BREEDING OF VEGETABLES 245 



reactions are known indicate (McRostie, 1919; Burkholder, 

 1918) that resistance to either the alpha or beta strain is inherited 

 as a simple dominant, involving but a single factor difference. 

 It seems, therefore, very easy to produce resistant varieties to 

 both strains by crossing and selection and thus to combine de- 

 sirable economic characters and anthracnose resistance. 



McRostie (1921) has recently published an interesting paper 

 on further studies of disease resistance in common beans. The 

 more extensive results obtained bear out the earlier views on 

 the mode of inheritance of resistance to bean anthraxnose. The 

 studies carried out show that bean mosaic susceptibility is in- 

 herited. In FI there was a partial dominance of susceptibility 

 over resistance and in F z a segregation which indicated a two 

 factor hypothesis. In crosses between susceptible and resistant 

 varieties in relation to the dry root rot, caused by the fungus, 

 Fusarium martii phaseoli Burk., there was a dominance in F\ 

 of susceptibility and a segregation in F 2 that appeared to be on 

 a 9 : 7 basis. In nearly all cases resistant F 2 plants bred true to 

 this character in F s . Results of this nature show the great 

 practical importance of the application of Mendelian principles 

 to breeding for disease resistance. It seems very likely that a 

 large part of our serious plant diseases will be controlled even- 

 tually by the production of disease resistant varieties. 



TOMATO 



Classification Characters and Inheritance. The tomato be- 

 longs to the genus Lycopersicum of which there are several 

 cultivated species. Tomatoes are classified on the basis of vine 

 habit, either standard or dwarf, leaf type, period of maturity, 

 size and color of fruits, and other characters. As a result of 

 breeding experiments, many different combinations of characters 

 have been made. Price and Drinkard (1908) were among the 

 first investigators to report on the simple Mendelian behavior of 

 certain tomato characters. Table LXIII, taken from similar 

 ones compiled by Tschermak (1916) and Jones (1917), presents 

 a brief summary of inheritance in the tomato. 



Fruit shape is dependent on several factors according to 

 Crane (1915) and Groth (1912, 1915). Some of the foliage 

 characters are also somewhat complicated in their inheritance 

 (Groth, 1911). The inheritance of each of the other characters 

 listed in the table is dependent on single factor differences. 



