20 Dec 2010 Crab apples, small and large

After a dinner at a community hall one year, I wandered through the surrounding garden and I was delighted to see this crab apple tree with all its fruit.  Since it was fall and all the leaves had fallen, these pink crab apples, small and large, made a showy and colourful picture.  Because I studied pollination and pollen loading of blueberries, I was off course interested to having a second look at the pollination of this tree.  I wanted to see if there were any patterns of where the large and small apples were located on the tree.  One pattern was very clear and can be seen in this photo.  The more accessible flowers on the outside of the canopy produced larger fruit.  This means that flowers on the outer canopy received more bee visits because more pollen was deposited on these flowers.   The lesser accessible flowers on the inside of the canopy are small and received fewer bee visits. Flowers close to the ground also produced small fruit. 

This tree did not receive optimal pollination.  If the plant is healthy, the two major reasons why poor pollination occurs is insufficient bees or poor weather or a combination of these two factors. If poor pollination occurs in good weather, then insufficient bees is the more likely reason for poor pollination. 

People often ask me how many mason bees must a garden have for good pollination.  Fruit production is a great way to tell if good pollination occurred during the previous spring.  If pollination is good for a series of 3-4 years, which includes a poor weather year, then sufficient bees are in the orchard.



Lack of good pollination produced both large and small crab apples.