44Q CALIFORNIA FRUITS: HOW TO GROW THEM 



Soils for the Walnut. The walnut makes most rapid growth 

 upon a deep rich, moist, loamy soil, and shows its appreciation of 

 good things of the earth as do other fruit trees, and yet it attains 

 satisfactory size and bearing in less favorable situations. Thriving 

 trees can be found in the clays and decomposed granite soils of the 

 foothills, as well as in the valley silts and loams. Adequate moisture 

 must, however, be had either by rainfall or irrigation, and the 

 walnut cannot be commended for dry, neglected places nor for soils 

 which overlie leachy subsoils. 



Irrigation of Walnuts. Over-irrigated walnut trees on heavy 

 soil are subject to die-back; on well-drained soil'they are liable to 

 be pushed into too late growth, which goes into the frost period 

 too immature, and is easily killed back by a temperature which 

 would not injure well-matured wood. It is not a matter of calendar 

 date so much as of condition, but usually irrigation after August is 

 undesirable except on loose soils prone to dry out in the late fall. 

 In the latter case, if rain does not fall, light irrigation should be 

 given at any time when the soil seems to be getting too dry to keep 

 the root-hairs alive. Too late growth on young trees can be pro- 

 tected by bundling with straw or stalks, or by wrapping with bur- 

 laps, but it is better to use less water, get less growth and let it 

 ripen and harden earlier but the soil must not be allowed to get 

 too dry. 



Propagation. The walnut tree grows readily from nuts treated 

 as described in Chapter VIII. For many years the use of seedlings 

 prevailed, and the nut was looked upon as coming sufficiently true 

 from seed. Recently, however, this has changed rapidly, and bud- 

 ding or grafting to secure a high, uniform grade and to secure 

 fruitfulness in spite of the blight is commanding wide attention. 

 In growing young trees it is being considered desirable to bud or 

 graft rather high so as to get a trunk of the hardier variety which 

 is used as a stock. 



The California black is now chiefly used as a stock for the 

 English walnut, and either budding or grafting resorted to. The 

 success of the English walnut on our native stock has long been 

 known. Mr. John R. Wolfskill, on Putah Creek^ in Solano County, 

 put in a bud in 1875 and the tree reached immense size and large 

 product. Since then many large native black walnuts have been 

 top-grafted with the English walnut with notable success, not only 

 in orchards, but along highways where the native black walnut has 

 been planted for shade and ornament. 



Mr. F. S. Leib, of San Jose, who has given much attention to 

 stocks for the English walnut, believes that the cross of the Cali- 

 fornia black and the Eastern black walnuts, and the California 

 black walnut straight, gives the best seedlings for roots for the 

 English walnut, but advises close selection of the nuts in the sprout- 

 ing bed (see Chapter VIII), as the nuts with the longest sprouts 

 make the strongest growth in the nursery or in open ground. 



The best nuts for seedlings are the native black walnut straight 

 and the Royal hybrid (every cross between the native Eastern black 



