Description:
<jats:sec>
<jats:title>Abstract</jats:title>
<jats:p>The egg-pathogenic fungus Paecilomyces lilacinus strain 251 (PL215) was
investigated under different temperature regimes for biocontrol activity
against the northern root-knot nematode Meloidogyne hapla. Biocontrol
activity by PL251 was affected by temperature and initial nematode inoculum
density. At 20/23°C (night/day) control efficacy reached 71% at a high
inoculum density of 10 000 eggs and juveniles (E + J) per 500 cm3 compared
to 65% control at the lower inoculum density (5000 E + J/500 cm3). By
contrast, average efficacy was 5% and 46% at low and high inoculum levels,
respectively, when temperatures were between 19°C and 21°C (night/day). A
significant interaction between the factors inoculum density and treatment
with PL251 was observed at low temperatures, when only few M. hapla galls
and egg masses developed after inoculation with 5000 E + J/500 cm3. When the
temperature was favourable for the fungal parasite (25°C), efficacy reached
90%. In glasshouse experiments with unfavourable temperatures for M. hapla
development (25°C-33°C), tomato plants repeatedly treated with PL251 showed
significantly higher fruit yield (23-102%).</jats:p>
</jats:sec>