San Antonio Express News
Sunday, February 20, 2005
LIVE OAK TREE PROBLEMS AND SOLUTIONS
By Dr. Jerry Parsons
I am hearing the hysterics of many Texans' at this time of the year:
"Help!!! My Live Oak is looking like a Dead Oak. It is has no leaves. It is usually evergreen all year long. The limbs are being killed by moss and there are scabby sections on the bark. There are little "balls" on the bottom of some of the leaves which have fallen off of the tree. There were millions of worms eating it last spring and summer, and I want to keep them off of the tree this year so they won't cause the Oak to have Decline and eventually Wilt. If I increase the soil micro organisms in and on the root system of the tree by adding compost tea, molasses, Quaker Oats, soil activator, root simulator and fauna flora motivator, will this solve my problems? If so, what amounts should I use of each and when should it be applied?"…All these questions from one person, signed "Anxiously awaiting and desparately needing your assistance!
Lord, Have Mercy! Settle down, folks! These Live Oaks have been living through all of these problems for hundreds of years before we got here, and I imagine they will be doing the same for hundreds of years after we have gone.
Let us take these dilemmas one at a time and see if we can console the populous. The first worry is about the lack of modesty being displayed by our naked trees- they were "disrobed" by the worst onslaught of insects and diseases in 2004 we have experienced in years. Every oak tree type (Burr, Texas Red, Shumardii, Live, Monterrey) was affected by a multitude of diseases such as powdery mildew, leaf spot fungus and leaf rust. The wet, cloudy weather last summer was ideal for these diseases. Some live oaks were defoliated as a result of the insects and diseases, but they will not be permanently damaged. No treatment was necessary or effective, i.e., changing weather patterns solved the disease problem naturally, and the insect population went on their merry way after they completed their foliage eating larval stage. There is nothing that can be done to avoid these naturally occurring problems except to plant the recommended trees and shrubs for this area which can survive these environmental adversities. The never changing list of these recommended plants are at: http://aggie horticulture.tamu.edu/ plantanswers/publications/southcnt.html. Also visit our Bexar County Extension website at: http://bexar-tx.tamu.edu/ and across from the Horticulture/Gardening section, click on the link for "Best Plants for Bexar County."
"The limbs are being killed by moss." Nope!! The ball moss is just "hanging on" for the ride. "There are scabby sections on the bark"-- it sounds to me as if you are not "lichen" the way your tree's bark is looking! Ball moss, Spanish moss, lichens and mistletoe are commonly found growing on shade trees in Texas. Of these, only mistletoe is classified as a parasitic plant on ornamental shade trees. Lichens, ball moss, and Spanish moss, although found on trees, are not feeding on the tree, but only using the tree for support. For more information see http://www.plantanswers.com/garden_column/mar03/3.htm.
Don't associate your fallen leaves with balls- These "balls" are galls. Gall formations have been observed in this area on red oak (cottony gall and apple gall), live oak (gouty oak gall), hackberry (nipple gall), pecan (phylloxera) and live oak (red "berry galls" on the bottom side of leaves). Spraying after you see galls won't make them disappear. They're part of the leaf, not the insect that causes them. Preventive spraying, repeated several times earlier in the year, possibly could have reduced the population of these tiny, wasp like insects that cause this growth. Despite their undesirable appearance, they don't kill or even maim trees. For more info on galls, go to http://www.plantanswers.com/oak_leaf_gall.htm and http:// insects.tamu.edu/ extension/bulletins/mp-1315.html.
As far as increasing the soil micro-organisms in and on the root syustem of the tree by adding compost tea, molasses, Ouaker Oats, soil activator, root simulator and fauna-flora motivator, and how much to use and when to use it...The Horticulture, Forestry and Plant Pathology Departments at Texas A&M University have been working for 30 years trying to find some answers to solve the Oak Wilt problem. Some advances have been made, but there is still a long way to go. When you hear someone on the media indicating they have the cure for Oak Wilt in the form of soil additives, you should be wary of ANY advice given by such a person. All such curative formulas have been investigated and found to be bogus. Granted, improving a contaminated plant's growing conditions may slightly increase the plant's life expectancy, but eventually the Oak Wilt claims the infected plant.
Improvement in environmental conditions on a large scale (such as some rainy years) of infected trees growing in shallow soils will increase the appearance of declining trees. However, the massiveness of an old tree's root system makes it difficult for compost tea and corn meal to do much good unless applied with a tanker truck for the compost tea and a dump truck for the corn meal to each infected tree. See http://www.plantanswers.com/garden_column/sep04/4.htm.
So remember, these large oaks were here when we got here, and they will be here when we are all dead and one. The leaves fall off every year at this time, but because of a combination of the aforementioned problems, there are less to fall off. Ignore the "naked trees," and soon the flush of green foliage will mask all of the seemingly insurmountable, devastating problems.
Extension has these publications-"Outstanding Landscape Plants for South Central Texas," "Ball Moss," and "Oak Wilt," (a color brochure showing stricken leaves). To receive a copy by mail, send a self-addressed, stamped envelope (name of the publication on front), to Texas Cooperative Extension, 3355 Cherry Ridge, San Antonio, TX 78230.
This article was written by Dr. Jerry Parsons, Extension Horticulturist (Vegetables) with Texas Cooperative Extension in Bexar County.BACK