Mt. Fauzi et al., The rust Puccinia abrupta var. partheniicola, a potential biocontrol agentof Parthenium weed: Environmental requirements for disease progress, BIOL CONTRO, 14(3), 1999, pp. 141-145
The rust fungus Puccinia abrupta var. partheniicola, a potential biological
control agent of parthenium weed (Parthenium hysterophorus), was evaluated
under controlled environmental conditions. A range of spore germination te
mperatures as well as dew period durations and temperatures were investigat
ed to determine some of the environmental requirements for disease establis
hment and disease progress. Plants were inoculated with urediniospores and
exposed to dew periods between 3 to 12 h at temperatures of 10, 15, or 20 d
egrees C. For disease expression, the inoculated plants were then grown in
a glasshouse at one of two temperature regimes (30/26 degrees C or 18/13 de
grees C; day/night). Urediniospores germinated best at 12 +/- 1 degrees C,
with lower germination rates at 5 degrees C or above 20 degrees C. No infec
tion occurred when the plants were exposed to dew periods of less than or e
qual to 3 h, regardless of the incubation temperature. The disease progress
ed most rapidly when plants were inoculated and incubated for a dew period
of at least 12 h at a temperature of 15 +/- 1 degrees C. The disease progre
ssed most slowly following inoculation at dew periods of 6 h or less. Disea
se progress was more rapid when the plants were exposed to a cool-temperatu
re regime (18/13 degrees C) than when exposed to a warm-temperature regime
(30/26 degrees C). This suggests that good infection of parthenium weed cou
ld be obtained when the urediniospores arrive on the plants during the afte
rnoon in the cooler months of the central Queensland autumn when relatively
long dew periods are expected. (C) 1999 Academic Press.