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Phaseolus and blackfly
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. |
Phaseolus and blackfly
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 |
Phaseolus and blackfly
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. |
Phaseolus and blackfly
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Phaseolus and blackfly
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. |
Phaseolus and blackfly
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. |
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