ACTA SCIENTIFIC MICROBIOLOGY (ISSN: 2581-3226) Volume 3 Issue 4 April 2020 Evaluating the Repellent Properties of Mexican Marigold (Tagetes minuta) Aqueous Extracts on Aphid Population in Rape (Brassica napus) Nyasha Sakadzo 1 *, Adonia Chisvuure 1 and Rumbidzai Nhara 2 1 Faculty of Agriculture, Zimbabwe Open University, Masvingo Regional Centre, P. O. Box 1210, Masvingo, Zimbabwe 2 Faculty of Natural Sciences, Department of Soil and Plant Sciences, Great Zimbabwe University, P.O. Box 1235, Masvingo, Zimbabwe *Corresponding Author: Nyasha Sakadzo, Faculty of Agriculture, Zimbabwe Open University, Masvingo Regional Centre, P. O. Box 1210, Masvingo, Zimbabwe. Research Article Received: February 06, 2020 Published: March 10, 2020 © All rights are reserved by Nyasha Sakadzo., et al. Abstract Keywords: Repellent; Brassica napus; Tagetes minuta; Aqueous; Brevicoryne brassicae Introduction Aphids (Brevicoryne brassicae) pose a threat to production of most vegetables including rape by sap sucking and transmitting viral diseases. A trial was carried out at the Jichidza High School, Masvingo Zimbabwe (2019) to evaluate the repellent properties of Mexican marigold (Tagetes minuta) aqueous extracts on aphid population in rape (Brassica napus). The experiment was laid out as a randomised complete block design (RCBD) with four treatments (0%, 2%, 4% and 6%) concentration of Mexican marigold extracts on rape replicated five times. Application of these concentrations was done at fortnight interval from week one after planting to week six of age. Data on growth rate, aphid counts, and cumulative leaf weight was collected from week three to week six after planting. The results showed that, the effects of Mexican marigold on growth rate, aphid population and cumulative leaf weight were significantly different (p < 0.05). Using 6% concentration of Mexican marigold aqueous extracts recorded the highest growth rate, lowest aphid population and highest leaf weight as compared to all other treatments. However, results from using 2% concentration of Mexican marigold aqueous extracts were not significantly different (p > 0.05) from the use of 4% concentration of Mexican marigold aqueous extracts in rape. From the results, it can be concluded that the use of 6% concentration of Mexican marigold in rape is an effective control method for aphids. From this study, it is recommended that poor smallholder farmers can utilise the repellent properties of Mexican marigold to reduce aphid yield losses in rape. Rape (Brassica napus) is a sub-tropical plant which belongs to the family Brassicaceae that include covo (Brassica carinata), mus- tard (Brassica juncea), cauliflower (Brassica oleracea) and other crucifers [1]. It is a popular vegetable in Zimbabwe rich in vita- mins and several other nutrients. Its leaves are rich in vitamin A, ascorbic acid, thiamine and has high levels of glucosinates which during preparation form compounds with anti-oxidants and have anti-cancer activities [2]. Unavailability of inputs and poor crop management has contributed negatively to the yield and quality of the crop [3]. Crop yields have remained far below the crop’s genetic potential in small holder sector due to diseases and pest attack. Several pests affect rape including bagrada bugs, diamond black moth, cutworm, white grubs and aphids (Brevicoryne brassica). However, aphids are considered the most common pest of rape by most farmers in Zimbabwe [4]. The aphids feed by sucking the sap from the plant leaves and tender tissues and in large numbers remove sufficient sap to kill the growing tip [5]. Infested seedlings become stunted and their Citation: Nyasha Sakadzo., et al. “Evaluating the Repellent Properties of Mexican Marigold (Tagetes minuta) Aqueous Extracts on Aphid Population in Rape (Brassica napus)". Acta Scientific Microbiology 3.4 (2020): 65-70.