8-1729 Texas Agricultural Experiment Station "s98 The Texas A&M University System A Fifty-Year History of the Weed and Brush Program in Texas and Suggested Future Direction Texas Agricultural Experiment Station - Edward A. Hiler, Director - The Texas A&M University System - College Station, Texas Contents Summary Contribution of the TAES Literature Cited Page "5 The U.S. Department of Agriculture Involvement 5 ARS Application Technology 13 15 The Extension Service in Rangeland Ecology and Management 2O A Assessment of Weed and Brush Research Needs 22 24 Acknowledgment The author wishes to thank the many chemical companies and their repre- sentatives who worked with us during this history. They include American Cyanamid Co., BASF Corp., Ciba Plant Protection, DowElanco, DuPont Agricultural Products, FMC Corp., Hoechst-Roussel Agri-Vet Co., Monsanto Co., Nor-Am Chemical Co., PBI/ Gordon Corp., Rhone-Poulenc Ag Co., Rohm and l-Iaas Co., Sandoz Crop Protection Corp., and many others. '% A Fifty-Year History "~ of the Weed and Brush Program in Texas and Suggested Future Direction Rodney W. Bovey' Summary Research on mesquite control was initiated by the Texas Agricultural Experiment Station (TAES) in the late 1930s. The U.S. Department of Agriculture (U SDA) also recognized the serious nature of the weed and brush problem on Southwest rangelands and established a cooperative program with TAES by placing a scientist at Spur, Texas, in 1948. By 1953, 2,4,5- T had been developed and was being used commercially for control of honey mesquite and associated weeds and brush. At the same time, control methods were being developed by TAES for brush in addition to mesquite, including cedar, pricklypear, oaks, and mixed brush in East-Central and South Texas. The USDA added a scientist at College Station, Texas, in 1952 to work on the basic principles of herbicide sprays, mesquite physi- ology, and herbicide effects on crop plants. This work was continued by other Agricultural Research Service (ARS) scientists stationed at College Station. Additional work included propagation of woody plants for experimenta- tion; evaluation of herbicides; absorption, translocation, and metabolism of herbicides in woody plants and forages; and the anatomy and morphology of woody plants. ‘Former Research Agronomist, U.S. Department of Agriculture, Agriculture Research Service, College Station, Texas. Present affiliation, Adjunct Professor, Department of Rangeland Ecology and Management, Texas ArSzM University, College Station, Texas 77843. In the 1960s, work was expanded in Texas supported by a Department of Defense (DOD) project to investigate woody plant defoliation and control with herbicides. Six ARS scien- tists, including an Agricultural Engineer, con- tributed to work on herbicide delivery systems. The USDA-ARS scientists worked closely with TAES scientists in woody plant research. The DOD support continued about 2 years, after which ARS supported the research. The ARS scientists added basic research support to the more applied research of TAES. During the 1960s, Texas Technological University at Lubbock received special state appropriations to intensify their brush control efforts. The TAES programs were significantly strengthened in the weed and brush control area in the 1960s and 1970s by the addition of g several scientists. ARS also added new scien- tists at Temple, Texas, in the 1970s and 1980s A to strengthen the brush ecology and biological weed control programs. The ARS Application Technology Research Unit has provided leadership and new technol- ogy in aerial application of herbicides and pes- ticides. The research unit is unique in that it is the only one of its kind in the United States. The TAES has made numerous contributions to the knowledge and practical use of range improvements and continues to do so, although funding and research efforts have greatly diminished. ARS no longer researches herbicides and TAES efforts are minimal. Part of this change has resulted from changes in philosophy. In the 1950s, attempts were made to eradicate or control weeds and brush. A more holistic approach to vegetation manage- ment developed in the 1980s and 1990s. New emphasis is on alternative methods to contain costs, such as prescribed burning and biologi- cal control. In addition adverse press against agricultural chemicals has contributed to this change. However, integrated weed and brush management systems will continue to utilize all methods of vegetation management appropri- ate for the situation. The Texas Agricultural Extension Service has played a vital role in providing information on management of weeds and brush on range- lands and in developing programs to integrate _weed and brush controlmethods with other management decisions. It is the recommendation of this report that all forms of weed and brush managment research be continued, including herbicides, and with special emphasis on revegetation research, computer decision-making programs, and investigation of the biology and ecology of problem weed species. The U.S. Department of Agriculture Involvement The weed and brush problems on Southwest rangelands were large enough to cause the USDA to establish a cooperative program with the Texas Agricultural Experiment Station (TAES), and to place a scientist at Spur, Texas, in September 1948. D.W. Young worked in cooperation with Charles Fisher (TAES) on control of honey mesquite (131, 132, 133, 134, 135, 136, 137, 226, 227, 228, 229, 230. 231, 232). Dr. Young moved from the USDA, Bureau of Plant Industry, Beltsville, MD, where he‘ had served as an Assistant Agronomist. By 1950, Dr. Young expanded his research to include control of salt cedar, red-berry juniper, pricklypear cactus, catclaw, johnson grass, yucca, and lotebush con- dalia. Dr. Young left Texas to join Iowa State University, Ames, Iowa, in the early 1950s. He was replaced by Mr. Bill Phillips, Associate Agronomist, USDA, Bureau of Plant Industry, in 1951 at Spur. W.M. Phillips reported in the 1951 annual report that cooperative work with TAES had resulted in experimental tests on more than 15,000 acres at 27 locations for control of mesquite. The tests includ- ed a wide range of mesquite growth types, soil moisture, season of application, and weather condi- tions at time of treatment. Tests extended from Falfurrias, Texas, in the south to Clarendon on the north, and from Henrietta on the east to Odessa on the west. Test areas ranged from 160 to 1500 acres at each location. W.M. Phillips transferred from Texas to the Kansas Agricultural Experiment Station and the position was not filled at Spur by the USDA. However, Dr. Richard Behrens, Plant Physiologist, Bureau of Plant Industry, arrived in College Station, Texas, in 1952 to study the physiological aspects of mesquite control and work on related projects and mesquite control at Spur. Dr. Behrens was housed in the Plant Physiology and Pathology Department. C. E. Fisher began work on mesquite control in 1937, and by 1953 data developed by TAES and USDA cooperators indicated that the low volatile esters of 2,4,5-T were relatively effective in control- ling mesquite. Rates of 2/ 3 and 3/4 pound per acre in 1 gallon of diesel fuel and 3 gallons of water gave the most consistent control (141). Most effec- tive control was obtained when treatments were made 45 to 95 days after mesquite first began to leaf out. The optimum date for treatment was 70 days after first leaves appeared. Seventeen publica- tions on mesquite control by TAES and USDA scientists were listed in the 1953 USDA annual report. In 1954, the USDA changed the name of the unit to Weed Investigations Section, Field Crops Research Branch, Agricultural Research Service (ARS), USDA. At College Station, Dr. Behrens com- pleted research on herbicide screening, transloca- tion of herbicides, and the effect of environment on herbicide response, as well as mesquite control (21, 138, 139). Brush control research at College Station in the Range Management Department started with stu- dent projects but soon became a major experiment station project. Mr. F.W. Anderwald was appointed field leader in 1947 and continued until he became Ranch Superintendent of the Pierce Ranch in 1948. During the 1950s, TAES weed and brush control workers at College Station included Drs. Robert Darrow and Wayne McCully. At Spur, Texas, per- sonnel in addition to C.E. Fisher included E.D. Robison and C.H. Meadors. E.D Robison joined the Spur staff in 1956 and worked until the mid-1960s when he accepted a commercial position. C.H. Meadors worked at Spur from 1951 until he resigned in 1959 to accept employment with an agricultural chemical company. P.T. Marion was an animal scientist and was promoted to superintend- ent of the Spur location after C.E. Fisher became superintendent of the Lubbock Station in 1957. Dr. Richard Behrens worked from 1952 to 1958 at College Station in cooperation with TAES in the Department of Plant