Pollination and Bee Poisoning
Table of Contents
- Pollination Requirements for Fruit Crops
- Using Honeybees Effectively
- Recommended Publications
- Bee Poisoning
Pollination Requirements for Fruit Crops
Most fruit crops benefit from or require insect pollination.
Apple cultivars grown in Ontario do not generally set fruit with their
own pollen. Pollination with pollen from more than 1 cultivar normally
results in larger fruit compared to fruit grown from a single source of
pollen. A bloom requires 8-24 visits by pollinators. A well-designed orchard
reduces the number of bee visits required. Good pollen movement is necessary
for fruit with high seed count. Good pollen movement in a higher density
planting is generally limited to 3-4 rows across the orchard. The distance
pollen travels down the row is limited to a few trees. For this reason,
2 or more compatible cultivars must be planted together in the orchard
to allow for cross-pollination and fruitfulness. Varying the placement
of beehives does not normally have a significant influence on pollen dispersal
distances within the apple orchard.
Most varieties are self-fruitful and may be planted in solid blocks.
Because apricots bloom early when the weather is unreliable, provide honeybees
to help with pollen transfer.
Blueberries are self-fruitful and may be planted in solid blocks. However,
cross-pollination of cultivated blueberries can give larger berries, higher
yields and somewhat earlier ripening. It is advisable to plant more than
1 blueberry variety. Honeybees help with pollination.
Sour cherries are self-fruitful and do not require pollenizer cultivars
for a commercial crop. For maximum production of sour cherries, use honeybees
at a rate of 2 strong hives per hectare. Sour cherries and sweet cherries
are different species, and will not pollinate each other.
Sweet cherries are not pollinated by wind; the honeybee - use 2 hives
per hectare - is the only effective pollinating insect reported. Many
sweet cherry cultivars are self-unfruitful and must not be planted in
solid blocks. Certain groups of cultivars will not pollinate each other.
Careful attention to planting arrangement of sweet cherries is required.
Recent sweet cherry cultivar introductions from the Vineland breeding
program are self-compatible.
Currants and Gooseberries
These are self-fruitful, but insects assist in pollen transfer. Honeybees
can increase crop yield.
All commercial varieties of grapes are self-fruitful and are pollinated
by wind. It is not necessary to provide honeybees for pollination.
Peaches and Nectarines
All commercial varieties grown in Ontario are self-fruitful and may
be planted in solid blocks. Honeybees readily work peach blossoms and
frequently cause a heavy set, resulting in extra thinning costs. For this
reason, do not put beehives in peach orchards.
All varieties in Ontario are self-unfruitful. Mixed plantings are necessary.
Insects are required for cross-pollination. Honeybees do not find pear
blossoms as attractive as most other fruit. Careful timing of the introduction
of honeybees to orchards is necessary. Place up to 8 strong hives per
hectare when the orchard is about 25% in bloom. Use pollen inserts to
help overcome pollination problems.
Consider both European and Japanese plums as self- unfruitful. Mixed
plantings and insect pollinators are essential. Honeybees readily work
Raspberries and Blackberries
Raspberries are self-fruitful. Their bloom is very attractive to bees.
Strawberries are self-fruitful, and are pollinated by gravity, wind
and insect transfer. Pollination by honeybees or other insect pollinators
may improve berry size and shape.
Tree Nut Crops
These rely on cross pollination achieved mainly by wind action.
Using Honeybees Effectively
The primary domesticated insect pollinator of cultivated crops is the
honeybee. Many growers facilitate the pollination process by arranging
to have beekeepers move honeybee colonies into their crops during the
blooming period. The following information will help you use honeybees
Obtain honeybees from a reliable beekeeper able to supply strong,
healthy colonies. Weak colonies are of little value for early spring
pollination when cool weather is often encountered.
Two to 3 colonies of honeybees per hectare provide satisfactory pollination.
Stocking rates vary depending on the type of fruit, the variety and
the planting density. In young orchards fewer honeybee colonies may
be required because there are generally fewer blossoms to pollinate.
On the other hand, for early blooming fruit crops such as apricots,
cherries and plums, you are better off to use more honeybee colonies
than the recommended stocking rates indicate. This precaution should
compensate for the negative effect of cold weather, which often occurs
during the pollination period of these crops.
