(7) CHEMICAL KILLING OF WEEDS ON AND REMOVAL OF KILLED WEEDS FROM THE ROADBED S. B. FISHER, Chairman; R. A. RUTLEDGE, Sub-Committee. Inasmuch as this Sub-Committee has worked under the belief that the application of chemicals to weed killing has only been recently initiated, and of rather limited use by some of the railways and trolley lines in our country, no general circular asking for data and information has been sent out; but the Committee has tried to obtain information by personal solicitation and letters to officers of the railways who have had charge of the work, and were thus in position to give facts and reliable data on this new subject. As there has seemed to be a partial or total reluctance to respond on the part of some from whom information was asked the data thus obtained this year is not as full as your Committee would desire, although responses by some were prompt, full and valuable. We have also been in communication with supply and contracting parties who very kindly gave us copious information on both the chemicals and their application and their views of the results which have been and can be obtained from the application of chemicals to weed destruction. The second part of the subject, the removal of killed weeds from the roadbed, was at first considered eliminated as the uniform testimony received was to the effect that the wind and train suction automatically removed the weeds from the roadbed, but lately cases are reported from California, where some of the weeds grow all the year and from Texas, in which it was considered advisable to run a weed burner over the road to burn the weed stalks after they were chemically killed, or to clean the track by hand. Chemical weed killing was first initiated in 1906 by Dr. Ortin of Galveston, Texas, and a limited success in a restricted area of application was attained by him, but he was not able to carry it to a commercial success. Confining our statements to present reports chemical weed killing was started in 1912 and 1913, with a few roads treating moderately long stretches of track. The war interfered with its progress like it did with other work, but since then during the last few years it has been resumed and is now being followed rather vigorously, thousands of miles of railway and trolley lines being treated each year, so far in yearly increasing mileage. One contracting company has at the present time seven trains equipped for this work. The scarcity and high rate of labor has, no doubt, stimulated this method of weed killing. The chemical mostly used, so far as found out, is a mixture or compound of Arsenic and Caustic Soda, using 8 to 10 per cent of the latter by weight, dissolving the solid chemicals in water. The chemical is shipped in accordance with needs or demands in cans, barrels, drums or tank cars, in concentrated form, and diluted with water at the place of application, as circumstances require, which is usually one part of the concentrated chemical to 18 or 20 parts of water, with the arsenic-caustic soda combination referred to above. The application is made on any desired scale from a hand car, single flat car, or entire train, all with proper equipment. The fully equipped train is the only method with which to work economically on a large scale. The train is made up of 6 or 8 cars. The front or pilot car of the train contains the sprinkling apparatus, composed mainly of pipes, perforated with small holes or nipples for the emission and diffusion of the poisoning liquid, valves, meters, etc., all under the complete control of the operator. In the same car are pumps and air compressor actuated preferably by motors of Marine type, to furnish pressure to the liquid, in applying it to spraying the weeds, and to furnish compressed air for mixing the diluting water with the concentrated chemical. The liquids are thoroughly mixed by means of compressed air before application. In the after part of this car may be living quarters for the crew. The main part of the train is made up of tank cars-all connected together with lines of pipes, and fully supplied with valves, meters, all necessary appliances. One of these tank cars is loaded with the concentrated solution which is drawn out as needed. The other tank cars carry a supply of the chemical diluted to the strength for spraying on the weeds. The last tank car contains Repellant, a liquid to be sprinkled over the weeds after the poison has been applied at road crossings, station grounds, etc., in places where cattle are liable to browse on the vegetable growth and be poisoned by the compound. This Repellant is bitter or contains something disagreeable to grazing stock, this however appears to be of doubtful value. Last of all comes the locomotive pushing the trains. Before starting to sprinkle-the tank cars carrying the diluted mixture are filled. The concentrated chemical is drawn from its storage car and mixed 14 to 20 parts more or less of water as practised by the company with largest equipment and doing most treatment on the roads, while another company dilutes with equal volumes of concentrate and water. Thus the amount of dilution must be determined in each case from the strength of the solution and the vigor of growth and thickness of the stand and kind or species of weeds to be killed. The volumes are measured by meters and gages. The tank cars ought to contain enough liquid to reach to the next water station, 20 miles or more. The solution is applied at a speed of about 20 miles per hour, and by following a freight or local train as a second section, there is no interference with traffic. When the next water station is reached, a stop of an hour is made-although half an hour is usually long enough to refill the empty tank cars with another supply. The rate of application in volume per unit of area varies according to condition as much or even more than the strength of solution. A very convenient unit of measurement is gallons of solution per foot of width per mile of roadbed, which appears to be ordinarily within the limits of 5 