January 27, 1912.] 



THE GARDENERS' CHRONICLE. 



53 



The great difficulty in the matter is that we 

 have not really known the nature of the disease, 

 and that we have sown and watered and tended 



appearance 

 bacterial causes. 



of the vascular tissues suggested RHODODENDRON BROUGHTONII AUREUM, 



Before the inclusion of Azaleas in the 

 genus Rhododendron, the generic name of Aza- 



These scrappy notes are all that we have had 



blindly, hoping against hope that the crop would to work upon, and one is inclined to ask how it i eo d en dron was applied to the subject of this 



be healthy, but utterly unable to ensure it. Ex- is that science has done so little towards the 



perience dashes our hones again and again ; a solution of an eight-years-old problem. I believe 



wet summer leads us to believe that damp, chilly it is the case, that many fungi are difficult to 



weather favours the progress of the disease. trace under normal conditions ; and unless fruit- 



This, again, is contradicted by its rampant pro- ing spores can be discovered, it is often impossible 



gress in the hottest, driest season known for to identify them. In the case under review, 



nothing was found except Thielavia, Fusarium, 



and Botrytis; but I wonder whether all the 



70 years. 



In the Sweet Pea Annual for 1909, Mr. George 



Massee says : 



" The disease is of a physiological nature . . . plaids 

 suffering from it having an absence of root nodules" After 

 some generalisations, we are farther told that " a suitable 

 quantity of the proper sort of manure would attain the 

 desired object," viz., a cure; and that an excess of manure 

 would be likely to have a deleterious effect. 



This brings me 



available tests were employed ? 

 to the relation of the discovery (though not by 

 recognised scientists) of another organism, which 

 comes near to providing us with an answer to 



our question. 

 Mr. YVm. Dyke 



pert 



In the same issue of the Annual a large num- and nurseryman— offered, early in this season, to 



investigate any of my plants in which the disease 

 _ _ should appear. I gladly accepted this offer, and, 



Btate that they pulled up and burnt the affected in due course, handed over to him two successive 



ber of members quote briefly their experience in 

 connection with the disease. Many of these 



note and similar hybrids, the result of crossing 

 evergreen Rhododendrons with the deciduous 

 kinds, still more generally spoken of in gardens 

 as Azaleas. Although raised many years ago, 

 R. Broughtonii aureum is still our best yellow- 

 flowered hardy evergreen Rhododendron. It3 

 nearest rival is R. sulphureum, which has more 

 of the true evergreen character, but the flowers 

 are a poor shade of yellow when compared with 

 those of R. Broughtonii aureum. True, the 

 Himalayan species R. campylocarpum has prim- 

 rose-yellow flowers, but the plant is not hardy in 

 this country except in favourable localities. 



R. Broughtonii aureum obtains its name from 

 the village of Broughton, in Peeblesshire, where 

 it was raised by crossing a yellow Azalea and a 

 seedling evergreen Rhododendron. There is also 

 in cultivation a plant very similar in some re- 

 spects, named R. Smithii aureum. This hybrid 

 the result of crossing a seedling of R. 



is 





[Photograph by E. /. Wallis. 



Fig. 29. RHODODENDRON BROUGHTONII AUREUM 



FLOWERS YELLOW 



plants. Other correspondents, unacquainted 

 with the disease in practice, suggested as a cause 

 the employment of too much nitrogenous 

 manure — a sound theory, but without such 

 manure it has been impossible to grow very large 

 flowers. 



batches, the second of which demonstrated be- 

 vond possibility of doubt that the cause of the 

 disease was Macrosporium, with which the 

 affected plants were literally swarming ! 



Mr. Dyke's report served to justify the theory, 

 long held by me, that the streak is a near rela- 



and the yellow-flowered R. flavum 



The raiser of this 



planD 



arboreum, 



(syn. Azalea pontica). 



was Mr. W. Smith, gardener to the Earl cf 



at Coombe Wood, and later of the 



Liverpool, 

 N orb it on 



Kingston-on-Thames. 



The 



Tri +1 l a c. „ . jy A 7 , 1niri .. five of the " Tomato stripe," and I cannot un- 



ln the biveet Pea Annual for 1910, one writer Vi , * at 



airs the theory that the cold, wet, sunless season 

 was detrimental to the nitrogen-fixing bacteria 

 in the soil, and hindered them in their work — a 

 theory completely disproved by the past summer. 

 The Annual for 1911 contains the report of 



common 

 having escaped the observation of the 



vious investigators. 



pre- 

 I can only think that, 



not expecting to find it, no attempt was made to 



ascertain its existence 



Althou & 



a common 



-mc mi num, iur it;ii contains me report 01 .. . , * * *^„^j • ii„ 



♦Ko C11 u „. „ -ii • . 1 , ■ x- x A i disease, it is one that can rarely be tound in the 



the sub-committee appointed to investigate the u . ' , , ., .. . 1 . , r. 



rr fo fruiting stage, unless the subject be kept for 



some time in a moist, warm atmosphere. Mr. 

 Dyke wrapped my own and several other speci- 

 mens in moist paper, and placed them in a warm 

 place ; in three days he could scoop up Macro- 

 sporium conidia by the thousand ! W. 



(To be continued.) 



disease ; but to all intent and purposes it is 

 merely a negative one. Mr. F. J. Chittenden, 

 who investigated a number of plants, could find 

 nothing beyond Thielavia basicola, eel-worm, 

 and Fusarium, and efforts to inoculate healthy 

 plants with Thielavia proved abortive. At 

 Reading no organisms could be found ; but the 



Nursery, 

 year 1838 is given as the date it was raised. 

 The plant illustrated (fig. 29) has slightly richer 

 yellow flowers than R. Smithii aureum, and the 

 undersides of the leaves are green. In R. 

 Smithii aureum the bottom surface of the leaves 

 is distinctly glaucous or silvery. 



The flowering season is May and early June. 

 In summer the plant resembles in habit an 

 Azalea, but the growths are looser. In winter 

 the evergreen character denotes its relationship 

 with the evergreen Rhododendrons. The aver- 

 age height of the plant is about 2J> feet. 



Cuttings of Azaleodendrons, which includes 

 the fragrant R. azaleoides (syn. R. fragrans), 

 root fairly readily towards the end of the sum- 

 mer. Half-ripened shoots should be chosen and 

 inserted in pots filled with sandy peat, placing 

 the pots in a propagating frame provided with 

 slight bottom heat A 0. 



