22 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY, 
or no effect. The only suggestions made are in favour of prevention 
rather than cure, by giving careful attention to the production of 
vigorous healthy plants, in preference to any attempt to check the 
trouble after it has once gained a hold. Endeavour to secure plants 
of ideal development. Grow the plants under conditions necessary for 
producing vigorous healthy growth and protected from conditions 
likely to induce disease. Keep the houses or frames clean, sweet, and 
devoid of all rubbish likely to harbour vermin or disease. Propagate 
only from healthy vigorous stock at the most favourable season. 
Select each spring none but perfectly healthy vigorous plants from 
the rooted cuttings for planting in the houses and frames. Old plants 
are sometimes carried over, but they are not so reliable as the young 
plants, and much more liable to all kinds of disease. Keep the plants 
clear of yellow, dead, or dying leaves, being careful to destroy them 
after removing them from the plants. Keep the plants free from 
insects and other animal pests. . , , Set the young plants early in 
the spring in the beds where they are to remain for the season, so that 
they may get well established before the hot dry weather of summer 
makes its appearance." 
I am convinced that this " spot" almost invariably appears on leaves 
which have already been damaged by red-spider. 
Other diseases are stem-rot and wart disease. I do not know what 
causes them, and I have seldom seen them. I only suggest, as Mr. 
Dorsett suggests, that healthy clean conditions, and getting things 
done at the proper time, is the likeliest method of obtaining immunity 
from these diseases. And if the plants are badly affected, burn them 
and get a fresh stock. 
And now with regard to red-spider. Mr. B. T. Galloway, in his 
little book on Violet culture, rightly says that this is one of the worst 
enemies with which Violet growers have to deal. It is present at all 
seasons of the year, and ready at all times to begin its destructive 
work. Such varieties as ' La France ' and ' Princess of Wales ' are 
particularly subject to red-spider. ' California ' and ' Luxonne ' 
resist it much more effectively. ' White Czar ' is seldom touched. 
The same is true of ' Noelie.' 
In doubles ' Marie Louise ' suffers worst. ' Lady Hume Camp- 
bell ' keeps very clean. 
Of red-spider it may be said emphatically that prevention is a 
thousand times better than cure. There are many effective cures for 
red-spider, but nine out of ten of them will also effectively destroy 
the Violets. You can get leaflet No. 41 issued by the Board of Agri- 
culture and Fisheries. This leaflet will give you a scientific descrip- 
tion of the whole family, a page and a half about its life-history, and 
a number of methods of control. 
I fear, however, that most growers will have to confess that we 
have not yet solved the problem of the red-spider. 
