MELAMPSORA PINITORQUA (BRAUN) ROSTR. AND PERIDERMIUM 

 PIN I (WILLD.) KLEB., INOCULATION PROBLEMS 

 AND TECHNIQUES 



Allan Klingstrtfm 



Institute of Forest Botany and Pathology 3 Royal College 



of Forestry 3 Stockholm; Sweden 



ABSTRACT 



The difficulties involved in carrying out inoculation tests 

 with Melampsora pinitorqua on pine have been discussed. The 

 handling of dry teliospores does not present much of a problem, 

 but basidia and basidiospores are extremely sensitive to 

 desiccation and higher temperatures. 



Concerning Peridermium pini , an account is given of a method 

 of inoculating pine shoots with spores suspended in water. 



The main biological features of these rust fungi have been known for 

 a long time, but this is not to say that successful methods exist for 

 inoculating them on a large scale in progeny tests. 



MELAMPSORA PINITORQUA 



Melampsora pinitorqua (Braun) Rostr. twisting rust on pine is but a 

 small part of an extensive Melampsora leaf rust complex (Gaumann, 1959) . 

 Among the hosts of Melampsora populina (Pers.) Le"v . group are the genera 

 Populus, Larix and Pinus , and in the Melampsora salioina Le"v. group are 

 to be found a number of host plants of interest in forestry, including 

 Salix i Abies and Larix. Probably other host plants of practical signifi- 

 cance in forestry are also involved. Pseudotsuga, for instance, has 

 been .mentioned by Longo, Moriondo and Naldini (1967). Studies of American 

 pine species in Europe with regard to M, pinitorqua have generally added 

 new species to the list of known hosts (Longo., et at. , 1967; KlingstrCm, 

 1969) . A corresponding complex of Melampsora species exists in North 

 America. From the point of view of European forestry it is worth noting 

 that in American tests Pinus silvestris L. is susceptible to Melampsora 

 rusts (Ziller, 1965) . 



M. pinitorqua occurs in the whole of Europe and in adjacent parts of 

 northern Asia. The fungus infects the annual shoots of pine with basidio- 

 spores during the axial extension period. These spores are distributed 

 from telia that have overwintered on the ground on dead aspen leaves. 

 The teliospores germinate in damp weather and, if this coincides with 

 the axial extension of the pines, infection can result. In other words, 

 the occurrence of pine twist rust on pine depends on the fortuitous 



313 