A pollen insert is a device that forces bees leaving the hive to
crawl through a shallow tray containing pollen from the desired pollenizer.
Pollen adheres to the legs and body of each foraging bee to enable
it to cross-pollinate the blossoms it visits.
When using a pollen insert, place hives in the crop after blossoms
have partially opened (earlier for sweet cherries, later for pears).
This encourages more bees to work the fruit blossoms in the immediate
surroundings, rather than foraging elsewhere. This recommendation
is extremely important to ensure the effective use of pollen inserts.
Have 5 colonies per hectare when using pollen inserts.
Weather is often cool during the pollination period for early-blooming
fruit crops. To encourage maximum honeybee flight during cool weather,
protect the colonies from cold spring winds. Place the colonies in
larger groupings in sunny, sheltered locations. Where there is no
natural windbreak, erect a temporary wind shelter using, for example,
bales of straw. Place the colonies so that the morning sunshine strikes
the hive entrances.
Provide water to colonies during bloom periods that are exceptionally
dry. Bees will abandon pollen collection in favour of securing water
for the colony. A shallow tub of water with floating sticks allows
bees to land without drowning.
Honeybees favour apple pollen over dandelion pollen. Apple pollen
provides a higher quality protein that bees require to feed colony
brood. Although bees will forage on dandelion as a protein source,
the vast majority will move to apple pollen quickly when it becomes
available. Apple growers do not need to be concerned about dandelion
bloom drawing bees away from apple bloom. A rigorous program of mowing
dandelion bloom in orchards is no longer recommended for Ontario apple
For information contact the OMAFRA apiary specialist at 1-888-466-2372
ext. 63595 or by e-mail at email@example.com.
For more information on pollination requirements of fruit crops,
refer to OMAF Publication 430, Fruit Cultivars, A Guide for Commercial
Bees are essential for the pollination of most tree and small fruits.
Insecticides, many of which kill bees, are required for insect control.
With careful management, you can obtain both pollination and insect
control. You can protect the bees by following these suggestions.
Do not apply insecticides while fruit trees are in bloom. The
Bees Act makes it an offense to do so in Ontario. Read
label for guidelines.
Time of treatment is important. In general, daytime treatments
when bees are foraging in the field are most hazardous. Insecticide
applications in the evening are the safest. Early morning is the
next best time.
Remove honeybee colonies as soon as pollination is complete and
before any postbloom insecticides are applied.
If there is a risk of honeybee poisoning, try to choose an insecticide
that is not highly toxic to the bees.
Honeybees frequently are poisoned by visiting cover crops, such
as dandelions or clovers, that are in bloom in the orchard. Clipping
or beating down such crops prior to spraying will help safeguard
The following groups found in Table 6-1, Relative
Toxicity of Pesticides to Honeybees, (chemicals used with
fruit crops) show the relative toxicity of pesticides to honeybees
as determined by laboratory and field tests.
Table 6-1. Relative Toxicity Of Pesticides
Group I - Pesticides Highly Toxic to Bees
Group II - Pesticides Moderately Toxic to Bees
Group III - Pesticides Relatively Non-Toxic
Severe losses may be expected if the following materials are
used when bees are present at treatment time or within a few
APM 50W Instapak
Cymbush 250 EC
Diazinon 500 E
DZN 600 WDG
Imidan 50 WP
Sevin XLR Plus
Success 480 SC
Sniper 240 E
These can be used around bees if dosage, timing, and method
of application are correct, but do not apply them directly on
bees, in the field or at the colonies:
Metasystox R 240EC
Captain 80 WDG
Dipel 2X DF
Elevate 50 WDG
Equal 65 WP
Ferbam 76 WDG
Funginex 190 EC
Gavel 75 DF
Manzate 200 DF
Manzate 200 WP
Maestro 80 DF
Ridomil Gold 480 EC
Ridomil Gold MZ
Extremely Toxic to Bees
This insecticide has caused more loss (confirmed cases of poisoning)
to bees in Ontario than any other of the materials mentioned in this
publication. Fruit growers and apiarists require close liaison when
and where Furadan is used.
For more detailed information on the toxicity of specific pesticides
to honeybees refer to the pesticide label.