BAY STATE, A RED FORCING TOMATO 

 BRED FOR RESISTANCE TO LEAF MOLD 



By E. F. Guba, Research Professor of Botany 



INTRODUCTION 



Approximately 1400 tons of greenhouse tomatoes are produced annually in 

 Massachusetts for nearby wholesale markets. About 76 percent or 1070 tons, 

 known locally as the spring crop, are harvested during April to August, inclusive, 

 representing a value of $257,000. The remaining 24 percent or 336 tons, known 

 in contrast as the fall crop, are harvested from September to February ami 

 represent a value of approximately $101,400.' This production represents a value 

 or gross income to the greenhouse tomato growing industry of about $358,400 

 annually. It is estimated conservatively that production for the spring and fall 

 crops could be increased by 8 and 30 percent respectively were not the tomato 

 leaf mold disease, caused by the fungus Cladosporium Julvum Cke., a deterring 

 factor. This would represent an increase of about 85 tons or $20,400, and 100 

 tons or $30,100 for the spring and fall cropping seasons respectively, or approx- 

 imatelj' 185 tons and $50,500 annually. Losses in greenhouse tomato production 

 as the result of this disease occur in the same general proportion all over the world 

 where tomatoes are grown under glass. 



Since 1925, the Massachusetts Agricultural Experiment Station has been en- 

 gaged in a study of the tomato leaf meld disease, and several bulletins and 

 scientific journal articles describing the results of these studies have been issued. 

 Since 1933, all of the effort has been directed toward the study of the reaction of 

 tomatoes to the fungus parasite, and the breeding of a commercially acceptable 

 resistant type. The serious nature of the disease and the inability of growers to 

 control it at reasonable expense and within the limits of usual greenhouse practice 

 have encouraged and justified this long effort. 



As a result of this study, a new tomato resistant to certain physiologic forms 

 of this prevalent and devastating fungus has been developed. The tomato has 

 entered commercial production under glass and has proved acceptable to many 

 growers. Therefore, an account of the development and a description of the 

 tomato is now considered desirable. 



SOURCE OF RESISTANCE TO CLADOSPORIUM LEAF MOLD 



The resistance of the Red Currant tomato to Cladosporium fulviim Cke. 

 was first recorded by Sengbusch and Loschakowa-Hasenbusch (10) in 1932 from 

 Germany and confirmed by Guba (6) in Massachusetts and Alexander (1) in 

 Ohio in 1934. This immunity leaction has been reported only for Lycopersicon 

 pimpinellifolium (Jusl.) Mill, and derivatives from it. Langford (9) in Ontario 

 found that, although no macroscopic symptoms ordinarily followed inoculation 

 of this species, the fungus penetrated the stomata and developed in the eaf tissue 

 to a very limited extent and in a few instances necrotic non-sporulating infection 

 flecks were produced from which the fungus was readily recovered. Bond (5) 

 in England found no external symptoms on the Red Currant tomato and 

 observed necrotic isolated cells only in immediate contact with the hyphae. On 

 inany other Solanaceae classed as immune, the course of infection after penetra- 



■Compiled from statistics furnished by the Massachusetts Department of Agriculture, Boston. 



