44 CURRANT. [1900 



So far as I am aware, the observations of the past year have shown 

 little, if any, practical advance in knowledge of preventive treatment 

 for Black Currant Gall Mite, which still continues to be as great a 

 pest as ever to growers. 



It may, however, be of service, in saving waste of time in experi- 

 ment, and also in saving adoption of useless remedies, to give a few 

 details of severe treatment which there was reason to hope would 

 succeed as measures of ea-tt-nni nation, but have failed; to mention two 

 insecticides which (recommended on authority) have proved valueless ; 

 and also to give a few notes on fumigation, regarding which, though 

 proof has been given that it will kill the Gall Mites if thoroughly and 

 strongly brought to bear on them, we do not as yet see how to bring 

 the plan to bear in circumstances where bushes are grown in large 

 areas, even up to fields of several acres. 



The history of the attack, as most of us know well, is that from 

 about the middle of July, when the yoiiny buds of the season are 

 fonniny, the swollen gall-growths may also be found commencing ; and 

 even at that date the mite may be found in all stages, from egg 

 onward. As time goes on the growth of the galled buds progress till 

 they are very noticeable as green mis-shapen balls of abortive leaves ; 

 or, when partially opened, as perishing rosette-like masses crowded 

 within with legions of the minute cyJindiical four-legged mites, too 

 small to be distinguished by the naked eye. 



The figure, p. 43, gives a representation of the mite so enormously 

 magnified as to be of service for scientific identification '■' ; and with 

 this is given a figure, life size, of the mite-galls, taken from a spray of 

 unusuallg large specimens with one gall expanded, and with the centre 

 withered. 



At p. 45 a figure is added showing a spray with two galled buds, 

 and one in the natural state, and also a specimen of P. ribis, enormously 

 magnified, but, though not such a perfect representation as the figure 

 at p. 43, giving a very helpful general idea of appearance as seen by 

 ordinarily accessible microscopic powers. 



In the course of 1898 it was considered desirable by the Director 

 of the Woburn Experimental Fruit Farm to institute some experi- 

 ments to ascertain whether, in cases where Black Currant plants taken 

 from infested plots were cut down to the ground and removed to 

 ground known to be clean of infestation after having the roots variously 

 subjected to treatment to remove or kill mite presence, this would be 

 followed by absence or by presence of Phytopti. 



• The length of the female mite is twenty-three hundredths of a millimetre — 

 that is to say, twenty-three hundredths of one-twenty-fifth of an inch — a size at 

 which (it is unnecessary to say) the mites, as single objects, are imperceptible to 

 the naked eye. 



