THE BRITISH NATURALIST. 



[June 



PREVENTION AND REMEDIES. 



In very bad cases I would certainly recommend that the bushes be 

 cut down in winter, and burnt on the spot, but this should never be 

 attempted at any other time of the year. In winter the mites are all 

 safely housed inside the buds ; therefore, the removal of the bushes at 

 such period could be accomplished with little or no fear of shaking the 

 mites to the ground, or scattering them to the winds. 



Where the disease is only partial, I would strongly advise hand- 

 picking the infested buds, and burning them ; they must on no account 

 be thrown to the ground, or "dug in." If hand-picking be annually 

 adopted, the disease in the course of three years would be reduced to 

 such a minimum that the crop would in no way suffer. 



In districts where black currants are grown on a large scale, hand- 

 picking is a serious item ; yet I cannot recommend any system that is 

 more effectual. 



If the grower wishes to apply insecticides, I may say that it is useless 

 to do so between the fall of the leaf and the expansion of the buds in 

 spring, because the mites, as already stated, are then carefully housed; 

 I have never found a single example outside the buds during that 

 period. The Board of Agriculture (I.e.) recommend "spraying. . . in 

 the autumn before the weather becomes cold, and just after the leaves 

 have fallen, if possible. This will economise liquid and labour, and 

 will affect the mites before they get into the buds." This statement is, 

 I venture to say, most misleading and inaccurate. I have proved 

 beyond doubt that the mites begin to enter the newly-formed buds in 

 July; therefore, any application made "after the leaves have fallen 

 would be practically useless in clearing off the mites. As a proof of 

 this, last winter I tried dipping the infested branches in the well-known 

 " Paraffin Emulsion," which had no apparent effect on the mites, thus 

 proving the uselessness of the application of insecticides while the mites 

 are in the buds. 



Some very useful insecticides are given in the pamphlet issued by 

 the Board of Agriculture (I.e.) ; and Miss Ormerod deals very fully 

 with these in her " Manual," and in subsequent reports, to which I must 

 refer the reader. But if insecticides are used, they should be applied 

 at the time I have already stated. 



During my investigations I found two larvae of the Lacewing Fly 

 (Chvysopa sp.), also numerous specimens of two species of Acari ; all 

 of which may possibly have been feeding upon the Phytopti, but I have 

 no conclusive proof that they did. I can only say that I found them 

 all inside the infested buds : the Chvysopa looking very pale and 

 suggestive of having lived very much in the dark. I also found several 

 specimens of a species of Thrips, in all stages, and all of them within 

 the old buds, looking very pale, as if they, too, had been living inside 



