April, 1920 



BETTER FRUIT 



The Value of the Different Roots as Stocks 



By W. L. Howard, Deciduous Fruit Station. Mountain View, California 



THE great shortage in nursery stock 

 this phinting season has caused an 

 unusual amount of discussion about the 

 value of different roots as stocks for 

 deciduous trees. This year nursery- 

 men were able to sell almost every- 

 thing they had. In the past year there 

 has been a slight demand for prunes 

 on roots other than myrobalan. Every 

 year a considerable acreage of prunes 

 is planted on peach and almond stock. 

 X few have, for various reasons, de- 

 sired to have prunes on apricot roots. 

 Many have inquired explicitly about 

 the value of this stock for French 

 prunes. We have very good evidence 

 to show that apricot is not a safe root- 

 stock for the French, although it seems 

 to be safe enough for sugar prunes, and 

 possibly for some other varieties. The 

 French, however, makes a very poor 

 union with the apricot root, and in the 

 case of one orchard recently examined 

 near Gilroy, the trees are rapidly break- 

 ing ofT at the age of five and six years. 

 Other instances have come to my at- 

 tention where the trees became much 

 older than this before breaking, but 

 eventually they do "pinch off." Some 

 old orchards in Napa County where 

 Imperial prunes were top-worked on 

 Royal apricots many years ago are still 

 in good condition. At the same time 

 French worked on the Royal was a fail- 

 ure. Many growers have told me that 

 sugar prunes do well on apricot root. 

 Sugar prunes, on the other hand, make 

 a very poor union with the peach, and 

 should not be used for that purpose. 

 Some plums behave similarly on the 

 peach, the Diamond being a conspicu- 

 ous example. 



Owing to the propaganda during the 

 last three or four years in favor of the 

 Japanese pear as a rootstock, nursery- 

 men have almost stopped using the 

 French stock. Indeed, I am told that 

 the large growers of seedling stock in 

 Kansas and elsewhere have almost 

 ceased to grow the French pear stock. 

 The wide use of the Japanese pear 

 stock has been advocated because it is 

 so much more resistant to pear blight 

 than the French stock, and further- 

 more because it has been found to very 

 successfully resist attack by woolly 

 aphis. Wierever pear blight is preva- 

 lent, there is no question that the Jap- 

 anese stock is much safer to use than 

 the French stock, although it is not 

 wholly blight resistant by any means. 

 In the coastal region, particularly in 

 the Santa Clara Valley, where pear 

 blight is no problem, there has always 

 been considerable discussion as to the 

 advisability of giving up the French 

 stock, which has been thoroughly tried 

 out and found to be satisfactory in 

 every way, except that it is injured by 

 wooily aphi.s. The big question in the 

 bay region, especially in the lowlands 

 adjacent to the southern end of San 

 Francisco Bay, is to know whether the 

 Japanese pear root will withstand as 

 much water in the soil as the French. 

 In that particular region, the woolly 

 aphis is said not to give much trouble. 



even to French stock. One nursery- 

 man who furnishes considerable stock 

 for the region under discussion thinks 

 that the growers there should stick to 

 the French pear stock by all means, but 

 he complains that, on account of the 

 general condemnation of French stock, 

 it is now becoming almost impossible to 

 procure it. 



I'ndoubtedly a rootstock entirely re- 

 sistant to blight will eventually be 

 found. At the present lime it is known 

 that some of the Siberian seedlings give 

 gieat promise; certain strains of varie- 

 ties are, for all practical purposes, un- 

 doubtedly blight resistant, but the prob- 

 lem is to isolate these resistant strains 



Page 19 



from closely related forms that are not 

 resistant and get them in suciffient 

 quantities to place them within the 

 reach of all nurserymen and growers. 



A few growers have been able to 

 start trees that were blight resistant so 

 far as trunk and the bases of main 

 branches were concerned by bench- 

 grafting long scions of the Surprise 

 pear on Japanese roots. These grafts 

 were planted deeply, so that the scions 

 in most cases formed roots. If the re- 

 sultant nursery trees are planted in the 

 orchard so that the Japanese root is six 

 or eight inches underground, there is 

 practically no danger of sprouts arising 

 from the seedling stock. The Surprise 

 pear makes a fine, shapely tree, and is 

 a vigorous grower. It is entirely safe 

 as regards attacks from pear blight. The 

 Surprise tree may be shaped up in the 



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