It seems this thread has petered out - maybe all the other robinia frisias have died by now? I leave this message in the hope that it may be useful to future generations/survivors of the zombie apocalypse/alien visitors.
About a decade ago, when my robinia started to suffer from leaf spot, premature leaf drop and dieback, I began treating it as if it had honey fungus, having seen it before in the garden. Every year during the growing season I'd give it Armillatox solution and during the winter I'd remove as many dead pieces as were within reach. And every summer the leaves would fall like rain during windy weather and the tree would die back a little bit more than it had grown. Still, the tree did seem to respond to the Armillatox immediately after each dose, and I believe this may account for its longevity.
However, matters came to a head this past winter when, with my stash of chemical contraband running low, and the company having gone bust, I came to realise that drastic action would have to be taken - it was kill or cure time. So I reduced the tree's height by half, to ten feet, in the process removing much of the dead and diseased wood. Then I poured a weak solution of fungicide over what was left. All that remained was to wait for Spring and see whether it had survived this brutal treatment.
To be continued...
I think you're on a hiding to nothing here. Ditch the chemicals, dig up the tree, refresh the soil and plant a gleditsia - similar colour and foliage. No disease. Make lovely big trees too if given time and space. Here's one in a garden I visited recently.
Vendée - 20kms from Atlantic coast.
"The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
Hello Obelixx. Thanks for the reply, and for the gleditsia photo. I seem to remember considering a gleditsia at the time I bought the robinia, but the latter seemed to promise a denser canopy, which is a major factor when you're trying to screen out nearby houses and is one of the reasons I'm so reluctant to let it go. Also, the label proudly boasted that it had the RHS award of garden merit - what could possibly go wrong?
Now, if I can just manage to take a half-decent photo and work out how to post it here, I'll be able to update the gripping story I started last night.
Here's a photo of my robinia now (apologies for the poor image quality) following drastic surgery during the winter. After a slow start it's exceeded my expectations and is full of healthy new growth. Despite the wet Spring, leaf spot disease has so far been minimal and I've been able to remove the few leaves which were affected. New leaves are forming properly with no gaps along the central rib which is a sign that honey fungus is not present, since this restricts the supply of water and nutrients to the extremities. The only downside is that I find myself checking the tree constantly for problems and it will be a long time before I can say with confidence that it's definitely cured. Until then, I'm going to enjoy the sight of all that lush new growth, and watch it like a hawk for signs of leaf spot.
Any update on your Robinia - am just considering whether to follow your example and cut my 20 year old tree down to around 15 ft...........It's really not doing well has reached a great height but many dead branches and small leaves with no flowers this year. Any advice?
I've accidentally rediscovered this thread and just seen your post from three years ago - you must have made your decision by now and I'd love to know what it was. As for my tree, halving the height was a desperate attempt to breathe new life into it and bring it into the reach of a sprayer. Even though it quickly regained much of its old stature, the problems remain and every Spring I wonder if this will be its last year. That was particularly true this year as the leaves started out yellow and soon began to drop. But then two things happened at once - the weather turned dry for weeks and I found a tin of tar-oil based tree wash (long since discontinued) in the garage and mixed a five litre solution to apply to the trunk. The dry weather held off the leaf spot disease and the tree wash seemed to encourage new, green growth.
Today has been stormy but I managed to snap this image and above it are photos of the leaf spots and the split bark, complete with woodworm-type holes and some fungus for good measure. Cutting back the tree was only the beginning and if you decided to do the same, I hope you've had at least as much success as I have. The work to keep it alive is continues but I don't think it could have survived without the drastic cutback and a succession of tar-oil products including some very old (and also discontinued) Jeyes Fluid. Perhaps you found something equally effective?
Good luck with your robinia or its replacement and maybe I'll see you back here in another three years?
Posts
Now, if I can just manage to take a half-decent photo and work out how to post it here, I'll be able to update the gripping story I started last night.
Here's a photo of my robinia now (apologies for the poor image quality) following drastic surgery during the winter. After a slow start it's exceeded my expectations and is full of healthy new growth. Despite the wet Spring, leaf spot disease has so far been minimal and I've been able to remove the few leaves which were affected. New leaves are forming properly with no gaps along the central rib which is a sign that honey fungus is not present, since this restricts the supply of water and nutrients to the extremities. The only downside is that I find myself checking the tree constantly for problems and it will be a long time before I can say with confidence that it's definitely cured. Until then, I'm going to enjoy the sight of all that lush new growth, and watch it like a hawk for signs of leaf spot.
Any update on your Robinia - am just considering whether to follow your example and cut my 20 year old tree down to around 15 ft...........It's really not doing well has reached a great height but many dead branches and small leaves with no flowers this year. Any advice?
Charlotte
I've accidentally rediscovered this thread and just seen your post from three years ago - you must have made your decision by now and I'd love to know what it was. As for my tree, halving the height was a desperate attempt to breathe new life into it and bring it into the reach of a sprayer. Even though it quickly regained much of its old stature, the problems remain and every Spring I wonder if this will be its last year. That was particularly true this year as the leaves started out yellow and soon began to drop. But then two things happened at once - the weather turned dry for weeks and I found a tin of tar-oil based tree wash (long since discontinued) in the garage and mixed a five litre solution to apply to the trunk. The dry weather held off the leaf spot disease and the tree wash seemed to encourage new, green growth.
Today has been stormy but I managed to snap this image and above it are photos of the leaf spots and the split bark, complete with woodworm-type holes and some fungus for good measure. Cutting back the tree was only the beginning and if you decided to do the same, I hope you've had at least as much success as I have. The work to keep it alive is continues but I don't think it could have survived without the drastic cutback and a succession of tar-oil products including some very old (and also discontinued) Jeyes Fluid. Perhaps you found something equally effective?
Good luck with your robinia or its replacement and maybe I'll see you back here in another three years?