Photo: Salt Cedar, Big Bend National Park. © 2017 Delena Norris-Tull
2,4-Dichlorophenoxyacetic acid (2,4-D): The birth of the petrochemical industry
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, October 2020.
2,4-D was the first chemical hormone herbicide put to use widely on farms and ranches. Developed during World War II, it went into use in agriculture rapidly beginning in 1945. In addition to use of 2,4-D on invasive forbs, it has been used as a defoliant. In forests, it is used for stump treatment and to kill brush, and it is used near waterways to kill aquatic weeds. Today, more than 1500 commercial herbicides contain 2,4-D.
2,4-D affects broadleaf plants, more so than grasses and grains. It was the first selective herbicide. It works by causing uncontrolled growth in the cells of the plant.
The use of 2,4-D in the 1940s
2,4-D and 2,4-5T (2,4,5-Trichlorophenoxyacetic acid) were developed during World War II in the USA, as part of an effort to develop chemicals for use in warfare. These two chemicals were developed for potential use in attempts to starve the Germans and Japanese by killing potato and rice crops. But potatoes and rice were tolerant to 2,4-D, and so it was not used as a weapon of war at that time. Immediately after the war, 2,4-D became available for use in agriculture, for killing broadleaf weeds within grain crops and lawns and turf. In the 1950s, 2,4-D went into use to control the size and enhance the color of potatoes.
In the Western USA, 2,4-D was first mentioned as an herbicide in the 1945 Western Weed Control Conference. Mr. C.T. Seeley, from the Agronomy Division of the University of Idaho gave a report on the new developments with the use of hormones in weed control. He described the use of 2,4-D: “It wasn’t until 1941 that Nevada thought you might be able to use it for weed control, and it wasn’t until 1944 that any actual work was done,… as far as weed killers was concerned. 2,4-D was picked primarily because it happened to be one that was easily manufactured and was available in large quantities.”
Mr. W.A. Harvey, of the University of California-Davis, gave a report on the effects of 2,4-D on soil. A research study of differing concentrations of 2,4-D on crop growth showed that different crops differ in their susceptibility to the chemical. “Oats survive at much higher concentrations than peas or sunflowers, and sunflowers tolerate higher concentrations than peas. However, by using a high enough concentration, it is possible to prevent growth of any of these plants. This is definite evidence that 2,4-D does sterilize soil to some extent, the amount of sterilization depending on the amount of chemical in the soil.
”The three soils (tested) also differ in the amount of toxicity shown by the chemical. The Stockton adobe clay shows the least toxicity or, putting it another way, it takes more of the chemical to show toxicity in this soil than in the others. The Hanford fine sandy loam shows the highest toxicity, and the Yolo adobe clay chosen intermediate toxicity…
”Thus we see that serious effects on crops are possible with very small amounts of the chemical in the soil. Now we don’t know yet how long this effect lasts in the soil. Apparently it lasts for 30 days at least and is definitely reduced in 60 days, but we are long way from having final data on it… In another year, we hope to have some of the answers but right now there are a lot of things we don’t know about 2,4-D.”
Various individuals asked more questions about this preliminary research. Mr. Harvey added that they have not yet done research on the rate of penetration of 2,4-D in the soils.
Dr. Crafts added, “With our past experience with leaching of chemicals in the soil, we have come to recognize two types of behavior. Arsenic will be fixed by most soils. On the other hand if you take nitrate and chlorate it will be distributed throughout the soil. 2,4-D may compare more with Borax which fixes loosely. We have tested eight California soils.”
Mr. Jerome Evans, from the Idaho Agricultural Adjustment Agency (AAA), asked: “Has anyone here any observances as to the effect of the 2,4-D on the microflora of the soil?”
Mr. Seeley: “I can give you some secondhand information...The Information I have is that it has pretty bad effects as far as soil bacteria is concerned, but very little effect on fungi.”
Mr. Robbins: “The bacteriologist at our station applied 2,4-D to his lawn. Following the application, he applied ammonium sulfate and he made the remark that he got no response out of the ammonium sulfate for a very long time, and he was wondering if [2,4-D] had any effect on the bacteria in the soil… We need to know more about that. Doesn’t this work indicate to you people that we had better go a little bit slow on our application of hormones to agricultural soil?… In the light of your work, what advice would you give [to farmers] with respect to seeding with alfalfa a few weeks after the application of hormones?”