Physiology and Pathology, Texas A&M University. Behrens’ classical paper on herbicide spray carriers published in 1956 (21) established certain basic principles of spray droplet deposit and plant toxicity and is still cited in the scientific literature. Dr. Behrens also pub- lished data on the effects of phenoxy herbicides on cotton (23). Dr. Behrens spent most of his career as a weed scientist at the University of Minnesota at St. Paul after leaving Texas. Dr. Howard Morton was also a Research Agronomist with ARS and worked with Dr. Behrens before Dr. Behrens’ depar- ture in 1958. Dr. Morton arrived in May 1957 and obtained his Ph.D. under Dr. Wayne Hall in 1961 (193). Dr. Morton continued working in the Plant Physiology and Pathology Department as a Weed Scientist until he transferred to Tucson, Arizona, in 1968. Dr. Robert Meyer, a new Ph D. Plant Physiologist from the University of Wisconsin, joined Dr. Morton as a co-worker in 1961. The USDA-ARS group was further expanded when Dr. Morris Merkle joined the group from Cornell University in 1963 and Drs. Rod Bovey and Frank Davis from the University of Nebraska joined the group in 1964 as Weed Scientists. Dr. Fred Bouse. Agricultural Engineer, USDA-ARS, transferred from Oklahoma State University to work with the College Station ARS group that same year. The work of Morton and Meyer in the early 1960s consisted of propagation of woody plants; evaluation of herbicides on woody plants; effect of environment on the absorption, translocation, and metabolism of herbicides in woody plants and for- ages; and the study of the anatomy and morpholo- gy of woody plants (184, 193, 195). The USDA- ARS, Crops Research Division, Crops Protection Research Branch, Weed Investigations - Grazing Lands was cooperative with the Texas Agricultural Experiment Station, Department of Plant Sciences and Range and Forestry, Texas ASzM University at College Station, Texas. The ARS Scientists added basic research data as well as applied efforts to the overall weed and brush research program in the southwest. Primary woody plants investigated included honey mesquite, live oak, Macartney rose, and pricklypear cactus. Drs. Meyer and Morton also worked with RH. Haas (1960-1980) in the Department of Range and Forestry on the relation- ship of environmental variables to the growth and development of mesquite. Dr. Haas worked in remote sensing and woody plant control from 1960 to the late 1970s. Dr. ].D. Dodd, Plant Ecologist, joined the RLEM faculty in 1963 and worked on the ecology and control of pricklypear cactus. Dr. Dodd later in his career had administrative duties in the grant program of the TAES. I-le retired in 1993. In the early 1960s, expanded research in Texas, Puerto Rico, and Fort Detrick, MD, was made pos- sible by a request from the Advanced Research Projects Agency (ARPA) of the office of the Secretary of Defense for information on the tech- nical feasibility of defoliating jungle with herbi- cides in Vietnam (41). It was proposed that defolia- tion of vegetation paralleling roads, airfields, depots, strategic hamlets, and outposts would reduce enemy attacks and increase visibility. There were also obvious benefits of the research to improve herbicides for agriculture. The ARPA, DOD, supported research about 2 years at College Station, after which ARS supported a majority of the work. Drs. Meyer and Morton were housed in the Plant Science Department while Drs. Bovey, Davis, and Merkle were housed in the Department 6 of Range and Forestry. Dr. Bouse was housed in the Department of Agricultural Engineering. In 1963, ARPA-supported research got underway on brush control and chemical defoliation of woody plants. Laboratory and greenhouse work was concentrated on the influence of light on the herbicidal properties of paraquat, residue effects of various families of herbicides under field condi- tions, and variations in carbohydrate content of whitebrush, live oak, and mesquite. A woody plant nursery to grow plant materials and plants for her- bicide studies was established. About 2000 plants of greenbriar, whitebrush, and Macartney rose, more than 1000 winged elm and mesquite, and about 500 live oak were planted ‘in 1963. Field sites were also established at Carlos, Llano, Victoria, Refugio, and Livingston, Texas, for field evaluation of herbicides for defoliation and plant kill. Woody plants included yaupon, post oak, blackjack oak, and winged elm at Carlos; whitebrush at Llano; live oak at Victoria; huisache and mesquite at Refugio; and mixed hardwood species at Livingston, Texas. In addition to the ARPA research, Morton and Meyer completed cooperative research between TAES and USDA-ARS on pricklypear cactus con- trol, woody plant propagation, mesquite growth, and anatomical studies and herbicide evaluations on seedling mesquite. The results were reported in their 1963 annual report and outside publications (22, 173, 194). In 1964, Dr. Bovey was assigned the Victoria and Refugio field sites; Dr. Davis the Carlos site; Dr. Meyer the Llano site; Dr. Merkle the Livingston; area and Dr. Morton the woody plant nursery and greenhouse. Two new greenhouses and a metal lab- oratory building were constructed for treating plants with herbicides, sample preparation, and chemical analytical work. Laboratory, greenhouse and nursery studies were done on a cooperative basis between scientists as needs and interests dic- tated. The opportunity for each scientist to concen- trate on one or few woody species resulted in best progress. Research continued on evaluation of her- bicides on woody plants, propagation of woody plants, absorption and translocation of herbicides, mode of action and fate of herbicides in woody and forage plants, development of new herbicides and analytical methods, application and distribu- tion of herbicides, visibility measurements in brush, herbicide effects on plant and animal populations, and anatomy and morphology of woody plants. Dr. L.F. Bouse cooperated with S.K. Lehman (1964-66) in Range and Forestry on spray distribution pat- tern studies. F.S. Davis and R.W. Bovey worked with S.K. Lehman on yaupon, winged elm, and live oak control. Dr. M.G. Merkle cooperated with Dr. A.F. Isbell in Chemistry on chemical synthesis and molecular configuration studies. R.W. Bovey coop- erated with Dr. U.G. Whitehouse of the Biochemistry Department on herbicide effects on ultra cell structure using the electron microscope. Dr. Morton cooperated with E.D. Robison at Spur on 2,4,5-T enhancement studies on mesquite and residues in forage. The young USDA-ARS staff was a well-trained and powerful research force ready to conquer the brush problem. The mid-1960s were productive years and excit- ing times because of the opportunities, resources, and expertise available. Data in 1965 showed that picloram or picloram plus 2,4,5-T and/ or paraquat was highly effective in defoliating and killing brush (40, 67). Gas chromatographic analyses were devel- oped for picloram and 2,4,5-T and showed that picloram was more mobile in bean plants than 2,4,5-T (116, 171). A thermoelectric method was developed for measuring moisture stress in plants, and when combined with gas chromatography analysis could monitor herbicide movement(168). Data in 1966 indicated that picloram entered most woody plants faster and in greater amounts than 2,4,5,-T (117). Gas chromatographic and radioisotopic analyses of 2,4,5-T in mesquite gave similar results when identical procedures were used (196). Picloram occurred in lethal amounts in green- house-grown huisache within 24 hours after treat- ment and persisted for at least 3O days in the plants with little or no apparent breakdown (66). Leaching of picloram is an important means of dis- sipation of picloram from the upper soil profile. Photodecomposition of picloram occurred if the herbicide remained on the soil surface for long periods of time (170). In 1967 several significant changes occurred. Partial financial support by ARPA, DOD, terminat- ed in March 1967, but the loss was replaced by USDA-ARS. Dr. ].R. Baur, plant physiologist, joined the brush research group to fill the vacancy created by Dr. M.G. Merkle’s resignation in 1966. Dr. C.R. Swanson transferred from Fargo, ND, to fill the vacancy of F.S. Davis who accepted a foreign assignment with the University of Nebraska. Dr. R.W. Bovey, Research Agronomist, was transferred to Puerto Rico for 1 year to conduct research on defoliation and control of tropical vegetation. Mr. Robert Hursey, technician and graduate assistant for nearly 4 years, received the M.S. degree from Texas ASzM University in Plant Physiology and accepted a position to work on a Ph.D. in Forestry at the University of Idaho. Ongoing research consisted of evaluation of new herbicides, herbicide combinations, and herbicide diluents and formulations on woody plant phyto- toxicity in the nursery and field. Laboratory stud- ies consisted of plant enzyme effects on herbi- cides, herbicide