Pollination 137 



WEATHER CONDITIONS AND POLLINATION 



Proper pollination is as important with staminate 

 varieties as with pistillates. Few blossoms are self- 

 fertilized, because the pollen and the pistils do not mature 

 together in the same flower. It is necessary for pollen 

 to be transferred from one blossom to another. This 

 is done to some extent by wind, but mostly by insects. 

 Probably over ninety per cent of strawberry pollination is 

 done by insects. The strawberry blossom does not pro- 

 duce much nectar, and bees prefer other pasturage when 

 it is available, much to the loss of the grower. 



Nubbins are the result of imperfect pollination or of 

 injury to the pistils ; either the pollen did not reach all 

 of the pistils, or fertilization was prevented (Plate XII). 

 Occasionally nubbins result from winter injury or from 

 the work of weevils or other insects. Warm, dry weather 

 favors good pollination. Insects are abundant on the 

 blossoms then, especially the honey bee. Over ninety per 

 cent of strawberry pollination is done by the honey bee, the 

 bumble bee and other wild bees. In searching for nectar 

 and pollen, their bodies become dusted with pollen ; this 

 is carried from flower to flower, thus effecting cross- 

 pollination. Cold or prolonged rainy weather is unfa- 

 vorable to pollination ; it prevents insects from working 

 upon the blossoms and may injure the essential organs. 

 Frosts, dry winds, prolonged rains and hail cause many 

 nubbins. Usually frosts injure only the blossoms that 

 are fully expanded at the time. Those that are not opened 

 are uninjured, and the crop is merely a little later in 

 ripening. Nubbins are most abundant late in the ripen- 

 ing season when the pollen supply is likely to be short 

 and the plants are somewhat exhausted. 



