462 PROTECTION AGAINST FUNGI. 



them, may, during the ensuing year, develop fresh aecidia. 

 The needles die and fall only when the disease is very intense. 

 The pine needle-rust, as the disease is termed by Massee, 

 comes from spores of species of Coleosporium senecionis, Fr., a 

 fungus infesting several species of Senecio, chiefly biennials, 

 S. vulgar is, L., S. viscosus, L., S. vernalis, W. et K. 



The fungus prefers plants 3 to 10 years old, but may attack 

 trees up to 30 years; it is widespread throughout Europe, 

 including the British Isles, but does little harm to the trees it 

 attacks. Weed out groundsell from pine woods that it attacks. 



16. Aecidium Abietinum, Alb. et Schw. 



This fungus causes a needle-rust, which appears at mid- 

 summer on the previous year's shoots of the spruce, the 

 needles then assume a dull reddish-yellow colour ; during 

 August, bright-red aecidia of the size of a pin's head project 

 from the needles, and at the end of August or the beginning 

 of September they burst and emit their yellow spores 

 in a cloud of dust. The affected needles, which on lateral 

 shoots are usually only on the upper side of the branches, die 

 and fall before the close of the year, and the fungus may be 

 thus distinguished from Chrysomyxa Abietis, Ung. The 

 alternate hosts of the fungus are several species of rhodo- 

 dendron in the Alps, and Lcdum palustre, L., in Finland and 

 parts of North Germany, and these plants carry the disease 

 through the winter. Spruce trees of all ages are affected, 

 especially in the Alps, from an altitude of 1,000 metres to the 

 highest limit of spruce, where whole spruce-woods sometimes 

 assume the yellowish-red colour. The disease is also very 

 prevalent in Eussia ; no practical remedy has been devised 

 against it. 



17. Aecidium columnar -e, Alb. et Schw. 



(Silver-fir Needle-rust.) 



Aecidia break out in July and August on both sides of the 

 mid-rib of silver-fir needles, in the shape of long yellow 

 blisters full of spores. This fungus alternates as Melampsora 

 Goeppertiana, Kiilm, on the cowberry (Vaccinium Vitis- 

 Idaca, L.), and causes that plant to become abnormally 



