8 BULLETIN 1015, U. S. DEPARTMENT OF AGRICULTURE. 



ton, and the Tennessee A 16-2, a wilt-resistant variety developed by 

 Bain and Essary, were almost free from wilt; while the John Baer, 

 Greater Baltimore, Stone, Royal Red. Delaware Beauty, Early Jewel, 

 Red Head, and Bonny Best were nearly destroyed by the wilt. More- 

 over, the differences were much greater than the figures in Table 1 

 show. 



Livingston's Globe and Livingston's New Globe possess consider- 

 able resistance to wilt, but not so much as the more highly devel- 

 oped resistant varieties. 



The Mansfield Tree tomato resisted the disease fairly well in the 

 one test made, but produced little fruit. It is by no means certain 

 that it possesses as much resistance as the results of this test indi- 

 cate. The Success and the Mississippi Girl gave good results in one 

 test, but poor results in another. 



From the results of these tests it is not surprising that the Bonny 

 Best, one of the most productive varieties grown in the Middle At- 

 lantic and Middle Western States, dies so rapidly in many places in 

 the South. No different results could be expected from so susceptible 

 a variety. The John Baer, Early Jewel, Royal Red, Delaware 

 Beauty, Red Head, and Willis would probably do no better. 



INTRA VARIETAL VARIATION. 



Most varieties of tomatoes differ little from one another in the wilt 

 resistance possessed by their individual plants. Very susceptible 

 varieties, such as the Bonny Best, Delaware Beauty, John Baer, and 

 Red Head, usually show about the same variation in intravarietal re- 

 sistance as the fairly resistant varieties, Livingston's Globe, Duke of 

 York, and Buckeye State. A few varieties, such as Stone, Greater 

 Baltimore, and Merveille des Marches, possess a much wider range of 

 intravarietal resistance than the average. By selecting and testing a 

 considerable number of plants from these varieties strains can be ob- 

 tained that transmit a high degree of resistance to their progeny. 



BEHAVIOR OF SELECTIONS. 



Most plants selected for resistance to wilt transmit to their progeny 

 no more resistance than is possessed by their parent varieties. A 

 few excel in this respect, but their number is very small. Moreover, 

 these few, even when selected from the same variety, differ in the 

 degree of resistance they transmit. 



Selections from a variety that transmits about the same degree of 

 resistance to all its individual plants seldom transmit increased re- 

 sistance. They are therefore probably fluctuations caused by in- 

 equalities in soil infestation, drainage, etc. A large number of selec- 

 tions from three such varieties, Livingston's Globe, Buckeye State, 

 and Duke of York, were tested by the writer, but not one surpassed 



