Insect Pests and Plant Diseases. 



203 



" poison." Cut a V-shaped slit in one side of the cork so. that the liquid may be 

 poured out in drops. Add the lime mixture to the d'iluted copper sulfate solution 

 until the ferro-cyanide test solution n'ill not turn broicii when dropped from the 

 bottle into the mixture. It is always best to add a considerable excess of lime. 



170. Bordeaux injury on apples. 



BORDEAUX INJURY. (Fig. 176.) 



Some plants are injured by the ordinary strength of Bordeaux even when 

 properly made. Others, like the apple, are sometimes injured by quite a weak 

 Bordeaux under certain weather conditions. The leaves of most varieties of 

 stone fruits, especially peaches, and Japanese plums are most sure to be in- 

 jured by Bordeaux except in very weak mixtures. The injury to these plants 

 consists usually of small holes in the leaves, very similar in appearance to the 

 shot-hole effect of certain fungi. The 

 injury on apple occurs on both the 

 leaves and the fruit. On the leaves it 

 consists of quite definite brown spots 

 very much like certain leaf spots due 

 to fungi. The injury on the fruit takes 

 the form of russeting. It may even 

 cause large cracks to appear. Some 

 varieties of apples suffer more than 

 others. Wet weather during spraying 

 season appears to be one of the cliief 

 factors in the production of Bordeaux 

 injury on apples. It has also been 



shown that "the more copper sulfate, the greater the injury." It is to be under- 

 stood, however, that injury from Bordeaux is much less common and serious than 

 injury from the fungous disease, to prevent which it is applied. For a fuller dis- 

 cussion of this subject see Geneva Bulletin 287. 



Copper carbonate, 5 oz. ; ammonia, 3 pts. ; water, 50 gals. Dilute 



the ammonia in seven or eight quarts of water. Make a paste 



of the copper carbonate with a little water. Add the paste to 



the diluted ammonia, and stir until dissolved. Add enough 



water to make fifty gallons. This mixture loses strength on 



standing, and therefore should be made as required. It is used in place of 



Bordeaux where one wishes to avoid the coloring of maturing fruits or ornamental 



plants. Probably, it is not as effective as Bordeaux. 



If large amounts of the above mixture are required, it is more economical for 

 the grower himself to make the copper carbonate. Proceed as follows : Dissolve 

 12 lbs. of copper sulfate (blue vitriol) in 12 gals, of water in a barrel. Dissolve 15 

 lbs. of sal soda in 15 gals, of water (preferably hot). Allow the solution to cool; 

 then add the sal soda solution to the copper sulfate solution, pouring slowly in 

 order to prevent the mixture from boiling up and running over. A fine precipitate 

 which will settle to the bottom after the mixture has stood about twelve hours is 

 formed. Siphon off the clear liquid above. Wash the precipitate by adding clear 

 water, stirring and again allowing to settle. Siphon off the clear water, strain the 

 precipitate through muslin, and allow it to dry. This is copper carbonate. The 

 above amounts will make about six pounds. 



Ammoniacal 



copper 



carbonate. 



