S. Kumar et al., Temperature and water potential effects on growth and pathogenicity of Rhizoctonia solani AG-11 to lupin, CAN J MICRO, 45(5), 1999, pp. 389-395
Rhizoctonia solani anastomosis group (AG) 11 causes serious damping-off and
hypocotyl rot of lupins (Lupinus angustifolius L.) and is wide-spread in t
he northern grain-belt of Western Australia. We compared growth of AG-11 to
AG-8, which causes bare-patch of grain crops including lupin. AG-11 grew s
ignificantly faster than AG-8 on potato dextrose agar (PDA) at several temp
eratures (10, 15, 20, 25, or 30 degrees C) and also grew best within the pH
range of 4-7. Growth of AG-8 was best at pH 7. There was no difference in
the linear growth in soil of both AGs at 10 degrees C, but AG-11 grew at a
significantly faster rate at 20 degrees C: Reduction in growth of AG-11 on
osmotically adjusted PDA at temperatures between 10 and 30 degrees C was mo
re pronounced than that of AG-8. AG-11 caused very little lupin pre-emergen
ce damping-off and hypocotyl rot at 10 degrees C, and most severe hypocotyl
rot was recorded at 20 and 25 degrees C. Severity of hypocotyl rot caused
by AG-11 at soil water potentials of -0.1, -0.07, and -0.05 MPa was higher
than at -0.03 MPa. It appears that AG-11 is well suited to the environmenta
l conditions of the relatively small area in Western Australia from which i
t is readily isolated.