Articles
Sensitivity of Septoria spp. associated with lowbush blueberry foliar disease to chlorothalonil and propiconazole fungicide
Article number
1357_36
Pages
251 – 256
Language
English
Abstract
Septoria leaf spot and canker diseases caused by Septoria spp. are economically important diseases affecting lowbush blueberry production in Canada.
The fungal diseases are responsible for premature loss of leaf area and reducing berry yields.
The application of fungicides including chlorothalonil (Bravo®) for control of Septoria is common.
In addition to this, fungicide applications of the active ingredient propiconazole (Tilt) for controlling other diseases while sporulation of Septoria spp. also occurs.
To assess the sensitivity of isolates of Septoria spp. to these fungicides, a total of 46 isolates of Septoria spp. collected in 2009 were evaluated in the laboratory.
Twenty-two and 24 isolates of Septoria spp. were collected from the blueberry fields near Debert and East River in Guysborough County, Nova Scotia, respectively.
Baseline sensitivities of isolates of Septoria spp. were evaluated by growing fungal isolates in yeast sucrose liquid medium in microtiter plates amended with different concentrations (0,0.001, 0.01, 0.1, 1.0, 10 µg mL‑1) of each fungicide (chlorothalonil and propiconazole). The 50% effective concentration (EC50) at which the fungal growth is reduced by 50% of each isolate for both fungicides were calculated.
EC50 values of 46 isolates of Septoria spp. for both fungicides varied substantially.
EC50 values of these isolates for chlorothalonil ranged from 0.22 to 9.74 µg mL‑1 with the mean value of 3.1 µg mL‑1, whereas EC50 values for propiconazole ranged from 0.07 to 15.6 µg mL‑1 with the mean value of 2.52 µg mL‑1. About 92 to 95% of Septoria isolates were sensitive to chlorothalonil (EC50 values ≤5 µg mL‑1) and only 5 to 8% isolates were less sensitive (EC50 values ranged 5 to 10 µg mL‑1). About 75 to 79% of fungal isolates were sensitive to propiconazole, while 5 to 8% isolates were insensitive (EC50 values >10 µg mL‑1).
The fungal diseases are responsible for premature loss of leaf area and reducing berry yields.
The application of fungicides including chlorothalonil (Bravo®) for control of Septoria is common.
In addition to this, fungicide applications of the active ingredient propiconazole (Tilt) for controlling other diseases while sporulation of Septoria spp. also occurs.
To assess the sensitivity of isolates of Septoria spp. to these fungicides, a total of 46 isolates of Septoria spp. collected in 2009 were evaluated in the laboratory.
Twenty-two and 24 isolates of Septoria spp. were collected from the blueberry fields near Debert and East River in Guysborough County, Nova Scotia, respectively.
Baseline sensitivities of isolates of Septoria spp. were evaluated by growing fungal isolates in yeast sucrose liquid medium in microtiter plates amended with different concentrations (0,0.001, 0.01, 0.1, 1.0, 10 µg mL‑1) of each fungicide (chlorothalonil and propiconazole). The 50% effective concentration (EC50) at which the fungal growth is reduced by 50% of each isolate for both fungicides were calculated.
EC50 values of 46 isolates of Septoria spp. for both fungicides varied substantially.
EC50 values of these isolates for chlorothalonil ranged from 0.22 to 9.74 µg mL‑1 with the mean value of 3.1 µg mL‑1, whereas EC50 values for propiconazole ranged from 0.07 to 15.6 µg mL‑1 with the mean value of 2.52 µg mL‑1. About 92 to 95% of Septoria isolates were sensitive to chlorothalonil (EC50 values ≤5 µg mL‑1) and only 5 to 8% isolates were less sensitive (EC50 values ranged 5 to 10 µg mL‑1). About 75 to 79% of fungal isolates were sensitive to propiconazole, while 5 to 8% isolates were insensitive (EC50 values >10 µg mL‑1).
Publication
Authors
R.R. Burlakoti, D.C. Percival
Keywords
Septoria, isolates, lowbush blueberry, fungicides, chlorothalonil, propiconazole
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