The Canadian Horticulturi^ 



Vol. XXXIV 



MAY, 1911 



No. 5 



Pollination of Apple Blossoms 



Mr. George E. Sanders, B.S.A., car- 

 ried on some most interesting investiga- 

 tions in the College orchard in 1905 and 

 igo6. Mr. Sanders defines two distinct 

 conditions which have to do with imper- 

 fect setting of fruit. The first is self- 

 sterilitv. which means that an individual 

 or a variety is incapable of fertilizing its 

 own blossoms even though perfect pollin- 

 ation may take place. The self-sterile 

 varieties when planted in isolated situa- 

 tions or in large blocks do not bear well. 

 The same varieties when planted in mix- 

 ed orchards may yield abundantly. Some 

 varieties have invariably proven self- 

 sterile, while others consistently prove 

 completely or partially self-sterile. Self- 

 sterile varieties bear as much pollen as 

 self-fertile ones, and the pollen is as good 

 for fertilizing other varieties as is the 

 pollen from a self-fertile sort. The rem- 

 edy for self-sterility is mixed planting 

 with any variety which bears an abun- 

 dant supply of pollen and blooms at the 

 same date as the self-sterile variety. 



IMPERFECT PEETILIZATION 



This condition may arise even in the 

 case of varieties which are capable of fer- 

 tilizing their own blossoms, and of 

 course, may also arise in connection 

 with self-sterile fruits even when effic- 

 ient poUinizers are close by. The indica- 

 tions of imperfect pollination are small, 

 mis-shapen fruits. On examination, one- 

 sided apples usually prove to be fertilized 

 only on one side, possessing a small 

 number of well developed seeds. As a 

 rule, cross-pollenized fruit is found to be 

 larger than that self-fertilized. It was 

 noted that imperfectly fertilized fruits 

 are more likely to be attacked by scab on 

 the side on which the seed does not de- 

 velop than on the fertilized side. Also, 

 it was noted that imperfecly fertilized 

 fruit drops more readily than perfectly 

 fertilized fruit. Thinning of the fruit on 

 the tree causes imperfectly fertilized fruit 

 to stay on better and grow larger than 

 it otherwise would. This is simply be- 

 cau.se the individual fruits are better 

 nourished than they would be if they were 

 all left on the tree. 



BEES THE EEMEDT 



The remedy for imperfect fertilization 

 is the introduction of bees, as it has been 

 clearly proven that insects perform prac- 

 tically all of the work of transferring 

 pollen in the case of tree fruits. The 

 inter-planting of varieties which bear 



Prof. J. W. Crow, O.A.C., Guelph 



abundant supplies of pollen is also use- 

 ful as an additional means of securing 

 more perfect fertilization. 



The above is a brief summary of Mr. 

 Sander's conclusions. These have, I be- 

 lieve, been verified by other investiga- 

 tors and experience also points out the 

 necessity of securing perfect pollination. 



With regard to the question whether 

 frosf is likely to be more injurious in 

 cases where pollination is delayed through 

 wet weather and lack of insects, I can 

 only say that in seasons such as last 

 spring, when frosts were commonly ex- 

 perienced, the injuries were more serious 



Results of Imperfect Fertilization 



The above shows the neceasity of perfect pol- 

 lination. Photograph furnished by Prof. Crow, 

 O.A.O. 



with those varieties or in those districts 

 where trees were in full bloom. Where 

 fertilization was sufficiently far advanc- 

 ed that fruit could be said to have "set," 

 the fruit remained on ,the tree and ma- 

 tured, although in many cases apples 

 were disfigured by injuries due to frost 

 experienced in the early stage. With this 

 fact in mind, it would certainly be cor- 

 rect to state that the keeping of bees in 

 orchards is desirable for the purpose of 

 bringing about fertilization at as early a 

 period as possible. Bees, are of course, 

 necessary before pollination can take 

 place at all. 



EFFECT OF PERFECT POLLINATION 



The accompanying illustration shows 

 the results of work done by the writer 



100 



in following up Mr. Sanders' investiga- 

 tion. Five lots of fifty apple blossoms 

 each were made use of. From one lot 

 (No. 5) four pistils were removed ; from 

 the second lot (No. 4) three pistils were 

 removed ; from another lot (No. 3) three, 

 and from a fourth lot (No. 2) one pistil 

 was removed. One lot of fifty blossoms 

 was left in normal condition with five 

 pistils, or rather the entire five sections 

 of the pistil in their natural condition. 

 Pollination was performed at the same 

 time and under the same conditions in 

 the case of all five lots of blossoms. The 

 accompanying photograph shows the 

 quantity of fruit produced in each case. It 

 wil be noted at once that the largest 

 number of apples was produced by the 

 normal blossoms and the decrease in pro- 

 ductiveness is almost in direct proportion 

 to the number of sections of the pistil 

 removed. On examination, however, it 

 was found that the largest number of 

 good seeds per apple was in the case of 

 lot No. 3. It is not well, of course, to 

 draw conclusions hastily, but in so far 

 as this one experiment can be made use 

 of as pointing towards any definite re 

 suit, it would seem to indicate that a sur- 

 plus of pollen has the effect of producing 

 fruit regardless of the actual degree of 

 fertilization which may take place. This 

 may or may not be correct, and I wish 

 simply to suggest the question for fur- 

 ther investigation. You will note that 

 lots Nos. I and 2 have reached consider- 

 ably larger size than lots Nos. 3 and 4 

 and 5, and the inference is plain, of 

 course, that thorough pollination influ- 

 ences very materially the size of the 

 fruit. It was also noted in connection 

 with this investigation that the apples of 

 lots No. I and 2 were decidedly better in 

 color than those of lots 3, 4 and 5. 



In planting I trim off all damaged roots 

 and a few of the longest ones, and cut 

 the stalk down to eighteen inches, leav- 

 ing four to five good buds to start the 

 head of the tree. I prune regularly, thin 

 out the branches so as to let in lots of 

 daylight, and keep the tree down, so that 

 the fruit can be easily picked. I picked 

 one hundred baskets from eight trees, 

 and could reach every peach from the 

 ground. I cultivate with some hoed crop 

 until such time as the trees need the 

 ground. — L. H. Robinson, Leamington, 

 Ont. 



