As an arboricultural officer for Southend-on-Sea, Rick Milsom is perfectly placed to cast light on the work of tree officers working for local authorities
As part of routine street tree management, some trees inevitably require removal at some stage for whatever reason and it is usually desirable to replace them.
We have various species of tree which have been historically harshly pruned and that are now somewhat problematic to manage. The worst of these are silver maples (Acer saccharinum). They produce profuse basal and epicormic growth and decay rather rapidly at these old ‘topping’ points, with Polyporus sqaumosus being an often seen coloniser. As we know, the best treatment for a topped street tree is getting rid of it. Obviously there is a distinction between pollarding and topping, so I am talking about trees that were mature when pruned, leading to large diameter cut surfaces. Crown reduction is fine as long as the species is suitable and the form of the tree lends itself to this treatment.
There are a few other challenges we have at present. One in particular seems to be the decline of many of our Sorbus species. The mountain ashes are faring particularly badly and the whitebeams not a great deal better. It may be they don’t like our rather dry climate in Essex so are always growing under stress. If that doesn’t finish them off, Nectria Canker and Fireblight are also problems.
So after bemoaning the above what are we going to replace all these with and what actually makes a good street tree?
We need something that is going to establish well, not need too much nurturing and carry on growing with some degree of vigour. A common maintenance problem is basal and epicormic growth. It tends to all happen at once and sometimes needs removing three times a year, so no more common lime in the streets.
I have no problem planting street trees which bear fruit as long as they are not something ridiculous like Pyrus communis ‘Beech Hill’, which for some reason has been planted in some locations alongside Pyrus calleryana ‘Chanticleer’ (a non-offender) but consideration is required when siting trees which may drop fruit on paths.
Talking of fruit, we have noticed that many of the cockspur thorns do not establish a very secure root hold although they continue to grow. This is a bit of a problem as they become top heavy and start to fall over. At the other end of the spectrum is Robinia. These grow at an astonishing rate and require regular staked tree maintenance. This leads me to my pet hates, which are seeing neglected staked trees or planting that is too deep. I can’t abide seeing choking ties, loose trees flopping about or broken stakes. Any tree planting programme needs to take account of future maintenance and particularly watering, so it’s wise to not plant a greater number of trees than you can realistically maintain. Quite obvious really but watering can be expensive on a large scale.
We generally plant containerised trees 10-12cm or 12-14cm girth in 45L pots. These are fairly easy to handle and store but some can be a bit weighty depending on what they are potted in. There is no great problem in storing containerised trees for a while as long as you have the room, and can water them if necessary. I actually can’t remember the last time we planted a bare root tree but we do occasionally plant root balled stock.
We have planted many species over the years and there are hundreds to choose from. I am particularly interested to see what a lot of cultivars are like when they are mature and how they differ from the species.
Starting out as an apprentice, Rick has worked in horticulture and arboriculture for 30 years, and is currently an arboricultural officer at Southend-on-Sea Borough Council.