Fruit and Vegetable Crop Pollination

BY MARION ELLIS, RETIRED

Extension Apiculturist (BEEKEEPER),

 University of Nebraska-LINCOLN

     Cross pollination, or the transfer of pollen from flower to flower, is an essential step in the production of many fruit and vegetable crops. Insect-pollinated crops produce small amounts of sticky pollen and rely on pollinating insects to transfer pollen from flower to flower. Inadequate pollination can result in deformed fruit or no fruit to harvest.
     Honey bees are the most important fruit and vegetable crop pollinators. However, populations of honey bees have diminished during the past decade due to the Varroa mite, a recently introduced parasite which has become a major pest in the region. The Varroa mite has caused extensive losses in managed colonies, and it has increased the labor and expenses required to maintain colonies. Of perhaps greater significance, the mite has killed most of the wild (feral) colonies which formerly existed in tree holes, hollow walls of buildings, and other protected cavities. This means that fewer honey bees are available in towns, cities and the surrounding countryside where homeowners have previously benefited from their pollinating activity.
     Fruit and vegetable growers can encourage native pollinators to help cover the current “pollination gap.” Providing backyard habitat for native pollinators such as bumblebees, leafcutter bees, and mason bees may become a necessary part of both urban and country gardening and fruit production. Alternately, honey bees can be kept to provide both pollination and a crop of honey. While Varroa mites have decimated wild populations of honey bees, skillful beekeepers can protect and care for honey bee colonies without suffering losses.
     Commercial growers should act quickly to ensure fruit set if pollinator activity is inadequate.  Studies show that six bee visits per blossom are required to obtain a uniform set of well-formed fruit for most apple varieties.
     Fruit and vegetable growers who have enjoyed the benefit of wild honey bee pollinators may find it necessary to manage pollinators to obtain good fruit yields in the future. Bee pollination is as essential as fertilizing, watering, pest control and other management practices. The following are things that growers can do to encourage pollinators:
          1. Plant forage plants such as sweet clover, Dutch clover, purple vetch, sunflowers, pussy willow, alfalfa or goldenrod to attract and sustain pollinators, and let them bloom so the bees can feed on the flowers.
          2. Plant shrub roses, raspberries and other brambles with hollow or pithy stems to provide nesting sites for solitary leafcutter and mason bees.
          3. Make an artificial leafcutter or mason bee habitat. Untreated 4" x 6" lumber works great. A 1/4” or 5/16" diameter hole can be drilled in smooth wood on 3/4 inch centers, 2.5 to 8" deep depending upon the size lumber used. A hole smaller than 1/4” or larger than 5/16” will attract undesirable bees and insects. A 5/16" diameter hole is important for attracting Mason Orchard Bees. Do not drill completely through the lumber. Attach a roof to provide protection from the midday sun and rain. Outside surfaces may be painted or stained, but do not use wood preservatives.

Copyright 2015

For more information go to:

http://www.ars.usda.gov/Main/docs.htm?docid=10743 ((Build a Nest Board, Agriculture Research Service, USDA)

http://king.wsu.edu/foodandfarms/documents/MasonBee.pdf (Orchard Mason Bees, Washington State University Extension Service in King County)

http://gage.unl.edu/artificialhabitatfortubenestingbees (How To Build Artificial Habitat For Tube Nesting Bees, UNL Extension in Gage County, NE)