- 22 - 
might be killed if poisonous sprays are used when the petals of the 
blossoms are showing . 
MacDaniels, L. H. , and Heinicke, A. J. 
1929. Pollination and other factors affecting the set of fruit, with 
special reference to the apple. N. Y. (Cornell) Agr. Expt. Sta. 
Bui. 497, 47 pp. 
pp. 4-5: The flowers of the appl e and of most of our fruit 
plants are adapted by their structure to insect pollination. The 
showy petals, the odor, and the nectar-secreting glands have the 
function of attracting insects which carry the pollen from flower to 
flower. The pollen itself is of the sticky type that adheres to the 
hairy coat of insects which visit the blossoms . . . rather than of the 
light dry type that is adapted to wind dissemination. When it is 
app reciat e d that it would tak e approximately 400 apple-pollen grains 
pla ced side by side t o reach fr om one end of a bee to the other, and 
that the number carried by _a_ s ingle bee might easily appro ximate 
1 00,000 , some idea of the possible effectiveness of insect pollination 
can be gained. 
Overholser, E. L. 
1927. Apple pollination studies in California. Calif. Agr. Expt. Sta. 
Bui. 426, 17 pp. 
p. 15: The use of bees as a means of effecting pollination 
in an apple orchard greatly increased the set of fruit when contrasted 
with the normal set. 
Cross-pollination increased the set of fruit, even with self- 
fruitful varieties like the Yellow Newtown. 
Swinson, C. R. , Weaver, F. P., Dadisman, A. J., Vernon, J. J., Gould, H. P., 
and Lincer, J. B. 
1927. Factors influencing the yield of apples in the Cumberland-Shenan- 
doah region of Pennsylvania, Virginia, West Virginia. U.S. 
Dept. Agr. Tech. Bui. 54, 25 pp. 
p. 21: A number of growers attributed low yields to failure 
of fruit to set. It was commonly observed that the low yields of the 
Winesap and varieties of the Winesap family were ascribed to this 
factor. These varieties are largely self-sterile and must be cross- 
pollinated by some other variety. Self-sterile varieties should not be 
planted in solid blocks or isolated from other orchards. Where self- 
sterile varieties have been so planted the results may be improved by 
top-working every fourth or fifth tree in every fourth or fifth row 
with some variety that is a good cross-pollinizer. Bees_ a re essential 
in any orchard and are effective in securing pollination even during 
cold, wet seasons . 
