CANKER OF SCOTS PINE CAUSED BY DASYSCYPHA SUBTILISSIMA. 1 85 



Two species, D. resinarta, Rehm, and D. abietis, Sacc, occur 

 on Picea exceha in Britain, both of which are indistinguishable 

 by the naked eye from D. Willkommii. D. resmaria has also 

 been recorded on Lan'x europcea and Pinus exceha, and, in the 

 United States, on Abies balsamea. 



D. subiilisstma, Cooke, another species closely resembling 

 D. Willkommii, appears to be not uncommon in Scotland. 

 It was first described by Cooke, ^ " on the bark of firs in 

 Scotland." It has been found in abundance, apparently as a 

 saprophyte on Pinus sylvestris, in the Tynehead district (Mid- 

 lothian). Recently a specimen producing a characteristic canker 

 on the Scots pine has been received from Carmichael (Lanark- 

 shire). Mr G. Mowat, who sent in the specimen, supplies the 

 following particulars. "The plantation from which the tree was 

 taken is situated at a slight elevation on a fairly dry gravelly 

 soil with a good covering of rough grass. It is enclosed with 

 rabbit-proof netting. It was formed in 1906 with 2-year 2-year 

 plants of Scots pine, and these were notched in. The average 

 height of the trees is now about 7 feet. A few larches are 

 mixed with the pines, but only two or three of these are attacked 

 by the larch canker. The wound on the specimen was about 

 6 inches from the ground, and was not quite clear of the rank 

 grass." 



The canker extends about half-way round the trunk, and 

 has produced a flattening and consequent constriction of the 

 stem as a result of partial or complete stoppage of cambial 

 activity in the infected area (Plate XIX. Figs, i and 2). 

 The canker is in an early stage of development and generally 

 resembles that produced on the larch by D. Willkommii. 

 The distribution of the fructifications is, however, rather 

 unusual; while in the case of the larch these are generally 

 found towards the outer parts of the canker. In the present 

 specimen they are grouped towards the centre of the diseased 

 area (Fig. i). 



The ascigerous fructifications (ascophores) closely resemble 

 those oi D. Willkommii in size and appearance, but as a general 

 rule they possess slightly longer stalks. There are, how- 

 ever, striking differences in the asci of the two species, those 

 of D. Willkommii being about twice the size of those of 

 D. subiilissima. 



^ British Fungi, Grevillea, vol. iii., p. 121, 1874-5. 



