Boxwood Blight Task Force

Boxwood Blight

The purpose of the Virginia Boxwood Blight Task Force is to provide leadership in safeguarding and protecting the ornamental horticulture industry, historical gardens and landscape plantings from boxwood blight.

The following BMPs are guidelines for boxwood growers to avoid introduction of the boxwood blight pathogen or, if the disease is already present, to manage the disease in the most effective manner and avoid spread of the disease to new locations. Each BMP is specialized for individual boxwood growing situations.

Best Management Practice Situation
Best Management Practices for Boxwood Blight for Virginia Landscapes, Public Grounds and Historic Gardens professional landscapers, public grounds and historic garden situations
Best Management Practices for Boxwood Blight in the Virginia Home Landscape residential boxwood growers
Best Management Practices for Boxwood Blight in Virginia Production Nurseries WITHOUT Boxwood Blight commercial nursery production
Best Management Practices for Boxwood Blight in Virginia Production Nurseries WITH Boxwood Blight commercial nursery production
Best Management Practices for Virginia Retail Nurseries WITHOUT Boxwood Blight retail garden stores
Best Management Practices for Virginia Retail Nurseries WITH Boxwood Blight retail garden stores
Best Management Practices for Boxwood Blight for Boxwood Greenery Producers boxwood greenery producers (i.e. used for holiday greenery) and boxwood tippers

Sanitizer recommendations for the boxwood blight pathogen

Note: Only ethanol products provide some control of microsclerotia and other pathogen structures (e.g. mycelium, spores, chlamydospores) in plant debris; thus, it is VERY important to wash off surface soil and/or debris before proceeding with any recommended sanitizing procedure.

Active ingredientExample of brand nameConcentrationContact time/application
Ethanol in spray or liquid formLysol disinfectant aerosol spray (Brand III)70% Ethanol or greater or Lysol Disinfectant Spray Brand III with 58% ethanol and 0.1% dimethyl benzyl ammonium saccharinateFor spray applications: Apply to surface and allow to air-dry. For liquid application dip tools for 5 min
Sodium hypochlorite (5.25% or 8.25)Clorox and other household brandsPrepare 1:9 solution of 5.25% bleach or 1:14 solution of 8.25% bleach. Must be prepared fresh10-15 min. for equipment surfaces; dip tools for 5 min
Hydrogen dioxideOxidate, Zerotol
  • Prepare 1:100 – 1:300 solution for use on clean, non-porous surfaces.
  • Prepare 1:50 solution for use on unclean surfaces.
5-10 min
Hydrogen peroxide, peroxyacetic acid, and octanic acidXeroton 3 (X3)
  • Prepare 1:500 – 1:1,500 solution for use on clean, non-porous surfaces.
  • Prepare 1:150 solution for use on unclean, non-porous surfaces.
  • Prepare 1:300 – 1:1,000 solution for use on tools.
10 min
Phenolic compounds (O-benzyl-p-chlorophenol)Lysol Brand Concentrate DisinfectantPrepare solution of 1.25 – 2.5 oz/gal.At least 5 min

Data compiled from: (1) Douglas, S.M., 2013.  Efficacy of sanitizing agents to refine best management practices for the boxwood blight pathogen Calonectria pseudonavicula. APS poster, Annual meeting , Aug. 10-14, Austin TX, (2) Shishkoff, N., 2014. Survival of microsclerotia of Calonectria pseudonaviculata (the boxwood blight pathogen) treated with a variety of sterilants. APS poster, Potomac Division Meeting, March 12–14, Annapolis, Maryland, (3) Dart, N. L., Hong, C. X., Allen, C., 2014.  Efficacy of bleach and ethanol as sanitizers on conidia and infected leaf tissue colonized with mycelium and microsclerotia of the boxwood blight pathogen, Calonectria pseudonaviculata. Unpublished.

