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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #393113

Research Project: Identification, Biology, Epidemiology, and Control of Foreign and Emerging Fungal Plant Pathogens

Location: Foreign Disease-Weed Science Research

Title: Effect of temperature on lesion area of detached leaves of different boxwood cultivars infected with boxwood blight

item Shishkoff, Nina
item XIAO, YANG - Clemson University

Submitted to: APS Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2022
Publication Date: 12/26/2022
Citation: Shishkoff, N., Xiao, Y. 2022. Effect of temperature on lesion area of detached leaves of different boxwood cultivars infected with boxwood blight. APS Annual Meeting. 112:11-S3.1.

Interpretive Summary:

Technical Abstract: One problem facing boxwood growers since the discovery of the invasive boxwood blight pathogen (Calonectria pseudonaviculata, or Cps) is uncertainty over which cultivars show the greatest tolerance to the disease. Cultivar response has been variable from test to test and region to region. It is also concerning that a second species, C. henricotiae (Che), invasive in Europe, might appear in the U.S. at any time. We wanted to test the reaction of six boxwood cultivars (Buxus sempervirens ‘suffruticosa’ and ‘Vardar Valley’, B. sinica var. insularis ‘Justin Brouwers’, Buxus x ‘Green Velvet’, B. microphylla ‘Little Missy’, and Buxus 'SB 108’) to both pathogens at four temperatures to determine if the cultivars behaved differently at different temperatures. We placed five leaves top-down in each of three Petri dishes lined with moist filter paper and sprayed them with a combined conidial suspension of three Cps isolates or three Che isolates at 8000 conidia/mL (or water alone for controls). Plates were incubated in growth chambers set at 12, 18, 24 or 30 °C for six days, then leaves were measured for percentage lesioned area and averaged it over each plate. The experiment was repeated three times. Analysis of variance and Waller-Duncan k-ratio t-test were carried out in R to provide grouping for statistical differences. At lower temperatures, ‘Varder Valley’ did not differ in lesion size from other cultivars, but had significantly larger lesions at 30 °C (P < 0.05). No difference in percentage lesioned area was seen for leaves inoculated with Cps and Che at 18 or 24 °C (P = 0.15-0.27), but Che caused larger lesions at the extremes, 12 or 30 °C (P = 0.03-0.47). Based on these results, it is possible that temperature contributes to the observed variable response of boxwood cultivars and somewhat more severe disease will be seen if Che is found in the U.S.