Cause Volutella pachysandrae and Coccinonectria pachysandricola (formerly Volutella pachysandricola), fungi. Much more severe on stressed plants such as those growing in full sun, wounded or weakened by scale insects or winter injury. Infection of wounds occurred for several days after the wounding event early in the growing season. Wounds occurring in the summer are much more resistant to infection.
Symptoms Leaves develop small brown to tan spots that enlarge and may cover the entire leaf. Concentric line patterns form within the brown spots as leaves yellow and fall off. Infected stems turn dark brown or black and soon die. Pink or salmon-color spores may be seen on the surface of dead stems under moist conditions. Large patches of plants die.
Cultural control
- Remove and destroy severely diseased plants.
- Use mulch that does not hold a lot of water.
- Avoid planting in heavily-shaded areas.
- Remove fallen leaves and other plant debris from beds.
- Do not overwater, and irrigate when leaves can dry quickly.
- Periodically thin plants in a bed.
Chemical control Likely more useful when used shortly after wounding.
- Chipco 26019 FLO at 1 to 2.5 quarts/100 gal water. Group 2 fungicide. 12-hr reentry.
- Copper-based products. Group M1 fungicides. O
- Badge X2 at 1.5 to 2 lb/A. 24-hr reentry.
- C-O-C-S WDG at 3 lb/100 gal water plus 3 lb hydrated lime. 48-hr reentry.
- CuPRO 5000 at 1.5 to 5 lb/A but only up to 2 lb/A when new growth is present. 48-hr reentry.
- Monterey Liqui-Cop at 3 Tbsp/gal water. H
- Nu-Cop 50 DF at 1 lb/100 gal water. 48-hr reentry.
- Daconil Weather Stik at 2.37 pints/100 gal water. Group M5 fungicide. 12-hr reentry.
- Ortho MAX Garden Disease Control at 3.75 teaspoons/gal water. H
- Phyton 27 at 1.3 to 2.5 oz/10 gal water. Group M1 fungicide. 48-hr reentry.
- Spectro 90 WDG at 1 to 2 lb/100 gal water. Group 1 + M5 fungicide. 12-hr reentry.
References Yang, X., Castroagudín, V.L., Daughtrey, M.L., Loyd, A.L., Weiland, J.E., Shishkoff, N., Baysal-Gurel, F., Santamaria, L., Salgado-Salazar, C., LaMondia, J.A. and Crouch, J.A. 2021. A Diagnostic Guide for Volutella Blight Affecting Buxaceae. Plant Health Progress. 22:578-590. https://doi.org/10.1094/PHP-02-21-0052-DG