United Kingdom 
I have victoria plum tree in large pot it is growing well and fruiting well but some fly or other is depositing what turns out to be a grub, the thing is the plums look lovely untill you open them and this horrible critter is in therethere are no marks on the out side so they must do it as they are fertilised when and what do i do next year to aviod this please,I put bands round last year to fend off moth .
18 Aug, 2010
Sounds like Plum Moth - you can get pheremone traps for these, but if you have lots of plum trees around you, it won't stop it happening, but what it will do is tell you when the best time is to spray with something containing bifenthrin, permethrin, pirimphos-methyl or fenitrothian. Usual time to spray is early summer, with a second application 3 weeks later, but check out the pheremone traps - these sometimes disrupt the females breeding to such an extent that it more or less resolves the issue. Chemicals mentioned may have been withdrawn from sale, you will have to check that and seek out substitutes if they have.
23 Aug, 2010