Answer: “Farmers should be advised to proceed cautiously until more is known of the effects of 2,4-D to soils.”
[Note: the lack of research on animals that year is alarming, as different species could be expected to react differentially to the chemical, just as do different species of plants.]
Mr. Buford E. Kuhns, from the Idaho Extension Service, gave a report at the 1945 Conference: “…We have supplied each of our county agents…with a number of what we call an information sheet. We’re asking them to carry on a little experimental work with these various 2,4-D preparations, and we are asking them to prepare a short information sheet, showing the location, date of application, type of soil, temperature, and all of the other factors that might be of interest, and give their notes on their observations... We will then assemble all that material and hope that we will get a little information. Starting July 1st, Idaho will employ a full-time man on weed research.”
The 1946 minutes of the Western Weed Control Conference show a rapid increase in the use of 2,4-D throughout the USA, despite the lack of a rigorous research program. Several statements within the minutes raise some concerns about its use. In the Wyoming report to the 1946 conference, the following statement is included: “Although the State Department has not recommended 2,4-D, because of the need for further experimental information, many individuals purchased it for personal use.”
The 1946 conference includes a report from the second North Central States Weed Control Conference. A report was given by F.L. Timmons, Agronomist, US Bureau of Plant Industry, Soils, and Agricultural Engineering: “The uniform program of experimentation with 2,4-D and other selective herbicides in the North Central States Weed Control Conference is a project of our Conference Research Committee.” This is the first report on noxious weed control research conducted under the leadership of a Federal Agency.
The North Central States’ report went on to state, “The Research Committee… set up a uniform plan for conducting research work with 2,4-D which was adopted and used by most of the federal and state weed research workers in this area, as well as several other states and several provincial workers and the Dominion Experimental Farms of Canada… This committee has done a considerable amount of work which has been recognized the nation over by weed research workers. The remaining committees are working at their jobs diligently but are working on problems that will require a longer time to accomplish results. The conference has appointed two new committees, one for the purpose of drafting a model herbicide law for states, and also a committee to draw up a constitution and by-laws for the organization…
“It might be of interest here to state that the general opinion of most workers seems to be that the results of 2,4-D for the first year were not sufficiently conclusive to warrant recommending its use for perennial weeds. It was recognized by all that the percent of kill and plant counts made according to surface indications did not correspond with live roots found by digging at 6 to 18 inches beneath the surface... Much more experimental work needs to be done to determine the proper place and use of 2,4-D for perennial weeds. According to the reports of the committee and some other workers, 2,4-D gave good results generally with certain annual weeds but not with all of them. The use of 2,4-D as a lawn herbicide was generally accepted and recognized by all workers. The speaker personally believes that 2,4-D can be accepted as the best dandelion killer in general lawn herbicide that has come to the attention of the ‘lover of nice lawns’... According to Dr. Krauss the near future should bring forth new weed killers far superior to 2,4-D.”
The archival minutes of the Western Weed Conference of 1946 indicate concerns by State Agency representatives that landowners were putting the new chemical into use before adequate research could be conducted on the potential damages of the chemical. It is alarming that the States and Federal Agencies were allowing farmers and ranchers to unleash a new chemical on the environment with so little research available.
Here is another quote from the meeting minutes, reporting from the 1946 North Central Weed Control Conference, regarding research on the implementation of 2,4-D in 1945:
“The course of events to come was accurately prophesied at the meeting in Omaha by Mr. L.W. Kephart of the USDA in his discussion of ‘Chemical Weed Killers After the War.’ After reporting briefly on preliminary results with 2,4-D in 1944, he advanced the opinion that revolutionary developments in chemical weed control would soon present weed research workers and control officials with problems that they were hardly prepared to handle. He predicted widespread publicity and sensational claims for the new weed killers and pointed out the need for a disinterested agency to assemble information, correlate the facts and act as an umpire in the situation. He suggested that our research committee was the logical group to do this in the north central area.
”By the end of January, 1945, much of Mr. Kephart’s prophecy had materialized. Several sensational articles and advertisements about 2,4-D had appeared in print, and the barometer of public interest was rising rapidly as indicated by the sudden flood of inquiries received by nearly every weed control and research worker in the country. It was immediately evident that our meager facilities and personnel for weed research would not be able to gain information rapidly enough to protect the public interest except through organized effort.”
