246 J. GREMMEN 



planted R. nigrum L. During the first 5 years all grafted trees 

 remained healthy, but since 1968 some plants have been observed to be 

 attacked by the blister rust fungus. 



Professor Patton 1 informed me that the scions sent to Dr. Rohmeder 

 in 1960 were of the following selections: I, 6, 30, 36, 191, 312, 327, 

 343, 353, and a susceptible control C-6. All of these are resistant 

 selections, but 191 might be classed as moderately resistant. Selec- 

 tion 1 seemed to be highly resistant, but no information exists on its 

 resistance-transmitting ability. No. 327 so far has given the most 

 promise of ability to transmit resistance to its progeny. 



Liese (1936) , when describing the attack of Peridermium pini (Pers.) 

 Lev. on Pinus silvestris L. stated that "in my opinion, the natural 

 tendency for the attack by Peridermium pini is heritable" (my transla- 

 tion) . Moreover, he believed this to be the same with regard to C. 

 ribicola in P. strobus , referring to some observations done by Eriksson 

 (1896). Eriksson raised eastern white pine plants in 2 different 

 garden beds with only 20 meter interspace. In one bed, a 90 to 95% 

 attack had been observed in a 7- to 8-year period, whereas not a single 

 trace of rust was observed in the other bed. 



Lehmann (1950/1951, citing a personal communication of January 2, 

 1950, from Liese) mentioned that before World War II extensive research 

 with regard to possible resistance in eastern white pine against blister 

 rust was carried out at Eberswalde (Germany) . Seed from 25 various P. 

 strobus provenances originating from natural localities of this tree in 

 the United States have been obtained. Liese stated that "it has been 

 demonstrated that all provenances contained susceptible as well as resis- 

 tant biotypes" (my translation) . 



Scholz (1960) assessed a P. strobus trial originally founded by 

 Professor J. Liese and Professor C. A. Schenck in 1938 in the Forest 

 Range Chorin near Eberswalde. This trial was non-replicated with some 

 sources having as low as 3, but up to 198 seedlings. It consisted of 

 10 German and 26 American provenances, originating from seed. During 

 1955 and 1956 the remaining trees were checked by Scholz on the presence 

 of the aecidial stage of the fungus. He observed a difference in attack 

 between the provenances, and within each provenance between the 

 progenies, varying from 6.8 to 23.1%. From a total of 56 progenies 

 (36 provenances), 13 progenies remained free from the disease, among them 

 1 provenance comprising 3 progenies from Tennessee (Emory River) . 

 Scholz informed me 3 that provenance 7 a-c (Tennessee, Emory River) is 

 still without attack. 



Scholz (1960) also mentioned another experiment dealing with research 

 on resistance in Pinus strobus started in 1954. For this trial 422 grafts 

 from 27 selected trees and 800 4-year-old nursery transplants were used. 

 R. nigrum and R. sanguineum Pursh . bushes were interplanted. In 1956 the 

 first symptoms of blister rust were observed in both grafted plants and 

 seedlings. Many of them showed the aecidial stage. In 1957 nearly all 

 P. strobus paints were , infected by the rust. In 1958 all grafted plants, 

 with the exception of one clone, were heavily infected or even killed. 

 Of the 800 plants all died except two plants. 



3 Personal communication 3 May 5 S 1969. 



