alexpeak

Robinia Frisia - brown spotted leaves - treatment?

Thanks for your suggestions, I'll look into Gleditsia.

I did email the RHS to see if they wanted any samples and they kindly replied to say that they have enough for analysis. I guess this means their research has pretty much come to a halt without anything more conclusive than just letting whatever fungus it might be take its toll.

Robinia Frisia - brown spotted leaves - treatment?

1. Would you treat the new hole with any kind of pesticide, to protect the new tree?

2. Are gleditsias large trees? Do different specimens come as different sizes? Could it be easily pruned to conatin it?

We would like to have a small to medium tree, so long as it can be contained to 10 metres height maximum. What would be the options ?

Thanks

Robinia Frisia - brown spotted leaves - treatment?

Obelixx,

Could you put the new tree (eg gleditisa) in the same place as the Robinia? Or does this risk the new tree?

Would you remove the entire tree including stump out of the ground, or saw it level to the ground?

Robinia Frisia - brown spotted leaves - treatment?

We have a 10 year old Robinia Frisia which came out with brown spotted leaves (normal size) this year. The lower part of the crown is worse, and has hardly grown this year, the upper part has grown branches and is also affected, but not as badly. We suspect this is a fungal infection  "Phloeospora robiniae". A good description is given on The Telegraph newspaper website on 04/09/2008, and of course on the RHS website. For a very good picture, type the disease name into Google and scan down to see "images for...".

What to do?

Would a pesticide treatment help? If so, which product(s) and when?

Other than that all we could find is suggestion to prune the crown to shape, and thin it to allow drying airflow, and to clear up debris.

Robinia Frisia - brown spotted leaves - treatment?