RESISTANCE TO BACTERIAL SPECK (PSEUDOMONAS TOMATO) IN TOMATO
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.