concentrations and effects in sub- cellular fractions, uptake and transport of herbi- cides, effect of herbicides on ultrastructure of chloroplasts, herbicide residues and lethal effects in plants, and herbicide effects on anatomy and morphology. Mesquite seedlings were analyzed for the presence of sucrose, raffinose, and stachyose. Only sucrose was found. In July 1968, Dr. R.W. Bovey transferred after 1 year from the Federal Experiment Station, Mayaguez, Puerto Rico. and was assigned project leader of the College Station brush research group replacing Dr. H.L. Morton who had served as team leader for several years. Dr. Morton transferred to Tucson, AZ, in August 1968 to fill the vacancy cre- ated by Dr. Fred H. Tschirley. Dr. C.R. Swanson, Plant Physiologist, transferred in ]uly 1968 from College Station, Texas, to the Southern Weed Science Laboratory at Stoneville, Mississippi, to become Director. All the personnel changes in 1967 and 1968 reduced the Weed Investigations staff to Drs. Baur, Bovey, and Meyer. During 1968 electron microscopy studies on mesquite leaves indicated that paraquat disrupted the plasmalemma followed by rupturing of chloro- plast (19). Uptake of picloram by potato tuber dis- cis was metabolic and physical (11, 211). Picloram applied to roots of seedling huisache and mesquite stimulated ethlene production (9). Picloram caused loss of leaf movement similar to fumigation with ethylene. Soil applications of picloram may not be effective in mesquite compared with huisache because in seedling mesquite picloram was redis- tributed and eventually lost over a 5-day period, whereas, neither redistribution nor loss occurred in huisache (10). Mixtures of 2,4,5-T plus picloram applied by air- craft gave best brush control and grass release in east Texas timberlands (169), but picloram alone was best on whitebrush (191). Aerial application of picloram or picloram plus 2,4,5-T controlled live oak in south Texas after spring or fall treatment (76, 92). Fall applicators also controlled huisache, blackbrush, whitebrush, catclaw, spiney hackberry, hog-plum, pricklypear cactus, and tasajillo. Texas persimmon, wolfberry, agarito, yucca, lotebush, and mesquite were resistant to these treatments. Application of picloram pellets at several locations and dates controlled live oak, huisache, and yaupon, but not mesquite (77, 80). Evaluations made in 1969 indicated that piclo- ram and picloram plus 2,4,5-T controlled yaupon, post oak, blackjack oak, and winged elm (78). The potassium salt of picloram was usually more effec- tive than the isooctyl ester of picloram for brush control in Texas (84). Laboratory studies showed rapid loss of the ester under UV light and high tem- peratures. Residues of picloram in yaupon and grass applied to a watershed diminished rapidly within the first 6 months after treatment (14, 15, 18, 20). Small amounts of picloram were detected up to 8 feet deep in the soil and < 6 ppb of picloram were detected in water by 3.5 months after treat- ment. Picloram at 100 and 1000 ppb added once in water decreased dry weights of crop plants but some crops were stimulated in growth at 10 ppb or less (16). Soluble protein increased in cotton and "cowpea. In 1970, hand defoliation of brush indicated that about 2 days were required for leaves to transport maximum amounts of 2,4,5-T, picloram, or piclo- ram plus 2,4,5-T into stems and roots for best con- trol (189). Application of 1 pound per acre of piclo- ram to a 15-acre watershed disappeared from the treated grass and woody vegetation in 1 year. Minute concentrations were found in soil and runoff water (14, 15, 18, 20). The years of 1968, 1969, and 1970 were highly productive with a good balance of laboratory and field studies as evident in the large numbers of pub- lications, including Dr. Bovey’s year in Puerto Rico from 1967 to 1968. Dr. Bovey worked with Dr. Robert Darrow and ]. Ray Frank, USDA-ARS, Ft. Detrick, MD, while in Puerto Rico. During this time, the Texas Technological College at Lubbock, Texas, also received special state appropriations beginning in 1967-68 to inten- sify their brush control research program. Their efforts were also supported by additional private grant funds and materials which made them a full- fledged partner in range improvement. Dr. Frank Davis returned from his Colombia, S.A., assignment in early 1969 to become a profes- sor and research scientist in the Range Science Department, Texas A&M University, for about 2 years before resigning. Dr. Charles Leinweber became department head in 1960 and was active during this time. Dr. Charles Scifres also joined the Range Science faculty later in 1969 after spending about a year at the Texas Agricultural Experiment Station, Texas ASzM University at Lubbock. Dr. Scifres resigned in 1988 to assume administrative responsibilities at Oklahoma State University. In early 1970, Dr. Robert Meyer transferred from the Plant Science Department at Texas A&M University to Range Science and Dr. Darrel Baker worked with Drs. ]oe Baur and Rod Bovey in a post doctorate position after completing his Ph.D. at Texas ASzM University in Plant Physiology. Dr. Baker worked on picloram residues in soil. In the 1970s, work was continued on mesquite, huisache, Macartney rose, live oak whitebrush, and other woody plants (53, 78, 87, 90, 91, 142, 174, 175, 176, 177, 178, 186, 188, 189, 206). Subsoil spray applications of herbicides showed promise with chisel plows (53, 93, 175, 176, 177). Work was also done on 2,4,5-T residues at five locations in Texas (50). Picloram and 2,4,5-T were monitored in sur- face runoff and subsurface water as well as in soils and vegetation (43, 60, 61). In the laboratory, soy- bean and cottonwood tissue cultures were used to determine the phytotoxicity of picloram, 2,4,5-T, and dicamba (81, 126). Picloram and 2,4,5-T were more resistant to thermal and UV light degradation than dicamba (12, 17). Picloram was found to affect cytoptasmic protein synthesis (7, 8). Considerable effort was also made to determine the environmen- tal effects on growth and development of mesquite and its response to herbicides (185, 190). Brush control work with tebuthuron was first ini- tiated by ARS scientists in ]anuary 1972. It proved to be a very effective soil-applied herbicide that could be applied in granular form by hand and by ground or aerial equipment. Work was also done to investigate its physiological effect and fate in the environment (13, 62, 86). Hexazinone, triclopyr, clopyralid, and many other herbicides were also investigated for brush management in the 1970s (178). Triclopyr was considered a possible replace- ment for 2,4,5-T (45, 59, 83). Weed control for for- age establishment on pasture and rangeland was initiated in the late 1970s. Dr. Meyer also published on the morphology and anatomy of Texas persim- mon (172). Dr. Bovey was assigned as Special Advisor, Office of the Secretary, U.S. Department of Agriculture, from 1972 to 1974 in preparing defense for the use of 2,4,5-T on rangelands for public hear- ing called by the EPA in 1974. The work involved preparation of pre-trial briefs, documentation, cor- respondence, and statements of testimony. It also included review of the literature, consultation with other experts, and attending numerous confer- ences and seminars. The work culminated in publi- cation by the Texas Agricultural Experiment Station of 10 bibliographies on the phenoxy herbi- cides (46, 47, 48, 49, 120, 121, 123, 124, 125), other supporting documents (64, 111, 119), and a book i (42) published by John Wiley 81 Sons, New York, NY. G.O. Hoffman, C.J. Scifres, J.L. Schuster, and R.W. Bovey also participated in a national effort to assess the benefits of 2,4,5-T (64). Despite gallant efforts by federal, state, and private industry, the EPA announced emergency suspension on February 28, 1979, of 2,4,5-T products on forests, rights-of-way, and pastures and suspension of silvex products for the same uses plus home, aquatic, and recreation areas. Cancellation of these products occurred in 1985 by the U.S. District Court, Washington, D.C. Dr. Charles Leinweber stepped down as head of Range Science in 1971 and retired in 1976. Dr. Wayne McCully was acting head during 1971 and 1972 until the position was filled by Dr. Joe Schuster of the Texas Technological College. The USDA-ARS was reorganized in 1972. Dr. Dayton Klingman, Weed Investigations, Grazing Lands, Crops Protection Research Branch, Crops Research Division, Beltsville, MD, who had been our leader for many years, and Dr. W.B. Ennis, Jr., Chief, Crop Protection Research Branch, no longer supervised our group at College Station, Texas. ARS was decentralized and reorganized by region. Our region became the Oklahoma—Texas Area, and later the Southern Plains Area in 1984 after adding Arkansas and New Mexico, with Dr. Rex Johnston as Area Director. Early on, the area reported to a regional administrator, Dr. A.W. Cooper, located in New