526 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



licences was issued in 1914 and 1915, and in only one or two doubtful cases did 

 the disease reappear. Corky Scab of Potatos, Silver Leaf, Dilophia graminis, 

 and Apple Mildew are also dealt with. 



Amongst insect pests the Japanese Fruit Scale (Diaspis pentagona) is the 

 most important to which reference is made. It was discovered in two nurseries, 

 having been imported on ornamental cherry trees. — G. C. G. 



Plants, Enemies of. By M. E. Lemee (Jour. Soc. Nat. Hort. Fr. April 1914, 



p. 229 ; figs.). — An article on witches' brooms, which are described and illustrated, 

 and the cause of each is given. In each case the removal and destruction of 

 the malformed partis advised, and other remedies are suggested. — M. L. H. 



Plums derived from Native American Species of Prunus. By W. F. Wight 

 (U.S.A. Dep. Agr., Bull. 172 ; 44 pp.). — An interesting compilation of American- 

 raised Plums, showing how far they are derived from native species. Prunus 

 americana has most to its credit, but none of these are known in this country 

 for the reason that they are vastly inferior to the domestica varieties upon which 

 we mainly rely. The parentage given cannot in all cases be accepted as un- 

 impeachable. — E. A. Bd. 



Polystachya paniculata (Bot. Mag. tab. 8618). — Tropical West Africa. Family 

 Orchidaceae. Tribe Vandeae. Herb, epiphytic. Stem 3-6 in. long, 3-4-foliate. 

 Leaves 5-7 in. long. Flowers numerous, small; lip recurved, orange; other 

 petals and sepals yellow, streaked with orange.— G. H. 



Populus lasiocarpa (Bot. Mag. tab. 8625). — China. Family Salicaceae. Tree 

 40-60 ft. high. Leaves ovate, deeply cordate, blade 4-5 in. long. Catkins 4-6. 

 Capsules densely woolly. — G. H. 



Potato Disease, A New. By Pierre Passy (Jour. Soc. Nat. Hort. Fr. July- 

 Dec. 1 91 4, p. 500). — A disease of the potato which affects the young sprouts, 

 and which has only recently been observed, is here described. The sprouts 

 when they appear are long, thin, and bent, and when planted soon perish and 

 produce no crop. The cause of the disease is still uncertain, and no cure for it 

 is known. For early planting all affected tubers should be rejected, but even 

 this precaution in main-crop planting on a large scale when the tubers have not 

 been first started will be practically impossible to carry out. — M. L. H. 



Potato Diseases in Michigan. By G. H. Coons (U.S. A . Agr. Exp. Stn., Michigan, 

 Special Bull. 66, March 1914, pp. 1-32 ; 13 figs.). — The commoner diseases 

 of the potato (Late Blight, Early Blight, Scab, Rhizoctonia, Dry Rot, Wet 

 Rot, and Deep Scab) are generally met with in Michigan. The bulletin gives 

 a popular account of these diseases and suggests various control measures, as 

 follows : — To control Late Blight and Early Blight, Bordeaux mixture (4-4-50) 

 should be sprayed when tops are a few inches above the ground, and repeated 

 every fourteen days during the growing season. 



To control Potato Scab, soaking the tubers in weak formalin solution for two 

 hours is useful. To control Rhizoctonia, Deep Scab, and Fusarium Wilt, it is 

 suggested that only clean smooth tubers should be used, though disinfection in 

 formalin solution is useful. — A . B. 



Potato Diseases, Investigations on. By G. H. Pethybridge (Jour. Dep. Agr. 

 and Tech. Inst., Ireland, xv., April 1915). — A test of powder spraying (copper 

 sulphate and carbonate of soda) against Burgundy mixture resulted greatly in 

 favour of the latter both in total yield and in percentage of disease-free tubers 

 (Phytophthora infestans). Similar trials with other powders containing copper 

 and with Bordeaux paste against Bordeaux mixture showed the superiority of 

 the home-made mixture over the others in preventing ordinary potato disease. 

 Burgundy mixture made with potassium carbonate instead of with washing soda 

 gave very slightly greater yields than the ordinary Burgundy mixture, and this 

 at considerably greater cost. 



Comparisons between the resistance of different varieties to potato disease 

 were made, with result that ' Champion II.' and ' Clifden Seedling ' remained 

 green throughout the growing season, while the other varieties succumbed to a 

 greater or less extent, ' Duchess of Cornwall ' giving 100 per cent, diseased tubers. 

 4 Shamrock,' ' Northern Invincible/ ' Summit,' ' Arran Chief,' ' Arran's Hope,' 

 ' What's Wanted,' ' Langworthy,' ' Golden Wonder,' ' Peacemaker,' ' King 

 Edward VII.' were the other varieties tried. Where diseased tubers were 

 planted either the set '' missed " altogether or gave rise to a healthy plant. 



Experiments with the sclerotium disease (Sclerotinia sclerotiorum) showed 

 that certain varieties, particularly ' Clifden Seedling ' and ' Summit,' were more 

 resistant than others. 



