Evening Republican, Volume 17, Number 137, Rensselaer, Jasper County, 9 June 1913 — BORDEAUX MIXTURE [ARTICLE]

BORDEAUX MIXTURE

C. G. Woodbury, Department of Horticulture, Purdue University Experiment Station, Purdue University Agricultural Extension. Bordeaux mixture was the first satisfactory .spray material ever developed and is still a standard fungicide. It is ft combination of copper sulphate (blue-stone, blue vitriol), lime and water. The copper sulphate is the active fungicidal agent and the lime is added to prevent burning of the foliage. When the materials are mixed a number of complex cheihical changes occur which unite the lime and copper sulphate in various ways. No free copper sulphate solution should be present in a properly made mixture. There are numerous formulas for Bordeaux mixture, but the one most generally accepted is as follows: Four pounds of copper sulphate, six pounds of lime and fifty gallons of water. Copper sulphate is purchased in crystal form and should not cost over 6 or 7 cents per pound in barrel lots. The lime used can be either stone lime or commercial hydrated lime. Air-slaked stone lime should never be used, In making Bordeaux mixture the copper sulphate is dissolved in one vessel and the lime slaked in another. These materials are then diluted to as near 25 gallons each as possible. The dilute copper sulphate solution and the milk of lime are then poured simultaneously through a strainer into the spray barrel. When the copper Bulphate solution and the milk of lime come in contact a precipitate is formed. If the material has been properly prepared, this precipitate will be light and flocculent and will stay in suspension with a minimum of agitation. Never mix the copper sulphate solution and the milk of lime in concentrated form as a coarse, heavy precipitate is formed, whioh settles very rapidly. 1 When making more than one barrel of Bordeaux mixture stock solutions of the raw materials are used. Stock solutions are prepared by weighing out a definite amount of each substance and then dir luting them to a known volume. One hundred pounds of copper sulphate is dissolved and made up to 50 gallons, This is easiest done by placing the copper sulphate in a gunny bag or a coarse splint basket and suspending it hear the surface of a barrel of water. The crystals will then dissolve over night If it is desired to hasten the process, übc warm water. Each gallon of the stock solution now contains two pounds of copper sulphate. One hundred pounds of lime

Is slaked in a shallow box. Oreat care should be taken to neither drown nor burn the lime, as a lumpy milk of lime will result in either case. Shovel this lime paste into a barrel and make up to 50 gallons. When thoroughly stirred, each gallon of lime stock so-, lution now contains two pounds of lime. When making a barrel of Bordeaux mixture (4-6-50), take 2 gallons of copper sulphate stock solution (4 pounds copper sulphate) and 3 gallons of the well-stirred lime stock solution (6 pounds of lime) and dilute each several times. Pour the two solutions simultaneously through a, strainer into the spray barrel and dilute to 50 gallons. The result is Bordeaux mixture. When large quantities of Bordeaux mixture are to be used, a mixing platform should be arranged. It should be high enough so that the materials can be run into the spray tank by gravity. The floor of this platform should be large enough to accommodate 4rom four to six fifty-gal-lon barrels. The stock solution barrels can be set to the rear of the platform and the dilution barrels near the front. The dilution barrels should each be equipped with spigots so that the solutions can be run by gravity through a common trough into the spray tank. In making 100 gallons on. this platform 4 gallons of copper sulphate stock solution are placed in one dilution barrel and six gallons of the lime stock solution in, the -second dilution barrel. The dilution barrels are then filled with water. The spigots on the dilution barrels are opened and the two materials run through the trough to the tank. As the two materials meet in the trough, 100 gallons of mixture is formed. A strainer is usually tacked over the end of the trough. Bordeaux mixture in itself is merely a fungicide and .has no beneficial properties in the control of Insect pests other than acting as a repellant. In order to make the material most efficacious it should be combined with arsenate of lead. Use two pounds of arsenate with every barrel of Bordeaux mixture. This combined spray will then control both the chewing insects and fungous diseases. Bordeaux mixture is now used as a fungicide on vegetable crops and as a standard means of controlling the bitter rot and apple blotch on the applet For a complete schedule of application, consult Leaflet 27. ,