938 



JOURNAL OE THE ROYAL HORTICULTURAL SOCIETY. 



are mostly to blame in encouraging these fungi ; and where either of the 

 two moulds give trouble, care should be taken to uproot these and other 

 cruciferous weeds that may be about in the garden. (M. C. Cooke, loc. cit. 

 p. 20.) 



Besides these two moulds there is the Turnip Mildew caused by 

 Erysiphc polygoni. This parasite is able to attack plants of various 

 orders, it being very common on those Polygonums which are garden weeds, 

 such as P. aviculare (Knotgrass) and P. Persicaria, and also on Vetches, 

 and other members of the Leguminosce. It is probably able to pass 

 directly from these weeds to Turnips.* 



MALVACEJE. — The Hollyhock Bust, already referred to, is the only 

 case we need notice here. Wild Mallows should not be allowed to grow 

 in the neighbourhood of Hollyhocks, if it can be avoided, as the disease is 

 often abundant on the former, and it would rapidly pass into the garden, 

 if a suitable host were at hand. When all diseased leaves are burnt in 

 the autumn, the attack will be diminished the following season. Care 

 should also be exercised in obtaining clean seed, as the fungus 

 (Puccinia malvaccarum) frequently forms pustules of spores on the 

 carpels themselves. (M. C. Cooke, loc. cit. p. 36, plate iii. fig. 42.) 



ACEBACEA<].—The large black blotches so common on Acer 

 campestre and Acer Pseudo-Platanus are caused by the fungus Bhytisma. 

 The ornamental foliage of garden Maples also is sometimes completely 

 disfigured by this parasite. The fungus ripens its spores in spring, on 

 the dead leaves that have fallen off the previous autumn, and on a dry 

 day these spores are exploded from the leaves in countless thousands, and 

 are blown about by the wind, thus inoculating the young unfolding leaves 

 on any Acers within reach. The obvious remedy, therefore, is to burn all 

 diseased leaves in the autumn. The burning of the leaves of the variegated 

 varieties alone will not suffice ; therefore, when practicable, those of A. 

 campestre or any other affected species should be destroyed. (G. Massee, 

 " Text-book of Plant Diseases," p. 142.) 



LEGUMINOSCE. — The Bust attacking Beans of various species is 

 caused by Uromyces fabce ; and it is also common on Vetches and wild 

 Lathyrus ; hence these should not be tolerated.t Pisum sativum, the 

 garden Pea, is favoured with two mildews : a false mildew {Peronospora 

 vicice), which is common on Vetches and allied plants ; and a true 

 mildew (Erysiphe polygoni). The latter is the same that attacks Turnips, 

 and the hosts mentioned for it there should be looked out for in this case. 

 Polygonum aviculare, the Knotgrass, is a very common weed, and it is often 

 covered with this mildew. 



BOS ACE JE. — This order has more than its share of fungus pests, 

 not a few of which have been imported into the garden from the hedgerows 

 and copses. 



BOSES. — Tho Bose Bust {Phragmidium snbcorticatum) is abundant 

 on wild Roses, and is often introduced into gardens by means of the stocks 

 which arc; employed for grafting &c. The foliage of the Briers used for 



* For full particulars of the Mildew Parasites, see A Monograph of tlic Erysiphaccce, 

 by E. S. Salmon (Mem. Torrey Hot. Club, ix. 1901). 



t Pot Kust Fungi, see A Monograph of the British Uredinccc and Ustilaginea', by 

 C. B. IMowright. 



