TY - JOUR
T1 - Field and growth chamber evaluation of powdery mildew disease on deciduous azaleas
AU - Long, Michael C.
AU - Krebs, Stephen L.
AU - Hokanson, Stan C.
PY - 2010/5
Y1 - 2010/5
N2 - Forty-one deciduous azalea (Rhododendron subgen. Pentanthera G. Don) cultivars were assessed for powdery mildew (PM) resistance in a two-location, 3-year field trial. Disease severity (percent leaf area affected) on abaxial leaf surfaces was used to rate the level of field resistance. This measure was proportional to (r = 0.83) but higher than estimates from corresponding adaxial surfaces. Eleven of these cultivars (27%) appeared to be highly resistant under field conditions, i.e., evidence of PM on the leaves was zero or near zero. Twenty-three of the cultivars evaluated in the field experiment were also evaluated in a growth chamber experiment. In contrast to the field study, PM was more severe on the adaxial leaf surface in the growth chamber but still highly correlated with the abaxial response (r = 0.93). Based on adaxial disease scores, no cultivars in the growth chamber experiments were completely resistant. Growth chamber disease ratings based on either leaf surface were predictive of field performance (r2 = 0.62), suggesting use of the chambers could serve as a low-cost, off-season, early selection component of a deciduous azalea PM resistance breeding program.
AB - Forty-one deciduous azalea (Rhododendron subgen. Pentanthera G. Don) cultivars were assessed for powdery mildew (PM) resistance in a two-location, 3-year field trial. Disease severity (percent leaf area affected) on abaxial leaf surfaces was used to rate the level of field resistance. This measure was proportional to (r = 0.83) but higher than estimates from corresponding adaxial surfaces. Eleven of these cultivars (27%) appeared to be highly resistant under field conditions, i.e., evidence of PM on the leaves was zero or near zero. Twenty-three of the cultivars evaluated in the field experiment were also evaluated in a growth chamber experiment. In contrast to the field study, PM was more severe on the adaxial leaf surface in the growth chamber but still highly correlated with the abaxial response (r = 0.93). Based on adaxial disease scores, no cultivars in the growth chamber experiments were completely resistant. Growth chamber disease ratings based on either leaf surface were predictive of field performance (r2 = 0.62), suggesting use of the chambers could serve as a low-cost, off-season, early selection component of a deciduous azalea PM resistance breeding program.
KW - Disease resistance breeding
KW - Hododendron subgen. Pentanthera G. Don
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U2 - 10.21273/hortsci.45.5.784
DO - 10.21273/hortsci.45.5.784
M3 - Article
AN - SCOPUS:77952556448
SN - 0018-5345
VL - 45
SP - 784
EP - 789
JO - HortScience
JF - HortScience
IS - 5
ER -