CHAPTEE XL. 

 RESULTS OF THE STUDY OF THE POLLINATION OF THE APPLE. 



The following is a resume of an article, 

 by Professor C. 0. Vincent, of Idaho 

 University, U.S.A., published in " Better 

 Fruit," for February, 1920. Apple trees 

 may be unfruitful for several causes : — (1) 

 Too vigorous wood growth; (2) defective 

 stamens; (3) location; (4) frost injury; 

 (5) rain during blossoming period; but 

 the principal cause is (5) the inability of 

 the pollen of a variety to fertilise its 

 pistils, or self-sterility. In trials in 

 Oregon, out of 87 varieties of apple, 59 

 were found to be self-sterile; 15 self- 

 fertile; and 13 partially self -fertile ; but 

 it is found, from reports in the U.S.A., 

 that occasionally a variety may be self- 

 fertile in one locality, but self-sterile in 

 another. Darwin wrote of a plant that 

 was self-sterile in Brazil, but when grown 

 in England for one or two generations 

 became self-fertile. Thus Yellow New- 

 town apple is listed as self-sterile in one 

 Government farmers' bulletin, self-fertile 

 in Oregon, and partially self-fertile in 

 Idaho. It is thought, therefore, in 

 America to be almost necessary to test 

 commercial varieties in different districts. 

 The following is the result of tests for self- 

 fertility in 1911-12 and 1914, at the Idaho 

 University (choosing as examples some 

 of the better known varieties) : — 



Percentage of Number of 



flowers that blossoms 



Self-Fertile : — set fruits. bagged 



Arkansas Beauty 38.8 216 



Yellow Transparent 33.6 107 



Duchess of Oldenburg 19.9 381 



Wagener 13.2 



Paetially Self-Fertile : — 



Eome Beauty 4.6 10,086 



Gravenstein 3.5 826 



Cox's Orange Pippin 3.2 1,277 



Wealthy 3.7 351 



Jonathan 2.9 19,081 



Yellow Newtown 1.5 133 



Ben Davis 1.2 708 



Bismarck 1.1 740 



King David 0.5 605 



Spitzenburg 0.4 250 



American Mother 0.4 487 



Twenty Ounce Pippin 0.2 552 



Self-Sterile : — , 

 Mcintosh Red, Northern Spy, Transcendent 

 Crab, Winter Banana and Bellflower set no 

 fruit at all. 



Out of 50 varieties tested at Idaho 

 University, 18 varieties showed them- 

 selves to be self-sterile, 7 self-fertile, and 

 25 partially self-fertile. 



The results indicate that the majority 

 of the varieties were practically self- 

 sterile, as in many instances only one or 

 two fruits set out of 300 or 400 blossoms 

 enclosed, and although classed as parti- 

 ally self-fertile, from a practical stand- 

 point they would be considered as self- 

 sterile. Another surprising feature of the 

 ^ork is that varieties when confined to 

 their own pollen may set a few fruits one 

 year, and none the next, this was found 

 with Bismarck, Cox's Orange, King 

 David, American Mother, Eome Beauty, 

 and Twenty-ounce Pippin. 



Under favourable conditions in the open 

 where two or more varieties are planted 

 together, a normal set of apples is about 

 32 per cent, of the number of blossoms, 

 thus very few of the varieties tried would 

 produce a crop if planted alone in large 

 blocks. 



To ascertain whether there was any dis- 

 advantage in testing varieties in paper 

 bags compared with enclosing a tree in 

 a muslin cage, 1,000 to 15,000 blossoms of 

 four varieties of apple were experimented 

 on in both ways, with the result that about 

 6 per cent, of the blossoms set in the 

 paper bags, and about 7 per cent, in the 

 cheese-cloth tents. 



As to seeds produced, generally the 

 more seeds in a fruit the larger the fruit. 

 Seven self-fertilised varietiesproduced from 

 seeds per fruit in the case of Yellow 

 Newtown, to 3.5 seeds in Maiden's Blush, 



