BLISTER RUST RESISTANCE OF WHTTE PINES IN ASIA 253 



appears to be absent around the infected plantations 2 although planned 

 surveys are necessary to confirm this. 1 



In the U.S. and Canada, this species has proved to be moderately to 

 highly resistant to the rust (Bingham, these proceedings) . 



PINUS PARVIFLORA 



Indigenous at higher elevations throughout Japan. 



This pine is moderately resistant to blister rust infection. The 

 rust is recorded sporadically on exotic plantings in Great Britain and 

 the United States (Spaulding, 1929) . It is quite susceptible under 

 artificial inoculation in the U.S. (Bingham, these proceedings). 



INTRODUCED WHITE PINES IN ASIA 



PINUS STROBUS L. 



Plantations of this species were established 50 years ago in Korea 

 and Japan. However, the plantations have remained free from blister rust 

 disease in both countries. Dr. S. K. Hyun 1 states that in Korea, a rust 

 believed to be C. ribicola was found on Ribes fasciculatum Sieb. et Zucc. 

 about 50 meters from a P. strobus plantation that remained uninfected. 

 C. ribicola is not recorded on P. strobus in Japan although the rust 

 apparently occurs on Ribes lati folium Jancz., R. rubrum L. and R. 

 saohalinense Nakai in that country. 3 



PINUS AYACAHUITE EHRENB. 



This species has been tried both in the nursery and in the field in 

 the Western Himalayas in India. No attack by C. vibioola is recorded, 

 though the trees have not been thoroughly and repeatedly examined. 



DISCUSSION 



It is difficult to understand the absence of any authentic record of 

 C. vibicola in Japan on indigenous or exotic 5-needle white pines, 

 including the susceptible P. strobus. Apparently the rust is recorded 

 on Ribes there. A similar situation occurs in Korea where 50-year-old 

 plantations of P. strobus have remained free from blister rust infection 

 nearby an infected Ribes bush. A different situation, however, exists in 

 Korea where P. koraiensis (in plantations) is severely attacked by C. 

 ribicola, and Ribes spp. possibly is absent around the infected pine. 

 This may possibly be explained by autoecism (pine-to-pine spread) in the 

 aecial stage of the rust, but autoecism has not been conclusively proved 

 (Spaulding, 1922). More recent reports indicating autoecism (Scholz, 

 1960) seem to be disproved by failure of attempts to inoculate P. strobus 

 by Boyer (1961). Our knowledge of the life history of the rust therefore 

 appears incomplete. An intensive survey of the blister rust, and also 



2 L. S. Yoorij personal communication 3 1969. 

 Dr. H. Saho s personal communication, 1969. 



