I look at orchard sanitation as a common sense approach. I try my best to practice it when I can.
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The first suggests sanitation reduced infection on leaves and apples by 18-56% compared to control, but no mention is made on what % of control apples were damaged by scab. At any rate an average reduction of 35% wouldn’t help the home orchardist a lot.
At most sites (excepting those with seldom mowed meadow underneath) I generally get full scab control with 2 apps that are my post petal fall sprays.
If you are blowing or raking your leaves anyway, might as well send them to a dump or truck them off a ways into the woods, but if you generally just let your leaves sit on your property otherwise, it doesn’t seem worth the effort to start gathering leaves to reduce inoculum, unless you are an organic grower. .
Speaking for scab on this. Scab is fairly specific to apples, but MLB infects at least several species.
Cornell didn’t even know it infected apples until I brought some infected leaves in.
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You’re right, Alan, the numbers for reduced infection are probably more significant than the numbers for ascospore production. May be worth noting that the 18-56% reduction in rates of infection covers three different methods of sanitation: leaf collection, leaf collection plus mulch cover, and leaf collection plus plastic cover, with effectiveness increasing in that order. So, leaf collection in itself might get you about 20%. That being said, people who are growing organic/very low/no spray might be looking to accumulate marginal benefits through a variety of different methods, rather than one knockout punch. If you can get a chunk through leaf collection, and a somewhat bigger chunk through leaf collection plus mulching, that can be pretty worthwhile as part of the larger picture.
That approach wouldn’t necessarily make sense for you, both because you have to manage a whole bunch of sites to your customers’ standards and because you have the expertise and equipment to spray effectively with a minimum of applications. But for me, I’m working with one small site that I only have to manage to my own satisfaction, so the math works out differently. (And I would be raking up the leaves anyway, so there’s that, too.)
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I think one of the two (decades-old) large apple trees that came with my property has Marssonina Leaf Blotch. I would very much appreciate a second opinion. This tree flowered and leafed out in spring normally, but both leaf and fruit growth has been extremely sparse as compared to the other old apple tree. I have never sprayed this tree but am planning to try copper starting this fall. I am open to advice while reading more on this. Would be wonderful to get this tree back into health.
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As you can see via this link. MLB does not arrive this early and it doesn’t cause death of healthy trees in my experience because the leaf drop is so late and trees get adequate energy to survive. I’m sure it would accelerate decline in a tree short for the world already, however.
Sometimes fertilization and a nice load of wood chip mulch can be stimulating if the tree isn’t too far gone, but I wouldn’t aim to stimulate growth this season because it’s a bit late although a single shot of quick release N would probably be OK if you did it in the next week or so. At least that would show you if the tree will respond to such treatment.
@alan
Thanks for the feedback again. I think you are right in that it’s a multifaceted decline.
Age could very well be the primary cause of decline. This tree could be over 40 year old, assuming it was planted along with the house of the same age. I gave this tree a liquid dose of N two weeks ago to see if it would leaf out a little better as it has many stunted half-sized leaflets that refuse to grow to full size. Leaves that did grow to full size have blotches. I don’t see any noticeable differences on this tree thus far after the N application.
I still suspect the blotches may be caused by MLB, based on visual similarities. I didn’t find the link you intended to set, but the article from Penn State read, "Primary symptoms appear in the middle of June, usually on mature leaves. However, we have observed the first symptoms as late as August and September. ". Given my location in (VA) warms in spring ahead of Penn State (State College, PA), it’s sensible to shift “Middle of June” (PA) to “End of May” (VA), which doesn’t invalidate the MLB theory for me.
I find many kinds of blotchy leaves resemble MLB and I’ve worked directly with a Cornell pathologist in identifying it in orchards I manage- even after studying it on a microscope there is some uncertainty. I was the first to bring Cornell a sample of it in apple trees they’d ever seen. so that first year I got special attention. You can always send a leaf to the university lab at the landgrant (agricultural) university in your state to get a more definitive analysis.
I’ve never seen leaf drop and infected leaves until mid-July, but I’m a zone north of you so it doesn’t surprise me that it may show up earlier there.
I control it with two sprays of Indar and Captan- one in early July and the other early Aug. They are not the fungicides that are supposed to work best against it according to what I’ve read lately, but they do the trick for me. Commercial apple orchards around here never had a problem with the disease (which is why Cornell hadn’t seen it- after I submitted my sample others started coming in from organic cider orchards in the state) because they keep Captan on trees throughout summer as a general rule. Indar has kick-back and doesn’t wash off in the rain, which I’m not sure the pedigreed gurus are taking into account. I also get pristine apples for customers that ask for them with about 3 fewer sprays than they recommend.
A 40 year apple tree should not already be suffering decline unless there are environmental factors taking a toll. I manage trees well over a century old and semi-dwarf ones well into their 80’s. That looks like a fence for horses or cattle- is the soil compacted red clay? Seems to be a lot of that your way. Maybe the tree is starving for oxygen.
@alan
Good information, I will keep in mind that the blotches are difficult to assess by eye
Regarding soil compaction, there have been horses on the property at some point, though there hasn’t been animals here for many years and near-surface soil isn’t compacted. I’ve excavated many nearby holes this year for planting and it’s quite loamy, at least to a depth of ~8 inches. Beyond that depth, it will have way more clay content.
