January, ipJi 



BETTER FRUIT 



Page 15 



Some Reliable Northwest Nurserymen 



Capital City 

 Nursery Co. 



Our Specialty: 



Apple, Prune and 

 Walnut Trees 



ORNAMENTAL AND FRUIT 

 REARING SHRURRERY 



A good line of trees for 

 WINDRREAK AND SHADE 



Address, Salem, Oregon 



Choice 



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We are wholesalers to the trade 

 only and believe we can make it to 

 the advantage of Nurserymen gener- 

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Portland Wholesale Nursery Co. 



971 Sandy Rlvd. 

 Portland, Oregon 



Results of Studies in Prune Pollination 



WITH a view to determining the fail- 

 ure of prunes to set fruit in some 

 years while bearing abundantly in 

 others the Division of Pomology of the 

 University of California has been carry- 

 ing on experiments for several years. 

 Among the varieties being studied are 

 the French which is grown quite ex- 

 tensively in the Northwest as well as 

 California where the acreage of this 

 variety is very large. In fact in the 

 Santa Clara Valley alone it is stated 

 that there are over 61,000 acres planted 

 to prunes largely of the French variety 

 with a few scattered plantings of Im- 

 perial and Sugar. 



While the study made was largely 

 confined to pollination, A. H. Hendrick- 

 son, who has issued a bulletin on the 

 subject, says that the lack of fruitful- 

 ness generally did not point altogether 

 to lack of proper pollination. In noting 

 the results of his experiments Mr. Hen- 

 drickson says: 



"While the Imperial, Robe de Sergeant 

 and Silver prunes have long been con- 

 sidered shy bearers, the French and 

 Sugar have continued to bear more or 

 less satisfactorily when set out in large 

 blocks of a single variety. Many grow- 

 ers in the Santa Clara Valley have no- 

 ticed an appreciable falling off in their 

 crops, and have been anxious for infor- 

 mation relative to the cause. Improper 

 pollination, due to self-sterility, was be- 

 lieved to be at least one important fac- 

 tor causing this imperfect set. Another 

 factor has already been shown to be 

 responsible to a degree for this failure 

 to set commercial crops. This factor is 

 the lack of honey bees in the orchards 

 at blooming time. Proper pollination 

 has been shown to be dependent upon 

 insect agencies to carry the pollen. It 

 is probable that other factors such as 



pruning, cultivation, fertilization and 

 irrigation will be shown to influence 

 the amount of fruit set." 



As a result of the experiments Mr. 

 Hendrickson notes: "The three vari- 

 eties of prunes, French, Sugar and Robe 

 de Sergeant experimented upon at the 

 university farm have set comparatively 

 high percentages of fruit and matured 

 fairly satisfactory crops considering the 

 age of the trees. The French and Robe 

 de Sergeant yielded consistently each 

 year, but the Sugars failed to blossom in 

 191C. As this failure followed a heavy 

 crop it was thought that the drain upon 

 the tree had been so great that it was 

 unable to mature fruit buds for the 

 following season. This variety again 

 in 1918 behaved in the same manner, 

 failing to produce any blossoms. This 

 seeming tendency towards alternate 

 bearing is an uncommon occurrence 

 with this variety. The general reports 

 concerning it are that it bears heavily 

 and regularly. However, from four 

 years' data at the university farm at 

 Davis, it would seem that if young 

 trees just coming into profitable bearing 

 are allowed to overbear one year, only 

 a light crop is produced the following 

 season. One of the most serious criti- 

 cisms of the Sugar prune is thai it tends 

 to overhear. 



"The French and Robe de Sergeant at 

 Davis, on the basis of regularity in 

 bearing, have proved In he more val- 

 uable than the Sugar. The former vari- 

 ety during the three years of 191."), 1916 

 and 1917 produced an average crop of 

 57.5, 41.7, and 145 pounds, respectively, 

 or an average of 81.4 pounds per year 

 for the three years. This crop resulted 

 from an average set of 28.7 per cent. 

 The Robe de Sergeant practically 

 equalled the record of the French. In 



three years the average crop per tree 

 was 95.1, 79.6, and 100.6 pounds, or a 

 total average per tree of 91.4 pounds 

 from an average set of 28.7 per cent. 

 Roughly speaking, the above yields ap- 

 proximate three tons of green fruit per 

 acre, which is a fairly satisfactory com- 

 mercial yield considering the age of the 

 trees (eight years in 1915). In the case 

 of the Sugar prune the average yield 

 is only available for two years, as no 

 crop at all was produced in 1916. These 

 yields were 30.1 and 147.3 pounds per 

 tree, or an average of 88.7 pounds per 

 tree for the two years, resulting from 

 the high average percentage of set of 

 41.6 per cent. If this yield is calculated 

 on the basis of three years, as might 

 properly be done, the average yield for 

 the variety is thus reduced to but 59.1 

 pounds per tree. 



"Two varieties of these prunes, the 

 French and Sugar, are self-fertile, while 

 the third, Robe de Sergeant, is self-ster- 

 ile. Four years' results with self-pol- 

 linating the French prunes have shown 

 great fluctuation in the percentage of 

 fruit obtained. Some years this per- 

 centage was high and in others it was 

 low, hut the average for four years 

 shows that this variety must be accept- 

 ed as self-fertile. Upon what factors 

 this self-fertility depends is not known 

 but it seems to be largely a matter of 

 applying the pollen at exactly the right 

 time. Climatic conditions following 

 the application of pollen may also exert 

 some influence on the resultant set. 

 This conclusion as to the self-fertilitj 

 of the French prune, which is empha- 

 sized by the Santa Clara experiments, 

 is of utmost importance In the prune 

 growers of California. It shows win 

 vast acreages of this variety have been 

 able In produce crops year after year 

 without the necessity of growing fillers 

 as pollenizers. The next problem is 

 to Qnd what environmental conditions 



