Robinia pseudoacacia ‘Frisia’ problems

Robinia pseudoacacia 'Frisia' is a popular yellow-leaved tree, widely grown in many gardens and public spaces. However, in recent years, this particular cultivar, 'Frisia', has suffered from a range of problems, causing the ultimate loss of the tree.

Robinia psuedoacacia 'Frisia' with unknown dieback problems.

Quick facts

Plants affected Robinia pseudoacacia ‘Frisia’
Main symptoms Early leaf fall, dead branches with younger trees completely dead
Caused by Unknown
Timing Spring onwards

What are the problems?

During the last few years, there have been many reports to RHS Gardening Advice of Robinia pseudoacacia 'Frisia' failing to come fully into leaf in spring. Some reports suggest that the leaves tend to lose their leaflets but the leaf rib remains on the tree. The tree commonly fails to recover and ultimately dies.

The green-leaved species Robinia pseudoacacia, has not been reported as affected.


The tree fails to come fully into leaf in spring and drops foliage prematurely. Brown spots may sometimes be present on the leaves. Shoots often arise from the trunk and boughs but, in the end, the tree does not recover.

Possible causes

Although it is unclear what causes these problems, there are several possibilities and problems that have been discounted. Analysis of samples taken from a small survey carried out on trees local to RHS Wisley, and samples sent to RHS Gardening Advice by RHS members allowed RHS pathologists to make the following conclusions:

  • There has been an increase in a leaf-spot fungus (Phloeospora robiniae), which is more prevalent in wet weather conditions, causing defoliation and weakening the trees
  • There have also been cases of two root diseases, honey fungus (Armillaria) and Phytophthora root rot, both of which can cause tree death
  • Bacterial rots have been recorded, resulting in the bark becoming soft and smelly
  • The unusually wet weather of recent years could well be a contributing factor, stressing the trees and making them more susceptible to disease (Robinia tends to perform best on well-drained soils)
  • Additionally we have consistently isolated the fungus Diaporthe oncostoma from lesions on branches of many trees examined

Until recently, D. oncostoma was considered to be saprophytic or weakly parasitic favoured by adverse conditions for plant growth. RHS laboratory and field experiments have been unable to confirm the pathogenicity of the fungus. However, the fungus has now been reported as a causal agent of canker and severe die-back disease of Robinia pseudoacacia (black locust) in Russia, Hungary, Italy, France and Greece.

It is possible that interactions between several factors could be involved in robinia decline in the UK.


There is no control as yet for this problem.

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  • Robinia Fan avatar

    By Robinia Fan on 07/11/2014

    I have a Robinia, which has been my favourite tree since moving in 15 years ago. It used to be huge, with long, leafy branches. Several years ago it developed the symptoms listed above and we finally decided to get it chopped down. Because I loved it so much I decided to get the trunk carved, so the surgeon cut the trunk off at about 10/12 feet. However, before I got the carving done, it started to grow branches and I relented, much to my family's disgust. 3 years later, it looks quite bushy and getting on for attractive during the summer. In winter it looks ridiculous - a trunk with spiky, twiggy branches. Am I being soft on this tree, or is it likely to grow and flourish? Why is it growing healthy branches? Should I cut it down? Should I get another sapling? Any advice welcome.

    0 replies

  • Janesunflower avatar

    By Janesunflower on 09/07/2014

    My Robinia has been poorly for the last few years, I originally thought this may have been caused by being overshadowed by a large Ash tree. This year I had the Ash reduced by 30%, & both Ash & Robinia look healthier, but today I noticed a large amount of bark had either been stripped or come away from the trunk of the Robinia. The Robinia is sited next to some Rhododendrons, which are old but seem healthy & have also benefited from the extra light from the Ash tree work, but I have read about Rhododendrons causing problems with Oaks, Also I feed the birds so consequentially have many squirrels, & I know they climb this tree. Therefore, after all that pre-ramble, do you think I have The above mentioned Robinia problem, or if fallen or stripped bark is not a sign, is it just squirrel damage? I have put a barrier of wire net fencing around the bottom of the tree, what else should I do to improve the situation, the amount of lost bark is fairly significant. Any advice would be most appreciated, thank you

    0 replies