Yield loss assessment of corn as affected by corn planthopper population density
2007
Dumaya, L.S. | Ogdang, M.P. | Leyza, P.S. | Hasigan, E.G., Department of Agriculture-Regional Crop Protection Center, Tacurong City (Philippines) | Motilla, E.J.C. | Lumbao, J.A., CEMIARC, Amas, Kidapawan City (Philippines) | Villar, L.P., CEMIARC for Upland and Lowland, Bulol-Mala, Tupi, South Cotabato (Philippines)
This study on yield loss assessment on corn as affected by corn planthopper population density was conducted at the seed production area of Malandag, Malungon, Sarangani Province which provide a year round population of the pests. It was enclosed in a cage covering an area of 20 square meter per plot (5 x 4 sq m) with four treatments replicated three times. The treatments were 20, 40, 60 DAP and control with 100 plants per cage. Forty planthopper per plant were introduced in the cages and a total of 4000 corn planthopper in every cage at the different days after planting. The number of planthopper introduced were based on the previous results of the series of population count conducted on the studies. Occurrence of corn planthopper on the three provinces of Region 12 [Central Mindanao, Philippines]. Of the four treatments, cages with 4000 corn planthopper introduced at 20 DAP got the highest number of leaves infected by sooty mold with 6 leaves below ear and 2 leaves above ear and lowest yield of 4,165 kg. The 40 DAP has 5-6 leaves infected with sooty mold and a yield of 6,165 kg. The 60 DAP plot has a yield of 8,070 kg and sooty mold infection of 1 leaf with only 25-50 percent part of the leaf infected. Control plot yield has a yield of 8,200 kg. Highest population was observed on the 6th weeks after introduction for 20 and 40 DAP and the population decline for the succeeding weeks as the plant matures. The plant hopper population at 40 DAP did not reach the same level of population as that of 20 DAP cages. For 60 DAP cage the population did not increase due to plants nearing maturity stage. The result: 20 DAP-45 percent, 40 DAP-27 percent and 60 DAP-5.06 percent indicates that the earlier the pest occur, the highest was the percentage of yield reduction.
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