Avocado production is severely affected by anthracnose disease in the field and after harvest worldwide. This disease causes losses in the field due to fruit abortion and as post-harvest disease affecting quality and quantity during marketing and storage. The management of this disease has been through the use of chemicals that toxify human beings and contaminate the environment. So, the development of alternative bio-pesticide, which is environment-friendly, is imperative. Therefore, this study was carried out to find an alternative to fungicides currently being used in the control of Colletotrichum gloeosporioides. This was achieved by evaluating the effectiveness of plant extracts from tree marigold (Tithonia diversifolia) and garlic (Allium sativum) in the inhibition of Colletotrichum gloeosporioides in vitro. The antifungal activity of the extracts was determined by the evaluation of their effectiveness in inhibiting the fungal mycelial growth and sporulation on PDA media. Fungicide, Atracol 70WP used to control the disease, was used for comparison purposes. Data obtained were analysed by ANOVA and Fishers mean separation test using Gestart version 6 software. Concentrations of 80 g/l of Allium sativum and 120 g/l of Tithonia diversifolia were significantly effective as antracol fungicides at 2 g/l which is the recommended rate by the manufacturer in inhibiting mycelial growth and sporulation of Colletotrichum gloeosporioides. However, further studies are recommended to evaluate the effectiveness of the extracts under field conditions.