TAPPING MAPLE TREES PART 2

I asked our friends Gab and Geneviève at La Ferme Älska their opinion. Here was their response: 

In order to limit damage, we use a 1/4” drill bit, whereas the old-timers used a 5/8. They used to go 2” deep; we go barely 1” deep because research has shown that yield of sap has nothing to do with size or depth of the drill hole. Healthy trees will heal by the following spring and often we are not even able to find the hole from the previous year or years. We all know that an open wound has a much higher chance of infection which brings me to my next point.

Research has also shown that the actual hole is indirectly not the problem. It’s the bacteria that can enter from the hole that causes all the problems (by not drilling deep we never reach the heart [coeur]; if the bacteria reaches the heart, it’s game over, as it will spread down into the roots). That is why we use seasonal taps so the part that goes into the tree is always free of bacteria, and we clean our tubes with alcohol after every season to create an environment where bacteria just cannot grow.

As far as treating the hole after the season, we tend towards letting the trees heal on their own. I know of some studies that have been done where they filled the hole with some sort of a “putty” after the season. The results were quite interesting because it led to some major rotting issues. The tree produces an enzyme that eats bacteria in the wound (self defence), but that enzyme is moist. So when they filled the hole with putty, the enzyme became trapped because of the lack of air flow, which resulted in the wood starting to rot around all the filled holes. 

Location of the tap is the most crucial factor in the amount of sap we can possibly harvest from the tree. Basically picture an old hole in the tree: draw an imaginary rectangle 3” on either side and 6” above and below the hole. That is the No Tap Zone . The wood in that rectangle is compartmentalized and shut off for future sap flow--perhaps another self-defence mechanism in order to prevent spreading bacteria.

TAPPING MAPLE TREES PART 1

This will be a two-part discussion, as I’ve asked some syrup producers to add to the dialogue.

From the perspective of an arborist, I approach the question by looking at how the spigot (spout) hole affects tree behaviour. Assume we are tapping a tree with at least an 18” diameter, and drilling approximately 5 cm into the tree in order to place the spigot: we are drilling into various layers of tree tissue. First, the bark is the layer of transport cells that carries carbohydrates manufactured in the leaves to the living cells throughout the tree. Just inside the bark is the vascular cambium (which creates those annual rings we use to count the age of the tree). The cambium contains of a bunch of different kind of cells, including fibrous support cells (for strength), dead cells, living cells which store starch (converted to sugar in key temperatures), and chains of vessels (the “plumbing” system) which carry water from the roots to the leaves and rest of the tree. By cutting into these vessels, we access the sap flowing through the vessels, which is sweetened by the contribution of starch-storing cells.

Now, trees don’t heal like humans. Trees compartmentalize wounds; that is, they wall off a damaged area to limit the extent of a wound. The vascular cambium dies off above and below the hole, but at the end of the sugaring season, “wood repair” tissue called “callus” will begin to fill the hole--if, of course, the spigot is removed! In essence, the taphole will result in a wound and will become a very small, nonfunctional area of the tree. However, the tree should be able to deal with the wound, or else, it should certainly be able to function without this very small area. A loss of sap does not affect the tree. 

Maple syrup producers have been tapping trees for hundreds of years, so it is clearly in their best interest to follow a standard of practice that is sustainable for their industry. I’ve heard about a North American Maple Syrup Producers Manual, and would be interested to find out what the regulations for managing tapping consist of.

Now, the question to be answered: how far away should you drill new holes from old tapholes?

CARING FOR APPLE TREES

It is easiest to start with young fruit trees, because they develop best when you “train” them through pruning. In terms of apple trees, you can pick the strongest “leading” upright trunk to structure the rest of the growth (scaffold branches) around in equal measure. By focusing on the strongest branches and cutting away the competing growth, weak or diseased limbs, and sucker branches, the tree will direct its energy in an efficient way (and you don’t risk the breaking of weak branches when the weight of the fruit shows--scaffold branches are strongest at a 90 degree angle from the trunk).

With all fruit trees, you need to do pruning and maintenance each year. With mature trees, you would probably need to do one heavy pruning the first year followed by some lighter pruning and maintenance in the following years in order to see some good results. You might think that cutting so much off the tree would harm or kill it, but if you use sharp tools, disinfectant, and you know where to make the cuts (not through the collar of the growth, but still close to the union), you will actually improve the tree’s growth. 

Fun fact: ever wondered why they call it a manicured garden? Manicure comes from the Latin for hand + care, “to care for by hand”. Pruning trees is a good example of a healthy relationship between man and trees--you can improve the yield of a fruit tree by using proper techniques, without hurting the tree itself. This is organic gardening at its best. 

You can watch this video in order to get a better idea of the shape of different training regimes, and exactly how to make the cuts: 

http://www.youtube.com/watch?feature=player_embedded&v=LxZvNR_N3kQ

 Something I don’t usually do, but is an option for trees plagued by certain insects and aphids, is applying a dormant spray: it is an oil which kills these pest by suffocating them -- organic products are available. Here’s another video.

http://www.youtube.com/watch?feature=player_embedded&v=KAgXhFGagM0#!

PLANTING TREES

Planting native species is most conducive to success (in the case of trees for privacy, I have suggested eastern white spruce or cedar). Some planting tips:

• Plant in the fall after leaf drop or in the spring before bud break; cool weather allows the tree to establish roots before spring rain/summer heat promotes too much top growth.
• Dig a SHALLOW and WIDE hole, 2 to 3 times wider than root ball (majority of roots develop in the first 12” of soil, so don’t dig too deep or it will inhibit growth!).
• If you bought a tree from a nursery, remove container/wrappings and straighten or cut circled roots.
• Identify the flare of the trunk (where it is widest at the base) -- it should be partially visible when planted.
• In CLAY areas, you can aerate the soil and add a bit of organic fertilizer, creating a mound, so that when you place your tree in the hole, the trunk flare sits 2-3” above grade. (Don’t use fertilizer in non-clay soil areas when first planting.)
• Hold a new tree by the root ball and not by the trunk; and plant it straight.
• Fill hole gently and firmly (to eliminate air pockets that may dry out roots -- watering during backfill may help you get rid of these air pockets).
• If you are using a bare root stock, you may need to stake; otherwise, trees develop stronger trunks without stakes.
• Mulch around the tree, leaving 1-2” of space around the base, and 2-3” deep (mulch could be any organic waste from leaf litter, wood chips, pine needles, bark, etc).
• In the summer, especially in periods of no rain in intense heat, the tree will really do best with once or twice a week watering (the soil under mulch shouldn’t get too dry).

It doesn’t take much to keep your newly planted trees happy. Mulch really makes your job easier. Also, some pruning may be required to help train the tree; I’ll cover the topic of pruning in a future article.