August 2011 - Do you have potential major hedging issues?

Today I want to talk about two popular hedging plants that are currently causing major problems for their owners around the Waikato and Auckland regions. 

BUXUS HEDGING

If you are planning on planting in your garden some of the ever popular BUXUS SEMEPERVIRENS hedge this coming spring, then, at the moment, I would strongly advise you not to use this variety and look for an alternative hedge.  Over the last 5 months I have seen dozens of properties in the Waikato that now have a major fungous disease problem (commonly called Box Blight - see in image above) in the foliage of the Buxus Sempervirens hedge. I was at a friends on Saturday and saw what used to be a beautiful mature Buxus Sempervirens hedge being rapidly defoliated by this fungous.  It seems to attack old and new hedges by causing the leaves to go brown and defoliate en mass making the hedge look unsightly very quickly.  The hedge, if left unsprayed, will slowly start to refurnish itself with another new lot of leaves but before long these too get attacked and slowly the plant loses its vigour and dies.

I am told that Octave is currently the best spray to use to kill this fungous disease but the public can't buy it from a local garden centre or plant shop as it can only be sold by chemical distributors to people who have a chemical Growsafe license. I am also told that a good preventative spray to use is the ordinary copper oxychloride if you do not currently have the disease and want to keep your plants clean for as long as possible.

I can see that the popularity of the common Buxus Sempervirens as a hedging plant will rapidly decline with these problems occurring in the Waikato at the moment. This fungous disease has been in Auckland for quite a few years but now seems to have spread throughout the Waikato region. I had this fungous attack some plants at our own Rukuhia Homestead Garden in February of this year and what surprised me was how quickly it can spread throughout the hedge.  At the moment the varieties of Buxus called B.Microphylla and B.Green Gem seem to have reasonable resistance to the disease and hopefully they will continue to do so. 

CUPRESSUSOCYPARIS LEYLANDII-(also called Leightons Greeen)

This has been a very popular hedge over the last 15 years planted in reasonably good numbers around the Waikato and Auckland regions in rural and lifestyle blocks.  This cyperus is a good, tough conifer that responds well to trimming and is extremely tough to the elements of wind and drought. The CYPERUS family can be attacked by a fungous disease called Cyperus Canker that gets into the sap stream of the plant and causes the browning of foliage which turns into dieback (see image above). The fungous can enter the sap through cracks in the bark or the hedges that are trimmed each year by shelterbelt trimmers. The  open cuts made to the stems by the large blades offer plenty of open stem material for the fungous to readily get into the plant.  Over the last year particularly I have noticed on my travels around Auckland and the Waikato regions that this disease is very damaging to the trees and is causing severe dieback to many shelterbelts. Personally, I think the disease has come from the old Lawsons cyperus hedges that were planted around the Waikato 50-70 years ago in big numbers.  Every cyperus hedge from this era has the cyperus canker disease in it and it has continued to spread onto other cyperus hedges in close proximity.  I feel sorry for many lifestyle block owners who I see have recently planted new hedges of CUPRESSUSOCYPARIS LEYLANDII as this disease is going to attack their young plants causing loss of vigour and eventually an unsightly looking hedge with lots of dieback. There is no cure for any trees with this fungous because of how it gets into the sap stream and causes weeping lesions in the stem. The best thing to do is replace the hedge with  another type of plant that is not susceptible to this disease.

It is important to know about these fungal issues with these plants as I don't want you to put in new plants that are going to cause you problems further down the track.  Apart from it wasting your money, it will also waste your time by having to replace the plants at a later stage. I don't have the space in this article to talk about good alternatives for each of these hedges but check me out on Facebook under Rukuhia Homestead Landscaping where I will provide some options.

Happy Gardening

Graeme