- Lead scientist
- Dr Béatrice Henricot
- Start date
- 2003
- End date
- 2008
- Keywords
box blight, Cylindrocladium, fungicides, host resistance, Buxus, chemicals, host susceptibility
- Benefits to gardeners
The project will provide information about the biology of Cylindrocladium buxicola, host susceptibility and also control measures that can be taken to manage the disease.
- The problem
In 2002, the cause of a new box blight disease was confirmed to be a new fungal species called Cylindrocladium buxicola. The disease is now widespread throughout the UK and causes great concern among box growers. It has also been recorded in other European countries including Belgium, France, Ireland, Germany, Italy, Slovenia, Spain, Switzerland and Holland. Outside Europe, the disease has only been confirmed in New Zealand.
The use of fungicides to control the pathogen is now widespread on box nursery stocks. An important mode of spread of the disease in gardens has been through the introduction of apparently healthy Buxus material carrying the disease into gardens or nurseries.
- Approach
Work on the infection process of C. buxicola was done using a light microscope to follow the infection process during a 12-day cycle. The work showed that this fungus penetrates directly the cuticle of box plants without forming any penetration structures.
Germination of the spores occurs as soon as three hours after infection and penetration follows five hours post-infection. The mycelium resurges through the stomata three days after infection and conidia are produced shortly afterwards. High humidity favours infection and in dry conditions, the spores will abort quickly.
Studies looking at the survival of C. buxicola in the soil were carried out by burying artificially infected leaves in the soil or placed on the soil surface. The fungus has been able to survive on decomposing leaf material for at least five years.
Pathogenicity assays showed that the host range of the fungus was not limited to the genus Buxus as Sarcococca was also susceptible. None of the 10 box species and cultivars tested were immune to the disease although B. balearica as well as Sarcococca showed significantly lower levels of infection as measured by the expression of leaf symptoms and the number of conidia produced on host tissue.
Laboratory experiments were carried out to study the in vitro effect of 10 fungicides on mycelial growth and conidia germination of the fungus. The results showed that carbendazim, prochloraz and kresoxim-methyl completely inhibited mycelial growth. Kresoxim-methyl was the most effective at inhibiting conidial germination.
- Further information
Read more on box blight
Read about the identification of the cause of box blight
Read about the evaluation of fungicides for the control of Cylindrocladium buxicola in the field
- References
Henricot B (2003). RHS update. In: LR Batdorf, Caring for box, Sage Press, pp 26-27.
Henricot B (2003). Box Blight. Topiarus 6: 28-30.
Henricot B (2004). Le dépérissement du buis. Bulletin des Buis et Topiaires (2): 3-5.
Henricot B and Gorton C (2005). Plant Pathogens on the move. Microbiology Today 32: 100
Henricot B (2006). Box blight: rampages onwards. The Plantsman 5(3): 153-157 (PDF file- Box blight rampages onwards)
Henricot B, Gorton C, Denton G, Denton J (2008). Studies on the control of Cylindrocladium buxicola using fungicides and host resistance. Plant disease 98: 1273-1279. (PDF file- Studies on the Control of Cylindrocladium buxicola Using Fungicides and Host Resistance)