On
29/1/2004, Steve posted:
I have a question for the science list
I have a veggie garden and sowed climbing beans well in time. The
plants are growing profusely and flowering very well. So far, no beans
have set. I just wonder if i'll have any beans this year/ I talked it
over with my, very knowledgeable, nursery man and he suggested
either too cold nights, or lack of bees.
Too much nitrogen can not be the cause, because the only fertiliser I
used was blood and bone, no nitrogen. As I hardly ever (never) see any
bees around I think that is the cause!
My question is: Where are the bees? I know that the drought is
very unkind to bees, but no bees at all? I live in a very leafy
suburb of Melbourne, Glen Waverley yo be exact
Podargus
replied:
> I talked it
over with my, very knowledgeable, nursery man and he
> suggested either too cold nights,
> or lack of bees.
I feel inclined to question his
knowledge. Beans IIRC self pollinate, the pollination takes place
before the flower opens. Therefore as much as it grieves me to
say it, lack of bees are not going to be the source of your problem.
> Too much
nitrogen can not be the cause, because the only fertiliser I
> used was blood and bone, no nitrogen.
Blood and Bone is a nitrogenous
fertiliser, 5%(?) it is just comparatively low release. One of
course tends to avoid nitrogenous fertilisers when growing legumes.
> As I hardly
ever (never) see any bees around I think that
> is the cause!
>
> My question is: Where are the bees? I know that the drought
is very
> unkind to bees, but no
> bees at all? I live in a very leafy suburb of Melbourne, Glen
Waverley
> yo be exact
>From this distance I can only hazard a guess. Bees of course
do not live on leaves;-).
The first requirement is somewhere
to live, not overly common in the built environment. So the leafy
bit needs to have hollows of suitable size, not common in many suburbs
unless an abundance of old trees have been left.
During poor/no flowering, and or
nectar secretion (and pollen) bees occupying an abode that is not large
enough may starve.
In newer suburbs whilst the
gardens tend to be better there is less access to suitable nest sites
in modern buildings.
The third thing that can limit
their distribution is not surprisingly, a suitable water supply.
I wouldn't expect this to be a problem in Melbourne, but it could be
depending on the local geography.
Notwithstanding the above, in
general managed bees do quite well in suburbia, they have a capacious
home provided by the beekeeper, and a nice variety of flowering plants
to provide the nectar and pollen.
Monica replied:
Here in NW Sydney I haven't noticed a lack of bees but yesterday in my
garden there was a bee quite different from any I've seen before. It
was bigger than normal, maybe 1.5-2 cm long and very thickset and the
stripes
were much brighter than normal, almost orange, and these stripes were
thicker than the bands of brown. It was also very noisy, I thought it
was a blowfly until I caught sight of it. Any idea of what it might
have been?
Gerald
Cairnes added:
I have been struck by a lack of
bees on the flowering trees here this year. Normally the din from
the buzzing is very loud while standing under the trees but it is
virtually silent as far as bees are concerned and difficult
even to find one??
Very strange.
Ray posted:
I'd guess the bee problem is regional, since there has been some
environmental outcry elsewhere concerning feral bees stinging the life
out of native bird chicks in trees as a nest thieving thing.
Otherwise, do not know.
Podargus
answered Monica:
Probably the Teddybear Bee,
Amegilla bombiformis, the specific name I suppose referring to bumble
bees, which are similarly robust and noisy.
There is a picture here
http://www.amonline.net.au/factsheets/adaptive_radiation.htm
and Gerald:
Two reasons are possible,singly or
together. There may be no bees around because either the feral
population has been depleted owing to poor conditions in SE Qld over
the last few years, or perhaps a beekeeper may have placed hives in the
area in the past, but not this year.
The second reason may be that the
trees you mention just do not have any reward for bees this
flowering. The Australian flora does not always yield either
pollen or nectar even though they might be flowering profusely.
The buzzing one hears is mostly
coming from pollen gatherers. When gathering pollen bees collect
it in their mouth parts and then hover whilst they rake it back to the
pollen baskets on their rear legs. When gathering nectar they sip
it up and zip to the next flower.
Keith Parker responded to Ray:
Why the hell would a bee want to steal a bird's nest????? Also I don't
know of any plant which is either wind or insect pollinated: they're
very specific usually being pollinated by only one family(often one
species) of insect.
Paul
Williams wrote:
I'm relying on memory but most of
this should be pretty right:
I think that 'scarlet runners' are
helped somewhat by bee pollination. These handle cooler nights
quite well.
These are also my favourite beans
- unfortunately they like the cold and Queensland is generally a little
warm for them. These should be semi-perennial in Melbourne. They
should re-shoot from the rootstock the following year (at least).
>From memory,
the second year is often better but poorer crops result if left in
longer.
