ESTIMATION OF AVOIDABLE YIELD LOSS IN MAIZE ZEA MAYS L. CAUSED BY THE FALL ARMYWORM SPODOPTERA FRUGIPERDA (JE SMITH) (NOCTUIDAE: LEPIDOPTERA)T. Srinivasan, P.S. Shanmugam, V. Baskaran, Zadda Kavitha, P. Yasodha, M. Ravi, N. Sathiah, R.J. Rabindra, S.V. Krishnamoorthy, N. Muthukrishnan, B. Vinothkumar, A. Suganthy A, N. Balakrishnan, S. Backiyaraj, G. Arulkumar, S. Jeyarani, M. Shanthi, M.R. Sr
Invasive fall armyworm Spodoptera frugiperda (JE Smith) (Noctuidae: Lepidoptera) has the potential to cause 70 â 80 per cent yield loss in maize. Field experiments to assess the avoidable yield loss due to invasive fall armyworm S. frugiperda (Noctuidae: Lepidoptera) was conducted across four major maize growing zones in Tamil Nadu, India. The treatments Complete Protection (T1), Window based insecticide application as per Tamil Nadu Agricultural University (TNAU) Integrated Pest Management capsule (T2) and Untreated Control (T3) were imposed in four maize zones of Tamil Nadu during 2020 - 21. In complete protection (T1) the recommended insecticides were applied as and when the incidence was noticed. Insecticides recommended for different widows viz., Azadirachtin 1% EC @ 2 ml/l. or Emamectin benzoate 5% SG @ 200 g ai/ ha for first window (15 â 20 days) and Spinetoram 11.7% w/w SC @ 30 g a.i/ha or Chlorantraniliprole 18.5% SC @ 40 g a.i/ha or Novaluron 10EC @ 100g a.i./ha were applied in the window based application (T2). The average avoidable yield loss for complete protection (T1) and window-based application (T2) was in the order Coimbatore > Madurai > Tirunelveli > Tiruchirappalli. The average avoidable yield loss in complete protection (T1) and window based application (T2) was 2600.25 and 2307.87 kgs/ha respectively. The number of insecticide sprays required to keep the fall armyworm population under control was ranged between 3 to 4, in complete protection (T1) whereas in window-based application (T2) two sprays were given. The average difference in avoidable yield loss between window based (T2) and complete protection (T1) was 292.38kgs/ha. Both complete protection (T1) and window-based application (T2) recorded same benefit cost ratio of 1.65 and average per hectare plant protection cost of Rs.11000/- and Rs.5413/- respectively. The timely interventions at critical stages of maize growth will check the fall armyworm population from causing any economic damage to the maize. The crop care at critical stages will be the ideal strategy for the fall armyworm management.