The Effectiveness of NEEM Seed (Azadirachta indica) Extract in the Control of Yellow Sugarcane Aphid in the South East Lowveld of Zimbabwe

Abstract

The yellow sugarcane aphid (Sipha flava) is one of the most economically damaging pests of sugarcane in the South Eastern Lowveld of Zimbabwe. Sipha flava was recorded for the first time in Zimbabwe in March 2014. Management of yellow aphid through the use of synthetic pesticides may result in resistance developing due to selection pressure, hence researchers are advocating the use of botanicals such as neem seed extracts (Azadirachta indica). A field trial was conducted at Emanzini Farm, Subdivision 07 of Triangle from November 2019 to April 2020 in order to determine the effects of neem seed extracts on the yellow sugarcane aphid. The specific objectives were to; (i) determine the effects of neem seed solution on the infestation by yellow aphids, and (ii) quantify the effect of different neem rates. The sugarcane variety N14 was used. The trial was laid out in a randomized complete block design (RCBD). Fifteen plots were randomly allocated in the field and each plot measured 14m by 6m with inter row spacing of 1.5m and one peripheral discard row on either side of the field. Five treatments namely 100ml neem seed solution per 15 litres of water, 75ml neem seed solution per 15 litres of water, 50ml neem seed solution per 15 litres of water, dimethoate 1litre per 100 litres of water and an untreated control were used. The treatments were replicated three times. Neem seed solution showed great potential on controlling yellow sugarcane aphid population. The 75ml neem seed solution showed significant efficacy by reducing leaf damage and Sipha flava colonies from 19 to 12 and 7.13 to 0.64 respectively. The 75 ml neem seed solution resulted in a significantly higher mean Pol % of 13.56%. This is so because if yellow sugarcane aphid is not controlled the content of soluble solids and the apparent percentage of sucrose in the juice of sugarcane plants will be affected greatly. There was a significant difference (P<0.05) on the mean Tons ERC among the five treatments. The 50 ml and untreated control had significantly lower cane yields of 13.03 tons and 13.27 tons respectively. The study showed that farmers can adopt the 75 ml neem seed solution as a viable alternative to the use of synthetic insecticides in the control of yellow sugarcane aphid.