THE BAY STATE TOMATO 3 



tion by the fungus was essentially the same; and among other species in other 

 families an extensive mycelium was never developed after penetration, even 

 under favorable conditions. This historical background is offered to rail atten- 

 tion to the consistency of reports showing the high degree of resistance of the 

 Red Currant tomato to the Cladosporium fungus, and the definite lack of 

 sporulation even in those rare instances where the fungus was observed to cause 

 a yellowish area about the point of infection. 



This new tomato was developed from cresses of Lycopersicon pimpinellifolium 

 (Jusl.) Mill, and L. esculentum Mill., two distinct species of tomato respectively 

 highly resistant and highly susceptible to tomato leaf mold. Three varieties of 

 esculentum tomatoes — Success, Belmont, and Break O'Day — were selected for 

 the first crosses after a comparative trial of varieties on outdoor trellis in 1933 at 

 Waltham. They are early maturing and bear large red tomatoes. Red color, 

 large fruit, and earliness were considered desirable, since the pimpinellifolium 

 tomato bears red fruits of extremely small size and because only red tomatoes are 

 wanted in the Boston market area. 



COMBINING RESISTANCE WITH DESIRABLE COMMERCIAL TYPE 



The entire population of the first generation was alike for all plant characters 

 and for resistance to leaf mold. The population o" the second generation was re- 

 solved into various unlike, desirable and undesirable characters, and resistance 

 and susceptibility to the disease. Selections for desirable characters and for le- 

 sistance to the disease were continued for two further generations. There ap- 

 peared to be nothing significant offered by the progenies cf one hybrid not also 

 offered by those of the other two; but the fruit, being only ^ to 1 inch in di- 

 ameter, was wholly inadequate fcr size. 



The varieties Success, Belmont, and Break O'Day under greenhouse culture 

 show many undesirable characters and, therefore, were considered unsuitable lor 

 further crossing with desirable types from the latest generations of the original 

 hybrids. For this purpose, and for a desirable greenhouse forcing type, an im- 

 proved selection of the Field Station Comet, now known as Waltham Forcing, 

 was employed. A large proportion of the greenhouse tomato production in the 

 Boston area is devoted to Waltham Forcing or s'milar types. Accordingly, this 

 type was judged to have the qualities most desirable for a greenhouse forcing 

 tomato. The objective then was to develop a type comparable to Waltham 

 Forcing and resistant to leaf mold. 



Three successive backcrosses were made with Waltham Forcing, each after 

 selection for three or four generations from disease-resistant and desirable types, 

 and without regard for their original pedigrees. After the third backcrossing the 

 progenies were satisfactory for fruit size and yield, and seed of the second gen- 

 eration of the third backcross was distributed to a few growers for limited trial 

 and selection purposes for the 1939 spring cropping season. 



In the fall of 1939, a larger F3 population was grown in several greenhouses. 

 The performance and the quality of the tomato were unusually promising, but 

 there were also some inherently bad features, notably an hereditary breakdown 

 manifested by yellowing, rusting, spotting, and necrosis of the foliage. Other- 

 wise, about 80 percent of the individuals in these plantings were highly resistant 

 to leaf mold and the foliage remained green and healthy throughout the entire 

 growth from the ground to the tops of the plants, or almost 7 feet. In contrast, 

 the remaining 20 percent of these plants and Waltham Forcing growing in the 

 same greenhouse were "burned up" by the disease. Several growers who met at 

 the greenhouses of Mr. Russell Eisenhaure, Concord, in the fall of 1939, to observe 



