1899] CURRANT GALL MTTE. 41 



Careful experiment has still been continued on all points which 

 appeared likely to throw light on means of prevention of the Black 

 Ciu-rant Mite Gall disease, which for so long has been a yearly cause 

 of great loss to growers on a large scale. So far as I am aware, how- 

 ever, none of the chemical applications which have been tried have 

 given satisfactory results by destroying the infestation without injury 

 to the plant growth ; but as these observations will, 1 believe, be fully 

 reported on in detail, I am only entering here on some parallel ex- 

 periments carried on in connection with observations at the Woburn 

 Experimental Fruit Farm, Ridgmont, Beds, which I have the pleasure 

 of taking some small part iu, and am permitted to mention here. 



The object of the investigation was to ascertain whether the attack 

 was propagated in part by Currant Gall Mites, that is, Phytoptus ribis, 

 harbouring in the earth at the roots or round the bases of the stems 

 of the Currant bushes. 



"We know that the mite is to be found in the Black Currant buds 

 during a great part of the year. From about the middle of July, when 

 the young buds of the season are forming, the swollen galled growths 

 may be found to be commencing, and even at that early date the mite 

 (or Acarus) may be found in all stages from egg onwards within ; as 

 time goes on the growth of the galled buds progresses, till they are 

 only too conspicuous as green mis-shapen balls of abortive leaves, or, 

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

 (as long as the vegetable matter is sufficiently soft to give support to 

 the parasites) with legions of the minute cylindrical four-legged mites, 

 of which an enormously magnified figure is given at p. 40. About the 

 beginning of June, if any of the old galls are still sufficiently alive to 

 furnish food, the Phytopti may be found in them, and they are also to 

 be found (both as old and young mites) between the base of the 

 leafstalk and the buds at the ends of the young shoots.* 



So far as appears, we are perfectly acquainted with the history of 

 the mite on the plants in their above-ground life ; but very careful 

 investigation was needed to discover whether spread of infestation took 

 place from mites sheltered in the earth at the base of the stems. 



For this purpose it was arranged that Black Currant plants taken 

 from the Woburn grounds, where the infestation was present, should 

 be quite cut down to the ground and removed, some with the earth 

 adhering, but no other way treated excepting in being quite cut down ; 

 and some others similarly cut down, and also washed in a mixture of 



* For precise history of P. ribis through the year, see "Recent Investigations 

 of the Currant Bud Mite (Phytoptus ribis),'' by R. Newstead, F.E.S., Curator of the 

 Grosvenor Museum, Chester, Lecturer on Economic Entomology for the Cheshire 

 County Council, pp. 5-7. Reprinted from ' The British Naturalist ' for June, 1894. 

 Price 3d. 



