The disease has been confirmed from at least 25 states to date ( Calabro 2018, LaMondia and Shishkoff 2017). 2012) and resulted in very significant losses in the ornamental nursery industry due to direct losses of plants due to disease, the removal of potentially infected plant debris, destruction of exposed plants and the subsequent costs associated with changes in plant production to prevent re-introduction of the pathogen ( AmericanHort 2017). The disease was first identified in the USA in 2011 ( Ivors et al. The pathogen appears to be clonal with limited genetic diversity within its known range ( LeBlanc et al. 2002, 2004) (synonym: Cylindrocladium pseudonaviculatum Crous, J.Z. & Crous.īoxwood blight in the United States is caused by the fungal pathogen Calonectria pseudonaviculata (Crous, J.Z. Species used in this study: boxwood ( Buxus L.), boxwood blight ( Calonectria pseudonaviculata (Crous, J.Z.
#Boxwood blight treatment plus
Index words: fungicide management, Buxus, chemical disease managementĬhemicals used in this study: azoxystrobin (Heritage 50 WG), azoxystrobin plus benzovindiflupyr (Mural 30, 50 WG), kresoxim-methyl (Cygnus 50 WG), propiconazole (ProCon-Z 14.3 L), pyraclostrobin (Insignia 20 WG), pyraclostrobin plus fluxapyroxad (Orkestra Intrinsic 21.26 SC), tebuconazole (Torque 38.7 SC), tetraconazole (Minerva 11.6 SC), thiophanate-methyl (3336 50% WP), triflumizole (Procure 480 SC). Experiments with ‘Green Mound' and ‘Green Mountain' boxwood cultivars and additional fungicides applied 48 h after inoculation demonstrated that propiconazole at 300 ppm, pyraclostrobin plus fluxapyroxad (150 ppm each) and azoxystrobin (135 ppm) plus benzovindiflupyr (67.5 ppm) reduced disease. ‘True Dwarf' boxwood plants treated with 450 ppm thiophanate-methyl, 120 ppm pyraclostrobin or 150 ppm propiconazole 48 h after inoculation demonstrated that only propiconazole reduced the number of diseased leaves, blight lesions and the frequency of pathogen re-isolation. Propiconazole also reduced the percent of leaf area diseased lesions were nearly 80% smaller with 300 ppm applied 48 h after inoculation. When leaves were treated post-infection with 300 ppm propiconazole, tetraconazole, tebuconazole, or triflumizole, the pathogen did not sporulate over 2 wks. Only propiconazole reduced diseased leaf incidence to at least half of the control. Fungicides were also applied 24 to 96 h post-inoculation. 24 h prior to inoculation reduced disease compared to the untreated control for all fungicides. Pretreating detached leaves with 30 or 300 ppm a.i. Azoxystrobin, azoxystrobin plus benzovindiflupyr, kresoxim-methyl, propiconazole, pyraclostrobin, pyraclostrobin plus fluxapyroxad, tebuconazole, tetraconazole, thiophanate-methyl, and triflumizole fungicides were evaluated for curative and anti-sporulant activity against boxwood blight caused by Calonectria pseudonaviculata on detached leaves and whole boxwood plants ( Buxus spp.).
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