Degree Type


Date of Award


Degree Name

Doctor of Philosophy




A 3500 tree plantation of poplar seedlings and clones established in the Netherlands in 1980 was observed to detail aspects of Melampsora species leaf rust epidemiology. Progeny from crosses of Populus deltoides Marsh., P. nigra L. and P. trichocarpa Torr. and Gray were rated for leaf rust resistance as were open pollinated progeny from selected P. maximowiczii.;Potential for increasing resistance through tree improvement is evidenced. Of observed seedlings and clones, resistance to Melampsora leaf rust was greatest in P. maximowiczii seedlings. P. deltoides imparted rust resistance to its progeny, P. trichocarpa and P. nigra imparted susceptibility to their progeny. Resistance to leaf rust in P. X euramericana 'Florence Biondi' was race non-specific. P. trichocarpa male clones imparted race specific resistance to progeny as did female clones of P. nigra, P. trichocarpa females and P. nigra males seem to carry genes for race non-specific resistance to leaf rust. Resistance to leaf rust in P. deltoides is polygenic in nature.;Silvicultural studies of intensive, short rotation poplar plantings in the north central states indicate the necessity of adequate weed management in establishment procedures. Where plant materials are not limited, long hardwood cuttings should be used and may be necessary to insure 90% survival levels and economic success.;Poplar clones of superior resistance may be used in mixed or mosaic plantations with clones of reduced resistance to provide genetic and physical barriers to pathogen population spread.



Digital Repository @ Iowa State University,

Copyright Owner

Rita Sonnelitter Schoeneman



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207 pages