Tuesday, October 13, 2009

The End of Summer?

Yes there is snow on the ground this morning. I guess this is good for oil prices?

It is definitely too early for temperatures this cold and the trees know it. After a warmer than expected fall with a leisurely and extended summer the frost came and it stayed. The first few frosts started turning the leaves and we had a bit of fall colour coming on. Some hardy old poplars even shed their leaves. Good for them. Now it is so bloody cold we are all checking on last minute seat sales and passport renewals. The trees can't leave town so they are stuck between the proverbial rock and hard place. Many leaves have frozen rigidly on the stems before they started to change colour and this is the worst case scenario.

What it means is that no abscission layer was formed between the leaves and the stems. Instead of slowly pulling in all the reusable nutrients and storing them away in the roots for use again next year, the leaves and stems froze rigidly on many trees and shrubs and the nutrients are now locked in the dead leaves and are hanging on instead of falling off. Woody plants and even old standby perennials like peonies usually put the minerals and sugars and nitrogen back into the roots and that way they have a resource come spring. The plants were caught with their pants down. Some arborists are not as worried. To paraphrase Anita Schill, Registered Consulting Arborist with Tree & Leaf in Calgary: "The short days have triggered plants to begin to acclimatize ... they have been storing away food for a month already" she said. She is not worried trees will lose all their hard labour and nutrients with this sudden turn of events and thinks there is something we can do to save them - water, water and water.

The nutrients will be reused by the tree if they are left on the ground because eventually the woody plant can bribe a few fungi with sugary photosynthate exuded from their roots and these fungi will break down the dead leaves into its usable components again next spring. I believe stems still holding leaves may now suffer from "winterkill" or freezing because they have too much water still in the cells. Dry trees, Schill emphasizes, are the problem. They are holding dry leaves right now so watering will help because the root fungi are still active and needing moisture.

Not just a sad day for gardeners, it is a sad day for new trees planted this year that may not have the reserves in place to fully overwinter. We won't really know until next May but it isn't looking good for any new plantings or lush growing plants right now. I agree with Schill- get out and check your moisture. The snow we've had is not enough for the soil borne organisms - give them a break by watering now.

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