Diggers,

You may remember that a short time ago I recommended using large modified
plant pots (8-9 inch diameter), inverted over runner bean plants to enable
watering and feeding liberally but not wastefully. Well, it has other
advantages apart from watering and slug/snail barrier for I've noticed no
ants which I reckon carry aphids from one part of a plant to another. The
beans still have blackfly but I keep them under control with regular
spraying with a soft soap/rainwater solution. Soft soap is made with
caustic potash instead of the caustic soda used in the manufacture of
household soap which is not anywhere near so effective against aphids.

However, not all in my bean patch is rosy! Some of the plants' leaves are
"bobbly" and become withered and dried at the edges. The affected leaves
are very frangible even though still green. Some - about half - of the
affected leaves had been attacked by aphids but I do not think they were the
cause.

Does anybody know what causes the problem and can suggest an environmentally
friendly way of control please?

Regards

Geoff

In article ,
"Geoff" writes:
|
| You may remember that a short time ago I recommended using large modified
| plant pots (8-9 inch diameter), inverted over runner bean plants to enable
| watering and feeding liberally but not wastefully. Well, it has other
| advantages apart from watering and slug/snail barrier for I've noticed no
| ants which I reckon carry aphids from one part of a plant to another. The
| beans still have blackfly but I keep them under control with regular
| spraying with a soft soap/rainwater solution. Soft soap is made with
| caustic potash instead of the caustic soda used in the manufacture of
| household soap which is not anywhere near so effective against aphids.

I have very little trouble with aphids on my runner beans - perhaps my
ants eat them all :-)

More seriously, I doubt that your pots have anything to do with the lack
of ants, just as much as I doubt that the ants have a significant effect
on the aphids. The long, miserable winter is more likely to be the cause
of a lack of ants.

Why do you invert the pots, incidentally, rather than just using them
the normal way up with the bottoms cut out (which I assume is your main
modification)?

| However, not all in my bean patch is rosy! Some of the plants' leaves are
| "bobbly" and become withered and dried at the edges. The affected leaves
| are very frangible even though still green. Some - about half - of the
| affected leaves had been attacked by aphids but I do not think they were the
| cause.

My guess would be a virus - probably aphid transmitted. And there is a
VERY high probability that the aphids that brought the virus were flying,
mature females. My observations on broad beans indicate that such a
female will lay eggs on several plants in a single trip.

If it is a virus, there is damn all you can do, except destroy infected
plants to stop it being spread by aphids (which can crawl, and be washed
by rain, from plant to plant, whether or not ants transfer them). If most
of your plants are affected, get what crop you can and hope for better
luck next year. Such viruses do not survive composting, incidentally.

If the new leaves on an affected plant don't show that trouble as they
enlarge, it isn't a virus.


Regards,
Nick Maclaren.

"Geoff" wrote in message
...
Diggers,

You may remember that a short time ago I recommended using large modified
plant pots (8-9 inch diameter), inverted over runner bean plants to enable
watering and feeding liberally but not wastefully. Well, it has other
advantages apart from watering and slug/snail barrier for I've noticed no
ants which I reckon carry aphids from one part of a plant to another. The
beans still have blackfly

On *runner beans*? I've never had that in forty years. The main reason I
don't grow broad beans is that I'm paranoid about blackfly, if I see them on
my beloved runners I'll - well, I don't know what I'll do!

Mary

"Nick Maclaren" wrote in message
...

In article ,
"Mary Fisher" writes:
|
| On *runner beans*? I've never had that in forty years. The main reason
I
| don't grow broad beans is that I'm paranoid about blackfly, if I see
them on
| my beloved runners I'll - well, I don't know what I'll do!

I get a few patches, most years, but a negligible number compared to those
on broad beans. Spraying with soft soap works fine - and I have to do it
only once or twice, unlike on broad beans. The same applies to French
beans.

There apparently isn't a major problem with growing growing broad beans -
the problem seems to be plants like philadelphus, viburnum etc. - i.e. the
alternate (winter) hosts. As quite a lot of common weeds are alternate
hosts, it is quite hard to avoid that aphid.

I'm sure you're right but I've only ever seen them on broad beans here.
Pity, I love them. Perhaps their hosts are in adjacent gardens.

Mary

In article ,
"Mary Fisher" writes:
|
| There apparently isn't a major problem with growing growing broad beans -
| the problem seems to be plants like philadelphus, viburnum etc. - i.e. the
| alternate (winter) hosts. As quite a lot of common weeds are alternate
| hosts, it is quite hard to avoid that aphid.
|
| I'm sure you're right but I've only ever seen them on broad beans here.
| Pity, I love them. Perhaps their hosts are in adjacent gardens.

Wouldn't make a huge difference - the aphids fly a respectable distance.

My experience is that the severity of the problem is very dependent on
the year's weather. This year, I had bad aphids on my first crop (very
late due to the cold spring), have had few so far on the second (why
not? Dunno), and few ants's nests survived the past few winters.


Regards,
Nick Maclaren.

"Nick Maclaren" wrote in message
...

