PLANT DISEASES. WILD PLANTS AS A SOURCE OF DANGER. 935 



PLANT DISEASES. WILD PLANTS AS A SOURCE 

 OF DANGEE. 



By A. D. Cotton, F.L.S., F.R.H.S. 



Many of the organisms that cause diseases in our commonly grown 

 Mowers, fruits, and vegetables are well able to exist on British wild 

 plants, which are often allowed to flourish on rubbish-heaps and other 

 out-of-the-way corners of the garden. This is especially the case with 

 diseases of plants caused by fungi ; and the object of this paper is to 

 draw attention to the risk that is run in allowing weeds to grow at all in 

 gardens, and to point out those wild plants which may be more especially 

 regarded as affording a home for diseases of plants caused by parasitic 

 fungi. Only those diseases which are of general occurrence in Britain 

 will be dealt with here. 



Some of these fungi make use of the wild plants they find at their 

 disposal, to tide over bad times when their favourite garden crops are not 

 at hand ; whilst others are always abundant on wild plants * and occasion- 

 ally make invasions into the garden and cause epidemics on cultivated 

 forms. It is thus evident that weeds are a distinct danger in the two 

 ways just mentioned. 



Weeding thus becomes a more important item in gardening than we 

 might at first sight imagine ; for we are apt to think that if it is regularly 

 attended to in the flower and vegetable garden, and other parts in cultiva- 

 tion, we have done our duty in this respect. Weeds are then left quite 

 unmolested at the backs of shrubberies, and such places, where they do 

 not attract attention ; whilst plots of ground that are not planted are 

 often allowed to produce an abundant crop. This is particularly noticeable 

 if the ground has been manured, or still more so if road sweepings have 

 been applied, when a perfect flora of weeds will make its appearance. 

 Now, quite apart from the fact that these weeds will probably produce a 

 stock of fresh, well-grown seed, which will be blown about, and come up 

 in due course where least wanted, they often prove to be very undesir- 

 able in encouraging diseases in the garden in the manner alluded to 

 above. 



As gardeners, we are all inclined to think that our cultivated plants 

 are much more subject to fungus pests than their relatives which grow 

 wild ; but a careful examination of wild plants would convince anyone 

 that this is not the case. Naturally a clump of diseased Hollyhocks in 

 a garden would be more conspicuous than plants of Malva sylvestris 

 attacked by the same disease at the roadside ; though it is a fact that 

 one can seldom find the wild Mallow quite free from the Hollyhock rust, 

 Puccinia malvacearttm. 



* Of course one would not for a moment condemn the use of British wild flowers 

 in gardens, as they have a charm of their own, and no garden should be altogether 

 without them ; but the weeds referred to are those which are not left because of their 

 beauty, but simply because it is thought they do no harm. 



