414 



UREDINEAE. 



The aecidia appear in June as wrinkled yellow sacs 

 emerging from the bark of swellings. They continue to develop 

 in succession for years on the living parts of attacked 

 branches, but according to Hartig they cease to make their 

 appearance on old sterns, even when a mycelium is present. 

 This disease is the cause of great damage to pines, especially 

 where planted as pure forest. One case is recorded l of a 

 forest near Kohlfurt where 90 per cent, of the trees in an 

 did plantation were "stag-headed" on account of a deficient 



Fin. 248. Peridermium pin!. Section through a diseased stem of Pine showing the 

 gradual killing of the cambium by the fungus, (v. Tubeuf phot.) 



supply of water in the crown accompanying attacks of this 

 fungus. Until more is known of its life-history, preventive 

 measures cannot be well extended beyond cutting down 

 infected trees. 



The following species of Peridermium have been observed 

 on species of Pinus: 



A. On the needles: 



Peridermium oblongisporium Fuck, (now Coleosporium senecionis) on 

 /'/,/.! sylvestris and P. oastriaca (p. 374). 



P. Klebahni, P. Soraueri, P. Stahlii, P. Plowrightii, and P. Fischeri. 

 On Pinus sylvestris ; related to various species of Coleosporium. 



P. piriforme Peck. On Pinus speciosa in U.S. America. 



P. cerebrum Peck. On 7Y//^.s- riijifla in North America. 



1 Marker at Schlesien. Forstverein, 1893. 



