Abstract:
Insect-proof nets are increasingly used by farmers in the dry zone of Sri Lanka to
control insect pests associated with chili cultivation including the Chili Leaf Curl
Complex (CLCC). However, some farmers report that these nets do not effectively
control CLCC. Therefore, this study was conducted to evaluate the effectiveness of
insect-proof nets in managing CLCC in the dry zone of Sri Lanka and to assess the
environmental impact of this cultivation method. Three treatment conditions were
evaluated: (1) insect-proof nets with fertigation, (2) open fields with fertigation, and
(3) open fields with flood irrigation. The Thrips and CLCC severity, whitefly
population levels, yield parameters, and weather parameters were collected from 28
farmers over three months at two-week intervals. The field-use Environmental Impact
Quotient (EIQ) was also calculated for each treatment. A sample of 30 farmers was
selected to complete the survey questionnaire. The results revealed that both the
Thrips Severity Index (TSI) and CLCC Severity Index (CLCSI) increased over time
across all treatments, with open-field flood irrigation (T3) showing the highest
severity levels. No significant differences (p>0.05) in TSI were observed between the
netted fertigation (T1) and open-field fertigation (T2) treatments, although T2 showed
a lower (30.56±5.75) CLCSI at 12 weeks post-planting (p<0.05). There was no
significant difference in yield among treatments; however, whitefly counts differed
significantly, with T3 displaying the highest count (158.23). Temperature and relative
humidity showed no significant impact on whitefly numbers. According to the survey,
93% of the farmers are willing to grow chili inside the insect-proof nets. The lowest
EIQ was observed in T1 (114403.92). The study suggested that although the insect
proof nets may not effectively reduce CLCC, they have a comparatively low
environmental impact.
