. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 0SL^^LTt, Washington, D. C. March 28, 1922 DEVELOPMENT OF WILT-RESISTANT TOMATOES. By Feed J. Pritchaed, Physiologist, Office of Cotton, Truck, and Forage Crop Disease Investigations. CONTENTS. Prevalence and characteristics of tomato wilt Development of resistant varieties Selection of material Preparation of the breeding plats Method of selection Varietal resistance Intravarietal variation Behavior of selections Page. Development of resistant varieties— Continued. Behavior of resistant varieties- 9 Effect of continuo
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 0SL^^LTt, Washington, D. C. March 28, 1922 DEVELOPMENT OF WILT-RESISTANT TOMATOES. By Feed J. Pritchaed, Physiologist, Office of Cotton, Truck, and Forage Crop Disease Investigations. CONTENTS. Prevalence and characteristics of tomato wilt Development of resistant varieties Selection of material Preparation of the breeding plats Method of selection Varietal resistance Intravarietal variation Behavior of selections Page. Development of resistant varieties— Continued. Behavior of resistant varieties- 9 Effect of continuous selection 9 Duration of resistance J. 10 Results of field tests 11 Origin and description of wilt-re- sistant varieties 15 Summary 17 PREVALENCE AND CHARACTERISTICS OF TOMATO WILT. Tomato wilt {Fustwium lycopersici) causes an estimated annual loss of more than 115,000 tons of tomatoes in the Middle Atlantic, Gulf, and lower Mississippi Valley As it is prevalent also in the Ohio River Valley, in California, and in parts of Colorado and Utah, it reduces the yield even more than is expressed by these fig- ures. This loss can and should be overcome by the use of wilt-re- sistance varieties. Wilt is characterized in its early stage by a wilting of the plant and an upward and inward rolling of the leaves (PL I, fig. 1). Later the lower and finally the upper leaves turn yellow and slowly die. When a branch is thus deprived of its foliage it dies back from the tip, turns brown, and shrivels. Some of these final changes and the varied progress of the disease in different branches are shown in 1 The loss from wilt in the canning crop of tomatoes estimated by the Plant-Disease Survey of the Bureau of Plant Industry from reports of State and Federal pathologists for the year 1918 was 115„000 tons, but this did not cover the whole area infested by wilt nor did it include the loss in the crop grown for trucking and home gardening. 68713°—22 1. Please note that these images
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