Commodity prices affect income, and can influence civil unrest in conflict-prone low-income countries. Agriculture facilitates employment and food security in these countries, and conflict and violence are often linked to this sector. A farmer may turn into a fighter if income from agricultural production drops; alternatively, a fighter is more likely to extort a farmer when the value of supplies increases. The seasonality of agricultural production may affect the opportunity cost of insurrection and the opportunities for fighters to fund themselves by appropriating farmers' supplies. Here I investigate the degree to which cereal prices have impacted civil unrest across Africa during 1997-2019. I find that battles (involving governmental forces, rebels, or affiliated parties) are more likely during the pre-harvest season, possibly as a strategic move to appropriate expected returns; while violence by and against civilians is more likely during the post-harvest season, possibly as a consequence or a repercussion of rapacity.