Home Gardening

Despite recent rains, drought stress still evident
The Coast Gardener Newspaper and Web Column - June 16, 2001

After witnessing the flooding rains on Monday, I was reluctant to write about drought stress like I promised last week. Even though we may have a temporary break in the drought, this is no guarantee that drought conditions will not prevail later this summer. The damage that has been done is not simply "fixed" by a rapid, heavy rainfall. An extended period of soaking rains is much more beneficial to a drought stricken landscape than a flash flood like we experienced.

We have had a rainfall deficit on and off for about three years. This extended period of drought conditions has caused considerable damage to our turfgrass, trees and shrubs. Even with the recent heavy rain, this relief did not come soon enough. In fact, drought stress sometimes does not show up until well after the initial damage is done.

A question that constantly arises goes something like this: "What's causing the leaves on my tree to turn brown along the edges before they fall off?" The most probable answer is leaf scorch. This condition affects popular landscape trees such as maples, Bradford pears and dogwoods. Leaf scorch begins after any extended period of hot, dry weather. It is sometimes worse when the high temperatures are combined with a steady wind. This condition occurs when water is lost from the leaves faster than the roots can replace it. Quite simply, tree roots cannot supply the foliage with an adequate water supply.

Dogwoods are extremely susceptible to leaf scorch because they have shallow root systems. They prefer to be underneath larger trees and like partial shade on the hot, humid Mississippi Coast. They can suffer greatly when placed in full sun in large open areas.

Dogwoods and other landscape trees are more susceptible to leaf scorch during the first couple of years after transplanting them. Watering newly transplanted trees to a depth of six to eight inches is important. This encourages the roots to grow deeper into the soil. Infrequent waterings are much

better than watering every day or so. Roots that are constantly wet are more susceptible to root rot.

In home landscapes, drought stressed trees and shrubs should receive water with a soaker hose or sprinkler system. The water must be applied in an area from the trunk out to the extent of the drip line. Large trees may require as much as eight hours of continuous watering to add any appreciable amount of water to the root system. Water trees once or twice a week until normal rainfall returns.

Mulching will help to conserve soil moisture around young trees. It will also help to prevent lawn mowers and string trimmers from injuring the trunk.

The soil plays a big role in the degree of drought stress that may be apparent on a given tree.

I have observed several water oaks in the Pass Christian area that are covered with a pinkish-gray fungus-like growth. These trees are growing in sandy soil that has poor water retention. The fungus is a secondary problem associated with drought stress. Ultimately, the drought is responsible for the trees' death, but the fungus gets the blame. The fungus will rarely affect healthy, vigorous trees.

As I discussed last week, it is very important to keep physical injury from construction projects to a minimum in times of drought stress. Injured trees are much less likely to survive a drought. Soil compaction or root damage will not allow water to be absorbed into the root system.

Remember that a healthy landscape full of beautiful trees and shrubs will add value to your home. In times of drought stress, we cannot do as well as mother nature, but we can certainly make an effort. It pays to take care of your investment.

These archived gardening columns were written by Chance McDavid, former Harrison County Extension Agent.