Orleans, Louisiana. Dr. L.F. Bouse, Agricul- tural Engineer at College Station, joined the Brush Control Research Unit in 1972. In 1973 Dr. Jim Carlton from Mississippi State transferred to our group and was supervised by Dr. Bouse. During the same years, the project acquired an aircraft pilot, Andy Anderson, and a Cessna agricultural aircraft from Beltsville, Maryland. Drs. Bouse and Carlton worked with Dr. Bovey, Research Leader of the Brush Control Research Unit, until late 1978 when the engineering group was assigned its own research unit with Dr. Bouse as Research Leader. In addition to the strong research program at Texas Technological College at Lubbock, the Texas Agricultural Experiment Station significantly strengthened the weed and brush control effort in Texas by hiring Mr. Bobby Cross, Research Associate, in 1968 and rehiring Cecil Meadors in 1969 for north Texas. Mr. Meadors retired in 1991. Mr. Harold Weidemann, Agricultural Engineer, was hired in late 1969 to develop aerial and mechanical control equipment and revegetation practices. Dr. Pete Jacoby also joined the faculty at Vernon, Texas, in 1976 to continue research on mesquite management and associated weed problems with herbicides and prescribed burning. Dr. Jacoby served as an Extension Range Specialist from 1970 to 1973 at Ft. Stockton, Texas, and resigned in 1993 to join the Extension Administration, University of Nebraska at North Platte. Dr. Jim Ansley, Plant Physiologist, joined the Vernon group in 1983 to work with Dr. Jacoby and is continuing mesquite management and physiology research. Dr. Darrell Ueckert joined the Texas Agricultural Experiment Station staff at San Angelo in 1976 to work on brush management and revegetation of rangelands. Dr. Steve Whisenant worked with Dr. Ueckert as a Research Associate from 1976 to 1980 at San Angelo. Dr. Whisenant resided in College Station from 1980 to 1982 to finish his Ph.D. in Range Science with Dr. Charles Scifres. After spending 6 years at Brigham Young University, Provo, Utah, Dr. Whisenant joined the Range Science faculty at College Station in 1988. Dr. Whisenant works in rangeland restoration research. Mr. Wayne Hamilton also joined the faculty at College Station in 1976 and works in rangeland improvement. During the 1970s and early 1980s ARS also strengthened its brush management programs by the addition of several new staff in biological brush control and brush ecology at Temple, Texas. Dr. Jack DeLoach transferred from the I-Iurlingham biocontrol laboratory in Argentina to Temple in’ 1974 to work on biological control of brush with insects. In 1977, Dr. Herman Mayeux finished his Ph.D. at Texas ASzM University in Range Science and accepted a brush control position dealing with herbicide use and fate in the environment. Dr. Mayeux later worked in brush ecology with Dr. Hyrum Johnson. Dr. Hyrum Johnson joined the Temple ARS brush ecology group in 1980 from BLM at Riverside, California. In the same year, Mr. Paul Bolt joined the Temple group from Rome, Italy, working on range weed control. Dr. James Cuda, an Entomology graduate of Texas AcSzM University, worked at Temple with the biocontrol group in the mid-1980s. Dr. Wayne Polley also joined the Temple ARS group in 1988 in a post doctorate position and was later converted to a permanent position work- ing in ecophysiology. Dr. C.R. Swanson, Plant , Physiologist, ARS, joined the Temple staff in brush management in 1978 from administration in New Orleans, Louisiana, to become Research Leader of the Temple group. Dr. Swanson proposed working on herbicide metabolism in mesquite and huisache but retired in 1979. One of Dr. Swanson’s final tasks was to write an in-depth assessment of research needs in rangeland brush and weed con- trol (210). Dr. Swanson suggested herbicide appli- cation technology be continued but also to expand critically needed basic information on ecology, physiology, and biochemical research on weed and brush plus establish feasibility of biological control. Dr. Swanson suggested continuing the present level of funding and staffing but encouraged basic stud- ies that would complement practical state pro- grams. The untimely death of Dr. ]oe Baur, Plant Physiologist (ARS), in 1979 significantly reduced the herbicide physiology, herbicide residue, revege- tation, and field research at College Station. Drs. Bovey and Meyer constituted the group after the loss of Dr. Baur, although cooperative work was continued with Drs. Bouse and Carlton, scientists at Temple, and other state cooperators in applica- tion technology research. In 1982 Dr. Bovey was assigned Research Leader of the Temple group in addition to College Station, which was named the Grassland Protection Research unit of ARS. Dr. Bovey continued as Research Leader until 1988. In February 1982 an ARS Research planning conference was convened for rangelands and relat- ed research at College Station (2). All appropriate USDA-ARS, scientists, local and key state researchers, and Extension specialists participated, as well as the appropriate national program lead- ers. Twenty-five ARS and state scientists met in College Station on February 24 and 25, 1982, to plan national and location research priorities on weed and brush control on rangeland and related integrated practices. Three National Research Program Leaders attended the conference includ- ing Drs. Shaw, Carlson, and Drea. The welcome and introductions were given by Dr. Bovey. Dr. Rex Iohnston, Area Director (Oklahoma-Texas Area), gave a brief history and significance of grassland research. Dr. Shaw, NRPL for Weed Control and Agricultural Chemicals Technology, outlined the objectives of the conference. Each researcher gave a short presentation about his research program to bring participants upto- date and to provide an information base for future planning. Special emphasis was given to forage establishment and maintenance with or after weed or brush control and related practices. Presenta- tions were also given by Dr. jack Witz, Agricultural Engineer, on the use of computer modeling in research and by Dr. B.]. Ragsdale, Extension Range Management Specialist, on technology transfer from researchers to land managers. A tremendous volume of quality information was presented by the ARS scientists and guest speakers. l0 On February 25, 1982, national and location research priorities were established by the confer- ence participants. The researchers were asked to submit location research priorities prior to the con- ference. At the conference all location priorities were rated by each scientist and the data summa- rized. The national research priorities were estab- lished, ranked and presented in priority sequence as follows: Priority 1. Study the biology, ecology, and edaphic factors as the basis for control technology. Priority 2. Brush and weed control on grazing lands with special emphasis on improving desirable vegetation. Priority 3. Absorption/ translocation/ metabo- lism of herbicides in weeds, brush and forage plants. Priority 4. Economic assessment of weeds and brush control technology. Priority 5. Develop improved herbicide formulations and delivery systems technology. Priority 6. Systems technology for vegetation manipulation, management and multiple use objectives. Priority 7. Foreign exploration and coopera- tion for biological control of weeds and brush. Priority 8. Evaluate multiple use strategies in biological control of weeds and brush. Priority 9. Develop and use models to improve weed and brush technology. Priority 10. Livestock grazing management to manipulate and manage weedy rangelands. Policy Issue: It was also suggested that Special Strike Force Funds be made avail- able to support high priority research when needed to acceler- . ate and complete important technological developments. The group also unanimously agreed more engi- neering technology was needed in our programs and every effort should be made to employ engi- neers to support ARS research and missions. With limited funds and personnel, not all priori- ties could be pursued, but in Texas priorities l, 2, 3, 4, 5, and 7 were well researched by ARS and state scientists in the 1980s. As indicated, several new ARS scientists were added to the Temple program in the 1980s, which complemented the ARS pro- gram at College Station and statewide programs of Texas ASzM University and Texas Tech. ARS scientists at College Station constructed and worked with a tractor mounted carpeted roller to apply herbicides to weeds and brush on range- lands (56). However, Dr. Herman Mayeux is credit- ed with developing the first working model and developing the procedures for honey mesquite con- trol (163). The device was very useful where drift from foliar spray applications of herbicides could have injured susceptible crop plants. The early 1980s is also when the sulfonylurea compounds became available from E.I. DuPont De Nemours 8: Co., Inc. Wilmington, Delaware, for crop and