Hi durango,
Pollinators:
http://www.beeculture.com/beeculture/book/chap9/sun.html
"Honey bees are the primary pollinating agents of sunflowers almost
wherever they are grown (Cardon 1922, Cirnu 1960, Fomina 1961, Glukhov
1955, Overseas Food Corporation 1950, Pritsch 1965, Radaeva 1954). If
there is a shortage of honey bees in the sunflower fields, a small
seed crop is harvested.
In some localities, bumble bees and sundry other wild bees visit
sunflowers (Cockerell 1914). Arnason (1966) indicated that in many
instances these bees are adequate, but all other researchers have
shown that the bulk of the pollination in commercial sunflower
production is by honey bees. Radaeva (1954) showed that honey bees are
much more effective than wild insects. The evidence indicates that if
sufficient flower heads are available for bees to collect honey
surplus to the needs of the colony, the ratio of bees per flower is
inadequate for maximum seed production.
The exact number of bees needed for maximum pollination has not been
determined. Measurements of bee activity have included bees per flower
head, bees per unit of row, bees per acre, and colonies per acre.
These have been correlated to some degree with seed production. For
example, Noetzel44 placed one colony per acre at the ends of different
sunflower fields in North Dakota. He counted the bees per head and
obtained seed production data at different distances from the apiary.
He obtained an overall increase of 20 percent due to the bees alone,
but beyond 400 feet from the apiaries he got no measurable increase in
yield.
Noetzel's production ranged from 1,350 to 4,962 lb/acre within 50 feet
of the apiary as compared to the range of from 734 to 2,249 lb/acre at
1,300 feet from the apiary. Robinson et al. (1961) harvested 1,231 to
1,653 lb/acre from their plots in Minnesota but gave no indication of
the pollinator population in the plots. Bees were not provided to the
plots, but apparently they were abundant in the vicinity. Furgala
(1954b) reported that three to five colonies per acre significantly
increased yield. Furgala (1954a) reported that a field produced 1,300
lb/acre near the apiary, 900 lb/acre at a distance of 400 feet, and
800 lb/acre at 1,000 feet, whereas the field not supplied with bees
produced about 700 lb/acre at all sites."
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A new pollinator for commercial sunflower
http://www.loganbeelab.usu.edu/accompli.html.
"The sunflower leafcutting bee (Megachile pugnata, is a native species
that specializes in collecting pollen and nectar from plants in the
sunflower family. Previous studies have shown that the sunflower
leafcutting bee readily visits and pollinates commercial sunflowers;
adopts artificial domiciles for nesting sites; and is easily
obtainable in large numbers from western wildlands. In this past
year, we have shown that the sunflower leafcutting bee is at least as
efficient as the honeybee at pollinating hybrid sunflowers in large
field cages: in 2,000 sq. ft. cages with 600 sunflowers plants, 100
sunflower leafcutting bees as many seeds/head, of equal (or larger)
weight, than 1000 honeybees. We have also developed rearing methods
which enable us to synchronize the developmental stage of immatures
for successful overwintering, and to avert the emergence of adults at
inopportune times late in the summer. We are currently experimenting
on the pollination of additional hybrid varieties, and on methods for
holding adults at low temperatures so that we will be better able to
synchronize bee emergence with sunflower bloom. In addition, because
some sunflowers are grown into late summer, we are experimenting with
rearing methods which will enable us to completely circumvent diapause
in immatures produced earlier in the year on sunflowers. If
successful, this will enable us to pollinate several crops of
sunflowers in the same year, and to build up populations of this bee
more rapidly."
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The Sunflower Stop's Home Guide To Growing Sunflowers
http://jstait.addr.com/sunflowers/howto.htm
Keyword search:
sunflower pollination
bees pollinate sunflowers
Best regards,
tlspiegel |
