62 
THE GARDEN ALBUM AND REVIEW . 
THE BLACK CURRANT MITE. 
Those interested in this devastating pest will 
find a very instructive account of it in 
the “ Memoirs of the Royal Caledonian 
Horticultural Society” for 1905, by Mr. P. 
Murray Thomson. It appears that the mite, 
known scientifically as Eriophyes (Phytoptus) 
ribis has been known for upwards of 30 years. 
In some districts it is unknown, while in others 
very few bushes can be found unaffected by it. 
The young leaf-buds which harbour the mites 
become swollen and distorted, and these are 
certain indications of the attack. Later these 
leaf-buds turn brown and dry without having 
unfolded. 
It cannot at present be said with certainty 
that the life history of the mite is completely 
understood and as it is not more than one- 
hundreth of an inch in length, and some six or 
eight times less in breadth, it may be readily 
understood what have been the difficulties in 
attaining an accurate knowledge of its habits. 
In a long extract quoted from a report of 
Mr. Cecil YVarburton, in the Journal of the 
Royal Agricultural Society (Vol. lxii. 1901, 
257, and lxiii. 1902, 131), it appears that during 
no single month of the year, except perhaps 
December, are the mites unaccompanied by 
eggs and young. Some survive the winter in 
diseased buds or infested bushes, and as these 
are the parents of all subsequent broods, 
peculiar interest attaches to their fate. The 
buds are either so slightly diseased that they 
open and put forth leaves, or they are so 
seriously injured that they never develop, but 
eventually die and wither. In either case the 
mite has to seek fresh quarters. During 
February, March, and April, the mites within 
the buds multiply rapidly. About the middle 
of May some of the buds may be observed to 
be cracked and the mites seen outside them. 
For three or four weeks from this onwards the 
buds are gradually drying up, and a constant 
migration of the mites is going on. They are 
not quick travellers, as it takes an energetic 
mite about ten minutes to cover an inch. At 
this slow rate of progression the problem arises 
as to how the mites pass from bush to bush and 
district to district. It is thought that they do 
so by the aid of passing insects with swifter 
powers of locomotion. As green fly (Aphis) 
are frequently on the bushes it is considered 
probable that they are the most likely carriers 
for the mite from one black currant bush to 
another. Of course the object of the mite 
travelling is to seek out new buds, and although 
myriads probably die every year by exposure 
to cold or want of food, still more than enough 
are left to carry on their depredations. 
The question of the mite laying eggs in the 
soil has been carefully considered. Soil has 
been examined microscopically under various 
different conditions, and the behaviour of the 
mites has been closely watched in the hope 
that they might be detected concealing them¬ 
selves in convenient crannies, or at all events, 
in depositing eggs. In no case, however, was 
such an act observed. The mites crawled 
about aimlessly for two or three days, and then 
died—which seems to prove that it is rather 
useless treating the soil to eradicate the pest. 
Nor were the mites detected concealing them¬ 
selves under loose bark or cracks in the stem. 
When are the new buds first attacked ? At 
the end of May they are visible in the axils of 
the leaves, and though quite small are beginning 
to swell. In the first week of June the mites 
were observed outside these buds in the loaf- 
axils, and on June 7 a mite was seen to work 
its way into a bud wriggling between the 
sheathing leaves. Almost daily during June 
new buds were removed and examined under 
the microscope for mites. They were first 
found on June 8, and from that date onwards 
they appeared in greater numbers, and always 
near the middle of the bud. One or two 
mature mites, within whose bodies eggs were 
clearly visible, were usually found in each bud. 
The first signs of multiplication were on June 
26 when eggs and larvae were found in the 
buds. Hereafter the increase was rapid, mites in 
all stages of growth being found within the buds. 
It appears that red-currant bushes also are 
subject in a slight degree to the attacks of the 
mite. Eggs and larvae have been found upon 
them, so that when both kinds are grown 
together, it may be that the red-currant bushes 
help to tide the mites over a period until the 
black currants are ready for attack. 
Preventives. It is considered a waste of 
labour and expense to remove the surface 
soil, or to apply a dressing of gas-lime beneath 
the bushes as the mites come to nothing here. 
If washing or spraying be resorted to, the best 
time apparently would be from the middle of 
May to the middle of June, but this is just the 
period when there are difficulties with regard 
to the blossom, so that washing at any time is 
of doubtful value. As the pests appear to be 
least numerous about the last week in June, it 
is suggested that the removal and burning of 
all new wood bearing next year’s buds ought 
practically to remove the whole of the attack, 
but it is quite likely that this suggestion would 
be condemned as impracticable, and too de¬ 
structive of next year’s crop. 
The old practice of hand-picking the diseased 
buds in winter still appears to be one of the 
best means of keeping the attack in check, and 
when raising new plants, cuttings should be 
selected from bushes free from disease. 
Another suggestion is to spray liquid manure 
from cowsheds over the bushes from the middle 
of May till the end of June or middle of July, 
and again in autumn, as such treatment actually 
proved effectual in one garden. 
Eleven Hundred and Fifty Guineas was 
the price recently paid by Messrs. Sander & Sons, 
St. Albans, for a small but healthy plant of the 
magnificent Odontoglossum crispum Pittianum 
from Mr. H. T. Pitt’s collection. 
