Lenore, Florida asked:
Can we prevent leaf miners in Tomato Plants?
John - Well, there are different kinds of insects that are called leaf miners, but the family that you were speaking about earlier with the horse chestnut leaf miner Cameraria ohridella, that family is the Gracillariidae and it may well be that that's the family that we have in Florida. But the treatment is going to be the same whether itís a small fly larva or whether itís a moth larva that's doing the mining. And that is to use one of the newer insecticides, particularly Imidacloprid. So you need to go to the hardware store or the garden centre and find in the small print, the active ingredient Imidacloprid and then that's the one to spray onto your plants. The reason I'm saying this particular chemical is it has some ability to penetrate the leaf and get through into where the leaf miner is.
Sarah - But there's no organic solution. Itís definitely a case of using a pesticide?
John - Well I think you can pull the leaves off that have got the miners and burn them or eat them, but no, Iíd prefer the burning I think really for tomato leaves, not so good to eating. I think cultivational methods probably don't work too well. At the moment, we very much like to attract in parasitic wasps to attack the leaf miners because they can actually get into the mine and attack the leaf miners very efficiently. But we don't really have highly specialised parasites for some of these leaf miners, but in Florida they may have and so, itíd be worth consulting people about encouraging populations. Perhaps you could grow some tomatoes that you might wish to sacrifice to keep a good population of the parasites to attack the leaf miners in your main stand.