hypothetical case

[wdmn]

Hello,

I have this hypothetical case study, and I'm wondering if any of you can give me examples of how you would approach the problem. I'm not looking for a definitive answer, which is probably impossible given it's a hypothetical situation with limited available data, just thoughts on what sort of approaches would be possible to solve the problem.

Thank you for considering it.

Case:
Over the last 5-10 years, about one-third of a mature (80-100 year old) sugar maple stand has started to show signs
of unusual decline. The stand, approximately 50 ha in size, is located in a maple woodlot in
Durham County north of Toronto and has been managed for syrup production for 25 years.

The trees that are affected show a progressive dieback from the outside to the inside of the
crown. Leaves are usually small, and have a tendency to curl upwards with yellowing at the
margins and between the veins. Foliage in the upper crown tends to fall prematurely. Breast
height increment cores of symptomatic trees show clear patterns of decline in radial growth over
the past few years. The dieback appears to be occurring fairly evenly throughout the stand,
primarily in the older canopy trees. The soil is a grey brown luvisol of the Chinguacousey series,
and the stand occurs in a low-lying area. Aside from regular pruning, very little site maintenance
has been practiced.


My first thoughts were that this was something to do with the soil: either a deficiency or a soil dwelling fungus. The deficiency seems less likely due to the sudden appearance of these symptoms on the site (though I suppose the soil could be depleted). Because the leaves are affected first at the outside of the crown it, that suggests that it's harder for nutrients and water etc to reach these parts of the trees, so something might be attacking the roots (a fungus in the soil)... Other thoughts were the fungus Anthracnose, or some sort of air pollutant (like  hydrogen fluoride).

Any thoughts are appreciated.

wdmn

[OntarioAl]

wdmn
Do some soil analysis for PH. and or other chemicals. It could be that the soil becoming less suitable for Sugar Maple (maybe acid rain?). Could the soil be subject to agricultural chemical residues carried by water as you state that the stand is in a low lying area.
Just some thoughts
Al

[wdmn]

Thank you Al, those are helpful thoughts!

[WDH]

I, too, would suspect some type of root rot.

[wdmn]

Thanks WDH, that is reassuring.

Found this possibility:

Xylaria root rot
This disease occasionally affects landscape trees, but is most common in forest stands where maples are subjected to repeated wounding of roots. Sugar maple roots in stands where trees are tapped for sap are most likely to be affected because early spring traffic in wet soils is likely to result in root wounds. Symptoms in the crown are like those of other root diseases, leaves are off-color and small, and some branch dieback is evident. X. mali produces its spores in tan (when young) to black club-shaped fungal structures that are 2-6 cm tall and 3-10 mm in diameter. These structures are produced in mid-summer but are tough enough to remain identifiable virtually all year.

with the other options being some kind of injury induced to the roots by mechanical entry for sap harvest.
This could make the trees susceptible to:

Armillaria root rot, or
Xylella fastidiosa, bacterial leafscortch.

[mesquite buckeye]

Check your rainfall data for the last 15 years, especially growing season rainfall.

Any herbicides applied to the area?

Any known infestations of defoliating insects?

Time period of maple sugaring operation. (years)

[wdmn]

Thank you sir.

[black spruce]

Just one toughs:

In quebec the maple stand that produce maple sirup a lot of them are fertilizing the soil with lime this seems to help re balance ph site and make it easier for the tree that are not strong to absorb soil nutrient.

I'm far from been a specialist in the area ( some are saying this is due to acid rain, some are saying this is just a cycle, but it is more and more popular and research seems to prove that it has some benefits.....

Couple years ago I went to a seminar on the maple tree farm . I was amazed how to complex it is to keep everything in balance I lift my hats to the family who have kept the stand from generation to generation ( you open too much light species pop up not enough too much tree of the same group are exposed and not regen on the ground....l

Good luck hope you fine some help to apply the right fix that your time to look at it

[Gary_C]

What is the stand basil area? Is it possible that stand density is too high for the present climate in the area? Has there been significant climate change that corresponds with the decline?

[wdmn]

I'm wondering about iron deficiency.

I've read that if soil is too damp or overly compacted, or if the pH is too alkaline, that trees can begin to suffer from iron deficiency.

Has anyone heard of this occurring in sugar bushes, say as a result of repeated mechanical entry during snow melt?

Would an iron deficiency account for these symptoms?:
The trees that are affected show a progressive dieback from the outside to the inside of the
crown. Leaves are usually small, and have a tendency to curl upwards with yellowing at the
margins and between the veins. Foliage in the upper crown tends to fall prematurely. Breast
height increment cores of symptomatic trees show clear patterns of decline in radial growth over
the past few years.


Thank you!

[mesquite buckeye]

Iron deficiency is generally restricted to alkaline soils. I can't imagine it being a problem unless the trees are growing on a limestone outcrop. Wet climates such as yours typically have excessive amounts of iron.

Iron deficiency symptoms start with a slight yellowing of new growth, especially with yellowing between the veins (interveinal chlorosis). If you have ever seen the symptoms you can pick it up on sight immediately. With increasing severity, the symptoms increase to marginal leaf death and eventually the tip of the branch. If that is the case, each new growth flush will show the most severe symptoms on the terminal parts of the branch. Excessive soil moisture intensifies the symptoms over time.

Iron deficiency is quite common in desert areas with alkaline soils, especially with poor drainage and low temperatures during growth flushes.

One other thing to look into while considering nutrient deficiencies. The area that I grew up in NW Ohio has a lot of lime plants, and a considerable amount of limestone dust can blow around from the kilns and just off the crushed limestone piles. The result for us was that the already low amount of zinc in the soil at that location got tied up  with the limestone and we got zinc deficiency in both our crops and animals. The hogs and cattle would strip the bark off trees and eat it as well as chewing wooden fences and other wood they could reach. If I remember correctly, there was a skin rash as well in severe cases.

Anyway, short version is you can see zinc deficiency very easily if present. Very similar in appearance to iron deficiency except the interveinal chlorosis is whitish instead of yellowish. Also most evident on new growth, particularly on shrubs, but also on crop plants. Generally worst in spring and cool parts of summer, especially if there is excess rainfall.

Lots of herbicide injuries mimic or induce nutrient deficiencies.

[wdmn]

Thank you mb, that is very helpful.

Because this case is a hypothetical one I don't have any photos to go by, but your description sounds like a pretty good match with the information that I have available.

The soil for the hypothetical site is a grey brown luvisol of the Chinguacousey series: "these tills were derived principally from locally occurring brown shales, sandstones, and fossiliferous limestone...." so there is calcareous parent material in the area.

However: "The underlying calcareous till is at depths ranging from 18 to 30 inches below the surface. The large acreage of Chinguacousy soils in the county make them very important agricultural soils in the area. They are excellent for general farming and are used extensively for the production of hay, oats, barley, fall wheat, and ensilage corn."

Seems like if the soils were prone to iron deficiency they would not be great for farming... and the farming suggests that maybe herbicide run off is more likely...

Anyway, I really appreciate the thoughtful response.


wdmn