graz- ing land use. These compounds are unique in that extremely small amounts (ounces or fractions of an ounce per hectare) are required for weed control. These compounds have gained widespread usage in cropland and for certain weeds on rangelands. They have also been useful for weed control in the Conservation Reserve Program. The 1980s and 1990s were very productive years with continued work in fate of herbicides in the environment and refining herbicide control practices. Considerable work was completed on evaluation of soil-applied herbicides such as tebutheron and hexazinone (44, 53, 86, 87, 88, 166, 175, 176, 178, 179, 180, 182, 187, 206). Work was initiated on evaluation of herbi- cides for weed control in newly established forage crops (51, 52, 69, 79, 82, 89, 94). Combinations of herbicides were evaluated for honey mesquite con- trol for synergism and optimum rate. Since new herbicides were not as common for grazing lands compared to cropland, attempts were made to increase available commercial herbicide effect by herbicide mixtures, the use of growth regulators, surfactants, and other adjuvants (54, 55, 57, 58, 63, 68, 70, 71, 73, 74, 75, 85). Investigations were conducted to answer why certain herbicides were more effective than others on honey mesquite (54, 70, 75, 181). Work with the ARS Agricultural Engineers was done to determine the important factors in spray deposition in the lab- oratory and field (72, 73, 85, 218). Herbicide forms were evaluated as well as diluents (68, 74). Dr. S.G. Whisenant worked with Dr. Bovey on many of these studies. Work was also continued on the biology and control of common pasture and rangeland weeds by Dr. Robert Meyer, but his retirement in 1988 curtailed the work. Work has continued on CO2 and other environmental effects on weeds and brush by the ARS Temple group, as well as biologi- cal control. Dr. Pete ]acoby resigned from the TAES in 1993 to take a job as an Administrator in the Extension Service at North Platte, Nebraska. Drs. Bovey and Bouse retired from ARS in 1994 and Dr. Herman Mayeux at Temple, Texas, became program leader for Range in 1996 and is stationed in Beltsville, MD. Some significant accomplishments of ARS-TAES included: 1. Investigations with TAES established by 1953 that 2,4,5-T effectively controlled honey mesquite. 2. Dr. Behren’s classical paper published in 1956 on spray droplet spacing, diluents, and phyto- toxicity on honey mesquite. 3. Dr. Morton’s work on metabolism of 2,4,5-T in honey mesquite in 1961. 4. Dr. Meyer’s detailed description of the anato- my and morphology of honey mesquite was published in 1971. 5. Develo ment of anal tical rocedures for P Y _ P picloram in soils, vegetation, and water sources in 1966. 6. Determination that certain herbicide combina- tions such as picloram plus 2,4,5-T (1:1 ratio) could increase control (synergism) of honey mesquite in 1968. 7. Development of control measures for problem woody plants with herbicides in tropical and subtropical areas (1969). 8. First to work with controlled release herbi- cides for weed and brush control in 1972. 9. Extensive research on persistence of herbi- * cides in grasslands. 10. Extensive research on the mode-of-action, absorption, and translocation of herbicides in herbaceous and woody plants. 11. Development of tebuthurion for weed and brush control (1978). 12. Initial work to show that 1:1 mixtures of clopy- ralid plus picloram or triclopyr were highly effective on honey mesquite (1985). 13. Defense for use of 2,4,5-T in agriculture and Dr. Bovey was senior author of an extensive text on the subject (1980). 11 14. 15. 16. 17. 12 Establishment that clopyralid was absorbed and transported in significantly greater con- centrations in honey mesquite than triclopyr, 2,4,5-T, or picloram (1980). Documentation of the effectiveness of pellet- ed herbicides on a number of weeds and woody plants (1980). Establishment of the effect of water soluble extracts of leaves, fruit, bark, and roots of tropical and subtropical plants on the growth of other plants (allelopathy) (1969). Initial work by Dr. Mayeux to show the effec- tiveness of the carpeted roller herbicide appli- cator for honey mesquite control and other weeds (1985). 18. Initial work to show the mode of clopyralid 19. 20. uptake and transport of clopyralid in plants alone and after foliar application with tri- clopyr (1988). Elucidation of the phytotoxicity and transport of different clopyralid formations in honey mesquite (1989-1990). The effect of spray deposition, droplet size. spray volume, surfactant, and herbicide for- mulation on the phytotoxicity and transport of clopyralid in honey mesquite (1991-1994). 21. Dissipation, movement and environmental impact of herbicides on Texas rangelands (1964-1993). \¢ ARS Application Technology Research Weed and brush work was complemented by help from the ARS Agricultural Engineers to improve herbicide placement on soils and plants. Dr. Fred Bouse transferred from Oklahoma State University in 1964 to work with the College Station ARS weed scientists and TAES personnel to improve pesticide application. In 1972 Dr. Bouse was assigned to the Brush Control Research Unit and in 1973 Dr. ]im Carlton was transferred from Mississippi State to the ARS brush group. During the same year, an aircraft pilot, Andy Anderson, and a Cessna agricultural aircraft were transferred to the brush group from Beltsville, MD. In 1978 the engineering group was assigned its own research unit and Dr. Bouse became the Research Leader. Although other research units and scientists in the late 1970s and 1980s (entomologists) were assigned to Dr. Bouse’s group, in the 1980s the core pesticide application unit consisted of Drs. Bouse, Kirk, Stermer, Carlton, and Latheef. Drs. Kirk and Latheef were both transferred to College Station, Texas, from other locations in 1987. Dr. I.W. Kirk was Center Director, Southern Regional Research Center, USDA-ARS, New Orleans, Louisiana. Dr. M.A. Latheef arrived from Oklahoma State University where he was a Research Associate. Dr. R.A. Stermer spent most of his career with ARS at College Station and was assigned to work in the Application Technology Unit in 1986. Dr. R.W. Bovey was assigned to Dr. Bouse’s group in 1988 and to the Beltsville, Maryland, Weed Science laboratory in 1991 until his retirement in 1994. Dr. Bovey, however, remained in College Station all of his career except for one year in Puerto Rico in 1967-1968. Dr. Bovey continued to work with Drs. Bouse, Stermer, and Franz in addition to weed and brush work until his retirement. Dr. Eric Franz joined the Engineering Unit in August 1989 from the ARS Aricultural Engineering Unit in Columbia, Missouri, about the same time Dr. Stermer retired. Dr. Franz passed away in 1994 after an extended illness. An aircraft hanger and research facility was constructed at the Texas A&M University Riverside Campus in 1974, and an agricultural air- craft was transferred from API-IIS in 1975. In the 1960s aerial spray research was conducted with a refurbished Gruman AgCat owned by Texas A8zM University. Termination of an ARS research project on aerial application at Yakima, Washington, in 1983 resulted in the transfer of equipment, two air- planes and a helicopter, to College Station along with increased funding. Funding for expansion of an aircraft hanger, shop, and laboratory space at the Riverside Campus in 1986 brought the existing facilities to more than 18,000 square feet of enclosed space. Work by Dr. Bouse in the mid 1960s was funded by the Department of Defense and consisted of developing improved defoliation of tropical and subtropical vegetation with herbicides. Emphasis of ARS funded programs in the late 1960s and early 1970s was on uniform droplet generation, spray drift, and penetration of aerially-applied sprays through woody plant canopies. In the early and mid 1970s, investigations were conducted on the use of foam, oils, low-pressure, and other noz- zle designs and spray additives to increase recov- ery and reduce transport of spray droplets. In the mid- to late 1970s, research focus was on electro- static charging of aerially applied spray, detection and measurement of airborne spray, and metering systems for applying dry herbicide formulations from aircraft. In the 1980s, research shifted to improved technology for automated measurement of aerial spray distribution, quantification of spray coverage on vegetation, herbicide pellet distribu- tion, and factors affecting the size distribution of aerially applied spray droplets (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 143, 144, 145, 146, 147, 149, 159, 160, 192, 215, 223, 224, 234). Some significant accomplishments of the engi- neering unit as related to brush management I involved: 1. Development of positive metering concepts for aerial application of granular and pelleted herbicides and identification of operational and atmospheric parameters affecting unifor- mity of distribution. 