The minutes of the 1946 meeting include the details of the extensive research project conducted by the North Central States Group. In a summary of the research project it is stated, “More than 80 copies of the uniform plan of experiments were sent to prospective cooperators and others interested. Many requests for copies were received from persons outside our North Central Conference, in states as far east as New Jersey, as far south as Texas and as far west as California and Oregon. Several copies of the plan was sent to workers in Canada.
”A total of 35 cooperators reported the results from a total of 160 different experiments on different weeds. Thirty-six of the experiments were conducted by cooperators in Canada at stations distributed from Newfoundland to Alberta.
”Our Research Committee was… assigned the task of summarizing and reporting upon the results... The task of summarization resulted in many a headache for these sub-committees. Despite the fact that the results reported were from experiments based on uniform plans, there were some variations in treatments and other details in nearly all cases, so that the problem of correlating the results and arriving at conclusions as to what they showed was a tedious and difficult problem…
“These reports demonstrated the value of our uniform program of research and also revealed some of its weaknesses. The uniform program was as successful in 1945 as could have been expected in the first year... The outstanding weakness of the program in 1945 was the lack of uniformity in conducting the experiments and the resulting inability to make direct comparisons in many cases. As one of the sub-committees stated it, ‘the only thing uniform about the individual experiments reported was their lack of uniformity.’ This variability in the supposedly uniform experiments in 1945 is understandable when one considers that the uniform plan was developed hastily and presented suddenly to the experiment station directors and research workers too late in the season for careful plans to be made.”
The Research Committee’s 1945 research project examined the effects of 2,4-D on crops, on lawns, and on weeds. While the 1945 research design did not include examination of the persistence of 2,4-D in the soil, the end-of-year report did include some of that data: “The injurious effects on crop plants of residual 2,4-D in the soil from spray applications were apparent during periods varying from only a few weeks to several months, apparently depending upon the amount of rainfall received after the spray application. The residual effects seem to persist longer in the soil in the dryer states like Kansas and Nebraska than in humid areas like Ohio. The residual effects of 2,4-D were most injurious to the more sensitive vegetable and legume crops and less detrimental to the grasses and cereals.”
For the Research Committee’s 1946 research plan, the committee added research on the persistence of 2,4-D in the soil. It is notable that the projects did not include research on the effects of 2,4-D on native plants, wildlife, livestock, or humans. Some anecdotal information is included, on the lack of effects seen on humans and livestock. The report also referred to the fact that 23 weeds appeared to be resistant to 2,4-D.
The 1946 Western Weed Control Conference minutes included one research report from Mr. Freed of Oregon, on the effects of 2,4-D on soils. His report on soil sterility stated: “In general, 2,4-D breaks down within a month in warm, moist soils but may persist for six months in cool or dry soils. A comparison of soil types under greenhouse conditions shows a higher toxicity of 2,4-D in sandy soils than in clay soils, but a more rapid leaching from the sandy soils. Under field conditions, the toxicity in the soil will depend on the amount of 2,4-D applied, the soil type, temperature, and moisture conditions.”
It should be pointed out that this hastily developed research program was in response to the realization that many farmers and ranchers were already using the new chemical, with or without research in place on its impacts. These experiments were conducted by various State Agencies, with scant support from Federal funding. In fact, the minutes also note that, although “An intensive research program on 2,4-D was also conducted by C.I. Seely, representing the U.S. Bureau of Plant Industry, and cooperating with the Idaho College of Agriculture…” in his report from the North Central Conference, T.F. Yost stated, ”In the weed control program the National Congress has curiously adopted what seems to be a hands-off policy. Maybe it would be better to say that the Congress seems not to be interested in the national weed control problem. Some of the states, in order to protect themselves against the weed menace, have been forced to initiate and support their own eradication and control program, while the Federal Government has set idly by and has not even done a good job of looking on. The weed problem is so broad in scope so devastating in effect and so complicated when considered from the overall standpoint, that we believe the time is here when Congress should sit up and take notice that there is a weed condition in our country that is of national importance, which if not properly handled will undermine the greatest resource of our nation, which is the soil. There are some aspects of the weed problem that cannot be handled on the state level. These problems cut across state lines and can only be handled by Federal action.”
