Welcome to spring in Colorado. One day the sun shines, the next day it snows and the weather turns cold. This year, the chance of a late freeze isn't the only concern of gardeners worried whether their fruit tree blossoms will set fruit.
They also must worry about honeybees -- will there be enough of them to pollinate their trees? Honeybees, the most important carriers of pollen for fertilization and fruit set, are in trouble. Their numbers have declined substantially in the last several years, largely because of two relatively new predators, the varroa and tracheal mites.
Until now, the familiar light brown and black striped honeybee has been a reliable spring pollinator. But a combination of mites that sap the bees' strength, along with normal winter hardships, has killed many hives. This leaves in question the pollination of apples, plums, sour cherries, peaches and other fruits.
It's likely that honeybee and wild bee populations will recover partially by mid-summer. This improves the outlook for pollination of vegetables such as squash, pumpkins and cucumbers. Still the situation is far from good.
As gardener caretakers of our environment, we need to use more caution in applying pesticides. Because many commonly used garden pesticides are toxic to bees, questions to ask include whether the plant to be sprayed is in flower and attractive to bees. If so, can pesticide applications be delayed until flowering is finished? Are there pest control solutions other than pesticides?
You can deal with this problem in several ways -- some as inexpensive and easy as knocking insects off plants with a strong stream of water. Or, you can handpick larger insects. Another approach is the use of floating row covers that can exclude insects from reaching plants. And, when you do choose pesticides, consider the use of those that are least toxic. Carefully read label precautions.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010