2. Determination of effects and physical proper- ties of spray mixtures, operational variables, and equipment parameters on the size distri- bution of spray droplets using a laser-based particle measurement spectrometer. 3. Developed basic information on electrostatic charging of spray droplets by aircraft. 13 14 . Made major advances in aerial spray deposit pattern measurement technology. . Made major advances in spray deposit tech- nology measurement on plant foliage. . Developed machine vision algorithms and software to increase the accuracy of an image processing system used to analyze spray deposits on artificial and foliar collectors. . Developed spray drift sampling techniques and identified operational aircraft parameters affecting spray deposit. 8. Developed pesticide injection system technol- ogy for agricultural aircraft that minimizes operator exposure and leftover tank mix, and permits rinsing the pesticide from the system over the target field. 9. Software and hardware were developed for in-flight measurement of flow fields near an agricultural aircraft, including a pitch/ yaw error indicator, data acquisition software, and mounting of hardware on a Cessna aircraft. Data indicated that nozzle type, placement, and operating conditions to minimize small droplets subject to drift be obtained for differ- ent types of agricultural aircraft. Contributions of the Texas Agricultural Experiment Station (TAES) Brush problems were recognized more than 100 years ago and the spread of noxious weeds on rangelands has been blamed on many factors including man's activities (233). Means to control weeds and brush have been intense the past 5O years with some successes. Darrow (115) stated that in the 1940s and 1950s the needs and accom- plishments in woody plant control in Texas could be assessed by yearly acreages of brush control carried out under the Agricultural Conservation Program of the Agricultural Stabilization and Conservation Committee. From 1940 to 1950, 0.5 to 3 million acres were treated yearly and from 1950 to 1960 an average of 1 to 1.5 million acres were treated yearly. Main species controlled were mesquite, cedar, pricklypear, oak, and mixed brush. In 1951 and 1952, more than 1 million acres were treated annually but drought in the mid-1950s reduced treatment. However, from 1936 to 1959 an estimated total of 40 million acress were treated by some method. Since the 1940s and 1950s, the approach and philosophy of weed and brush control has changed dramatically. Attempts to eradicate weeds and brush in the 1950s have now changed to vegetation manipulation by a holistic approach using integrated brush management systems (IBMS) complemented with economic assessment (150). Scientists of the TAES have produced many use- ful practices and data helpful to ranchers and land managers. One of the first significant foliar herbi- cide treatments effective on honey mesquite was 2,4,5-T, developed in the late 1940s and early 1950s (21, 23, 132, 133, 134, 135, 136, 137. 138, 139, 141. 193, 227, 228, 230, 231, 232). The investigators also included physiological responses of mesquite to herbicides, timing of application, and other factors affecting foliar sprays (132, 134, 136, 193, 227, 231). Individual plant treatments with herbicides and/ or diesel oil applied to cut surfaces (131), or as basal treatment (226), were also investigated in the late 1940s. Concurrently, mechanical, chemical, burn- ing, and grazing practices were described for the control of oak and associated species in the post oak-blackjack oak areas of Texas (113, 114). Recommended individual plant treatment with her- bicides in addition to foliage or aerial spraying with 2,4,5-T or silvex included basal trunk spray, stump spray, frill spray, trunk injection, and soil injections with monuron or fenuron. Fenuron pellets were adapted for oak control on sandy soils. Goat graz- ing was also mentioned as an effective and eco- nomical method of sprout and underbrush control on cleared oak areas. Another significant development in chemical control of honey mesquite was the 1:1 ratio of picloram plus 2,4,5-T discovered by E.D. Robison (200) and developed by other investigations (65, 118, 140, 155). This development lead to other herbi- cide combinations for honey mesquite control such as 1:1 mixtures of picloram plus dicamba (174, 202). In the late 1970s triclopyr and clopyralid were found effective in controlling honey mesquite (45, 87, 156, 157, 158). Data indicated that triclopyr was equal to or slightly better than 2,4,5,-T, whereas clopyralid was more effective than 2,4,5-T in con- trolling honey mesquite. ]acoby et al. (158) in west Texas showed that clopyralid alone or with equal ratios of 2,4,5-T killed more honey mesquite than combinations of picloram plus dicamba, picloram plus 2,4,5-T, picloram plus triclopyr, dicamba plus 2,4,5-T, or 2,4,5-T or triclopyr applied alone. Bovey et al. (59) in east Texas showed that clopyralid, or clopyralid plus picloram, or triclopyr at equal rates were more effective than picloram plus 2,4,5-T, picloram plus triclopyr, picloram plus dicamba, tri- clopyr plus 2,4,5-T, or triclopyr plus dicamba. The clopyralid plus triclopyr mixture is synergistic (57, 58) and results in increased transport of clopyralid into honey mesquite when applied in clopyralid plus triclopyr mixtures (72). Recent strategies in mesquite control in west Texas to significantly reduce cost and herbicide usage involves application of foliar sprays of clopy- ralid plus triclopyr as individual plant treatments to regrowth mesquite 4 to 6 years following pre- scribed burning (213). This method kills about 90 percent of the mesquite plants and reduces costs more than 50 percent compared with conventional aerial spraying. Individual plants can also be treat- ed without burning but this treatment is successful on trees no taller than 6 feet. Extremely low cost treatments can also be done with about 90 percent root kill using low-volume basal sprays (213). This method involves a special adjustable cone nozzle to apply reduced triclopyr and diesel fuel rates. 15 Dr. Ueckert, in addition to mesquite control, has contributed to research on biological control, weed and brush control with herbicides, prescribed burn- ing, and grassland restoration (212, 217). Dr. ].D. Dodd joined the Rangeland Ecology and Management Department in 1963 and worked on the ecology and control of pricklypear cactus and other plant species in south Texas (127). Both mechanical and chemical control methods were developed. In addition to research, Dr. Dodd also had teaching responsibilities and joined the TAES administrative faculty late in his career. He retired in 1993. Dr. Ueckert presently works on the ecolo- gy, physiology, and control of pricklypear cactus. He discovered that prescribed fire during winter followed by aerial application of picloram at 1/8 to 1/ 2 pound per acre around May 1 resulted in near- ly complete pricklypear control (214). Another strategy involves utilizing two prescribed winter fires 6 to 10 years apart to reduce pricklypear abundance. On about May 1 following the second fire, high-volume sprays of 1 percent picloram applied to individual plants results in almost com- plete control and reduces cost by more than 5O percent compared with conventional aerial spray- ing. Scifres et al. (205) worked on the concept of grid placement of karbutilate spheres (pellets) by hand and aerial application to determine optimum spac- ing for brush control and minimum effect on desir- able vegetation. Karbutilate residues were also investigated to determine karbutilate movement and dissipation (197). A temporary effect on desir- able vegetation occurred only at the point of con- tact of the pellet with the soil. Another interesting contribution is the variable herbicide rate pattern designed to reduce cost, improve botanical diversi- ty, and improve the livestock and wildlife habitat (201). Design is dependant upon weed species to be controlled, wildlife species present, and environ- ment. Dr. Scifres made many contributions to weed and brush control and rangeland improve- ments in Texas and is presently Dean of Agriculture at the University of Arkansas, Fayetteville. A noteworthy advance in mechanical control of brush is the tractor mounted grubber developed by Wiedemann et al. (221, 223) to control redberry juniper, Ashe juniper, and other small weed trees on rangelands. Wiedemann and Cross (222) also developed a disk chain with a triangular pulling configuration that reduced draft requirements by 36 percent and increased the operating width by 23 percent compared with the two-tractor diagonal 16 pulling method. The device is cost effective for preparing seedbeds on rough, log-littered, and root- plowed rangeland. H.T. Wiedemann and B.T. Cross are presently employed by TAES at Vernon, Texas. Dr. Henry Wright, Texas Tech University, and his co-workers were leaders in west Texas in the late 