Effects of phosphorus fertilization and seed dressing fungicide on occurrence of pea aphid (Acyrthosiphon pisum) and yield of lentil

Abstract

Study on the effect of phosphorus fertilization and seed dressing fungicide on occurrence of pea aphid, Acyrthosiphon pisum and yield of lentil was conducted at Debre Zeit and Chefe Donsa for six consecutive years. Lentil genotypes Alemaya and ILL-7664 were sown at the rate of 60kg/ha on 2m wide and 4m long plots. Treatments consisted Apron star 42WS (@ 2.5g per kilogram seed), phosphorus fertilizer (DAP @ 100kg/ha), dimethoate (@ 1.8l/ha in spray volume of 200l/ha) as standard check and untreated control. Pea aphids were sampled by gently beating lentil plants on 20cm by 39cm counting board. The insecticide was applied when the average pea aphid density was ≥20 per 130cm². The treatments were combined in factorial combination and tested in randomized complete block design with four replications. Pea aphid infested lentil on all treatments at both locations and in all years. Although statistically nonsignificant, fertilized and seed dressed lentils had greater pea aphid density than the untreated control. On the other hand, spraying insecticide (dimethoate) significantly reduced pea aphid density. However, in all years and both locations, the yield of phosphorus fertilized, seed dressed and insecticide treated lentils were not statistically different from the untreated control.