Integrated management of box blight in gardens

RHS project team
Dr Matthew Cromey
National Trust
Start date
20/03/2015 00:00:00
Cylindrocladium, Buxus, box blight, cultivar resistance, plant architecture, field trials
The problem
Box blight, caused by caused by Cylindrocladium buxicola, is a serious disease of box (Buxus) in the UK and elsewhere.

There is a second blight of box, known as Volutella blight, that is much less serious and easier to manage.

Current recommendations for the management of box blight in UK gardens focus on sanitation to keep it out and on destruction of affected plants if it is detected. With the disease now widespread, a set of IDM strategies is required to ensure that box will continue to have a place in UK gardens.

The experiments in this project examine some of the elements that contribute to IDM.

Early infection
Box blight - early stages of infection
Severe infection
Box blight - severe infection
This project is made up of several individual experiments, the results of which will be combined to contribute to the development of IDM strategies for box blight. Two fungicides have recently been registered for the control of box blight in home gardens. We will develop strategies that incorporate the use of fungicides with other management strategies; we will also develop strategies for pesticide-free gardens.

Experiment 1: Rehabilitation of a severely infected box hedge
This experiment utilises a severely infected box hedge that has been moved from the RHS Wisley Country Garden to our field research facility at Deers Farm. A combination of pruning and fungicide treatments are being applied to determine how to manage the disease without removing infected plants.

Experiment 2: Contribution of cultivar to box blight management
Cultivar resistance is a common way to manage plant diseases. The most common box varieties are highly susceptible to box blight but some cultivars are reported to be less susceptible. We are examining how partial resistance can be incorporated into IDM with or without use of fungicides.

Experiment 3: Manipulating architecture to manage box blight
Plant architecture contributes in various ways to encouraging or discouraging epidemic development. The natural architecture of box is routinely modified by pruning to hedge, ball or topiary shapes. We are examining how adjustments to these processes will influence disease, in particular: shape (round or square); canopy density; and frequency of trimming.

Experiment 4: New treatment options
This preparatory experiment aims to develop methods to make initial assessments of new treatments that can be incorporated into more detailed IDM experiments. There will be separate growth chamber and field experiments and they will use one fungicide and one potential biopesticide (allicin) as model treatment.
Benefits to gardeners
The project will provide the scientific knowledge required to develop integrated disease management (IDM) strategies and demonstrate that box blight management is feasible in gardens without wholesale removal of plants.
Advisory information
Box blight

Box problems

Box blight management
Henricot B, Culham A (2002). Cylindrocladium buxicola, a new species affecting Buxus spp., and its phylogenetic status. Mycologia, 94: 980–997.

Henricot B, David J, Ivors K, Heungens K, Spooner B, Pérez Sierra A, Daughtrey M (2012).  Proposal to conserve the name Cylindrocladium buxicola against C. pseudonaviculatum (Ascomycota). Taxon 61: 1119–1120.

Henricot, B., Gorton, C., Denton, G., and Denton, J. 2008. Studies on the control of Cylindrocladium buxicola using fungicides and host resistance. Plant Disease 92:1273-1279.

Henricot B, Pérez Sierra A, Prior,C (2000). A new blight disease on Buxus in the UK caused by the fungus Cylindrocladium. Plant Pathology 49: 805.

Henricot B, Wedgwood E (2013). Evaluation of foliar fungicide sprays for the control of boxwood blight, cause by the fungus Cylindrocladium buxicola. Plant Health Progress.

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