CXCviii PROCEEDINGS OF THE ROYAL HORTICULTURAL SOCIETY. 



diseased with the attack of a black mould new to the British Isles. The 

 leaves were dead or dying at the ends of the branches, and the under 

 surface sprinkled on the dead parts with black dots, which proved to be 

 the tufts of conidia probably produced by Coniothecium Questieri, Desm., 

 which w r as found and described in France in 1857 on leaves of Comas 

 sanguined. The conidia are brown, very variable both in form and size, 

 and muriformly septate, clustered in glomerules, and mixed with a few 

 slender threads, This parasite has appeared so seldom that no experi- 

 ments have been made upon it, but it is recommended to strip off, sweep 

 from the ground, and burn all fallen leaves, so as to prevent the diffusion 

 of the pest. Even when this is done, if there is any foliage left, it should 

 be sprayed with one of the copper solutions to destroy the germinating 

 powers of the conidia." 



Flax Wilt. — Dr. Cooke said : — " Since the last meeting of the Com- 

 mittee I have learnt that experiments have been undertaken at the 

 N. Dakota experimental station (Bulletin No. 50) to ascertain the cause 

 of the disease known as * Flax Wilt ' and ' Flax-sick soil,' a disease which 

 appears to be known in Ireland, as well as in Belgium, Germany, and 

 other Flax-producing countries of Europe. I may premise that it has 

 long been known that Flax cannot be grown continuously for any long 

 period upon the same soil, because the soil becomes 1 sick ' and the Flax 

 seedlings die off and do not produce a crop. The cause of this has 

 hitherto been a mystery, but has generally been attributed to exhaustion 

 of the soil. From the result of these experiments it appears to be, not 

 the exhaustion of any of the chemical constituents of the soil, but the 

 prevalence of a minute fungus in the soil, which preys upon the debris 

 of the previous year's crop, and attacks the young seedlings of the new 

 year, causing them to wilt and die. The name of this new T fungus is 

 Fusarium Lini." 



Outgrowths on Potato Tubers.— Dv. Cooke supplied the following 

 additional facts upon this disease, lately reported upon : — " It was at- 

 tributed to a newly described fungus under the name of Gh/rysophlyctis 

 endcbiotica, although at the time I advocated its decided affinity to the 

 tumour produced on Beetroot. More recently specimens have been sent 

 to Berlin, with the result that Dr. Magnus has not only confirmed this 

 affinity, but has demonstrated that it is the same species, which is known 

 as GtJdomyccs leproides, Trabut, so that the 1 Beetroot tumour ' and the 

 1 Potato tumour ' are caused by the same fungus. This should be noticed, 

 since the form on Potatos has for two years been destructive in several 

 localities in the British Isles, and is quite capable of infesting Beetroot 

 in like manner" (see page cxliv). 



Iris Black Mould. — Dr. Cooke also reported upon diseased Irises sent 

 to the committee : — " Since the last meeting a plant of Iris ochrolcuca 

 has been submitted to me for examination. The roots were in a perfectly 

 sound condition, but the leaves were affected in a similar manner to those 

 of other specimens sent to the committee recently, and of which I find 

 no record in the reports of our meetings. The leaves turn yellow and 

 sickly, and then brown, dying towards the tips. Upon these brown 

 patches occur sooty or blackish spots, often of considerable extent, rather 

 velvety under a lens, which manifest the appearance of a black mould 



