Tllb: MONTHLY lUJLLETIN. 211 



slaking- it witli tlir watci- it slioulil he allowt'd to cool Ix'l'oi'c; hciiiK used 

 ill iiiakiiifj;' paste IT covcri'd to avoid ovaporation, each ingri'dicnt will 

 keep indetinitcly, bul, ni'lvv mixing-, the paste slowly deteriorates. 

 Where it is lieing: used over a nuinher of days or weeks, just enou.u:]i of 

 the wet slaked lime and the hluestone solution should he mixed to make 

 })aste eiiougli to last for one day, leaving the remainder unmixed in 

 separate vessels. It may be applied with large brushes, as is whitewash. 



Conclusions. 



The control of crown gall may be summarized as follows : 



(1 ) Resistant stock is the most satisfactory treatment for this trouble. 

 The ex[)(M-imental work at jn-esent is of necessity incomplete, but certain 

 of the more resistant stocks will doubtless soon ])e available. These will 

 be found for the most part among the Domestica and Damson plums. 

 P. pumila has not been sufficiently tested to know its real merits as a 

 stock, but it will doubtless dwarf the tree more or less and should only 

 be grown in an experimental way for the i)resent. The so-called 

 Duane Purple stock has been grown in commercial orchards and should 

 be farther tested under various soil and climatic conditions. 



(2) Inspection of trees before and after planting is important and 

 should be rigidly employed. Clean stock planted in ground free from 

 infection is to be strongly recommended. 



(3) Tree surgery will never be of general application, as it is 

 expensive in time, labor and patience and will not appeal to the 

 average grower. 



CALIFORNIA CERTIFIED SEED POTATOES. 



By W. V. Shear, Secretary of the West Coast Potato Association and A.ssistant 

 Horticulturist, United States Department of Agriculture. 



Last year certified seed potatoes were grown for the first time in 

 California. Between 2,000 and 3,000 sacks were produced and will 

 be planted the coming season, mostly to grow more certified seed. 

 Besides these, several cars of certified seed potatoes have come into 

 the state from other states. The movement for the production of good 

 seed potatoes in California is, therefore, well under way. Owing to 

 the necessary care in the production of this stock, last year a marked 

 improvement was made over the seed stock previously grown in this 

 state, and it has elicited much praise from those Avho have been able 

 to secure a portion of it for this season's planting. However, since the 

 methods of production of certified seed are comparatively little known, 

 as yet, throughout the state, and since there is naturally considerable 

 misunderstanding regarding its production in different localities and 

 its value under all circumstances, it may be well to mention a few of 

 the important phases of this industry. 



The certified seed law is a standardizaiioih law — it estal)lishes a 

 standard for this product and determines what qualifications potatoes 

 must have to be sold as California certified seed. It therefore has 

 little to say al)cut hmr these potatoes shall be grown, but says con- 

 siderable about what they must be after they are grown. It does not 

 state what kind or what quality of potatoes shall be used for seed to 