Links to next sections on herbicides
Next Sections on herbicides and other pesticides:
2,4-Dichlorophenoxyacetic acid (2,4-D): The birth of the petrochemical industry
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, October 2020.
2,4-D was the first chemical hormone herbicide put to use widely on farms and ranches. Developed during World War II, it went into use in agriculture rapidly beginning in 1945. In addition to use of 2,4-D on invasive forbs, it has been used as a defoliant. In forests, it is used for stump treatment and to kill brush, and it is used near waterways to kill aquatic weeds. Today, more than 1500 commercial herbicides contain 2,4-D.
2,4-D affects broadleaf plants, more so than grasses and grains. It was the first selective herbicide. It works by causing uncontrolled growth in the cells of the plant.
The use of 2,4-D in the 1940s
2,4-D and 2,4-5T (2,4,5-Trichlorophenoxyacetic acid) were developed during World War II in the USA, as part of an effort to develop chemicals for use in warfare. These two chemicals were developed for potential use in attempts to starve the Germans and Japanese by killing potato and rice crops. But potatoes and rice were tolerant to 2,4-D, and so it was not used as a weapon of war at that time. Immediately after the war, 2,4-D became available for use in agriculture, for killing broadleaf weeds within grain crops and lawns and turf. In the 1950s, 2,4-D went into use to control the size and enhance the color of potatoes.
In the Western USA, 2,4-D was first mentioned as an herbicide in the 1945 Western Weed Control Conference. Mr. C.T. Seeley, from the Agronomy Division of the University of Idaho gave a report on the new developments with the use of hormones in weed control. He described the use of 2,4-D: “It wasn’t until 1941 that Nevada thought you might be able to use it for weed control, and it wasn’t until 1944 that any actual work was done,… as far as weed killers was concerned. 2,4-D was picked primarily because it happened to be one that was easily manufactured and was available in large quantities.”
Mr. W.A. Harvey, of the University of California-Davis, gave a report on the effects of 2,4-D on soil. A research study of differing concentrations of 2,4-D on crop growth showed that different crops differ in their susceptibility to the chemical. “Oats survive at much higher concentrations than peas or sunflowers, and sunflowers tolerate higher concentrations than peas. However, by using a high enough concentration, it is possible to prevent growth of any of these plants. This is definite evidence that 2,4-D does sterilize soil to some extent, the amount of sterilization depending on the amount of chemical in the soil.
”The three soils (tested) also differ in the amount of toxicity shown by the chemical. The Stockton adobe clay shows the least toxicity or, putting it another way, it takes more of the chemical to show toxicity in this soil than in the others. The Hanford fine sandy loam shows the highest toxicity, and the Yolo adobe clay chosen intermediate toxicity…
”Thus we see that serious effects on crops are possible with very small amounts of the chemical in the soil. Now we don’t know yet how long this effect lasts in the soil. Apparently it lasts for 30 days at least and is definitely reduced in 60 days, but we are long way from having final data on it… In another year, we hope to have some of the answers but right now there are a lot of things we don’t know about 2,4-D.”
Various individuals asked more questions about this preliminary research. Mr. Harvey added that they have not yet done research on the rate of penetration of 2,4-D in the soils.
Dr. Crafts added, “With our past experience with leaching of chemicals in the soil, we have come to recognize two types of behavior. Arsenic will be fixed by most soils. On the other hand if you take nitrate and chlorate it will be distributed throughout the soil. 2,4-D may compare more with Borax which fixes loosely. We have tested eight California soils.”
Mr. Jerome Evans, from the Idaho Agricultural Adjustment Agency (AAA), asked: “Has anyone here any observances as to the effect of the 2,4-D on the microflora of the soil?”
Mr. Seeley: “I can give you some secondhand information...The Information I have is that it has pretty bad effects as far as soil bacteria is concerned, but very little effect on fungi.”
Mr. Robbins: “The bacteriologist at our station applied 2,4-D to his lawn. Following the application, he applied ammonium sulfate and he made the remark that he got no response out of the ammonium sulfate for a very long time, and he was wondering if [2,4-D] had any effect on the bacteria in the soil… We need to know more about that. Doesn’t this work indicate to you people that we had better go a little bit slow on our application of hormones to agricultural soil?… In the light of your work, what advice would you give [to farmers] with respect to seeding with alfalfa a few weeks after the application of hormones?”
