MELAMPSORA PINITORQUA (BRAUN) ROSTR. AND PERIDERMIUM 

 PINI (WILLD.) KLEB. ON PINES - SOME .ASPECTS 



Allan Klingstro'm 



Institute of Forest Botany and Pathology , Royal College of 



Forestry 3 Stockholm, Sweden 



.ABSTRACT 



Pine terminal shoots normally contain several substances that 

 have an inhibiting effect on Melampsora basidiospore germina- 

 tion. The amount of inhibitors declines in conjunction with 

 the axial extension of the pine, about the time when infection 

 by Melampsora pinitorqua occurs. Germination-inhibiting sub- 

 stances have also been found in leachates from the surface of 

 pine shoots. Clones and progenies of Pinus silvestris 

 with different attack frequencies as regards Melampsora 

 pinitorqua have been described. Clones with different degrees 

 of sensitivity to the disease can also differ as regards the 

 inhibitor content. The difficulty of registering the attack 

 frequency in an acceptable way has also been dealt with. 



As regards Peridermium pini , an account is given of an inocu- 

 lation test on progenies produced for studying the fungus 

 in question. 



Studies of these endemic rusts on pines, aimed at practical breeding 

 in Sweden, are still at an early stage. No drastic event, such as the 

 introduction of white pine blister rust into the Xorth .American continent 

 has to similar degree focused interest and resources on these parasites. 



MELAMPSORA PINITORQUA 



A number of European pine species are susceptible to attack by 

 Melampsora pinitorqua (Braun) Rostr. Several American pine species used 

 in European tests also have shown themselves to be susceptible. An 

 attempt to summarize the results of these tests has recently been made by 

 the author (KlingstrCm, 1969) . 



INFECTION BIOLOGY 



The actual infection biology is still not fully known. Basidiospores 

 usually are not disseminated over large areas; the danger zone is 

 generally considered to be about 200 meters. A summary of available 

 reports on spread of this rust has been made by Regler (1957) . The usual 



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