Version 1, published December 2014

Downloadable Fungicide Guide

Table 1. Fungicides for boxwood blight management, home grower use.
Active ingredient Trade name Efficacy1 FRAC group2
Chlorothalonil Broad Spectrum Landscape & Garden Fungicide (Ferti-lome); Vegetable, Flower, Fruit and Ornamental Fungicide (Hi-Yield); Fung-onil (Bonide); Ortho Max Garden Disease Control or Ortho Diseease B Gon (Scotts) E M5
Table 2. Fungicides for boxwood blight management, professional use
Nursery Green-
house
Land-
scape,
non-resid-
ential
Land-
scape, resid-
ential
Active ingredient Trade name Effi-
cacy
1
FRAC group2
  Propiconazole Banner MAXX, Procon-Z F-G 3
  Tebuconazole Torque G 3
  Propiconazole + chlorothalonil Concert, Concert II E 3+M5
    Trifloxystrobin + triadimefon  Strike Plus 50 WDG G-E 3+11
    Myclobutanil Eagle WSP, Rally 40WSP F-G 3
Myclobutanil Myclo-
butanil 20EW T&O
F-G 3
Thiophanate methyl Cleary 3336 F, Fungo Flo  F 1
Azoxystrobin Heritage F 11
Pyraclostrobin Insignia G 11
Trifloxystrobin Compass G 11
Fludioxonil Medallion G-E 12
Mancozeb Fore 80 WP Rainshield, Protect DF G M3
Chlorothalonil Daconil Weather Stik Flowable Fungicide E M5
Chlorothalonil + thiophanate methyl Spectro 90WDG E 1+M5
Boscalid + pyraclostrobin Pageant G 7+11
  Cyprodinil + fludioxonil Palladium F-E 9+12

1F=Fair, G=Good, E=Excellent

  • Effectiveness ratings are based on limited research.  Results can vary depending on environmental conditions, formulation of a pesticide, and application method and timing. These ratings are intended as general guides only.
  • Sources of efficacy information: Gehesquière B. (2014). Phd Thesis. Ghent University, Belgium; Ivors, et al. 2013. Plant Dis. Manag. Rep. 7:OT014. doi: 10.1094/PDMR07; LaMondia, J.A. 2015. Plant Dis. 99: in press; Henricot B. and Wedgwood E. 2013. Plant Health Progress. doi:10.1094/PHP-2013-1024-01-RS; and unpublished research.

2FRAC Group: classification based on fungicide mode of action (www.frac.info). Rotate any fungicide at risk of resistance development with products that have a different mode of action (i.e., in a different FRAC group).

It is the user’s responsibility to read and follow product label directions for all products. Commercial products are named in this publication for informational purposes only. Virginia Cooperative Extension does not endorse these products and does not intend discrimination against other products which also may be suitable. 

Published 2/26/15

Member Title Affiliation
Anton Baudoin Associate Professor of Plant Pathology Department of Plant Pathology, Physiology and Weed Science, Virginia Tech
Adria Bordas Extension Agent Virginia Cooperative Extension, Fairfax County
Elizabeth Bush Extension Plant Pathologist Department of Plant Pathology, Physiology and Weed Science, Virginia Tech
Norm Dart State Plant Pathologist Office of Plant Industry Services, Virginia Department of Agriculture and Consumer Services
Mary Ann Hansen Extension Plant Pathologist Department of Plant Pathology, Physiology and Weed Science, Virginia Tech
Chuan Hong
Professor and Extension Specialist of Plant Pathology Hampton Roads Agricultural Research and Extension Center, Virginia Tech
Ping Kong Research Scientist Hampton Roads Agricultural Research and Extension Center, Virginia Tech
T. Mike Likins County Agent Chesterfield County Extension
Tina MacIntyre State Cooperative Agricultural Pest Survey Coordinator Office of Plant Industry Services, Virginia Department of Agriculture and Consumer Service
Sasha Marine Postdoctoral Associate Department of Plant Pathology, Physiology and Weed Science, Virginia Tech
Debra Martin Program Manager Office of Plant Industry Services, Virginia Department of Agriculture and Consumer Services
Xiao Yang Postdoctoral Associate Hampton Roads Agricultural Research and Extension Center, Virginia Tech