and 15, or a minimum application of 5 gallons for width of 3 feet will take 40 gallons per mile, while a maximum application of 15 gallons per foot for 14 feet width will take 210 gallons. The rate of spraying per unit of surface is regulated either by controlling the amount of liquid allowed to escape from jets, which can be made under the control of the operator, or by varying the speed of the train or by both means. The rate of emission should be directly proportional to the weed growth and must be controlled by the judgment of the operator. It is claimed by some roads using the chemical weed killer that the weeds should be allowed to attain their full growth before application, so that the sap in descending the stocks will carry the poison to the roots. Others claim that the chemicals should be applied to the growing weeds in order to eliminate them from the roadbed during the summer season. It should be applied before cutting the weeds, as cutting causes the weeds to seal over the cut, preventing the poison penetrating to the roots. It should not be applied immediately after a rain as the cells of the weeds will be full of water and prevent much poison entering. It is claimed in some reports that the chemicals should not be applied immediately before rain, as rain washes the solution away so it will not enter the plant. It is claimed by others that rain after application is beneficial, because the solution being dried, is redissolved by the rain and is then absorbed by the plant. It is claimed by the advocates of chemical weed killing that successive application in lessening quantities per year for three years will completely extirpate the weeds, and the only ones afterwards growing will come from seed blown or carried in on the right-of-way. It is also held that the ground may be completely sterilized by the chemicals so it will grow weeds, but no instance of it actually being done has been given. Only one case has been reported so far of complete killing of weeds after three years' application. Some reports indicate that the most effective method is to make the first application so strong that all the weeds are killed-that successive weak applications tend to make the weeds immune. Some grasses and weeds, such as Johnson, Burmuda, Salt, Blue Stem, Wire, Crab Grasses, Horsetail, Ragweed and Bull Thistle, do not appear to be killed by a single application, and their complete destruction is still a problem. One road reports that after four years' application it was decided to discontinue entirely the use of the weed killer and resort to the weed burner, claiming that the "weed killer" did not destroy all the weeds and those that did succumb were dried and left to foul the ballast and otherwise giving an unsightly appearance to the roadway, and also that the cost was far in excess and also the results less satisfactory with the weed killer than with the weed burner. Attention is directed to the application of common salt to weeds on 454 miles of the Erie Railroad, as reported by Mr. I. H. Schram, Regional Engineer. The salt was applied from the car by shoveling on chutes which made the distribution in work train service at the rate of eight tenths car loads per mile. The cost was for labor and train $13.40 per mile, for foreign freight $18.75, total $32.20. The cost of hand weeding in that district has been $73.33-which gives cost of salt application 44% of cost of hand weeding. The salt was good mined salt, but rejection from crusher account being too coarse for market, and was received without cost. Approximately 40 tons per mile was used. The application was very effective and killed all the weeds. In this part of New York, in the vicinity of Rochester, salt has been used for a number of years for weed killing. Care, however, must be exercised in its application to prevent interference with automatic signaling. CONCLUSIONS Your Committee does not believe it has as yet enough data to report definite conclusions. It has many favorable reports of successful application and some of unsuccessful, or at least unsatisfactory ones. The reports nearly all cover only one year's work-the results of at least three successive applications ought to be definitely known before framing conclusions. The railroads that have been using it are generally continuing it on a yearly enlarged program, although a few have discontinued. There are cases where the contractor has been asked to do the work over again account unsatisfactory results in first application. How much this is due to unfavorable circumstances and how much to the system itself has not yet been ascertained. The reports so far received indicate that a very large percentage of the soft annuals or tender weeds are killed by the first application-running in many cases up to 85 or 95 per cent, but a smaller proportion of perennial and hardier annuals only are exterminated; about 50 per cent more or less so far as reported. The Committee can only report considerable work done and little progress for the past year, and would recommend a continuation of the study-as several roads are now gathering information which will be of value on the subject for future report. Your Committee has consulted with the Masonry Committee and are advised the above subject was assigned them in 1917. Progress reports and tentative specifications have been submitted by that committee and will be found on pages 748 to 762, Vol. 19, and pages 697 to 701, Vol. 20 of the Proceedings of this Association. In 1919 the Masonry Committee reported that "while progress has been made they feel that further investigation as to the distribution and transmission of pressures from engine loads and earth fills is necessary before a conclusion can be reached." Other Societies, having the same subject also under consideration, appointed a Special Committee in 1920, composed of two members from each of the following societies: American Society of Civil Engineers. American Highway Association. American Concrete Pipe Association. American Railway Engineering Association. |