INOCULATION WITH PINE TWISTING AND SCOTS PINE BLISTER RUST 315 



When collecting aspen leaves for inoculum it is necessary to check 

 each year to be sure that the teliospores are germinable. The conditions 

 required for germination, referred to above must be satisfied. If the 

 leaves are soaked in cold water for a few hours and then laid out on a 

 damp surface or in Petri dishes at 15 to 20°C, after a few hours it is 

 possible to detect the formation of basidia with the naked eye. Should 

 the telia either fail to germinate or germinate only after a few days, 

 the aspen leaves were collected too early. However, it is seldom possible 

 to force development of basidiospores on more than a small percentage of 

 the aspen leaves. Also, it is usual for the basidiospores on individual 

 leaves to form simultaneously on only a part of the leaves. 



Hetanpsova species are difficult to identify just from the appearance 

 of teliospores on aspen leaves. This is true particularly where both 

 Pinus and Larix are common and where Melampsora Zariai-tremulae Kleb. may 

 be as common as M. pinitorqua. The situation can be complicated even 

 further by the presence of Mercuridlis s Chelidonivam. or Allium , which can 

 carry aeica of other Melampsora spp . , all with uredospores and teliospores 

 on species of Populus. The situation must be assessed from area to area. 



Inoculation experiments on pine plants can be carried out with a 

 degree of certainty, either in the greenhouse or nursery. In nurseries, 

 use must be made of damp weather or a suitable temperature. Night 

 inoculation usually ensures suitable humidity and temperature conditions. 



In more extensive field tests, with slightly larger plants, the 

 prospects of controlling infection are reduced. The plants may be brought 

 into contact with aspen leaves carrying teliospores (Klingstrom, 1963a) , 

 but the weather is still the determining factor. If one has a nursery for 

 resistance tests, the pine plants can be watered artificially during axial 

 extension, and then aspen leaves can be introduced or, alternatively, aspen 

 can be cultivated on the test site. While successful test inoculations 

 with M. pinitorqua should be possible in theory, as yet no systematic 

 pine resistance tests are being carried out. 



The above comments on inoculation of pine with .V. pinitorqua should 

 be compared with the supplementary information elsewhere in these 

 proceedings which is based on Swedish tests concerning ?. silvestris 

 and ?. tremula. l 



PERDERMIUM PIN I 



Peridermiurr. pini (WillcL") Kleb. is usually described as an autoecious 

 strain of Cronartium asclepiadeun (Willd.) Fries. This non-alternating 

 Peridermium is extremely common, at least in northwest Europe. Its range 

 within the whole of the enormous distribution area for the host-alternating 

 C. asalepiadeun- -Europe , North Asia to Korea and Japan--has not yet been 

 fully established. Older works on the taxonomy of C. asolepiadeur. and the 

 non-alternating Periderrriur.s have been collocated by Bolland (1957) , 

 Gaumann (1959) , and van der Kamp (1968) . .And the most recent addition to 

 the scientific naming is Endacrov.artvim (Hiratsuka, 1969) . 



1 See paper by A. Klingstrom 3 these proceedings. 



