The devastating 2011 drought left 301million trees dead across Texas, 10% of the total.
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And while drought can certainly increase tree problems of insects and disease, the real bottom line is that trees need water. And right now, most of them aren’t getting enough. Water allows trees to transport nutrients from their roots to their leaves. Almost all of the water moving through a tree is used to keep stomata open, which are the pores that let in carbon dioxide, allowing a tree to carry out photosynthesis. Without water, hydraulic failure occurs and trees have to depend on stored sugars and starches and they’ll run out if the drought continues long enough. There are other reasons trees die during drought, according to this study by the National Science Foundation, but lack of water leads the list.
So how do you know if your tree is dying from not enough water? Matt Petty from Davey Trees says look for these signs:
• Wilted, drooping, or curling leaves that may turn brown at the tips or edges. Brown edges especially indicate lack of water. To confirm, try this trick: Poke a long screwdriver into the dirt beneath the tree. If it’s hard to push in, you probably need to water your tree.
• A sparse canopy of off-color and undersized leaves, leaf scorch, or yellowing
• Premature fall color and early leaf drop
• Limited twig growth coupled with small, poorly-formed buds
So how much water do they need? Mature trees need an inch a week (you can put a coffee can out to measure the inch). And given that a lot of water can evaporate before reaching the tree roots, a soaker hose is best. Mulch helps keep moisture in and, of course, annual fertilizing keeps a tree healthy!
And Matt advises giving trees priority when water is scarce as trees take decades to replace, unlike other plants and grass.
In addition to their shady canopy, one, large hardwood tree creates a net cooling effect equivalent to 20 room-size air conditioners operating 20 hours a day, says the USDA. Considering temperatures in the shade are 15° cooler that stands to reason!
Enjoy those trees and don’t take them for granted! We didn’t go through the freeze just to lose trees to a drought!
Frank