Best
to replant new seeds after every second year - in a different spot.
Climbing snap beans (string beans)
and bush beans, I believe, don't benefit much, if at all, from bees.
(My guess is that bees wouldn't
benefit much from these flowers either)
My blood and bone bag lists
nitrogen content at 9.5%. It is a slow release form, as Podargus
mentions, and shouldn't hurt if the application was not too heavy.
Your beans are flowering so I
don't think this would be the problem anyway.
Blood and bone also supplies
phosphorous but no, or negligible, potassium.
If you grow beans in the same
place every year you may end up with disease problems.
It may be that the weather has
been too dry - too wet?
The ground is too dry?
The soil pH is wrong?
It's unlikely to be the cold at
this time of year.
If your beans look healthy and, as
you say, they are flowering, you should have beans...
If there are nodules on the roots,
they should be fixing nitrogen happily.
Potassium may be needed?
Possibly trace element deficiency?
- this can be related to soil pH.
Sunshine?
Buying trace elements on their own
is a ridiculously expensive way to go. If you are organic gardening? a
mix of well rotted manures and compost is best. (These are best
incorporated into your garden well before planting - of course).
I haven't tried them on beans but
some of the low nitrogen slow release fertilisers made for Australian
native plants may work well? Many of these are low in phosphorous as
well but blood and bone should fix that.
BTW: Commercial bush bean growers
up here in Gympie use lots of nitrogenous fertilisers on their crops -
after they've started flowering. Well grown beans will have 5,
sometimes 6 major picks - progressively poorer (naturally enough).
If all else fails try different
varieties - or perhaps, something else...:-)
Podargus replied:
> > PS Wind might be
sufficient for pollination of many plants, especially
> > those self fertile species.
Bit of a contradiction in terms there Ray. Being self fertile
means it does not need pollination.
Then "Keith Parker" said
> Why the hell would a bee want to
steal a bird's nest????? Also I don't
know of any plant which is either wind or insect pollinated: they're
very
specific usually being pollinated by only one family(often one species)
of
insect.
Why indeed you may ask. 'A' bee would not, but social bees
such as the commercially used honeybee very well might do so. The
incidents referred to by Ray were in a Catalyst ( IIRC ) program
towards the end of last year. In the case referred to it was
claimed that swarming bees were taking over tree hollows that already
had red tailed (?) cockatoo nests in them. Knowing something
about the matter I can report that it was largely another Catalyst beat
up, not that it couldn't or wouldn't happen at times.
I am not sure what to make of -"Also I don't know of any plant which is
either wind or insect pollinated: "!
Many plants are wind pollinated and some of these are attractive to
pollen feeders, which presumably may also do some pollination.
The grasses immediately come to mind, but many flowering plants are
also wind
pollinated. Pines, sheoaks, pecans, rye grass and ragweed and
even the beloved wattle release copious quantities of wind dispersed
pollen, much to the distress of hayfever sufferers.
-"they're very specific usually being pollinated by only one
family(often one species) of insect"
This statement would be better reversed.
There are indeed a few plants, orchids come to mind, that have evolved
a close relationship with a single species of insect to affect
pollination. This is not always by giving a food reward but can
be by 'tricking' the
insect into 'mating' with the flower.
However most non wind pollinated plants will accept many
pollinators. The eucalypts are often pollinated by a vast array
of insects as the flower is not at all specialised in this
matter. Bats and small mammals such as sugar
gliders may actually be the main pollinators. Birds are also
major, in some cases the main pollinator for some other natives.
It is true however that solitary bees of which there are some 2500 spp
in Australia can be fairly specific as to the plants they work.
This is not surprising as they have to time their breeding to something
flowering at just the right time, but because of our irregular climate
it doesn't pay to be too selective.
Ian
Musgrave, replying to Monica and Podargus:
Really make sure its the Teddybear
bee, if Bumble bees have hit the mainland, AQIS needs to be alerted.
Ray responded:
Podargus, doesn't self fertile mean
that the flower of a particular species pollinates from its own stamen?
That is, it uses its own pollen when
there may be none other available and still requires pollination to
produce seed.
Podargus
replied:
> Podargus,
doesn't self fertile mean that the flower of a particular species
> pollinates from its own stamen?
>
> That is, it uses its own pollen when there may be none other
available and
> still requires pollination to produce seed.
Yes it does, but in my defence I
was replying to-
> > PS Wind might be
sufficient for pollination of many plants, especially
> > those self fertile species.
> Bit of a contradiction in terms there Ray. Being self
fertile means it does
> not need pollination.
Perhaps I should have said;
...... Being self fertile means it does not need pollination by
outside agents. ?
and
to Ian:
And
AQIS will do????????????
Podargus, in uncharacteristic cynical
mode.
