Hi Alan, just thought I’d add my two penny worth.
I’ve been managing a wood in Wiltshire that my parents bought in 2019. Before that, it seems like not a lot of positive woodland management had been done for a long time, save some felling and replanting (which has really enhanced the species and age class diversity). There are some excellent stoned tracks which has been great for a major thinning carried out in the hot summer of 2022.
Anyway, about the pendulous sedge. The wood is split roughly in two, with one half mainly a PAWS with some nice Douglas fir and larch but some areas overrun with birch - lack of maintenance when it was restocked in the early nineties - and the other half mostly mixed broadleaves dominated by oak and sweet chestnut with some ash and some other natives, and patches of larch. Parts of this area are very tall, over 30m, and it is here that the sedge has started to take off.
A previous owner created a number of paths through the area and these, along with the existing rides, are quite heavily used by deer (as well as people, to a lesser extent!). It seems quite clear that the deer are a vector for the spread of the sedge, as until I started controlling it a couple of years ago it was beginning to form almost a hedge along both sides of one path in particular. They must carry the seeds on their coats. This and the fact that deer don’t like eating sedge gives it another opportunity because it can grow at the expense of more palatable plants when there are too many deer. As well as the path lining, there are a couple of dense patches of pure sedge which have formed in more open areas of the wood and must act as a reservoir for spread. I expect the harvesting operation in 2022 helped to spread seed about too.
Your observation that the sedge has been spreading in your wood seems to back up the deer theory, as deer numbers have exploded in the south of England, and elsewhere, over the last 20+ years.
As to control, I have experimented with a couple of methods, both of which seem to be working but may or may not be practical in your circumstances. Physically cutting the stems that carry the seed heads, as well as the main plants down to ground level, is quite effective at knocking them back and helping to reduce the seed levels and can be done with a battery hedge trimmer very effectively. I did this along the paths and rides for a couple of years and it has made a massive difference to the rows of dense overhanging sedge which used to line them. Now they are regrowing and their babies are popping up in the vicinity (thankfully the sedge still seems to be localised) and I have started spraying them with a knapsack and glyphosate. I did this last summer and have done it again this week (April) as the areas I sprayed last year have been killed. As well as spot spraying the “hedges” and individual plants, I have sprayed one of the large (approx 100 square metres) patches, so we will see how effective that has been later in the year. Although the clumps are sporting the beginnings of seed heads I think they are still only at the flowering stage so hopefully spraying them now will prevent the seed from forming, but I’ll have to wait and see.
I don’t like using chemicals in woodland management but I feel this is justified because it is localised and is helping to keep an unnatural situation caused by an overpopulation of deer under control. Glyphosate isn’t residual and if some other beneficial plants get oversprayed the ground vegetation will quickly recover through natural processes.
I also have rhody and have started using glyphosate in the knapsack sprayer for that too. Thankfully it is in its early stages of spread so there are only a few tall clumps which will require some mechanical control before I can spray them. I have seen woods with wall to wall rhododendron so I know how important it is to eradicate it now.
Incidentally I have been culling the deer over the past two years so hopefully the natural balance will be restored in due course and the sedge can be left to its owner devices - I will be monitoring it!
I see your original post was from a couple of years ago so it would be interesting to hear how you have got on. No single measure with these sorts of problems is normally enough and I hope my multi pronged approach works and reading about it may help others- I Googled “invasive pendulous sedge” and your post popped up so I figure some others may be dealing with a similar problem.