White Paint, Aluminum Foil, and Plastic Tubes … Why?
If you’ve ever been in an orchard, you’ve likely seen a puzzling practice or either White Paint on the trees, Aluminum Foil wrapped around them, or those plastic tube things covering the trees. Why do people do that? Interestingly, all 3 of those practices serve fairly similar and very practical purposes. We’ll quickly review those and maybe next time you see a tree wearing one of those things, it will be your tree.
Winter Sun Scald Protection
Sun Scald refers to tree damage caused by the warming and subsequent rapid freezing of a tree in the winter.
If it weren’t for the fact that trees sense the approach of winter and slowly prepare themselves for it, the first deep cold snap of the year would do significant damage to the tree, even to the point of killing it. On the outside you can see the tree preparing for winter through the leaves falling off. What you dont see is that the tree is hardening off from a winter freeze by reducing the amount of water inside of it.
The danger here is one of the tree receiving too much sunlight and warmth during a winter day, thereby causing water to move back into the warmed tree bark. In Texas especially it isn’t uncommon to have a warm day in the winter followed by a hard freeze the next day. If there is a sudden temperature drop the water that moved under the bark may freeze and expand, causing tissue damage to the tree. Unfortunately it doesn’t even have to get warm outside for a tree to be in danger. Direct and reflected sunlight can cause warming of the tree bark far higher than the air temperature around the tree. If you know what you’re looking for, you can often find this damage on the south facing side of a tree where the sunlight hits it most directly. This is referred to as Sun Scald. While this damage isn’t likely to kill a mature native tree, it can cause death in a young, transplanted fruit tree.
White Paint, and Aluminum Foil both can reflect the sunlight away from the tree while a plastic tube can shade the tree from that sunlight altogether. By doing so, you protect a tree from Sun Scald damage by only allowing the tree to warm up when the air temperature allows it.
Weeds and grass can out-compete a baby tree for nutrients easily, resulting in as much as a 90% loss in first year growth in a tree. This staggering forecast for loss of growth should prompt a determined response if you want your trees to flourish. For us, that means using an herbicide like Roundup. Unfortunately herbicides could kill the tree too, so careful measures must be put into place to ensure it doesn’t come in contact with the tree. Aluminum Foil, Paint, and plastic tree shelters all provide an excellent barrier for protecting the tree from overspray and drift of herbicides when they’re being applied. The weeds die, and the tree explodes with new growth as it doesn’t have to fight another plant for the resources and nutrients that it needs in order to thrive.
Bud and Branch Suppression
In a previous post I talked about the need to properly shape the peach tree by careful choice of which branches we will keep. Part of this process is to make sure you cut off any branches on your brand new tree that are growing below 18 inches. But what if you could keep those branches from growing in the first place? Rather than prune off those branches later, Aluminum Foil can suppress those buds, preventing them from turning into branches in the first place. A tree shelter and paint are similarly supposed to suppress those buds, but in our experience Aluminum Foil reigns supreme in effectiveness here. By wrapping the tree in 18 inches of foil when you first plant it, you’ll reduce or eliminate the need to prune out branches growing below 18 inches.
Should I use Foil, Paint, or Tubes?
If you’re planting a new tree this winter, I would absolutely use Aluminum Foil. It’s cheap, widely available, and works! Tree shelters (those plastic tubes) work OK, but they’re more expensive and less effective at suppressing buds from turning into branches. They may look a little nicer, but in the end you’re paying more money for a less effective tool. After a few months, the aluminum foil will begin to wear out. With the wind blowing it around, foil eventually tears and can fall off. At this point (late April for us) the threat of those lower buds branching out has greatly reduced and the threat of winter sun scald is gone. Rather than replace the foil with a fresh sheet, we simply paint the tree trunks in a coat of white paint to protect them from later applications of herbicides.
In the second year of tree growth, branches are much less likely to appear lower on the trunk body so we dont replace the foil the next winter either. Instead we’ll simply maintain the layer of white paint as the tree grows, protecting it from herbicides during the growing season and protecting it from sun scald in the winter.
There are several other benefits to using White Paint on a tree as it matures. We’ll discuss those in a later post.