APRIL 15, 1913 



255 



that plum pollen is not transmitted through 

 the air in sufficient quantities to ensure self- 

 IDollination. Profs. Lewis and Vincent 

 (Oregon State Agricultural College, Bulle- 

 tin No. 104), experimented with plums, and 

 reached the same conclusions. Their experi- 

 ments on the action of the wind in apple 

 pollination with varieties known to grow 

 abundant j5ollen at the height of their 

 bloom, and with a strong wind blowing, 

 shoAved no effective deposit of pollen twen- 

 ty feet from the trees and nine feet from 

 the ground, nor thirty feet away, and at a 

 height of six feet. 



The writer's belief, from observation of 

 some forty years in Colorado, where we 

 liave much wind, is that the winds are a 

 positive damage to effective apple pollina- 

 tion. We have often observed apple trees 

 that had little or no fruit on the north and 

 west sides (from av hence our prevailing 

 winds). The deduction was that the pollen 

 and petals were blown away. But we not- 

 ed, also, later, that bees rarely visit blos- 

 soms when the pollen is gone, hence no 

 proper fertilization and little fruit. For 

 verification we cite the experiments of Lewis 

 and Vincent, where all the petals and sta- 

 mens were removed from the 1500 blossoms 

 on a seven-year apple tree, leaving it ex- 

 posed to both the wind and insect visita- 

 tion. This tree was 20 feet from another 

 that bloomed profusely. Out of the 1500 

 blossoms emasculated, only five set fruit. 

 During the whole period (days) that the 

 pistils of these blossoms were receptive, only 

 eight bees visited the tree. More than twice 

 that number were seen in one half-hour on 

 the tree twenty feet away. 



Certainly the forest trees and bushes, and 

 most of our field crops, seem to secure 

 proper pollination by the winds; but all 

 authorities now agree that our tree fruits 

 secure it effectively only by insect visits. If 

 the theory is true, that all bloom which, in 

 the economy of nature, supply nectar, re- 

 quire insect visits for effective fertilization 

 and reproduction, tlien the bees wliich gath- 

 er honey so largely from alfalfa clover are 

 a necessary factor in growing alfalfa seed. 



Prof. M. B. Waite, United States Depart- 

 ment of Agi-iculture, Bulletin No. 5, " The 

 Pollination of Pear Flowers," made experi- 

 ments to determine the value of insect vis- 

 itors in pear pollination. Of 36 varieties of 

 pears tested on 142 trees, only nine proved 

 self-fertile above five per cent. The experi- 

 ments showed a great increase, both in the 

 yield and size of the fruit, from cross-fer- 

 tilization. Waite says, " It hfis been proved 

 that cold weather, during the flowering pe- 



riod, renders some plants incapable of self- 

 fecundation, although they still retain the 

 ability to be cross-fecundated." Obser\ a- 

 lions by growers in Indiana and Utah con- 

 firm the truth, also, that cross-poUinized 

 apples have more vitality to resist freezing 

 weather and insect and fungous injury. 

 Waite says, "Apples ai'e more inclined to 

 be sterile to their own pollen than the pears. 

 * * * * 111 the majority of eases no fruit 

 resulted from self-polliration." 



The experiments of Prof. S. W. Fletcher, 

 Virginia Agricultural Experiment Station ; 

 of Prof. A. J. Cook, Horticultural Commis- 

 sioner of California; of Profs. Lewis and 

 Vincent, and others, all reach the same con- 

 clusions. They give little value to pollina- 

 tion by wind, and all give due credit to' 

 the busy bee. Fletcher's experiments show- 

 ed that Bartlett peai-s, on 3081 tests fer- 

 tilized with their own pollen, produced only 

 six small pears, or one fruit to 513 blos- 

 soms; while with pollen from other vari- 

 eties it grew one fruit from seven to ten 

 blossoms, and these pears were over fifty 

 per cent larger in size. Also, the Kieffer 

 pear, on 1268 blossoms fertilized with its 

 own pollen, greiv but five fruits, or one to 

 263; while on cross-pollination, with other 

 varieties, it yielded one fruit from three to 

 seven blossoms. 



In the Lewis and Vincent tests, self-pol- 

 linated Spitzenberg apples proved inferior 

 in size, and ill-shaped, compared with the 

 cross apples, and were practically devoid of 

 plump seeds. On the yellow Newtown apple 

 tests the results were the same, except that 

 the average Aveight of the seeds from the 

 cross-fertilized apples was forty-six times 

 greater than from the self-fertilized fruit. 

 Imperfect pollination can not produce per- 

 fect fruit. It is often " lop-sided." 



Oregon circular bulletin No. 20 says, 

 " Careful experiments have shown that very 

 little if any pollen of our tree fruits, other 

 than nut-trees, is transported by the wind. 

 Probably 99 per cent or more of the trans- 

 fer of pollen is done by insects. Prime 

 among these may be mentioned the honey- 

 bee." 



The Bureau of Entomology, Wasliing-fon, 

 says the annual value of honey produced 

 in the United States is $20,000,000; but 

 that the service the bees render in fertiliz- 

 ing the blossoms of fruit trees is worth 

 many times twenty million dollars a year. 



The bloom period of tree fruits is very 

 short. The winds waste the pollen ; the rain 

 Avashes it from the blossoms, and drouth in- 

 jures it. The pollination period is often 

 greatly shortened by rains or cloudy days^ 

 when the bees do little work. For their 



