P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

Has anyone got any insights?


Regards,
Nick Maclaren.

On 21 Oct 2016 12:33, Nick Maclaren wrote:
P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

Has anyone got any insights?


Regards,
Nick Maclaren.

I am a little baffled, I have grown runner and French beans of various
varieties over very many years and have never seen any blackfly on them,
I was told very many years ago that broad beans are best planted in
Autumn as the blackfly seem to prefer the shoots of spring planted
shoots as they are more tender and that seems to be the case. Might it
be geographic in some way? I did most of my gardening in West Cork.

--
Flying on Per Ardua ad Astra

In article ,
Zephirum wrote:

P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

I am a little baffled, I have grown runner and French beans of various
varieties over very many years and have never seen any blackfly on them,
I was told very many years ago that broad beans are best planted in
Autumn as the blackfly seem to prefer the shoots of spring planted
shoots as they are more tender and that seems to be the case. Might it
be geographic in some way? I did most of my gardening in West Cork.

They probably all washed off in the rain :-) More seriously, autumn
planted broad beans don't do well here, because we sometimes get
frost and wind. Bu, on the runners, they attack all of young shoots,
flowering shoots and older stems - the actual growing shoots move too
fast for them! But I have never seen more than one patch every half
dozen plants. Very unlike the way that they attack broad beans.


Regards,
Nick Maclaren.

In article , says...

On 21 Oct 2016 12:33, Nick Maclaren wrote:
P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

Has anyone got any insights?


Regards,
Nick Maclaren.

I am a little baffled, I have grown runner and French beans of various
varieties over very many years and have never seen any blackfly on them,
I was told very many years ago that broad beans are best planted in
Autumn as the blackfly seem to prefer the shoots of spring planted
shoots as they are more tender and that seems to be the case. Might it
be geographic in some way? I did most of my gardening in West Cork.

My experience (in Scotland) is the same. I've never seen blackly on
runner or french beans ; broadbeans so infested I don't bother growing
them any more.

Janet

On 22/10/16 12:47, Janet wrote:
In article , says...

On 21 Oct 2016 12:33, Nick Maclaren wrote:
P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

Has anyone got any insights?


Regards,
Nick Maclaren.

I am a little baffled, I have grown runner and French beans of various
varieties over very many years and have never seen any blackfly on them,
I was told very many years ago that broad beans are best planted in
Autumn as the blackfly seem to prefer the shoots of spring planted
shoots as they are more tender and that seems to be the case. Might it
be geographic in some way? I did most of my gardening in West Cork.

My experience (in Scotland) is the same. I've never seen blackly on
runner or french beans ; broadbeans so infested I don't bother growing
them any more.

Janet


Do you cut the top 6^" off each plant as soon as the first bean sets on
the plant? I've had great success doing this. You do get small colonies
on lower leaves occasionally, which are easily removed by rubbing with
your fingers every few days during the worst times.

On 22/10/16 10:38, Nick Maclaren wrote:
In article ,
Zephirum wrote:

P. vulgaris (French bean) seems essentially immune, but I get quite
dense localised infestations on P. coccinea (runner bean). What
puzzles me is why they don't spread, the way that they do with broad
beans, and to a great extent most of their other summer hosts. They
don't spread on their winter habitats, of course, but these cases
occur during summer and autumn and look far more like summer ones
than winter ones.

I am a little baffled, I have grown runner and French beans of various
varieties over very many years and have never seen any blackfly on them,
I was told very many years ago that broad beans are best planted in
Autumn as the blackfly seem to prefer the shoots of spring planted
shoots as they are more tender and that seems to be the case. Might it
be geographic in some way? I did most of my gardening in West Cork.

They probably all washed off in the rain :-) More seriously, autumn
planted broad beans don't do well here, because we sometimes get
frost and wind. Bu, on the runners, they attack all of young shoots,
flowering shoots and older stems - the actual growing shoots move too
fast for them! But I have never seen more than one patch every half
dozen plants. Very unlike the way that they attack broad beans.


Regards,
Nick Maclaren.



What type of bean are you planting? I've been using 'Aquadulce' and get
a reasonable crop most winters.

In article ,
RedAcer wrote:
On 22/10/16 12:47, Janet wrote:

My experience (in Scotland) is the same. I've never seen blackly on
runner or french beans ; broadbeans so infested I don't bother growing
them any more.

Do you cut the top 6^" off each plant as soon as the first bean sets on
the plant? I've had great success doing this. You do get small colonies
on lower leaves occasionally, which are easily removed by rubbing with
your fingers every few days during the worst times.

I pinch out the tops, leaving 4 layers of flowers, mainly to eat them,
but it does little good against blackfly. What I do notice is that
the blackfly don't leave their winter hosts until the weather starts
to warm up, so early sowings are fairly OK and later ones less so.
I can easily believe that the problem is very location-dependent.

I also spray the hell out of infestations with soft soap until the
beans have set solidly, which is almost essential, or the beans
aren't worth eating. Soft soap works as well as anything, and is
completely non-toxic (including to the plants).


Regards,
Nick Maclaren.