Question
This year my pyracantha has become covered with the leaf miner, making the leaves separated and silvery.  Most of the plant is infected and the plant covers part of the front of my house (10ft X 10ft).

Would you be able to suggest any remedies, particularly those that don't involve having to dig it out!

Thank you

Answer
Leaf miners are difficult to control since they spend most of their life inside the leaf protected by the cells of the leaf. Timing of insecticide sprays can be done before the larvae enters the leaf surface (normally in early April). Some help in done by picking off infested leaves before the spring but sometimes this would mean picking almost all the leaves. The good news is that leaf miners populations vary greatly from year to year and the problem may not be as bad this next year. Also the leaf miners do not kill the tree but do make the leaves look bad.




When necessary, leafminers on ornamentals are best controlled with applications of insecticides that are carried systemically throughout the plant. This activity allows the insecticide to be carried to the insect larvae, which otherwise are effectively protected within leaves. Make these applications during the egg hatch period or shortly afterwards, before the larvae and mines get very big. Insecticides with systemic activity include acephate (Orthene) and imidacloprid. Carefully read label instructions ?certain insecticides can injure plants. None of the systemic insecticides available to homeowners may be used on food crops.


Control also can be achieved with an insecticide applied when eggs are being laid. Adults and newly emerged larvae can be controlled with these treatments, but they are ineffective after tunneling begins.

Check with your local nursery for a systemic insecticide there are some that can be added to the soil that will work good. These may be sold under some type of Rose name since this is the major plant that they are used on.