This tree in decline appeared to have been either (A) planted deeply OR (B) buried by additional externally eroded soil over the years. Very heavy rain (1 inch per hour), washes much dirt and organic material from high elevation to lower elevation and we have several such events per year. This tree sits downstream to a hill that peaks 400feet higher and is very close to a surface storm gutter that is parallel to the fence you see on the right side. I have seen this area very soggy for a few days last year when mother nature dumped a foot of rain over the course of a week. This tree, generally stays dry otherwise.
A few weeks back, I tried to find the root flare of this tree and after removing ~2 inch of soil around the trunk, I still couldn’t find a large root, although I did spot one little 1/2 inch caliper root sticking out, which makes me think theory (B) is more convincing. I will dig a bit deeper to expose the main root flares to see if that helps.
Thanks!
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It sounds like your soil is plenty good for fruit trees, especially apples. You really don’t want too rich and deep a soil for them as the goal is moderate growth for the best fruit.
You may be on the right track with the plant being planted too deeply to begin with, although I’m surprised it would be a factor so many years later. However, not all apple varieties de-differentiate in a way that easily allows them to root out from their trunks.
Nematodes?
This has been an unusually bad year for ceder apple rust. Is it also bad for other fungal diseases?
@alan
I get where you’re getting at, that the decline may be primarily root related as this tree lost vigor. I don’t know if it’s nematodes but just within a stone’s throw is a similarly sized crabapple tree which is full of vigor. Soil conditions between the two trees are as identical as possible, but obviously crabapple is a different tree. Maybe there’s some latent underground root girdling going on in the sick tree…more answers may yield as I excavate further around its rootzone.
To illustrate the root flare, below is the crab apple trunk (~1ft caliper) in foreground, while the apple in decline is in background. I consider the crabapple root flare “normal”. A lot of suckers come up from this every year.
The root flare of the apple tree in decline is almost non-existent. I do see slight widening where trunk meets soil, but it still looks too much a telephone pole which struck me as red flag. I’ve never seen a sucker from this tree.
The other big (healthy) apple tree not shown yet has a big root flare like that of the crabapple tree, and many large root leaders (not sure if correct term) are visibly sprawling above ground. Some suckers are produced yearly but nowhere near that of the crabapple.
I haven’t even seen an unusual amount of CAR or scab, but most of the trees I’m looking at got adequate myclo to knock it out. Just two sprays starting at petal fall usually erases it. What I have seen for the first time is terrible bacterial spot on my Tomcots which is a common problem on my EarliMagic J. plum. The plum gets a fair amount of morning shade so I’m thinking I will graft it to a tree on the property that gets western shade instead and not too much of it.
I harvested a very nice crop of Early Blush apricots that were pristine after receiving only a single fungicide spray at apple petal fall. I probably need to get some copper on the Tom- but there’s very little insect damage even though none of my cots got any insecticide. A few wormy fruit is all.
The fruit is not quite sweet enough to be great, but, of course, far better than store bought. I’m hoping my Alfred provides the full sugar and perfect cot texture. It is carrying a huge crop being a very large tree.
The crabapple is probably on a different rootstock and that could make a big difference. Also for some soil conditions the pathogen may be present in the soil and not present 20 feet away.
It could be some type of root rot but identifying the exact cause will probably be difficult. You could remove more of the soil around the crown than you already have and see how it looks. I would look at couple of guides to root rots with pictures so you can identify the condition if it’s present.
Looking at the leaves it looks like some frogeye leafspot is also present but it doesn’t look bad. I would get some spray coverage on the leaves of the tree as soon as you can. The leaves produce the energy needed to fight off the condition the tree has whatever the condition may be. You don’t want to lose a bunch of foliage if the tree is weak already. You could spray with Captan mixed with Indar that Alan already mentioned or Captan mixed with myclobutanil. Myclobutanil goes by trade names of Rally, Immunox and Eagle. I don’t think you should use copper as your main defense as it’s effectiveness is going to be limited.
I think I may have some Captan in the shed I can spray. I don’t think I have Indar at hand and would need to order some.
I did excavate another inch, and only scraped a few pencil-thin roots. What’s interesting is I found the “burlap” bag the roots were buried in. The material must be some petroleum based polyester mesh instead of real burlap or cotton since it didn’t disintegrate after being in the earth for so long. This means this sick tree was probably not planted as a bare root tree and perhaps the polyester mesh surrounding the root ball confined the roots at young age.
I’m not sure what a bud graft union would look like after decades, but I can’t find anything resembling a discontinuity in the lower trunk in either the the crab or on my other old apple tree.
Yes, I’ve had healthy trees of same species next to dead ones with absolutely no explanation of why one survived the freeze conditions that killed the other. Often something kills one tree out of many even between complete, top to bottom clones.
Hort-sleuthing is fun but often provides no definitive answer…
I did find a major root flares, but they skin of the root were mush and decomposed. There were also a tunnels about 1inch diameter, probably from the cicadas I also found.
Unfortunately it looks like my tree is a goner, but due to roots. The fungal issue was secondary.
Hard to say if it’s a goner. The root issues don’t look good but there are many apple trees that live on with problems that you think would kill the tree for sure.
I’ll give it another year. Hopefully excavating all that dirt to expose the root flare and also removing the synthetic burlap around the trunk helped. I’ll also remove the nearby tree across the fence in case it’s fighting an underground war of some kind.
If and when this tree goes, my son is going to be very disappointed. This tree doubles as his favorite climbing tree.
I once created a lot of regret in a client by removing a very large and low limb from a century old apple tree that his children used to use to climb up it. No putting it back, except maybe by opening up the base to a lot of light and hoping for a new bud to sprout there. Perhaps a bark graft.