Two field experiments were conducted in the Central Rift Valley of Ethiopia in the hot and cool dry seasons of 2016/2017 with the objective to develop an insecticide resistance management program on thrips infesting onion. The first experiment dealt with the evaluation of four different insecticides namely profenofos, λ–cyhalothrin, imidacloprid, and spinetoram in different sequences on thrips population and their effect on yield. The second experiment examined the effect of admixing the surfactant organosilicone with imidacloprid, spinetoram and dimethoate. A Randomized Complete Block Design with three replications was used for both experiments. Data on number of thrips, bulb yield and economic returns were collected. The insecticide imidacloprid and spinetoram resulted in fewer numbers of thrips and higher yields than profenofos and λ –cyhalothrin. Application of the more effective insecticides when the thrips population was high followed by less effective insecticides resulted in better control and higher economic return. Surfactant added insecticides gave a fewer numbers of thrips and higher yields than the corresponding insecticides applied without surfactant. The sequential application of spinetoram and imidacloprid with less effective λ-cyhalothrin and profenofos by mixing with adjuvant are recommended for thrips control as an integral component of thrips management in the Central Rift Valley of Ethiopia.

A survey was conducted in 2016 in the major onion producing areas of the Ethiopian Central Rift Valley. A structured questionnaire was used to assess farmers’ management practices with a focus on the use of insecticides. Plant samples were collected to assess species composition of thrips and their abundance. Results showed that insecticides were the only control methods for onion growers to control thrips infesting onion. The insecticides diazinon, dimethoate, profenofos, lambda-cyhalothrin and spinetoram were commonly used. Level of insecticide use was higher in Meki than Melkassa and Werer. The volume of insecticide for thrips control and thrips population was noted to be on the increase over the years. Frankliniella occidentalis and Thrips tabaci were present in all surveyed areas with T. tabaci accounting for a higher proportion. The relative species composition varied significantly with location. The highest proportion of T. tabaci was recorded at Werer, where insecticide use was relatively minimal. On the other hand, F. occidentalis was highest at Meki where insecticide use was also higher. The study suggests that thrips infesting onion have developed resistance to the commonly used insecticides. Further studies are required to confirm and develop a thrips resistance management program in the area. Key words: Frankliniella occidentalis, Thrips tabaci, onion, species composition.

The study was conducted to evaluate effects of bread wheat variety and fungicide application on yellow rust epidemics under natural field conditions at Debre Markos University research site, East Gojjam Zone in the main cropping season of 2021/2022 year. Three different fungicides (Tilt (25EC), Natura (250 EW), and Takeoff (293 SC) including fungicide unsprayed combined with five improved wheat varieties (Honkolo, Wane, Liben, Lemu and Kakaba) were used in the experiment and the experiment was laid out in RCBD design with factorial arrangement and replicated three time. Disease data’s (severity, AUDPC, incidence and grain yield were recorded. The maximum disease incidence (100 %), initial and final disease severity (39.75 at 57 DAP and 66.66% at 78 DAP) and AUDPC (1770.71 %-day) recorded from fungicide unsprayed plot on Honkolo variety. But the lowest disease incidence (1.50 %), initial and final severity (1.89 % at 57 DAP and 2.36 % at 78 DAP) and AUDPC (78.93 % - day) were recorded from the combination of Liben variety with Natura (250% EW) fungicide treatment. Moreover, the maximum grain yield (6.00 t/ha) was obtained from combination of Kakaba variety and Natura (250 EW) fungicide treatment plot. While the minimum yield (3.00 t/ha) was recorded from fungicide unsprayed Honkolo variety. Natura (250 EW) fungicide sprayed varieties were effective to against yellow rust and gave the highest values of yield over unsprayed plots and other fungicides application. However, Combination of Kakaba variety and Natura (250 EW) fungicide application was more feasible than other treatments.