1970s in use of fire for rangeland vegetation manipulation (150, 225). TAES scientists also con- tributed significantly to the literature especially in south Texas. Box and White (95) published on fall and winter burning of south Texas brush ranges. Pretreatment included shredding, chopping, scalp- ing, root plowing, and root plowing plus raking. Fall burned areas produced the most grass; winter burned areas contained the most forbs. Dodd and Holtz (128) published on the integration of burning with mechanical control in south Texas grasslands. Following Dodd, Scifres and co-workers (including Dr. Herman Mayeux, Wayne Hamilton, D.L. Drawe, and others) published several papers on prescribed burning in south Texas and Scifres and Hamilton, 1993, published a book “Prescribed burning for h brushland management.” Dr. Ueckert and Steve Whisenant also contributed significant data to the literature. Prescribed burning has become an important established practice in Texas rangeland management (150, 203, 209). Extension personnel have also greatly contributed to its development (150). An important aspect of weed management on rangelands is economic assessment. Dr. RE. Whitson worked from 1974 to 1982 and Dr. ].R. Conners from 1981 to the present in providing this expertise. Numerous papers have been published (150, 167, 208, 219, 220) in addition to those sited here. Dr. Conners is a key member of the IBMS group and RLEM Department. Dr. R.E. Whitson became head of the RLEM Department in 1993. Integrated brush management systems (IBMS) evolved from research in weed and brush manage- ment prior to the 1980s. IBMS provides manipula- tion of rangeland vegetation through a holistic approach that considers and incorporates the major interactions with the system (150). Major development of IMBS occurred in Texas in the early 1980s as a result of efforts by Scifres and co- workers (204, 207, 208, 209). IBMS are designed to enhance responses of rangeland resources as a whole over many years rather than brush control response from a single treatment for a few years (150). Present coworkers in IBMS not mentioned heretofore are Dr. ].W. Stuth (RLEM), faculty mem- ber since 1975, and ].M. Inglis, professor in the Department of Wildlife and Fisheries Sciences. EXSEL (a computer based expert brush and weed control program) (151) was developed through a cooperative effort of TAES and TAEX to assist in selection of appropriate control technolo- gy for a target species based on predicted efficacy of the treatment. Users receive instructions for treatment application and guidance on post-treat- ment response from target species and associated vegetation. The system requires a minimum of data input to perform treatment selection accurately and allows for easy updating to add species, tech- nologies, regulations, responses or other informa- tion as it becomes available. Present and past faculty who have made contri- butions to weed and brush control through teach- ing or research include Drs. ].L. Schuster, FE. Smeins, M.M. Kothmann, C.A. Taylor, C. Call, D.D. ‘Briske, 3.1.. Hatch, R.W. Knight, T.C. Thurow, T.W. Boutton, S.R. Archer, M.K. Owens, R. ]. Ansley, ].R. Cox, R.K. Heitschmidt, HD. Blackburn, S.F. Zitzer, and j. Mutz. Dr. D.P. Sheehy was a visiting assis- tant professor from 1989 to 1991 and Dr. Bob Lyons from 1992 to 1994. Recent work by Steve Archer and co-workers in shrub ecology has been useful in determining why weed and brush infesta- tions occur and reasons for their persistence and effects (5, 6, 96, 97, 198). Water relations and water use patterns of honey mesquite have been investigated in relation to brush management (3, 4, 98, 112, 129, 130, 161). Herbage production and water yield have also been investigated where herbicides have been used (153, 154, 199). These data have been highly useful in learning more about the influences of water on mesquite growth and possible benefits of control programs. 17 Figure l. Sampling >oil> tor herhicide residues. Figure 2. (Lu chromittogiupliy imtrttiiieiitnttioii tor iticxistiriiig herhicicie in plants. soils or miter Figure 3. Iii’l.(f insu UIHCIIIJUUH tor lnCtlhLlfilig herhicicie in plant.» >oils or \\'.1lc‘I'. Figure 4. QiYCUIIiIitLwc‘ QYJiLlJliUHS oi honey mesdtiite control with herhicicies. Figure 5 Figure 6 Figure 7. (A) ;\erial application ot herbicide tor brush control. (B) Sampling spray deposit trom aircratt Stllnlillllg herbicide treated areas for torage production and herbicide residues. livaluating herbicide residues on water sheds and in runoff WJICI‘. Figure 8. (A) Eyaluitting herbicide movement through the soil profile in t1 lYSlIHCIQII (B) Water collecting instrutnents helow the lysimeter Figure 9. (A) Growing liye oaks in a woody pldllt nursery tor herbicide trials. (B) Fl\'C-}'€¢1I'-Ol l huiertche trees in a woody plant i1ursery' Ftgure ll) 1A: l arge ltot.e_\ ntwqtttte tree (Br 56ml ltltttltrelittlr H011) ltortet 0 tnemltr e new latwtotk tan retnlest gla/lltg =.tlit,l\ a> >QCtls pa» throtrglt thezr tltgestttt‘ tract.» Ftgure ll. Control o1 Xleliartney rose ttrth pteloratn apphetl by airetatt. Ftgure l2, (A) Untreated lrve oak on the (lull (loam ol lexas (B) lave oak control I year» alter aerial applteatttvtt of pelleted telauthtlritwn. Note the relea>e ol grass SPCtYlQS The Extension Service in Rangeland Ecology and Management The Texas Agricultural Extension Service plays an essential role in management of weeds and brush on rangelands. This is accomplished by tech- nology transfer to ranchers and users of critical information in written and oral form. Only person- nel in the Rangeland Ecology and Management Department and associated Extension Specialists located throughout the state have been included, although Extension Specialists in Wildlife and Fisheries Sciences, Soil and Crop Science, Veterinary Medicine, Animal Science, and other disciplines have played a complementary role. The Extension Service is charged with providing information to the public on rangeland manage- ment including plant identification, weed and brush control, range nutrition, watershed management, grazing management, wildlife management, restora- tion ecology, economics, and other educational programs vital to rancher success. Weed and brush control programs are integrated with other management decisions and most prac- tices resulted from numerous demonstrations in the field under many conditions. This has resulted from Extension personnel testing or using data from scientific research from state, federal, private industry, or individuals working cooperatively with researchers or other Extension personnel, or by developing practices independently and/ or with land managers. Extension Service personnel have developed or helped develop the chemical, pre- scribed burning, mechanical, and biological weed and brush control methods and other practices used on rangelands today. Mr. A.H. (Fred) Walker became the first Range Specialist at Texas ASzM University in 1947 and established range management and weed and brush demonstrations and training courses through- out Texas (1). Although Mr. Walker was promoted to State Agricultural Leader in the Extension Service in 1957, he maintained a close association with RLEM even after retirement in 1972. Dr. B.]. Ragsdale was appointed Extension Associate Range Specialist in 1958 and to Range Specialist in 1967. Dr. Ragsdale promoted Range Management through the Extension Service in Texas. He retired in 1990. Mr. GO. Hoffman served as Extension Specialist from 1954 to 1967 (1). He helped develop 22 range Extension programs for youth and adults. In 1967 he was appointed Extension Range Brush and Weed Control Specialist and helped advance prac- tices in noxious plant control. Mr. Hoffman retired in 1979, and passed away about a year later. Mr. ].D. (Dan) Rodgers served as Extension Range Specialist from 1967 to 1980. In 1980 he accepted a job with the University of Wyoming at Laramie. In Texas, Mr. Rodgers gave leadership to state and national youth programs in range. Dr. TommylG. Welch was first employed at Texas A&M University in the Rangeland Ecology and Management Department from 1972 to 1974 as an Assistant Professor. From 1974 to 1979 he served as Extension Range Specialist at Vernon, Texas, but returned to College Station from 1979 to 1995. Dr. Welch also served as Associate Depart- ment Head and Program Leader for Extension in RLEM before retiring in 1995. Dr. Welch was very active in the weed and brush program. Dr. Barron S. Rector, Extension Range Specialist in Range Nutrition, was hired in 1973 and is still very active in the RLEM Department, as is Dr. Larry D. White who transferred from Uvalde in 1993. Dr. White is Extension Range Specialist and Professor and has been employed by Texas A&M University since 1978. Other locations for Extension Range Specialists included Corpus Christi, Ft. Stockton, San Angelo. Uvalde, and Vernon, Texas. At Corpus Christi, Dr. C. Wayne Hanselka