120 



EXPERIMENTAL FARMS. 



AN EXPERIMENT TO PROVE THE EFFICACY OF PARIS GREEN WHEN APPLIED WITH BOR- 

 DEAUX MIXTURE. 



This simple experiment was suggested by fruit growers, who, having used the com- 

 bined fungicide and insecticide, found at harvesting time a comparatively large per- 

 centage of wormy fruit, this led them to suspect that the Bordeaux mixture exercised 

 a weakening influence on the toxical qualities of the arsenic, or, combined with it in 

 such a manner as to render the arsenic comparatively innocuous to insects. 



On this point Mr. A. H. Pettit in submitting his report on spraying experiments, 

 says : " I am inclined to think though I have no means of knowing it to be so, that the 

 Bordeaux mixture does to some extent destroy the action of Paris green, otherwise the 

 percentage of fruit of first quality would have been much larger." The unusual amount 

 of wormy fruit, however, may undoubtedly be attributed to the presence of a second 

 brood of Codling Moth, which occurred in Grimsby during this season. This occurrence 

 is discussed by Mr. Fletcher in the report of the Entomologist. 



The chemical action consequent upon the addition of Paris green to Bordeaux 

 mixture is discussed by Mr. Shutt, who also gives the results of laboratory experiments. 

 The conclusions reached are quite in line with results gained from practical trials in the 

 orchard, which may be described as follows : — 



Two trees each of three varieties of crabs were selected, all promising a heavy 

 crop of fruit. Immediately after the blossoms had fallen one tree of each variety was 

 sprayed with Bordeaux mixture to which was added 4 ounces of Paris green, one ad- 

 ditional application was given two weeks later. The remaining tree of each variety 

 was sprayed with Paris green in water in the same proportion and on the same dates 

 that is, 1 lb. to 200 gallons. The fruit was picked in the autumn, windfalls being kept 

 distinct from the hand-picked. The number of wormy fruits in each case, separated 

 and counted. The results are given in detail in the following table : — 



Showing Percentage of Wormy Fruit under both Treatments. 



Variety. 



Grabs. 



Orange 



do 



do 



do 



Hyslop 



do 



do 



do 



Quaker Beauty . 



do 

 do 

 do 



•{ 



How Treated. 



Paris green 

 Bordeaux mix. 

 Paris green .. . 

 Bordeaux mix. 

 Paris green 



do 

 Bordeaux mix. 

 Paris green 

 Paris green 



do 



do 

 Bordeaux mix. 

 Paris green . . 

 Paris green .. 



do 



do 



Average of all treated with Paris green 



do do Bordeaux mixture. 



Grade of 

 Fruit. 



- Handpicked 

 1 



Windfalls. 



Handpicked 

 Windfalls. . . 



J- Handpicked 



Windfalls 



Handpicked 

 Windfalls 



r Handpicked . . 



Windfalls 



Handpicked 



Windfalls 



Percentage 

 Wormy. 



803 



266 

 20 13 



9'55 



20 65 

 1176 

 15-67 



672 



15 00 

 1182 

 20 81 



Averages. 



801 



11 



15 



13 



10 



16 



13 

 11 



39 



10 



71 



86 



31 



80 

 32 



The above table shows that trees treated with the combined insecticide and fungi- 

 cide had 2*48 per cent less wormy fiuit than those treated with Paris green alone. The 

 difference is trifling, but sufficient to settle any doubt or uneasiness, that might be 

 experienced on the question of the efficacy of Paris green as an insecticide when applied 

 with Bordeaux mixture. 



Previous experiments show that the amount of wormy fruit might be reduced 8 

 to 12 per cent by using Paris green with the fungicide. 



