Tuesday, February 28, 2017


Kartohardjono, A. dan Arifin, M. 2004. Ambang ekonomi ulat grayak, Mythimna separata (Lepidoptera; Noctuidae) pada tanaman padi. Ekologia. 4(2): 41-46.

Arifin Kartohardjono1 dan Muhammad Arifin2
Balai Penelitian Tanaman Padi (BALITPA)
Balai Penelitian Bioteknologi dan Sumber Daya Genetika Pertanian (BALITBIO)


Pest becomes one of productivity handicap in the field of irrigated rice plantation. One type of the potential pest with its sudden attack and often cause a yield failure is the larvae of Mythimna separata (Lepidoptera: Noctuidae) which are called armyworm (ulat grayak). The aims of this research are 1) to determine the stage rice plant destruction due to the larvae attack, 2) to determine the rice yield loss due to the attack, 3) to obtain an integrated pest control packet for rice plant, like: a) economic threshold for the pest larvae, b) the loss of economical yield to becomes in basis making a decision to control the pest larvae. This research was conducted at the greenhouse of Balitpa, at Bogor on April 2001 and at the yield station (1500 m2) at the area of Indramayu, West Java, starting at the dry season on June 2001. Paddy variety involved is IR64 with a planting period of 30.45 and 60 days after transplanting. Larvae density treatment is 0; 1; 2; 3 and 4 larvae of 3rd instar per hill. Replication taken is 3 times at the field and 4 times at the greenhouse. Experiment done are using random group program which is factorial designed with 2 factors (larvae density and plant age). Observation is conducted against plant destruction and yield component. Observation results show that: 1) one larvae causes plant damage at the age of 30,45, and 60 days after planting at a rate between 7.21% - 22,69% and able to decrease the yield from 16.9% to 36.7%, 2) the threshold of the yield decrease for plants with an age of 45 dap (days after planting) is around 2 to 3 larvae per hill, while for the plants age of the 30 dap, 4 larvae per hill will decrease the yield up to 69%, 3) the economical threshold with an assumed control cost of Rp 185,000,- per ha with paddy yield price of Rp 14,000,- per kg is taken for case of larvae at 3rd instar,  while for the plant age of 30 dap has a value of 10.8 larvae per hill.
Key words: rice, armyworm, economic threshold

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