Trees suffer during prolonged drought
Contributed by The Tree Care Industry Association

Drought continues to straddle much of the nation, especially in the Southeast and Southwest.

"While it's impossible to keep every tree in good health in times of severe drought, taking a proactive approach for a prized or sentimental tree can support its good health," said Tchukki Andersen, staff arborist with the Tree Care Industry Association

A tree's first damage from drought occurs beneath the soil line in the form of root damage, long before showing outward signs of trouble.

After a tree's unsuccessful attempts to conserve water by closing stomates, feeder roots die back, sometimes so drastically that the tree is unable to take up enough water to support itself.

That's when opportunistic pests make their move. Boring insects are thought to be drawn by the odors and acoustic signals of stressed trees.

The sound of water columns breaking cues the borer to invade the tree and lay eggs. Andersen recommends applying treatment by spray or injection to protect trees from borers.

Another danger to stressed trees is fungus, which makes initial contact with surface roots. When a chemical change in the tree signals a weakened state, the fungus penetrates the bark, wood, and cambial zone with fan- like, leathery clumps, cutting off the water supply to the tree.

While all trees are at risk during long period of drought, some are more prone to its effects. New transplants are highly vulnerable to drought stress, and supplemental watering for the first few years of establishment is necessary, to the extent that it's allowed. But even mature trees are suffering.

Watering trees deeply with soaker hoses or irrigation systems - as opposed to brief, surface watering - helps sustain trees. But it's very difficult to do much for a large tree because of the massive amounts of water it needs. With so many trees affected, Andersen recommends watering only those trees that you can help.

The after effects of the current drought will likely ripple for the next three to five years, with the strongest trees surviving. Trees have developed their own mechanisms for coping with these cycles, but some trees are on the brink of survival and could go either way.

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