Friday, July 31, 2009

Trees Don't Die, Do They?

This statement has really amazed me, “I didn’t think my tree would die and since my tree died it must have a contagious disease or insect problem.” Well I guess most folks don’t consider it strange but considering the severe drought it sure seems like lack of water would be blamed first!

First trees do get old and die. We do hear about trees that are hundreds of years old or even some trees recorded to be thousands of years old but generally speaking trees live less than 50 years with some maybe living to be a hundred years old. In this part of Central Texas we do have a few trees that are really old but most have only been around 50 years or less. Williamson County is essentially two very different ecological areas with the west half being Hill Country and the east being Blackland Prairie. Neither region is noted for having old, old trees mostly because of the shallow soils.

Trees die for a variety of reasons but insects and disease are not normally the primary. We do have a problem with Oak Wilt in some species of oaks but outside that we lose trees mostly because of physiological problems typically caused by the environment. One of the primary reasons is shallow soils. As trees get bigger they need more room both in the top and also in the roots. Shallow soils inhibit root growth and if we cant grow roots we cant grow top. We could also add overcrowding to this problem, too many trees in too small a space. Then along comes a once in a lifetime drought and trees simply fall apart. They were cramped and crowded to begin with and now there is a lack of water to both cool the tree, move nutrients and supply plant cells. It is no wonder they die!

Once stressed trees are then more susceptible to all kinds of insect and disease problems. One of the primary causes of oak tree deaths right now is Hypoxylon Canker which can only affect an oak when it is stressed. But I am also seeing hackberry, elm, pecan, magnolia, and cedar die every day simply because it is too dry.

Now back to the Oak Wilt disease which is a severe problem in all of Williamson County and certainly all of the Hill Country. The Texas AgriLife Extension Service and the Texas Forest Service have conducted numerous programs about Oak Wilt and its treatment for area residents. Recently though we offered an intense one day shortcourse on Oak Wilt for our Master Gardeners to certify them as Master Gardener Oak Wilt specialists. Over the last two months we have been directing call to the Extension office about Oak Wilt to these specialists and the public has had nothing but praise for this team. If you think you have Oak Wilt or just want to know more about it call or send an email to the Williamson County Extension Office and you will soon get a response back.

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