382 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



California black, the latter at least in the southern part of the State, 

 or for varieties which come out early in the spring. A very good illus- 

 tration of the difference in respect to this disease produced by differ- 

 ent roots was seen in a walnut orchard near Whittier during the past 

 season. In this case trees of the Placentia Perfection variety had been 

 double planted, the permanent trees on southern black root and the 

 fillers on English. During the latter part of the season of 1911 the 

 difference between the trees on the two roots was very marked, those on 

 the English being smaller, with yellow foliage and narrow leaflets, the 

 leaves falling to the ground early in the fall. The alternate trees on 

 southern California black root were larger, bore a better crop and had 

 dark green, vigorous looking foliage which remained on the trees much 

 later than that of the other trees. 



SHRIVELED MEAT. 



Much trouble is experienced with walnuts in certain seasons on 

 account of the meat being shriveled and poorly developed. This affects 

 some varieties and some individual trees more than others and is often 

 much worse the same year in certain localities than in others. The 

 trouble is more apt to affect varieties which come out late in the spring 

 than those which develop early. It is usually, though not always, 

 worse on such varieties in the southern part of the State than in the 

 northern, and this indeed is one of the principal reasons why very late 

 varieties are not adapted to southern California. A tendency toward 

 this trouble is one of the worst faults of the Eureka in the southern 

 part of the State, and the same is true of Franquette, Hale, Concord, 

 San Jose, and in fact almost every late variety that has been tested in 

 southern California. The northern part of the State is by no means 

 free from this trouble, but it is less common there and is usually con- 

 fined in certain seasons to certain localities, although it does not affect 

 the same locality every year. In 1911, for instance, the Franquettes 

 were quite generally poorly filled and light meated in Sonoma 

 County, while in the vicinity of San Jose and Stockton such was not 

 the case. In other or, in fact, in most years, Sonoma County Fran- 

 quettes have been as well filled as any. The cause of this poor devel- 

 opment or shriveling of the meat has been ascribed to various influences, 

 none of which have been positively proven to bring about this trouble. 

 The influences suspected have been the same as those to which per- 

 foration or non-development of the shell have been laid, namely poor 

 pollination, lack of soil moisture, and the attacks of the walnut aphis. 

 Which of these actually causes the trouble has not been positively 

 determined. In the southern part of the State it is probable that the 



