on the leaves I don't see a reason to spray more sulfur yet. I want to spray nutritional sprays tomorrow but don't know if anything clashes with the copper/sulfur dust that's on it now.

The question is, what makes sense to use when there's still fungicide on the leaves.

I have fermented horsetail tea and the fermented beneficial bacteria ready to spray. Beneficial bacteria should be OK because the fungicide is killing fungi, not bacteria, right?
The horsetail tea should be OK because it's essentially a silicon delivery system.

Michael says in the "Just Talk" section, "Tim makes a good point about halting secondary infection with nutritional/ fatty acid sprays. Part of this is immune function at full bore; part of this is calcium and silica boosts to the cuticle of leaf and fruit alike." That makes me guess it would be OK to spray some neem on but I remember reading somewhere that I need like ten days between sulfur and oil. By now it will be I think six days. Is it too early to use neem? Or are we at a point in the season where if we are seeing scab, then obviously we're deep into secondary infection and spraying with neem is shutting the barn door after the horse is gone. So the bigger question is, is it actually too _late_ to use neem?

And what about liquid fish? It seems to me just nutritional, don't see how it could clash with the sulfur or copper. Is it too early to spray with liquid fish?

And isn't this the time I should be spraying the earth with some nematodes? Would the sulfur kill them?

Savage Cider Orchard
Zone 4b, Weld, ME
Re: scab conundrums
July 03, 2015 06:09AM
Shelah Horvitz Wrote:
> Moving forward next year, I will want to balance
> out my apple varieties with a low-acid base apple,
> because except for one Cortland, I don't have any.
> I am thinking of Baldwin, especially because I
> understand it is disease- and insect-resistant.
> What other scab-resistant apples have cold-weather
> growers had success with? Would Liberty be a good
> choice? What about Pomme Grise?

This is getting off topic here as we should be on scab... But you probably mean high-acid base apple, as all mentioned (Cortland, Baldwin, Liberty, Pomme grise) are medium to high acidity varieties. I think the four are good although I don't have direct experience with Baldwin. Here in Quebec, Liberty is certainly a very commendable variety, very productive and easy tree. Pomme grise has fantastic flavor but not as productive.

Jolicoeur Orchard
Zone 4 in Quebec
Author, The New Cider Maker's Handbook
Re: scab conundrums
July 24, 2016 03:50PM
How many people are having luck with scab control using Michael's holistic programme this season, rather than the "continuous sulphur bath" approach?
We had the cleanest crop we have ever had in 2016, but that was mostly due to our district having its driest Spring on record.

Kalangadoo Orchard
On the “other side” in South Australia
Re: scab conundrums
July 24, 2016 04:00PM
This year we've had zero scab. The trees are so healthy I've only sprayed them with the nutritional neem/beneficials once. They're bursting with life and are making great progress. I think this has everything to do with the dry spring, plus the good attentions of last year (i.e. ramial mulch, mycorrhizal injections, weekly nutritional sprayings). We have had no blossoms but this is only the second year after planting so I don't want them trying to make fruit this year. So I have not sprayed for scab, codling moth, nothing, and the trees are doing great.

What's more, last year (which was the first year we had the property) all the apples, peaches and plums that existed from the previous owners were plagued with borers. They looked like they had never been pruned and were all tangled with vegetative growth. During the winter I cut them back severely. I figured they were about to die, I had nothing to lose, and this was part of my practice in learning how to prune. This year, I see no frass on the apples and no oozing on the plums and peaches. Trees I thought were going to die are now vigorous and I'm even seeing plums and peaches. I did not expect that pruning would give the trees the strength to fight the borers.

So this has been a very good year.

Savage Orchards
Weld, ME
Zone 4

Edited 2 time(s). Last edit at 07/24/2016 04:04PM by Shelah Horvitz.
Re: scab conundrums
July 26, 2016 04:55PM
Michelle & Chris , I have been following Micheal for about 8yrs now . Because of events one day I was IPM the next I was holistic and I have not looked back since . The one year that I did have scab other orchards around me were totalled . At worst mine was about the size of a pencil eraser but most looked liked CM stings and from memory I'm going to say about 10% effected . Michael was kind enough to offer to ship me over some real scab , ( just for experience purposes of course )

I don't know if it's just dumb ass luck or if theres more to how things happen here for me . Because of off farm work , weather conditions , my timing is definitely not as precise or scientific as Michael would be , but at this time I am more then happy with how things have gone .

Hillview Farms
Vernon , BC
Zone 5
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