102 INJURIOUS INSECTS OF 1903. 



If the lime is of good quality and the mixture is made 

 as directed, there will be no burning of the foliage. How- 

 ever, it is always best to determine whether enough lime 

 has been used by testing the mixture. 



"There are three simple tests which may be used. 

 First, hold a clean, bright knife blade in the Bordeaux Mix- 

 ture for at least one minute. If it becomes copper-plated 

 more lime should be used. Second, pour some of the Bor- 

 deaux Mixture into a shallow dish and, holding it up to 

 the light, blow gently across its surface. If properly made 

 a thin pellicle will form on the surface of the liquid. If 

 this does not form more lime should be added. Third, 

 dissolve one ounce of ferro-cyanide of potassium in 5 or 6 

 ounces of water. Pour some of the Bordeaux Mixture 

 into a white dish and add to it a few drops of the ferro- 

 cyanide solution. If sufficient lime has been used no 

 change will be noticed. If a brownish-red discoloration 

 takes place more lime should be added." 



Up to the present year the only practical method in 

 which to use this fungicide was in the liquid form. 

 Thanks, however, to the work of Dr. Bird, of the Missouri 

 Experiment Station, a successful dust spray having the 

 same chemical composition as the liquid spray has been 

 discovered. Previous to this time the dry product, sup- 

 posed to be Bordeaux, had a very different chemical com- 

 position from the true Bordeaux Mixture, and was of very 

 little fungicidal value. 



The following is an account of the dust spray of Bor- 

 deaux, written by J. M. Steadman in the "Country Gentle- 

 man" of Aug. 13, 1903 : 



"The new Bordeaux powder can be made by an}'- fruit 

 grower or gardener with very little trouble, and at a very 

 nominal expense. It can be made during the winter and 

 stored in a dry place, where it will keep indefinitely. 



"In order to make this new Bordeaux powder one 

 should first make a large quantity of air-slacked lime. 

 This can be readily done by taking about 75 pounds of 

 good quick lime, pounding up the lumps and spreading it 

 over a large area, thus allowing it to air-slack readily. 



