22 2 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



Two Diseases new to Scotland caused by Species of 

 Hypoderma. 



It has often been observed that considerable damage frequently 

 occurs in plantations of the Scots pine owing to the loss of foliage 

 and consequent loss of increment in growth. This is often 

 due to attack by Lophodermium Pinastri, but in a considerable 

 number of cases no obvious fungus is present and the damage 

 is consequently put down to climatic influences. Such specimens 

 of the Scots fir, showing considerable defoliation and discolora- 

 tion of the needles, were collected by Dr A. W. Borthwick near 

 Dalmally in September of the present year, and forwarded for 

 investigation through the headquarters of the Forestry Com- 

 mission in Scotland. At the first glance the specimens showed 

 no obvious sign of attack by a fungus, but subsequent investiga- 

 tion has proved that the damage is due to a fungus which has 

 been provisionally identified as Hypoderma pinicola, Brunch. 

 This species was discovered in Norway in 1892 by Brunchorst, 

 and was subsequently recorded in Denmark and Germany. 

 In the Scottish specimens brownish or yellowish-grey areas 

 occur on the needles, and the abundance of these areas gives 

 the whole shoot a greyish tinge. . Examination of the discoloured 

 areas with a lens reveals minute slits in the epidermis from which 

 exude drops of resin. On soaking in water the slits, which are 

 found in series on both surfaces of the leaf, open widely and 

 reveal the elongated fructifications of the fungus. These, which 

 are 1-2 mm. long, are pale red in colour and are covered during 

 the earlier stages of development by a dark-coloured layer of 

 fungal tissue which, when the fructification opens, is only seen 

 as a narrow band just inside the ruptured epidermis. The 

 reddish mass consists of asci and paraphyses; the asci are club- 

 shaped and contain eight club-shaped spores each provided 

 with a layer of mucilage ; the paraphyses are long and filiform. 



Brunchorst states that the disease attacks the young needles 

 immediately after their development; after the lapse of a year 

 the discoloration appears, the fructifications of the fungus 

 mature in July and the needles fall in the autumn or winter of 

 the second year. Lind, in Denmark, states that the disease is 

 particularly prevalent during cold and wet summers. 



Specimens of the fungus have been received from other 

 localities in Scotland, and it appears that the disease is wide- 



