Role of Cover Crops in Amendment of Soil Physio-Chemical Properties for Suppression of Fusarium Wilt of Cashew

Fusarium oxysporum f.sp. anacardi is a causal of Fusarium wilt of cashew in Tanzania. Considering high disease incidence and severity of Fusarium wilt of cashew, the present study was undertaken to develop a sustainable disease management approach which involves the soil amendment. In the experiment, four cover crops including soybean, mucuna, green gram and cowpea were used. The experiments were conducted on farmer’s fields in 2021/2022 and 2022/2023. Treated plots significantly reduced Fusarium oxysporum f.sp. anacardi load and disease severity compared to non-treated plots (P≤0.05). In the first cropping cycle (2021/2022), disease severity ranged from 9.0% to 39.42% compared to 57.12% in non-planted plots. In the second cropping cycle (2022/2023), disease reduction ranged from 7.0% to 33.50% compared to 62.50% in non-planted plots. Mucuna was the most effective crop with disease severity rates of 9.0% and 7.0%, followed by cowpea with 9.78% and 11.30% in 2021/2022 and 2022/2023, respectively. The findings also showed both positive and negative correlations between disease severity and soil physiochemical properties. Iron depicted positive correlation with disease severity at ρ=0.52 while potassium, total nitrogen, zinc and soil pH exhibited negative correlations at ρ=-0.515, -0.310, -0.667, -0.619, and -0.333 respectively. These results suggest that cover crops play a crucial role in enhancing soil physiochemical properties by replenishing soil mineral nutrients. Which underscores the importance of integrating soil nutrient replenishment and soil shading through cover crops in a comprehensive strategy for sustainable disease prevention.