WestTxAg06 brought up an interesting subject in a post on 8/4/06 in regard to the need for brush control, and in particular Mesquite brush, to conserve ground water.
Out of control Mesquite brush is a problem all over West Texas. Some farm and ranch managers have a handle on it in some places but not far away from their locations you will see other pastures completely choked with Mesquite brush (and Pr*ckly Pear) too dense for grass to penetrate.
A typical West Texas Honey Mesquite
I will pass along a history of the Mesquite in West Texas as relayed to me more than 60 years ago, and from my observations of control practices in the late 40s through the 50s that created most of the problems folks are having to solve today.
My grandfather told me that when he first came to Jones County in 1890 and to Fisher County in 1900 there was no Mesquite brush. Some trees were scattered about but for the most part the area was a sea of grass. When I came on the scene in the early 30s, large mature Mesquite trees were commonplace and there was a good bit of scattered Mesquite brush. For the next 20-25 years I observed the disappearance of the mature trees and the proliferation of brush. What was taking place in Fisher County in those 50-60 years?
In the beginning years Mesquite trees were a main source of firewood for heating and cooking on the plains. My grandfather would harness a team of mules, hook on to a wagon and harvest Mesquite wood to last a few months. To pen his livestock he would save the longer, straighter branches 4-6 inches in diameter for fenceposts. Mature Mesquite trees commonly had 4 or 5 main branches coming up from the base of that size. In the 30s and 40s we had less need for firewood but we still cut Mesquite posts. We also knew that if we cut all the main branches from the base that the base would resprout with 6-10 smaller branches ... but we had plenty of pasture and did not consider it a problem. This was common practice. And some pastures were cut out worse than others.
Recall that Bulldozers did not make an appearance until after WWII. The question should be, "How did those old timers clear all that farmland?" The answer is that clearing was done by Grubbing Hoe and a team of mules. The early day folks knew about Mesquite trees and how to clear them out.
A Mesquite Tree has coming out of its basal node a Tap Root that goes down as far as 50 feet to find a water table if necessary. In addition, from the basal node 6-12 inches below the soil surface it sends out lateral (crown) roots that I know go out 30-40 feet in an older tree. (Burn a big Mesquite stump and 3-4 days later see wisps of smoke rising from the ground as the roots burn out.) Now, to kill a Mesquite tree you have to kill that basal node all the way to the lateral roots or it will come back as a bush. That simple. When clearing farmland farmers would dig down to the lateral roots with a grubbing hoe, cut the lateral roots with a heavy bar with a sharp cutting end, then snap off the tap root with the team of mules. That was a lot of work and that is the reason most farmsteads today cultivate only the land that was cleared by hand by someone's great-grandparents 70-100 years ago.
How did Mesquite come to West Texas and why is it so hardy. First, Mesquite is a good food source for animals. When ripe the beans fall to the ground and animals large and small, wild and domestic, find the beans palatable. Now the seeds within the beans reportedly have up to 30% protein; unfortunately, the seed coat is so tough it generally passes through horses and cattle undigested ... but those animals can survive on the beans if nothing else is available. (The problem is if they consume too many the gut can become impacted and cause death.) The seeds are so tough they will not germinate without scarification ... but one pass through a horse or cow solves that problem, so Mesquite came to West Texas inside animals ... from some drifting up from South Texas and probably many that crossed the Chisholm Trail up around Ft Worth as they were moved from northeast Texas in those 1880-1900 migrations.
So by the 1940 we were beginning to have a problem with Mesquite brush, some places and areas more than others. And by 1946 with WWII behind us, a progressive attitude in the air, and a Soil Conservation Service rejuvinated with appropriations from Congress, attention was turned to brush control to return a lot of land back into grassland pasture or cultivation.
The first attempts at clearing Mesquite were crude. With new big Bulldozers in the arsenal, folks figured you could just push all that brush into a big pile and burn it. The next idea in order to speed up the process was to get war-surplus anchor chain, about 200 feet of it between a couple of dozers and let that dragging chain knock the brush and trees down. Things looked fine for a couple of years then all realized that the brush was coming back in multiples of its former self. Where you see a pasture now with Mesquite so thick you can't walk through it, that is a pasture than was abandoned after one pass with a dozer or the anchor chain. That is also the genesis of those place you see frequently where Pr*ckly Pear has overtaken a place. Dozers and anchor chains broke up Pr*ckly Pear into a hundred pieces and scattered it all over the ground being worked ... and every piece sprouted a new Pr*ckly Pear plant. Dozer pushing and chaining knocked trees and brush down but did not damage the basal node to speak of.
By the early 50s folks realized the earlier methods did not work and so they tried Root Plows. Now this was generally effective in reducing Mesquite regrowth, provided it was followed by raking into big piles. As long as that root crown was attached to at least one root that bush was coming back. But as you can see, the expense to clear the brush was getting into the high-dollar level ... up to the point where clearing land was costing as much per acre as cleared land.
So, still in the 50s the next try was with aerial spraying of pasture land. As with other chemicals, from pharmaceuticals to Ag Chemicals, nothing suitable for brush control was commercially available until 1946. The first for brush was 2,4,D, a compound developed in Britain in 1942 for broadleaf weed control in field crops. 2,4,D was mixed with diesel and water in West Texas and found to be very effective in killing Mesquite if painted or sprayed on the base of tree or bush ...(About 80% kill.) Aerial spraying got about 70-80% Above Ground Mortality but only 40-50% Whole Plant Mortality. Something stronger was needed obviously.
So that something else was a cousin of 2,4,D called 2,4,5-T. 2,4,5-T had been developed in 1944 by the same Brits who developed 2,4,D in 1942.
It may be interesting to know that 2,4,D was called by its developers as Agent White. And 2,4,5-T was called by the same developers as AGENT ORANGE. Among the differences in 2,4,D and 2,4,5-T was that the latter contained something called Dioxin.
Little has been made of the fact that Agent Orange was used in West Texas for Mesquite control for 15 years before it was introduced in Vietnam. And the fellows who did the aerial spraying of Agent Orange beginning in the mid-60s were known as "Ranch Hands." I was always a bit curious if Operation Ranch Hand evolved from the West Texas cropdusters who applied Agent Orange in area pastures.
2,4,5-T was outlawed in the early 80s so we are back to 2,4 D sold under a bunch of brand names, along with Round-up and other newer chemicals. Those chemicals may be powerful but the Mesquite is a tough old tree to deal with.
So, WestTxAg06, that is a bit of history of Mesquite brush control in West Texas. You now know that your great-grandfathers unknowingly got us into the current mess, and the grandfathers just made it worse. So, if you can think of a cost-effective way to get farmers out of this pickle, more power to you. But from my perspective, with all of the cropland and grassland pasture currently in CRP, I doubt anyone is willing to put out the cash that would be required to reduce Mesquite population, even to preserve ground water.
Two facts every West Texan should know about Mesquite trees:
1. A Mesquite tree will not leaf out in the Spring until after the last frost. Do not start a garden until after the Mesquites leaf out.
2. The reason Mesquites are so hardy is that they are able to fix their own nitrogen from the air so they have an advantage over other growing plants.
[This message has been edited by fossil_ag (edited 8/9/2006 11:55p).]