214 SCIENCE AND FRUIT GROWING 



The bushes which formed the subject of the experiments at 

 Woburn (II, 7; XIV, 69) were, for the most part, planted in 

 the autumn of 1895, and formed an extensive, but not crowded 

 plantation. The varieties composing it were Black Naples and 

 Baldwin's Black. Though the ground had never been used for 

 growing black currants before, signs of infection by the mite 

 appeared in 1896, and, in spite of continuous removal of the 

 affected buds, the disease increased rapidly. Thus, in the case 

 of five selected bushes, where the affected buds were counted 

 and removed each year, the average number of them in three 

 successive years were 933, 1797 and 6875. 



Experiments with various insecticides were carried out in 

 1897 and 1898, with the assistance of Mr. R. Newstead and Miss 

 Ormerod. They consisted in either spraying or painting the 

 bushes with, or lifting and dipping them into, various liquids, 

 the sprayings being repeated once a month, but using the spray- 

 fluids at a continually diminishing strength after the buds had 

 expanded. Thus, with paraffin emulsion, various strengths up 

 to 10 per cent, were used on the bushes while dormant, and 

 whatever the initial strength was, it was gradually reduced to 

 1-25 per cent, before the end of the season. The buds were 

 examined microscopically one week after each treatment from 

 February 26 to September 22. In the first series of experiments 

 the substances used, and the maximum strength at which they 

 were applied, were 



Carbolic acid . . . 2 4 1 per cent. 

 Calcium sulphide . . .5 ., 



Paraffin . . . . 10 l ,, 

 Antinonnin 2 . . i ,, ,, 



Turpentine, applied to dormant bushes only. 



In the case of the bushes treated with turpentine, all the 

 mites were found to have been killed, and in those treated with 

 the strongest carbolic acid and antinonnin, half of them were 

 killed. But such success was useless, for all three of these 

 dressings had seriously injured the bushes, partially killing them, 

 and entirety killing the buds, so that the mites may have been 

 killed only as a consequence of having had their food supply 

 cut off. A good deal of injury to the bushes was done by the 



1 Carbolic acid, 2 per cent., and paraffin emulsion, 5 per cent., had 

 been recommended by the Board of Agriculture for the destruction of 

 the mite. 



2 Sodium orthodinitrocresylate. 



