This study was conducted in Pangalengan,
Bandung (West Java) from June to August 2001.
Two plots (206100 m each), separated by 100 m,
were planted with potatoes. No insecticides were
used on these plots, but several fungicides were
applied twice a week to control leaf blight.
Fungicides used were Mancozeb 80% (Vondozeb
80 WP), Simoksanil 8.36% and Mancozeb 64.64%
(Curzate 8/64 WP), Propamocarb hydrochloride
722 g/l (Previcur-N), and Maneb 80% (Pilaram
80WP). These chemicals were applied in rotation.
For comparison, two potato plots of the same size,
but treated by a farmer were also studied. The
farmer applied the same regime of fungicides as in
the treatment plots, and also applied the insecticide
Carbosulfan 200 g/l (Marshal 200 EC) weekly to
control insect pests.
In each plot, 24 sampling units (each unit
consisted of three adjacent plants) were selected
for monitoring. Once a week, the numbers of
L. huidobrensis and C. humilis flies in the canopy of
the three selected plants were counted in the
morning. Leaves infested with leafminers were also
collected regularly as described above and monitored
in the same way for emergence of parasitoids. To
estimate level of crop damage, 16 potato plants were
randomly selected in each field, and scored for
damage using the same scale as in Trial 1.