A hedge against disease

WALLY RICHARDS
Last updated 07:07 11/03/2014
Southland Times photo
Fairfax NZ
Buxus hedging provides a great edge to a garden but needs to be cared for.

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We're at the calendar start of autumn but in real terms we have had autumn-like weather for a few months now.

Maybe we are getting a late summer, which would be nice rather than missing out altogether.

The advantage for gardeners in regions where the weather has been poor is low numbers of insect pests on outdoor plants. In sheltered areas and in glasshouses the conditions have been more favourable to insect pest populations growing and needing frequent spraying.

On the other hand the weather conditions have been stressful to many garden plants such as roses where we see the results in blackspot and rust. Even mildews have happened which is not normal for the months of summer.

A few years back a disease started attacking the box hedging and topiary of the very common Buxus sempervirens and several other species.

For those gardeners with specimens of the buxus you will likely be very familiar with the symptoms.

Box blight is the name of the disease effecting the leaves and stems caused by two fungi, Cylindrocladium buxicola and Volutella buxi. The two are often found together.

This is a disease specific to buxus.

Both fungi cause leaves to go brown and fall, leading to bare patches; C buxicola, the more damaging of the two, also infects young stems causing black streaks and die back.

In wet conditions the spore masses of the fungi may be seen on the under sides of infected leaves, white for C buxicola and pink for V buxi.

I have written on the subject previously and recommended to ways to control.

The continual trimming of the foliage causes a dense plant which hampers air circulation and this means moisture hangs around making a perfect breeding ground for the diseases.

Rather than continual trimming of the foliage, the removal of some branches to open the plant up to better air circulation is an obvious remedy.

Then to further prevent the spore of the diseases settling on leaves a three monthly spray of Vaporgard is used for complete coverage. This puts a film over the leaves making it difficult for the spore to establish.

Gardeners that have used both these two methods have been successful, from the feedback I have heard.

Problems? Phone me on 0800 466 464 or email wallyjr@gardenews.co.nz.

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- The Southland Times

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