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in Problem solving
I grow many shrub and climbing roses in my walled garden and have been troubled by leaf0rolling saw-fly for at least 3 years. This is getting worse. I have picked off leaves, looked after the soil beneath and exposed it to birds, used sticky traps, covered with netting and fed the roses extra to compensate for leaf loss. Can anyone with experience of this pest give me any more ideas?
Only spraying with systemic insecticide before they appear. You seem to have done everything else.
Thanks, Alina. I can't bring myself to spray with systemic insecticide as this will also ill many visiting bees and much more. Guess I just have to live with it. For the record, this year's roses look really good in mid June onwards!
Issybee, the only way a systemic insecticide will kill bees is if you are careless and spray while the bees are active. Spray yours roses safely and get rid of the pests.
I am sorry, but you are wrong on that one. A systemic insecticide works through a plant and kills when insects, etc, bite or otherwise damage a plant part. Bees can sometimes pick it up when they go into a flower, as bees do. They can then carry it back to the hive and eventually kill the whole hive. You don't have to actually spray the bee to damage it. Humans need bees, so I won't use this type of killer.
The RHS suggests trying to prevent the insects laying eggs with the use of Deltamethrin (Bayer Sprayday Greenfly Killer) or lambda cyhalothrin (Westland Plant Rescue Fruit & Vegetable Bug Killer), which do not have the same problems. They do point out that you will have to spray several times as the adult sawflies are active over a six to eight week period in late spring-early summer.
Alternatively, you can avoid the problem with thiacloprid and the like by not spraying when the flowers are open, nor allowing them to flower for three weeks after spraying - the chemical works its way out of the plant after a few weeks, which is why you have to re-apply.
It seems to me that not allowing the plant to flower and re-spraying every three weeks would mean no flowers - certainly on the time-table of my roses! The saw-fly were laying here from mid April to the third week of June this year.
I am not a great fan of RHS suggestions for using chemicals to deal with garden pests.
But I am still open to suggestions that do not use chemicals.
Of course, using home made, non registered, pesticides is illegal. However, if a few rhubarb leaves were to fall into some boiling water and said water was strained and allowed to cool you would have to get rid of it somehow.lol lol lol
I've just been removing leaves where I've seen this problem. It will get to a stage where that's not possible, by the sound of it, from how hard you've tried to eradicate them.
I only learned what these were last year when I bought lots of new roses & saw one of the flies on a rose stem. When I tried to flick it off it was very firmly attached. So I looked it up & found out that they sound very hard to get rid of!
Good luck with yours.
The info on bee-killers (and others) can be read at:
Diatoum - more info on rhubarb preps if you have it, please.