serves as Associate Depart- ment Head and Program Leader for the Extension Range Specialists. Dr. Hanselka has been employed with Texas ASzM University since 1976. In addition to his other duties, he has been active in weed and brush management on rangelands. At Ft. Stockton, Texas, several excellent Extension Range Specialists have served including Dr. Robert Steger (1968-1970), Dr. Pete jacoby (1970-1973), Mr. George Sultmeier (1973-1978), Dr. W.A. McGinty (1979-1995), and Dr. Charlie Hart (1995-present). Dr. Robert Steger served the San Angelo area in the early 1970s followed by Dr. RQ. (]ake) Landers, ]r. from 1979 to his retirement in 1994. Dr. McGinty, formerly at Ft. Stockton, relocated to San Angelo in 1995. Dr. Larry D. White served the Uvalde Center starting in 1978 before accepting a position as Extension Range Specialist at College Station in 1993. Dr. Robert K. Lyons now serves as Extension Range Specialist at Uvalde. Dr. Tommy G. Welch served the Vernon Center from 1970 to 1974. Mr. ].F. Cadenhead III has been active in that position since 1980. Dr. ]erry Cox also serves as an Extension Range Specialist at that location. The Head of RLEM, Texas A&M University, has Extension Service responsibilities and works with Extension personnel within the RLEM Department. The individuals are: Department Name Head Years Range Management L.A. Stoddart 1945-46 Range 8: Forestry V.A. Young 1946-59 Range 8: Forestry R.A. Darrow (Acting) 1959-60 Range Sciencea C.L. Leinweber 1960-71 Range Science W.G. McCully(Acting) 1971-72 Rangeland Ecol. 81 MgmLb ].L. Schuster 1972-93 Rangeland Ecol. 8: Mgmt. R.E. Whitsonc 1993-present aName changed in 1965 bName changed in 1991 CRLEM and Agricultural Economics faculty, 1974-1981 A 50-year anniversary dinner took place the evening of April 27, 1996, to celebrate 50 years of range- land education and research for the people of Texas and the nation. 23 Assessment of Weed and Brush Research Needs Weeds and brush are serious barriers t0 eco- nomic livestock production, wildlife habitat, water- shed yield, recreation, and aesthetics on many rangeland sites. Much of the problem is due to man’s activities and economic pursuits. However, the problem grows larger each year and cannot be solved without man’s interference and sound man- agement. Noxious weeds and brush are dominat- ing much of the western U.S. and control efforts need intense political and public support or the land will become nearly useless and costly to restore. Weed and brush management is part of the restoration scheme and all present and future forms of herbicides, prescribed burning, mechani- cal, and biological control methods will be required to deal with the problem, either alone or in some possible combination (integrated weed manage- ment systems or integrated brush management systems). Mechanical methods of weed control are the most common on rangelands, including handgrub- bing, mowing, or bulldozing. These practices have been developed by man’s necessity to control weeds and brush. Although there is a lot of hand- held and power equipment for weed and brush control (216), there are always ways to improve cur- rent technology as demonstrated by Weidemann et al. (221, 222, 223). Mechanical methods will contin- ue to be an important means to control brush and weeds on rangelands alone and in combination with other methods. Herbicides have limitations on rangelands because of cost; however, on selected sites herbi- cides will continue to be very useful. On certain sites they are the only means possible. Herbicides have unjustly received bad press (41, 42), limiting their use and increasing the cost of application. Harris and Reid (152) indicated herbicides are use- ful in California to economically control exotic plants that destroy native habitats on which many endangered species depend. Even though herbicide use on rangelands may be very infrequent (every 20 years) compared to cropland, future use will be further reduced and delivery systems will be more efficient, as in the individual plant treatments of Ueckert (213) on mesquite and pricklypear cactus and the herbicide carpeted roller (56, 163, 165). Aircraft can now apply small amounts of pelleted herbicides (36) 24 and new developments in aerial sprays (38, 107, 146) improve spray deposit and reduce drift. Electronic sensors, monitors, and control systems on ground sprayers can spray only the target species with precison (24). New generation herbicides such as the sulfony- lurea and related compounds control weeds at extremely low rates (fraction of an ounce per acre). Other new developments will follow in finding new and improved chemistry, formulations, and deliv- ery systems. Herbicide research in agronomic crop- ping systems has been well supported by private. state, and federal funding. Herbicide research for rangelands has been well supported in the past, but now funding is essentially non-existent. Many argue that chemical companies can pro- vide the necessary data for agriculture use without input from private, state, or federal research. Although the chemical companies provide very useful and timely data, much of it comes from state and federally supported research. Also the informa- tion required for environmental safety, minor crop use, and other details is sometimes too overwhelm- ing for the company and they need help to expand opportunities of mutual interest. Prescribed burning for weed and brush control will continue to be important in Texas especially in connection with other practices (213). Historically fire was a major natural event in controlling weeds and brush and renewing of grasslands. Prescribed burning has become more attractive because of high costs of other practices. It can definitely be beneficial in remote areas with enough fuel to carry the fire. Biological control, especially with insects, is receiving a lot of attention in ARS and some state programs. Weed and brush management may also be enhanced by intensive short duration grazing systems in which deer, goats, and cattle can use woody and herbaceous plants more efficiently. Enough vegetative cover needs to be left to protect wildlife, but also be compatible with livestock use. Forthcoming research should develop best stock- ing ratios of livestock and wildlife. More creative use should be made of exotic game and goats. Some success has been gained with insects and plant pathogens for control of weeds, but most pro- grams have been unsuccessful. Control with insects and plant pathogens is highly expensive (until acceptable control is achieved), extremely slow, uncertain, and risks escape of organisms that may feed on desirable vegetation. Even though these bio-control organisms are an environmental risk, they may be the only means to suppress vast acreages of range weeds in the U.S. and further work should be encouraged. One area needing renewed and increased effort is in revegetation of pastures and rangeland. Research work in the past has been poorly support- ed and sporadic. This involves investigation of native and introduced plant species for establish- ment and maintenance of stands under grazing use. Weed control is usually necessary for seedling establishment and can be accomplished by herbi- cides, mowing, or cultivation. Use of forage crops with allelopathic properties to suppress weeds should be studied. Ecological restoration of range- lands is high priority research and should be given considerable attention and support. Further research on integrated weed and brush management systems should be given high priority, looking at all possible combinations of mechanical, chemical, fire, biological, and plant competition/ allelopathy/revegetation to fit the site, cost, and purposes of the land manager. Combinations of treatments are selected on the basis of availability, weed species, cost, effectiveness, and other fac- tors. Computer decision-making programs such as EXSEL (151) will be continually improved as data input and technology dictate. Finally, to know the life cycles, ecology, physical and physiological characteristics, environmental responses, and growth characteristics of each weed and brush species we are dealing with is essential to understanding their nature of encroachment and persistence on rangelands. Dr. R.E. Meyer (ARS) and coworkers attempted to obtain such informa- tion through numerous investigations, including his classical work on the anatomy and morphology of honey mesquite and other weeds and brush (164. 172, 183, 184, 185, 190, 232). This kind of research was not encouraged in the 1960s or 1970s by ARS or by the TAES. However, at the 1982 ARS Research Planning Conference (2) in College Station, Texas, “Study of the biology, ecology, and edaphic factors as the basis for con- trol technology” was given first priority. Dr. Meyer and co-workers continued to work in this area of research until he retired in 1988. 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