382 ROBERT F. PATTON 



inoculations. Theoretically, exposure of progenies should encompass the 

 broad range of genetic variability in the rust. We still know very 

 little about the existence of pathogenic races of the rust for pine, and 

 if more than one is identified, the problem of how to test progenies 

 against all of these must be faced. This, again, is a problem concerned 

 with source and supply of inoculum. 



The major improvement in orogeny testing methods and techniques must 

 come from (1) a better understanding of factors influencing needle pene- 

 tration and initiation of infection, and (2) better ways of applying the 

 basidiospores to the infection court, such as in liquid suspensions, 

 aerosols, or air currents. Ideally, a method is needed that will allow 

 the controlled deposition of inoculum on test plants in a relatively 

 uniform manner, so that disease escape is eliminated and host response 

 can be quantitatively related to inoculum amount. The technique described 

 by Snow (1968) for C. fusi forme and modified by Dwinell (these proceedings) 

 is an approach toward this end. 



The choice of an inoculation method might depend on whether the 



objective is large-scale progeny testing or infection for experimental 



purposes on a relatively small number of individually handled plants. 

 There is need for efficient and reliable methods for both uses, and a 



successful method designed for small-scale use should be examined with 



the view of adapting it for large-scale progeny tests of a resistance 

 breeding program. 



LITERATURE CITED 



Ahlgren, C. E. 1961. Progress with direct bark inoculation for white 



pine blister rust. J. Forest. 59: 208-209. 

 Borlaug, N. E. 1966. Basic concepts which influence the choice of 



methods for use in breeding for disease resistance in cross-pollinated 



and self-pollinated crop plants, p. 327-344. In H. D. Gerhold, 



et al. ( e d.) Breeding pest-resistant trees. Pergamon Press, Oxford. 



505 p. 

 Boyer, M. G. 1962. Studies on white pine blister rust. Interim Report, 



Can. Dep. Forest., Forest Entomol. $ Pathol. Br., Forest Pathol. Lab., 



Maple, Ontario. 38 p. 

 Boyer, M. G. 1964. A note on the artificial inoculation of white pine 



seedlings with the blister rust fungus. Can. J. Bot . 40: 335-337. 

 Bromfield, K. R. 1967. Some uredospore characteristics of importance 



in experimental epidemiology. Plant Dis. Rep. 51: 248-252. 

 Ellingboe, A. H. 1968. Inoculum production and infection by foliage 



pathogens. Annu. Rev. Phytopathol. 6: 317-330. 

 Emge, R. G. 1958. The influence of light and temperature on the formation 



of infection-type structures of Puacinia graminis var. tritici on 



artificial substrates. Phytopathology 48: 649-652. 

 Heimburger, C. 1956. Blister rust resistance in white pine, p. 6-11. 



In Proc. 3rd Northeastern Forest Tree Improv. Conf . , Cornell Univ., 



Aug. 1955. 85 p. 

 Hirt, R. R. 1942. The relation of certain meteorological factors to the 



infection of eastern white pine by the blister-rust fungus. New York 



State Coll. Forest. Tech. Publ. 59. 65 p. 

 Kinloch, B. B., Jr. 1964. Evaluation of resistance to fusiform rust 



(Cronartium fusi forme') in loblolly pine {Pinus taeda) . M.S. Thesis, 



North Carolina State Univ., Raleigh. 62 p. 



