214 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



good dressing of stable manure with a heavy mulch of the same mate- 

 rial, in order to retain moisture as well as add fertility to the soil. 



As the trees grow they should be staked up if necessary and trained 

 to a single stem which eventually should be cleared of side branches 

 up to about five feet. It is not, however, necessary or desirable to prune 

 the tree to a single, bare shoot from the very first, since side branches 

 shade the trunk from the sun and also assist in growth, particularly that 

 in diameter. It is, therefore, better to take off the laterals gradually 

 from below at the end of each season rather than keeping them all 

 cleaned off continuously. For the best success of this method it is not 

 well to hasten the grafting too much, as better permanent results will be 

 obtained by allowing the trees to reach considerable size before graft- 

 ing. Grafting when the trees are less than three inches in diameter 

 at a point five feet from the ground is of doubtful advisability, and it 

 is better to wait until most of the trees in the orchard have reached 

 at least this size before commencing grafting. It is not advisable to 

 graft each year a few of the largest trees, thus scattering the grafting 

 over several years, on account of the unevenness of an orchard treated 

 in this way. For methods of top grafting, see page 230. 



RAISING THE TREES IN THE NURSERY. 



This, as we have shown in discussing other methods, is ordinarily 

 much the most satisfactory and successful, and the quickest and cheapest 

 method of starting a walnut grove. 



SEED TREATMENT. 



Walnuts to be used for planting in the nursery should, after gath- 

 ering, be kept in sacks or other receptacles in a cool, not too dry place 

 until planting time. If allowed to become extremely dry after gath- 

 ering the nuts germinate much less easily than otherwise. They will 

 usually keep in good condition if tied up in sacks and piled in a cool, 

 shady place. It may be found desirable to allow the outer hulls to 

 dry somewhat before sacking up the nuts, especially in the case of large 

 hybrid nuts, since if sacked and put away quite green the hulls decay 

 and become extremely soft and mushy. Early in the winter, not much 

 later than January, the nuts should be layered in sand or light strawy 

 earth in order to sprout them and segregate the best ones from those 

 that germinate feebly or not at all. This is most conveniently done by 

 constructing a frame about 18 inches deep, either above or below 

 ground, in the bottom of which should be placed 3 or 4 inches of sand, 

 then the layer of nuts which may be either one or several nuts in depth, 

 according to the available space. The nuts are then covered with 3 

 or 4 inches of sand, which should be washed down thoroughly between 





