A DISEASE OF PINES CAUSED BY CRONAETIUM PYEIFOEME. 7 



Comandra umbellaia observed in a number of these localities was also 

 free from the rust. 



In 1914 the senior writer found Pinus pungens, P. rigida, and P. 

 virginiana closely associated in a mixed forest near Greenwood Fur- 

 nace, Pa. In this instance Pinus pungens was attacked by Peri- 

 dermium pyriforme so badly that in some places more than 50 per 

 cent of the trees were killed, and although Comandra umbellata plants 

 bearing the telial form of the rust were present in abundance, no pines 

 of either of the other species were diseased. This indicates that these 

 two species of trees are immune and that neither can be the host. for 

 the type specimen that Ellis found at Newfield. Of the five species 

 of pines known to be the secial host of this fungus, not one is a strictly 

 three-needle pine. All have either two or two to three needles in the 

 leaf clusters. This makes it seem improbable that Pinus rigida was 

 the host of the type material. Pinus ecJiinata is a two to three needle 

 pine found in southern New Jersey, and this species may have been 

 the host of Ellis's type. 



The cultural work done by the writers with Peridermium pyriforme 

 Peck proving it to be the gecial stage of Cronartium pyriforme (Peck) 

 Hedge, and Long on species of Comandra completes the life history 

 of all the caulicolous species of Peridermium as now recognized in the 

 United States. There are four native and one introduced species and 

 each constitutes the secial stage of a species of Cronartium : 



(1) Peridermium pyriforme, which is the secial stage of Cronartium pyriforme. 



(2) Peridermium cerebrum Peck is the secial stage of Cronartium cerebrum (Peck) 

 Hedge, and Long on species of Quercus and Castanopsis. This is a well-recognized 

 eastern species and, including its western form, Peridermium harknessii Moore, is the 

 only native gall-forming Peridermium in the United States. P. harknessii on Pinus 

 radiata Don is synonymous with Peridermium cerebrum, since it is associated with. 

 Cronartium cerebrum on Quercus agrifolia Nee on the Monterey Peninsula in California. 

 The other forms of Peridermium harknessii may not belong here, and until cultural 

 proof of their identity with P. cerebrum is obtained, the forms on Pinus ponderosa, 

 Pinus contorta, and other western pines remote from species of Quercus and Cas- 

 tanopsis can only be doubtfully referred here. 



(3) Peridermium comptoniae (Arth.) Orton and Adams, a well-known eastern species, 

 usually occurring on the pitch pine (Pinus rigida Mill.) in the eastern and north- 

 eastern United States, but also attacking two to three needle species, is the secial 

 stage of Cronartium comptoniae Arth. which attacks Comptonia peregrina (L.) Coult. 

 and Myrica gale L. 



(4) Peridermium filamentosum Peck on Pinus ponderosa and Pinus contorta is the 

 secial stage of Cronartium filamentosum (Peck) Hedge, which attacks a number of 

 species of Castilleja in the western United States over a wide region, ranging from the 

 Rocky Mountains to the Pacific coast. Peridermium stalactiforme Arth. and Kern 

 and Cronartium coleosporioides (Dietel and Holway) Arth. and Kern are synonymous 

 with this species. 



(5) Peridermium strobi Kleb., an introduced species, is the secial stage of Cronar- 

 tium ribicola Fisch. de Waldh., which attacks many species of Ribes. In Europe this 

 Peridermium attacks several species of white (5-needle) pine. In the United States 

 it has been found on only one species, Pinus strobus L. 