In article ,
"Mary Fisher" writes:
|
| There apparently isn't a major problem with growing growing broad
beans -
| the problem seems to be plants like philadelphus, viburnum etc. -
i.e. the
| alternate (winter) hosts. As quite a lot of common weeds are
alternate
| hosts, it is quite hard to avoid that aphid.
|
| I'm sure you're right but I've only ever seen them on broad beans here.
| Pity, I love them. Perhaps their hosts are in adjacent gardens.

Wouldn't make a huge difference - the aphids fly a respectable distance.

My experience is that the severity of the problem is very dependent on
the year's weather. This year, I had bad aphids on my first crop (very
late due to the cold spring), have had few so far on the second (why
not? Dunno), and few ants's nests survived the past few winters.

I have never seen ants here (inner city Leeds).

Mary


Regards,
Nick Maclaren.

"Nick Maclaren" wrote
..

My experience is that the severity of the problem is very dependent on
the year's weather. This year, I had bad aphids on my first crop (very
late due to the cold spring), have had few so far on the second (why
not? Dunno), and few ants's nests survived the past few winters.


Regards,
Nick Maclaren.

"Nick Maclaren" wrote ((snip))

Wouldn't make a huge difference - the aphids fly a respectable distance.


Read an article recently which said that scientists have found aphids being
taken to the upper atmosphere by thermals freezing and being blown a long
way before dropping down, thawing and going about their business.
Frightening!
Hope it's not true.

--
Regards
Bob Hobden
17mls W. of London.UK

In article ,
"Bob Hobden" writes:
|
| Wouldn't make a huge difference - the aphids fly a respectable distance.
|
| Read an article recently which said that scientists have found aphids being
| taken to the upper atmosphere by thermals freezing and being blown a long
| way before dropping down, thawing and going about their business.
| Frightening!
| Hope it's not true.

It's plausible. They are at about the limit of complexity where they
could survive that - especially if they got slightly dehydrated first.
The consequence of that is that such aphid species and the diseases
they carry would be circumpolar - I don't know if they are or not.


Regards,
Nick Maclaren.

"Bob Hobden" wrote in message
...

"Nick Maclaren" wrote ((snip))

Wouldn't make a huge difference - the aphids fly a respectable distance.


Read an article recently which said that scientists have found aphids
being taken to the upper atmosphere by thermals freezing and being blown a
long way before dropping down, thawing and going about their business.
Frightening!
Hope it's not true.


I wonder how they do that. The scientists I mean, not the aphids. I mean,
how do they know the aphids they've got are ones that have done the grand
tour, and not local yokels? Maybe they get their passports stamped at
altitude or send those postcards like you get that say "posted at the top of
Snowdon" or wherever.

Steve

"shazzbat" wrote in message
...

"Bob Hobden" wrote in message
...

"Nick Maclaren" wrote ((snip))

Wouldn't make a huge difference - the aphids fly a respectable distance.


Read an article recently which said that scientists have found aphids
being taken to the upper atmosphere by thermals freezing and being blown
a long way before dropping down, thawing and going about their business.
Frightening!
Hope it's not true.


I wonder how they do that. The scientists I mean, not the aphids. I mean,
how do they know the aphids they've got are ones that have done the grand
tour, and not local yokels? Maybe they get their passports stamped at
altitude or send those postcards like you get that say "posted at the top
of Snowdon" or wherever.

Steve

I wondered that too but didn't like to show more ignorance than is obviously
apparent!

Mary

In article ,
"Mary Fisher" writes:
|
| Read an article recently which said that scientists have found aphids
| being taken to the upper atmosphere by thermals freezing and being blown
| a long way before dropping down, thawing and going about their business.
|
| I wonder how they do that. The scientists I mean, not the aphids. ...
|
| I wondered that too but didn't like to show more ignorance than is obviously
| apparent!

I don't know about this case, but there are several ways you can deduce
that sort of thing. One is the distribution pattern of new strains (and
strains of diseases carried by aphids) - which is one reason that I don't
believe that ants are a significant aphid vector. If such things are
carried by that method, they will appear at random locations downwind,
a long way away from the source. If they are carried by aircraft, then
there will be an association with routes. And so on.

There is also the possibility of sampling them by balloon and seeing them
revive as they come down. There has been quite a lot of such sampling
recently, though it wasn't looking for aphids.


Regards,
Nick Maclaren.

"shazzbat" wrote in message
...

Snip
. . . . . . being taken to the upper atmosphere by thermals freezing and
being blown a long way before dropping down, thawing and going about
their business. Frightening!
Hope it's not true.


I wonder how they do that. The scientists I mean, not the aphids.

Have a look at the windscreen of an aircraft!

Geoff

"Geoff" wrote in message
...

"shazzbat" wrote in message
...

Snip
. . . . . . being taken to the upper atmosphere by thermals freezing and
being blown a long way before dropping down, thawing and going about
their business. Frightening!
Hope it's not true.


I wonder how they do that. The scientists I mean, not the aphids.

Have a look at the windscreen of an aircraft!

I bet those buggers don't thaw out and get back to work on the beans :-))

Steve

In article ,
"shazzbat" writes:
|
| I wonder how they do that. The scientists I mean, not the aphids.
|
| Have a look at the windscreen of an aircraft!
|
| I bet those buggers don't thaw out and get back to work on the beans :-))

If they do, the only insecticide that has a hope in hell is kryptonite.


Regards,
Nick Maclaren.