Buxus Growing Advice

Buxus Growing Advice (Box Blight)

Managing and Monitoring your Box Plants - A Palmstead Guide


Buxus is a very popular and regular seller, but there is a risk that plants may suffer from a fungal infection known as “Box Blight” which is now becoming quite widespread.  Our experience so far is that this infection affects a relatively small proportion of Buxus plantings and the risks are usually very low if plants are well planted and maintained.  As no other plant performs quite as well as box it is therefore important to maintain this plant in its optimum condition and managing the risk becomes highly worthwhile.

At Palmstead we sell plants propagated from clean stock which are grown on our nursery, as well as supplying plants produced by partner growers in Holland & Belgium (the centre of Buxus growing in Europe).  However, all growers of Buxus including Palmstead are treating their plants regularly with fungicides to help prevent fungal diseases, including the two fungal infections causing “Box Blight”.  No grower is risking their crop by not applying a regular treatment and none can guarantee their plants are free of the fungal spores which are now widespread.  Current RHS advisors consider that these treatments suppress the fungus but do not always kill it off.  However, they are not advising against planting or to remove Buxus but suggest it is managed by best practise.  Our best advice at this time is to continue with regular treatments of the plants in their planted locations.  Unfortunately, we cannot be liable for issues developing in planted locations where this maintenance is not carried out.

While there may be fungal spores harbouring on plants and in the site soils, or possibly distributed from nearby Buxus plantings and other sources, it usually takes a trigger for infections to take hold.  For example, humidity and/or stress; warm and humid conditions favour fungal infections.  However, plants with good air flow around them, good light levels rather than deep shade and plants in good health and vigour will be far more resistant to infection.  Plants stressed by drought or lack of irrigation, wet soils or other reasons may also succumb.  Buxus is great for topiary shapes, but these dense bushes do not have good air flow and therefore can be more susceptible to “Box Blight” infections. There are both cultural and chemical treatments available to maintain your plants health and vigour and we highly recommend the following practices:

•Good husbandry with regular removal of old leaf litter;

•Cutting out and burning any infected parts of the plant; it will be stimulated to re-grow;

•Do not water overhead as soil based watering is better; watering heavily once a week and not daily, allowing the foliage to dry out between watering’s;

•Plant Buxus plants so they have good air flow around them and good light levels, some gardeners give it a clear boot space before planting other plants;

•Mulching helps considerably by reducing spore movement by rain splash; mulch around the plants with straw, woodchip, bark or pine needles which will absorb some of the raindrop energy and reduce splash bounce;

•Feeding – Buxus are hungry plants and will flush with new growth in April, June and August; a light dressing of quick release fertilizer just before these flushes will promote healthy growth. Do not over feed as very soft growth may be more susceptible – follow recommendations. Other recommendations from gardeners include using a bio-stimulant such as SB Plant Invigorator, as healthy plants are more resistant to infections;

•A monthly to 6-8 weekly application of the plant tonic Top Buxus Health Mix during the growing season (March - October) will feed and strengthen the plant and improve vigour. It also contains some copper and sulphur which have anti-fungal properties. It is not a pesticide so spraying certificates are not required;

•Clipping plants at the right time - traditional trimming advises trim 1 mid-May - June, trim 2 September – October.The best practice advice now recommends one trim a year in September in dry, cool and perhaps windy conditions. Avoid clipping in bright hot sunshine which can cause leaf scorch. Comb through the plants to collect and remove all clippings. Clean all pruning equipment between plants;

•Fungicides for domestic use are available in garden centres and currently the fungicides Bayer Fungus Fighter (tebuconazole) and Bayer Fungus Fighter Plus (tebuconazole and trifloxystrobin) carry label recommendations for use against box blight. Both can be applied without any formal certification but do read and follow the label instructions;

•Professional fungicides are also available for professional users and most nurseries will rotate 2-3 fungicides to keep their crops clean and reduce the risk of resistance. Palmstead use (as of 2016) Signum; Octave or Switch. Always read the label carefully for use by suitably certified, competent persons only. This information is offered as a guide only;

•Regular maintenance and inspection can nip infections in the bud by pruning out infected areas as soon as possible and treating to encourage new growth. Infections left untreated may make plants unsightly or even kill them.

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