Sunflowers decimated

sampullman

Please can someone tell me what the heck is devastating my sunflowers? I have three plants in pots and all are equally damaged. The largest leaves seem most affected and it all happened within a few days. It’s not snails or slugs and there is no sign of aphids or ants. 

The stem and so far the flower part (that hasn’t flowered yet) appear undamaged but I bet the appetite of something so ferocious isn’t going to walk/fly away without some serious persuasion. 

I've given the whole plant a liberal spray of home -made insecticide made up of vegetable oil, washing up liquid and water, but it's not made any difference.

Any suggestions of who the enemy is and how to get rid of it would be gratefully accepted. Thanks in anticipation

young codger

I would be treating in the same way as if it were Aphids-better than doing nothing, until you I'D the culprits. You can cover the foliage in suds from a bowl of water with washing up liquid in it.

sampullman

thanks @young codger I've already used the suds trick every day but alas the plants are now beyond saving. shame because it's the first time in about 30 years that I haven't had sunflowers to show my kids and grandchildren. I went out during the night hoping to spot something having a midnight snack but whatever has done the damage either sees me coming or is invisible. 

AnniD

The way the damage is in the centre of the leaves as opposed to the edges, makes me think it could be earwigs perhaps? 

herbaceous

That looks remarkably like sawfly damage Sam, I know you say you have checked for the culprits but the caterpillars can be really hard to spot.  Best place to look for them is on the least damaged leaves.

Hope you find out what caused the damage 

AnniD

Think you may be right about the sawfly @herbaceous

sampullman

Thanks @AnniD I did see one small earwig but left it there as I read they eat aphids and in the past I have always found them hiding in the petals and never seen such terrible damage.

Thanks @herbaceous I've just searched for Sawfly on the internet and and found very similar pictures to what my leaves look like. I think you may have nailed it I will certainly follow up on this suggestion and maybe it's not too late to try and get some new plants growing to take their place.

herbaceous

Just be aware sampullman that the eggs will be in the soil if it is sawfly. You should be careful how you re-use the compost and quarantine the affected plants.

sampullman

Ah very useful tip! I will definitely take note of that. I've got some lovely Nasturtiums in the same area and apart from a few incidents of leaf-miner activity they are so far spared the onslaught of the sawfly. Thanks for that great advice 

Rhuben

Go out around midnight with a torch and I'm almost certain you'll find those sunflowers swarming with earwigs. My dahlias and sunflowers have been stripped bare by an onslaught of earwigs this year. Putting down jars part filled with olive oil is what solved the problem. Earwigs find olive oil irresistible and end up falling in, the oil also prevents them climbing back out. When the traps need emptying I scoop the earwigs out with with an old fork onto a piece of kitchen towel to dry off the excess oil and then the robins and blackbirds get to enjoy a tasty treat. 

sampullman

Thanks @Rhuben I did check on them in the dark but didn't find anything. Maybe I will put out an olive oil trap just before I dispose of the plants (very little left now). If that was the problem it sounds much easier to deal with than the elusive Sawfly. I will keep you posted