1921.] 



Pollination of Fruits. 



1 25 



two-thirds; and of cherries, not more than one-third, when 

 grown in the open air; but under the more favourable con- 

 ditions of glass-house culture a larger proportion of varieties 

 {nature fruit with their own pollen. 



The best system of planting, as indicated by observation, is 

 to intermix varieties to a certain extent. Thus, for an orchard 

 two or three varieties having somewhat the same blossoming 

 period should be chosen. In other words, the grower should 

 avoid planting varieties that flower very early with those that 

 flower very late. It is also preferable to plant lines of 

 trees with a different variety — e.g., Cox's Orange Pippin and 

 Worcester Pearmain — in alternate rows. In cases where a whole 

 orchard or a large block has been planted with one variety, 

 such as Amber Bigarreau cherry, every fifth tree or so may be 

 regrafted or replanted with another variety, choosing, perhaps, 

 Frogmore Bigarreau, the two varieties being found to cross- 

 pollinate well. In the case of cherries, it is found that not 

 all varieties are inter-fertile, and it may be advisable, therefore, 

 to plant three different varieties in an orchard. 



Pollenizing Agents. — Nature's pollenizing agents are chiefly 

 the wind and insects. In the case of walnuts and cob nuts, 

 the wind carries the light pollen from the catkins to the nut 

 blossoms. In the case of gooseberries and black and red 

 currants, the pollen of which is glutinous, it is necessary for 

 insects to transfer the pollen from flower to flower, for the wind 

 is unable to carry it. In the case of apples, pears, plums and 

 cherries, very little pollination appears to be due to the wind. 

 Hive bees, bumble bees and other wild bees appear to be the 

 insects best adapted for carrying the pollen. 



Experiments on the Pollination of Fruits. — From trials 

 in America, Australia, at the Pioyal Horticultural Society's 

 Gardens at Wisley, and at the John Innes Horticultural 

 Institution at Merton, observations have been made as to the 

 movement of pollen by the wind. The effect of placing muslin 

 around fruit trees in order to exclude insects was also 

 investigated, and it was found that trees so enclosed produced 

 either no fruits or very few fruits, whereas similar trees in the 

 open produced hundreds of fruits: which showed that wind did 

 not help much and that insects were necessary. 



In the writer's own trials, straicherrics under muslin which 

 allowed a certain amount of air movement but excluded insects 

 matured good fruit, the weather being sunny. With straw- 

 berries in pots under glass, more perfed and Larger fruits 



