Is the timing of the colour change in the fall, a predictor of how the sap flows in t

[Swingpure]

This year our forest were lush with abundant rainfall this summer. The leaf colour change this year, is about two weeks later than last year. I think this is partially due to the health of the forest. It made me think, if the trees are very healthy going into winter, is that any kind of predictor for the sap run in the spring, or is that purely dependent on the weather in the spring?

Gary

[DrTimPerkins]

Maybe, maybe not. There are a lot of factors that affect leaf color change timing and brilliance. To my knowledge that relationship hasn't been tested. We do have the data on that for our site in Underhill, Vermont, along with hundreds of other variables. We've done some testing of relationships of different things on sap yield and sap sugar content, and there are a bunch of factors which are correlated to syrup yield. Most of them are related to sap sugar content. Thoroughly analyzing these data will be a project for my last year before retirement....coming up before too long. Although this past spring was a terrible year for sap sugar content, it gave us a good data point for the extreme low range of data, so useful in that regard.

In general however, you can think of the leaves as the engine of the tree. The basic efficiency of the system (think of it as HP) is related to the environment (is it a canopy tree or a suppressed tree) and genetics. A big healthy tree might be a Turbocharged V12 ready to roar. A small understory tree would be a 4-cylinder that functions to just get by. When photosynthesis is running at its optimum, the engine churns out sugar at a rate based upon its situation. In the short term there isn't a lot you can do to push the engine to run harder (maybe tweaking the nutrition a little), but as long as there is the tree is healthy, there is a decent amount of sun, and sufficient water, the engine cranks along. But anything that impacts that engine will push the sugar production downward...poor nutrition, lack of water, insects, diseases, rainy summer (lack of sun), etc. It's pretty much the same reason that tapping a large tree doesn't have much (if any) real impact....it's a small loss of sugar that is negligible to the tree, whereas the same amount of sugar taken from that small understory tree has a potentially larger impact.

[Sugar Bear]

In general however, you can think of the leaves as the engine of the tree. The basic efficiency of the system (think of it as HP) is related to the environment (is it a canopy tree or a suppressed tree) and genetics. A big healthy tree might be a Turbocharged V12 ready to roar. A small understory tree would be a 4-cylinder that functions to just get by. When photosynthesis is running at its optimum, the engine churns out sugar at a rate based upon its situation. In the short term there isn't a lot you can do to push the engine to run harder (maybe tweaking the nutrition a little), but as long as there is the tree is healthy, there is a decent amount of sun, and sufficient water, the engine cranks along. But anything that impacts that engine will push the sugar production downward...poor nutrition, lack of water, insects, diseases, rainy summer (lack of sun), etc. It's pretty much the same reason that tapping a large tree doesn't have much (if any) real impact....it's a small loss of sugar that is negligible to the tree, whereas the same amount of sugar taken from that small understory tree has a potentially larger impact.

I have seen a lot of this on leaves this year. I am hunching that it is a side gift along with all the rain we have received this year. Can you explain to me what it is and how it effects the overall performance of the engine.

22525

[DrTimPerkins]

I have seen a lot of this on leaves this year. I am hunching that it is a side gift along with all the rain we have received this year. Can you explain to me what it is and how it effects the overall performance of the engine.

22525

Two things....maple leafcutter (insect) and anthracnose (fungus). Neither are particularly terrible. Anthracnose is from wet conditions. Seems to be a fair amount of it this year. At this time of year the engine is coasting a bit as it comes to an end, so early defoliation isn't real serious, but it will cut back on carbohydrate acquisition (sugar production and storage) a little. Probably not enough to be noticeable.

[Swingpure]

Two things....maple leafcutter (insect) and anthracnose (fungus). Neither are particularly terrible. Anthracnose is from wet conditions. Seems to be a fair amount of it this year. At this time of year the engine is coasting a bit as it comes to an end, so early defoliation isn't real serious, but it will cut back on carbohydrate acquisition (sugar production and storage) a little. Probably not enough to be noticeable.

We had a wet summer as well, but the forests were as lush and healthy as I have ever seen them. The colour change is a couple weeks later than last year, but is picking up pace now. We might hit the colour peak on our Thanksgiving weekend, which is next weekend.