Asian Journal of Research in Agriculture and Forestry

Ethiopia has enormous potential to produce the onions throughout the year both for domestic use and export market. It  is  also the  most  cultivated  and  high market  value  of  vegetable crops  in  Tigray  Northern Ethiopia. However, the productivity of onion is highly constrained such as insect pests, diseases, lack of improved verities, lack of improved management practices etc. The major insect pest of onion is Onion thrips and important pests especially in areas where onions are grown under irrigation. The purpose of this study was to test the insecticide chemicals application and application frequency on the Onion production technologies. Therefore, field experiment was conducted to evaluate the insecticide chemical applications with frequency application in 2017 and 2018 under irrigation conditions. Thirteen treatments were used three different insecticide types namely Karatae 5% EC, Dimethote 40%EC, Profit72%EC with four different spraying frequency and untreated (control) laid out in Randomized Complete Block Design (RCBD) with three replications. The current findings showed that the profitable yield was obtained Karatae 5% EC (1^st spray) (14.25 t ha^-1) followed by Profit72%EC (4^th spray) that is (20.25 t ha^-1) and the obtained profit was 128053 &181788 birr per ha with the maximum Marginal Rate of Return of 3025 & 2417% respectively in Tselemti woreda.  In Medebaayzana woreda also, the profitable yield was obtained Karatae 5% EC (1^st spray) (25.79 t ha^-1) followed by Karatae 5% EC (4^st spray) at (27.75 t ha^-1) & Dimethote 40% EC (3^rd spray) at (25.78 t ha^-1) and 231976, 249463 & 231544 birr per ha obtained profit with the maximum Marginal Rate of Return of 2634, 2395 & 2311 % respectively. Therefore, Karatae 5% EC (1^st spray) in Tselemti & Medebayzana woreda & Profit72%EC (4^th spray) in Tselemti woreda and Dimethote 40% EC (3^rd spray) in Medebayzana woreda was profitable preventive Onion Thrips for Onion production in the studies area.