Answer: “Farmers should be advised to proceed cautiously until more is known of the effects of 2,4-D to soils.”
[Note: the lack of research on animals that year is alarming, as different species could be expected to react differentially to the chemical, just as do different species of plants.]
Mr. Buford E. Kuhns, from the Idaho Extension Service, gave a report at the 1945 Conference: “…We have supplied each of our county agents…with a number of what we call an information sheet. We’re asking them to carry on a little experimental work with these various 2,4-D preparations, and we are asking them to prepare a short information sheet, showing the location, date of application, type of soil, temperature, and all of the other factors that might be of interest, and give their notes on their observations... We will then assemble all that material and hope that we will get a little information. Starting July 1st, Idaho will employ a full-time man on weed research.”
The 1946 minutes of the Western Weed Control Conference show a rapid increase in the use of 2,4-D throughout the USA, despite the lack of a rigorous research program. Several statements within the minutes raise some concerns about its use. In the Wyoming report to the 1946 conference, the following statement is included: “Although the State Department has not recommended 2,4-D, because of the need for further experimental information, many individuals purchased it for personal use.”
The 1946 conference includes a report from the second North Central States Weed Control Conference. A report was given by F.L. Timmons, Agronomist, US Bureau of Plant Industry, Soils, and Agricultural Engineering: “The uniform program of experimentation with 2,4-D and other selective herbicides in the North Central States Weed Control Conference is a project of our Conference Research Committee.” This is the first report on noxious weed control research conducted under the leadership of a Federal Agency.
The North Central States’ report went on to state, “The Research Committee… set up a uniform plan for conducting research work with 2,4-D which was adopted and used by most of the federal and state weed research workers in this area, as well as several other states and several provincial workers and the Dominion Experimental Farms of Canada… This committee has done a considerable amount of work which has been recognized the nation over by weed research workers. The remaining committees are working at their jobs diligently but are working on problems that will require a longer time to accomplish results. The conference has appointed two new committees, one for the purpose of drafting a model herbicide law for states, and also a committee to draw up a constitution and by-laws for the organization…
“It might be of interest here to state that the general opinion of most workers seems to be that the results of 2,4-D for the first year were not sufficiently conclusive to warrant recommending its use for perennial weeds. It was recognized by all that the percent of kill and plant counts made according to surface indications did not correspond with live roots found by digging at 6 to 18 inches beneath the surface... Much more experimental work needs to be done to determine the proper place and use of 2,4-D for perennial weeds. According to the reports of the committee and some other workers, 2,4-D gave good results generally with certain annual weeds but not with all of them. The use of 2,4-D as a lawn herbicide was generally accepted and recognized by all workers. The speaker personally believes that 2,4-D can be accepted as the best dandelion killer in general lawn herbicide that has come to the attention of the ‘lover of nice lawns’... According to Dr. Krauss the near future should bring forth new weed killers far superior to 2,4-D.”
The archival minutes of the Western Weed Conference of 1946 indicate concerns by State Agency representatives that landowners were putting the new chemical into use before adequate research could be conducted on the potential damages of the chemical. It is alarming that the States and Federal Agencies were allowing farmers and ranchers to unleash a new chemical on the environment with so little research available.
Here is another quote from the meeting minutes, reporting from the 1946 North Central Weed Control Conference, regarding research on the implementation of 2,4-D in 1945:
“The course of events to come was accurately prophesied at the meeting in Omaha by Mr. L.W. Kephart of the USDA in his discussion of ‘Chemical Weed Killers After the War.’ After reporting briefly on preliminary results with 2,4-D in 1944, he advanced the opinion that revolutionary developments in chemical weed control would soon present weed research workers and control officials with problems that they were hardly prepared to handle. He predicted widespread publicity and sensational claims for the new weed killers and pointed out the need for a disinterested agency to assemble information, correlate the facts and act as an umpire in the situation. He suggested that our research committee was the logical group to do this in the north central area.
”By the end of January, 1945, much of Mr. Kephart’s prophecy had materialized. Several sensational articles and advertisements about 2,4-D had appeared in print, and the barometer of public interest was rising rapidly as indicated by the sudden flood of inquiries received by nearly every weed control and research worker in the country. It was immediately evident that our meager facilities and personnel for weed research would not be able to gain information rapidly enough to protect the public interest except through organized effort.”
