ARTIFICIAL VS. FIELD INOCULATION WITH FUSIFORM RUST 339 



the slowest growing of those tested. Hence, its resistance may be an 

 indirect result of mediocre growth. Low vigor and resistance are often 

 related in cases of obligate parasitism (Heimburger, 1962; Illy, 1966). 

 Whatever the underlying causes, the departure of 11-6 from agreement 

 demonstrates that joint artificial and field tests can identify selec- 

 tions having different forms of resistance. 



LITERATURE CITED 



Arnold, J. T., and R. E. Goddard. 1966. Variation in resistance of 



slash pine to southern fusiform rust, p. 100-103. In Proc. Eighth 



So. Conf. on Forest Tree Improvement, Ga. Forest Res. Council, 



Macon, Ga. 161 p. 

 Davis, T. C. and J. Goggans . 1968. Fusiform rust in southern pines. 



Auburn Univ. Agr. Exp, Sta. Highlights of Agr. Res. 15: 10. 

 Heimburger, C. 1962. Breeding for disease resistance in forest trees. 



Forest Chron. 38: 356-362. 

 Henry, B. W. , and F. F. Jewell. 1963. Resistance of pines to southern 



fusiform rust, 4 p. In Proc. World Consult. Forest Genet. £ Tree 



Improvement, Vol. 2, FAO, Stockholm, Sweden, n.p. 

 Illy, G. 1966. Note on the resistance to pine twist rust caused by 



Melampsora pinitorqua in the offspring of Pinus pinaster , p. 125-125. 



In H. D. Gerhold, et at. (ed.) Breeding pest-resistant trees. 



Pergamon Press, Oxford. 505 p. 

 Jewell, F. F. 1960. Inoculation of slash pine seedlings with Cronartium 



fusifovme. Phytopathology 50: 48-51. 

 Jewell, F. F., and S. L. Mallett. 1964. Resistance to fusiform rust in 



slash pine as shown by artificial inoculation. Phytopathology 54: 



1294. 

 Jewell, F. F., and S. L. Mallett. 1967. Testing slash pine for rust 



resistance. Forest Sci. 13: 413-418. 

 Kinloch, B. B. , Jr. 1968. Genetic variation in susceptibility to fusi- 

 form rust in (control- and wind-pollinated progenies of) loblolly 



pine. Ph.D. Thesis N.C. State Univ., Raleigh. 54 p. 

 Kinloch, B. B. , Jr. and A. Kelman. 1965. Relative susceptibility to 



fusiform rust of progeny lines from rust-infected and noninfected 



loblolly pines. Plant Dis. Rep. 49: 872-874. 

 LaFarge, T. and J. F. Kraus . 1967. Fifth-year results of a slash pine 



polycross progeny test in Georgia, p. 86-91. In Proc. Ninth So. 



Conf. on Forest Tree Improvement, Eastern Tree Seed Laboratory, 



Macon, Ga. 138 p. 

 Patton, R. F. 1961. The effect of age upon susceptibility of eastern 



white pine to infection by Cronartiion ribicola. Phytopathology 51: 



429-434. 

 Smith, H. C. 1968. Plant breeding for disease resistance. Span 11: 



89-91. 

 Steel, R. C. D. and J. H. Torrie. 1960. Principles and procedures of 



statistics. McGraw-Hill Book Co., Inc., New York. 481 p. 



FLOOR DISCUSSION 



Due to late submission this paper was not presented by Dr. Dinus at 

 the Study Institute except in summary form, from the floor. Floor 

 discussion was withheld until after the following, related paper by 

 Dr. R. A. Schmidt. 



