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Lime Sulfur Induced Chlorosis or Ham Fisted Amateur?

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Lime Sulfur Induced Chlorosis or Ham Fisted Amateur? Empty Lime Sulfur Induced Chlorosis or Ham Fisted Amateur?

Post  wabashene Thu Apr 16, 2009 11:24 am


Am having a major problem with a specimen cotoneaster horizontalis and am looking for advice on possible causes/solutions.

In mid Feb I re-potted the tree and noted that root growth was not particularly extensive althought the tree had thrived over the past 2 years since I aquired it. I did no real root work on the cotoneaster but carefully re-potted in my usual porous mix of Kittydama, Akadama, bark and Hydroleca.

At this stage the tree had, as usual, stayed green and in full leaf throughout the mild-ish UK South coast winter.

All my trees had a light spray or two of dilute lime sulfur over the winter.

We had a bit of a cold snap with 3-4 nights of frost about this time.

A week or two later (early March) I treated the extensive deadwood areas with Lime sulfur. I was reasonably careful to prevent run off onto the soil, but some did occur.

End of March I noticed that large areas of the foliage were turning a dark yellow brown and now, as of last week this process is 99% complete.

I've moved the tree to a larger pot in fresh soil now. Inspection of the roots shows no obvious problems although they do look rather brown with no real white tip growth showing.(but not sure cotoneaster show this trait anyways)

The majority of the foliage has been brown for over 2-3 weeks now but is attached firmly and glossy. (i.e. not going crispy and falling off atm)

fwiw the cambium at trunk base and branch tips remains a healthy green.

Thinking about it, I did some more checking on lime sulfur (calcium polysulfide) and find the the pH is near on 12 (yipes!)

Accordingly, I've dosed the tree with an acidifying iron supplment with a tad of Growmore and await the results.

The tree is very small < 20 cm and has a lot deadwood so I'm wondering if the re-pot, with associated cold weather and the heavy LS application has done for it.

Do we think there's any chance of a totally brown, but otherwise healthy tree making it?

Is it too much to hope for that it's just thrown a wobbler and having a late autumn?

btw I seem to have a very bad track record with the supposedly indestructible cotoneaster. This could be 3 good ones gone west in 2 years.

A problem shared is a problem halved as they say.

atm I'm looking at the lime sulfur as a potential culprit as my other 2 coton's have had the same physical treament but no LS applied recently.

Any opinions?



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Post  Rick Moquin Thu Apr 16, 2009 12:21 pm


Interesting question, glad to see you up and about.

I hear your plight as cotoneasters are indeed extremely robust. Our climate is pretty similar and mine grow like weeds.

My cotoneasters that were in the cold frame are a beautiful green and although I didn't use dormant oil on them this past winter they were always green. Having said that, they only received a spray when given in the fall before going to bed for the winter.

The cotoneasters that I have planted in the ground are all brown. The leaves are still very much attached to the branches and I am not sure if they fall off or not once spring comes along or just change colour as I never paid much attention to the phenomenum.

I see you sprayed them a couple of times over the course of the winter. I am not sure if that is common practice or not. It is my understanding that one spray in the fall is all that is needed, if they are put away under shelter (cold frame greenhouse etc...) vice left in the open.

I was always told to avoid run off of LS into the soil, it may be the culprit but, considering that you have lost a couple in the last couple of years leaves me to believe there might be a common denominator here, in other words maybe the timing of some of your practices may be a little off.

Not fully knowing your climate it seems that mid feb is a little early for repotting trees. IN general terms (my understanding anyway) is that it is carried out just before bud break, this is the signal vice the calendar. Having said that I have repotted cotoneasters (healthy) going into the summer right up until the end of June without any ill effects. Mind you spring for us is much later and outside of the winter of '05/6 where buds broke in early to mid feb, normally mid to end of march before trees that are in the cold frame will break buds.

I have lost several trees over the last couple of years that were store in the cold frame and have come to the conclusion that they remained in the cold frame too long into spring and that I had fried them (the ones in the back row) as the cold frame faces south. This year I took it upon myself to move my trees (deciduous) to the greenhouse (unheated) when they awoke, moving all the conifers that have overwintered in the greenhouse to my benches. So far so good all the cold frame trees are thriving and several are in leaf (protected). The conifers seem to be doing well as well. Ground trees are still very much dormant and will be for the next couple of weeks anyway. Spring was late this year for us Canucks as Easter was last week end, which is a better indicator of spring than the calendar. We have chances of frost here right up until Victoria day.

So Tim I am not quite sure what happened there. You did good with the fresh repot and as cotoneasters are weeds should rebound without to much human interference. Keep it in npartial sun and give it fresh water it should rebound for you.

As an update since we haven't spoken for so long, the trees of choice for my climate are cotoneasters, boxwood and Hinokis. I am no longer going to go against the grain and will concentrate on these species. It has been like that for the last couple of years. I have a burning bush that is coming along extremely well, the downside, this particular species turns really really late in the fall, well after the others in the area have displayed their fall plumage and have since dropped their leaves.
Rick Moquin
Rick Moquin

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Post  JimLewis Thu Apr 16, 2009 1:19 pm

I'm not an expert on cotoneaster, but two of mine have dark leaves now -- after a winter with a few very cold days. Green leaves are coming in after them. Don't know if the dark leaves will green up again, or if they just have to live out their normal lifespan that way, but the trees (both very small) seem to be thriving.

I don't think I'd lose sleep over it. I also don't think the LS spray had anything to do with it, since mine have never seen the stuff.

Jim Lewis - - Western NC - People, when Columbus discovered this country, it was plumb full of nuts and berries. And I'm right here to tell you the berries are just about all gone. Uncle Dave Macon, old-time country musician

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Post  wabashene Thu Apr 16, 2009 1:40 pm

Thanks Rick and Jim for quite a bit of re-assurance.

I am losing a bit of sleep as this is an unusual occurance plus I badgered the creator in a good natured way until he gave in and sold it to me.

I don't mind killing my own creations

Very Happy

I've had cotoneasters for 12 years and never had a healthy one do this - the odd leaf for sure but not a 100% brown out when everything else is in full spring push. The two that did go 100% brown in early summer both died rapidly.

I've got one that drops all its leaves and re-grows each spring deciduous style , one that drops half and two that don't drop any at all including the one in question.

Ostensibly they're all the microphylla/ horizontalis type with the deciduous one being a cutting from the semi deciduous one in fact?????

Don't feel that I moved too early on it re-pot wise and only changed the soil in effect.

Let's hope its some king of bi-annual freak out and thanks


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