R.E. Pitblado, E.A. Kerr
Bacterial speck has been increasing in Northeastern U.S.A. and Canada for several years. Losses have ranged up to 50%. In 1978, three related, advanced breeding lines numbered "Ontario 7710", "Ontario 7611", and "Ontario 782", showed near-immunity under field conditions. Tests in the laboratory showed that the only resistant cultivar in their ancestry was "Farthest North" which had been derived from "Bison" X an accession of L. pimpinellifolium. Other cultivars showed variation in the severity of infection in the field but these proved susceptible under laboratory conditions. Several cultivars which may trace back to "Farthest North" are also resistant. Tests of F1 and F2 populations have shown that this resistance is conditioned by a single dominant gene.

The incidence of bacterial speck of tomatoes, caused by Pseudomonas tomato (Okabe) Altstatt has been increasing in Canada and the U.S.A. in recent years (6, 7, 8). A survey conducted in southwestern Ontario, the most concentrated tomato producing area in Canada, indicated that 80% of the tomato fields were infected with bacterial speck in 1978 (6). Considerable attention has been given to demonstrate practical control measures using predominantly copper bactericides (4). Chemical control methods similar to those recommended for bacterial spot, caused by Xanthomonas vesicatoria (Doidge) Dows have not been entirely successful (2, 4, 9).

During the summer of 1978, an advanced tomato breeding cultivar trial was found to be naturally infected with bacterial speck. Within the 40 cultivars, a range of tolerance and susceptibility to bacterial speck was noticed (5). Three closely related lines, ontario 7710, Ontario 7611 and Ontario 782 showed good resistance under field conditions. On the basis of these observations, studies were initiated to determine the inheritance of resistance to bacterial speck in tomatoes.

Pitblado, R.E. and Kerr, E.A. (1980). RESISTANCE TO BACTERIAL SPECK (PSEUDOMONAS TOMATO) IN TOMATO. Acta Hortic. 100, 379-382
DOI: 10.17660/ActaHortic.1980.100.40

Acta Horticulturae