Putting up a live Christmas tree can be a lot of work. You have to make sure that the tree has plenty of water, sometimes having to crawl beneath the branches while trying not to dislodge any of the breakable ornaments. And then there's the clean-up. No matter what you do, the tree is going to shed needles destined to become lodged in the bottom of your foot. Now scientists from Canada, reporting in the journal Trees, have figured out why those needles fall off, and they've come up with a couple of solutions that could keep needles on longer.
There are plenty of myths advising how you can better keep the needles on your tree. When the Mythbusters tested several of them—adding fertilizer, Viagra or bleach to the water, for example, or coating the entire tree with hairspray or polyurethane—most of the home remedies weren't much help, or they turned the tree a sickly color. But these solutions don't address what the scientists now say is the cause of the needle loss: ethylene, a plant hormone. That's the same molecule that ripens many fruits, and the reason why adding a ripe banana to a bag full of green tomatoes will turn them red. In the balsam fir trees of the recent study, ethylene is produced around 10 days after the tree is cut and signals to the tree that it should drop its needles. And by 40 days after cutting, the branches were bare.
The researchers then tried two ways of interfering with the ethylene. First they added 1-methylcyclopropene (1-MCP) gas to the chamber where they had put cut fir branches in water. Needle retention rose to 73 days. 1-MCP blocks ethylene receptors in the cell and is used by ornamental horticulture and apple industries to prolong the life of their products, and it could be used during the transport of Christmas trees from field to market.
In their second test, they added amino-ethoxyvinylglycine (AVG), which inhibits the production of ethylene, to the water in which the fir branches sat. Needle retention rose to 87 days. Because AVG can be easily dissolved in the tree's supply of water, it's more likely to find use in the home.
The scientists caution that they have yet to scale up their experiment from single cut branches to whole trees, but "what is really encouraging is that we managed to double the needle retention period of the branches," says study co-author Seeve Pepin of the Universite Laval.