DETERMINASI ARAS LUKA EKONOMI LARVA OSTRINIA FURNACALIS PADA TIGA FASE PERTUMBUHAN TANAMAN JAGUNG

SUBIADI, Prof. Dr. Ir. Y. Andi Trisyono, M.Sc.

2012 | Tesis | S2 Ilmu Hama Tumbuhan

Penelitian lapang dilaksanakan untuk mengetahui hubungan kepadatan populasi larva Ostrinia furnacalis terhadap tingkat kehilangan hasil pada tiga fase pertumbuhan tanaman jagung, dan untuk menghitung nilai Aras Luka Ekonomi (ALE) larva O. furnacalis dan nilai Ambang Ekonomi (AE) kelompok telur O. furnacalis pada tiga fase pertumbuhan tanaman jagung (V10, R1, dan R2). Interaksi faktor tingkat infestasi larva dan faktor fase pertumbuhan tanaman jagung menghasilkan pengaruh yang tidak signifikan terhadap hasil biji, sedangkan faktor fase tanaman dan faktor jumlah larva per tanaman menghasilkan pengaruh yang signifikan terhadap hasil biji. Selisih hasil biji antara tanaman yang tidak diinfestasi larva (kontrol) dengan infestasi enam larva per tanaman untuk fase V10, R1, dan R2, masing-masing 59,81; 58,76; dan 49,20 g/tanaman. Model regresi linier menunjukkan bahwa setiap pertambahan satu larva per batang pada fase V10, R1, dan R2 akan menurunkan hasil masing-masing 4,94; 4,56; dan 3,76%; dan setiap pertambahan panjang gerekan sebesar 1 cm per batang pada fase V10, R1, dan R2 akan menurunkan hasil masing-masing 0,63; 0,63; dan 0,47%. Nilai ALE dikalkulasi dengan asumsi pengendalian dengan pestisida akan menurunkan populasi larva O. furnacalis sebesar 67%. Nilai ALE terendah terdapat pada fase V10 sebesar 0,31 larva per tanaman ketika biaya pengendalian Rp.125.000 per ha dan nilai tanaman Rp.12.000.000 per ha. Nilai ALE tertinggi terdapat pada fase R2 sebesar 1,24 larva per tanaman ketika biaya pengendalian Rp.250.000 per ha dan nilai tanaman Rp.8.000.000 per ha. Nilai AE fase telur meningkat dengan meningkatnya nilai ALE dan nilai proporsi peletakan telur (PO). Nilai AE tertinggi terdapat pada fase R2 sebesar 18,8 kelompok telur per 100 tanaman ketika nilai ALE 1,24 larva per tanaman dan nilai PO = 1.

A field experiment was conducted to investigate the effect of infestation levels of Ostrinia furnacalis larvae per plant on corn grain yield reductions, and to determine economic injury levels (EIL) of O. furnacalis larvae and economic threshold (ET) of egg masses at three corn growth stages (V10, R1, and R2). The interaction between corn growth stage and number of larvae per plant on grain yield was absent. Either corn growth stage or number of larvae per plant significantly affected grain yield. Differences in yield between the uninfested and highest infestation levels (six larvae per plant) in V10, R1, and R2 were 59.81; 58.76; and 49.20 g/plant, respectively. Based on the linear regressions, average grain weight reduction by each larva when feeding was initiated during V10, R1, and R2 was 4.94, 4.56, dan 3.76%, respectively. When estimation was based on the length tunnel, the average of grain weight reduction per cm when stalk feeding was initiated during V10, R1, and R2 was 0.63, 0.63, and 0.47%, respectively. The calculation of EILs was based on the proportion of yield loss per larvae per plant on three corn growth stages with the assumption that pesticide control reduced 67% of O. furnacalis population. The lowest EIL was 0.31 larvae per plant at V10 when the cost of control reaching Rp.125,000 per ha and crop value of Rp.12,000,000 per ha. The highest EIL of 1.24 larvae per plant was found at R2 with the cost of control of Rp.250,000 per ha and crop value of Rp.8,000,000 per ha. An increase in EIL and the proportion of the total egg masses deposited (PO) increased ET value of egg masses. The highest ET value was 18.8 egg masses per 100 plants at R2 with EIL of 1.24 larvae per plant and PO of 1.

Kata Kunci : Ostrinia furnacalis, jagung, kehilangan hasil, Aras Luka Ekonomi, Ambang Ekonomi.