Gooseberries: Leaves eaten by sawfly larvae
Question: Last summer my gooseberry bushes had at lost two thirds of their leaves to green caterpillars eating them. Could you please tell me how I can prevent this happening again this year, and I can use to give a good crop. Thank you for your help. (Mrs P Homeyard, Swaffam)
The problem with your gooseberry bushes is common gooseberry sawfly this is one of several sawfly species that attacks gooseberry and red/white currant bushes during late spring and summer. The damage is caused by the caterpillar-like larvae of sawfly pest that devour the leaves. The common gooseberry sawfly is the most troublesome pest of gooseberries. It can have three generations a year, with the larvae active in late April to June, July, and August to September. The female sawflies lay eggs on the underside of leaves low down in the centre of the bush, so the young larvae go unnoticed until they have eaten their way upwards and outwards, devouring the leaves as they go. Regularly check the plants from mid-April onwards for sawfly larvae and pick them off by hand.
A pathogenic nematode, sold as Nemasys Grow Your Own, can be watered onto infested plants. The nematodes enter the bodies of the sawfly larvae and infect them with a bacterial disease.
Spray when young larvae are seen, with an insecticide approved for use on gooseberryand red currants.
Suitable insecticides are thiacloprid (Provado Ultimate Bug Killer Ready To Use or Concentrate), lambda cyhalothrin (Westland Plant Rescue Fruit & Vegetable Bug Killer), or an organic pesticide such as pyrethrum (Py Garden Insect Killer, Scotts Bug Clear Gun for Fruit & Veg, or Doff All in One Bug Spray).