36 BULLETIlSr 957, U. S. DEPARTMENT OF AGRICULTUEE. 



(143, 144) that squirrels ate the swollen bark from the infected parts 

 of the branches. (PL III.) They undoubtedly run over fruiting 

 cankers and pick up seciospores on their fur and feet. Porcupines 

 may act in the same manner. Birds undoubtedly carry these spores 

 to some extent, and as in the sscial season they begin nesting and 

 largely remain in the same locality they, too, act only as local carriers. 

 Some indications have been noted where a road traverses a narrow 

 valley, or a narrow clearing in a forest, that automobiles create drafts 

 which carry spores to some distance along the highway. It seems 

 entirely possible for steam trains and electric cars to do the same 

 thing. 



POSSIBLE AUTGECISM OF THE ^CIOSPORES. 



The possible autoecism of the geciospores of Cronartium rihicola has 

 been considered. As early as 1913 field observations were made with 

 this point in view, but no evidence of the spread of the fungus directly 

 from pine to pine was found. 



The question whether seciospores of other stem-inhabiting pine 

 Peridermiums are capable of infecting pines has received considerable 

 attention. In 1907 Liro (82) stated that he had made 169 inocula- 

 tions of Pinus sylvestris with seciospores of Peridermium pini from 

 the same host. No infections resulted. In 1914 Haack (48) stated 

 that he had made similar inoculations and obtained abundant infec- 

 tions. His experiments were performed out of doors, with no pro- 

 tection from natural infection and with trees which already were 

 naturally infected ; hence, his results are worthless. In 1913 Meinecke 



(95) made successful inoculations with seciospores of ^'Peridermium 

 harlcnessii^' upon Pinus radiata under controlled conditions. Later 



(96) he changed the name of the fungus to Peridermium cereirum and 

 reported that he had successfully inoculated Pinus radiata with 

 seciospores from P. radiata and from P. attenuata; and P. muricata 

 with seciospores of P. cerebrum from P. radiata. 



In 1915 Hedgcock (51) successfully inoculated trees of Pinus 

 ponderosa var. scopulorum, P. contorta, P. sahiniana, P. carihaea, 

 P. mariana, P. pinea, and P. lialepensis with seciospores of "Peri- 

 dermium Tiarlcnessii" from P. contorta. He has also successfully 

 inoculated P. ponderosa and P. virginiana mth seciospores of "P. 

 Tiarlcnessii'' irom. P. 2)onderosa. 



In 1918 Klebahn (73) published the results of successful inocu- 

 lations made by him with seciospores of Peridermium pini upon 

 young twigs of Pinus sylvestris, both with and without wounds, 

 under controlled conditions. These results throw doubt on the 

 strict heteroecism of the seciospores of all the stem-inhabiting pine 

 Peridermiums. 



The following tests have been made with the seciospores of Cro- 

 nartium rihicola: Klebahn (68, 70) repeatedly inoculated young 