The minutes of the 1946 meeting include the details of the extensive research project conducted by the North Central States Group. In a summary of the research project it is stated, “More than 80 copies of the uniform plan of experiments were sent to prospective cooperators and others interested. Many requests for copies were received from persons outside our North Central Conference, in states as far east as New Jersey, as far south as Texas and as far west as California and Oregon. Several copies of the plan was sent to workers in Canada.
”A total of 35 cooperators reported the results from a total of 160 different experiments on different weeds. Thirty-six of the experiments were conducted by cooperators in Canada at stations distributed from Newfoundland to Alberta.
”Our Research Committee was… assigned the task of summarizing and reporting upon the results... The task of summarization resulted in many a headache for these sub-committees. Despite the fact that the results reported were from experiments based on uniform plans, there were some variations in treatments and other details in nearly all cases, so that the problem of correlating the results and arriving at conclusions as to what they showed was a tedious and difficult problem…
“These reports demonstrated the value of our uniform program of research and also revealed some of its weaknesses. The uniform program was as successful in 1945 as could have been expected in the first year... The outstanding weakness of the program in 1945 was the lack of uniformity in conducting the experiments and the resulting inability to make direct comparisons in many cases. As one of the sub-committees stated it, ‘the only thing uniform about the individual experiments reported was their lack of uniformity.’ This variability in the supposedly uniform experiments in 1945 is understandable when one considers that the uniform plan was developed hastily and presented suddenly to the experiment station directors and research workers too late in the season for careful plans to be made.”
The Research Committee’s 1945 research project examined the effects of 2,4-D on crops, on lawns, and on weeds. While the 1945 research design did not include examination of the persistence of 2,4-D in the soil, the end-of-year report did include some of that data: “The injurious effects on crop plants of residual 2,4-D in the soil from spray applications were apparent during periods varying from only a few weeks to several months, apparently depending upon the amount of rainfall received after the spray application. The residual effects seem to persist longer in the soil in the dryer states like Kansas and Nebraska than in humid areas like Ohio. The residual effects of 2,4-D were most injurious to the more sensitive vegetable and legume crops and less detrimental to the grasses and cereals.”
For the Research Committee’s 1946 research plan, the committee added research on the persistence of 2,4-D in the soil. It is notable that the projects did not include research on the effects of 2,4-D on native plants, wildlife, livestock, or humans. Some anecdotal information is included, on the lack of effects seen on humans and livestock. The report also referred to the fact that 23 weeds appeared to be resistant to 2,4-D.
The 1946 Western Weed Control Conference minutes included one research report from Mr. Freed of Oregon, on the effects of 2,4-D on soils. His report on soil sterility stated: “In general, 2,4-D breaks down within a month in warm, moist soils but may persist for six months in cool or dry soils. A comparison of soil types under greenhouse conditions shows a higher toxicity of 2,4-D in sandy soils than in clay soils, but a more rapid leaching from the sandy soils. Under field conditions, the toxicity in the soil will depend on the amount of 2,4-D applied, the soil type, temperature, and moisture conditions.”
It should be pointed out that this hastily developed research program was in response to the realization that many farmers and ranchers were already using the new chemical, with or without research in place on its impacts. These experiments were conducted by various State Agencies, with scant support from Federal funding. In fact, the minutes also note that, although “An intensive research program on 2,4-D was also conducted by C.I. Seely, representing the U.S. Bureau of Plant Industry, and cooperating with the Idaho College of Agriculture…” in his report from the North Central Conference, T.F. Yost stated, ”In the weed control program the National Congress has curiously adopted what seems to be a hands-off policy. Maybe it would be better to say that the Congress seems not to be interested in the national weed control problem. Some of the states, in order to protect themselves against the weed menace, have been forced to initiate and support their own eradication and control program, while the Federal Government has set idly by and has not even done a good job of looking on. The weed problem is so broad in scope so devastating in effect and so complicated when considered from the overall standpoint, that we believe the time is here when Congress should sit up and take notice that there is a weed condition in our country that is of national importance, which if not properly handled will undermine the greatest resource of our nation, which is the soil. There are some aspects of the weed problem that cannot be handled on the state level. These problems cut across state lines and can only be handled by Federal action.”
Links to next sections on herbicides
Next Sections on herbicides and other pesticides: