Nasturtiums and blackfly?

My nasturtiums are beginning to be infested with these - I think they are probably blackfly.

Quite a lot of the leaves are mottled too - I suspect a virus introduced by these insects.

Can I remove existing flowers to protect the bees and give them a good spraying with bug killer? I have some vague idea that nasturtium really don't like chemicals, but I may be wrong.

 

Apologies, have just realised I have posted this to the wrong part of the forum ....

 

I think the leaves go like that because it's a physiological condition cause by the greenfly sucking out the sap -so not a virus.
However, a severe infestation will probably ruin the plants anyway so take swift action. If the chemicals don't kill them the blackfly will, so you might as well spray, if you don't object to chemicals. If the infestation is still small try squashing the bugs with your fingers or spraying with detergent solution.

 

I have quite a lot of nasturtiums, and I'd say every plant there's just one leaf with blackfly on.. they must have babies and then just stick together on one leaf, which I pull off and throw out

 

No worries Canna, sorted

Have you got any ladybirds around your way ? A few of those put on the plant would sort it out.

Funny year for them this year, hundreds down on the Dorset Plot, but not a single one On the Somerset one

Had bad blackfly on the West Bay beans last year, till the ladybirds came.

This year, no blackfly at all so far.

 

How interesting that it is the blackfly directly causing the mottling, not via a virus....

The infestation is too big for squashing. I think I will try a detergent solution first. It would be great if that worked.

 

Sadly mine have spread rather a lot, mostly onto flower stems, but also onto some of the leaves.

You are lucky that yours are so well behaved

 

I would be absolutely delighted if ladybirds could solve the problem - or even just go some way towards solving it. Regrettably I haven't seen one this year....

 

It is now the end of the summer, and I've just come back to say I solved the problem by cutting all my nasturtiums right back (they were absolutely covered in blackfly). I then fed them. After a few weeks of looking awful they started putting out new leaves and flowers, and they are now looking fantastic....and not a blackfly in sight. This for me will be the way I will treat this problem in future when I get an infestation...

 

I didn't get much blackfly this year on mine. I seem to be getting aphid on my sweet peas all of a sudden...

 

The thing about nasturtium, and one of the reason they are sometimes grown as a 'decoy' plant to protect your crops, is that they are very popular with pests like slugs, snails, caterpillars and aphids. They can usually survive pretty well though because they grow so vigorously once established, and of course you can cut away unsightly bits, which then quickly get replaced with new growth.

The lower leaves often go yellow, partly I guess because they are too shaded by the leaves higher up, and partly because its usually the lower leaves that get attacked.

Regularly cut off the bad bits not only keeps the plant pretty and healthy, but it responds by putting on lots of new growth.