Effect of cover crops on the suppressiveness of root rot and on the agronomic characteristics of cassava

Abstract

Cassava (Manihot esculenta Crantz) is a major staple food in many developing countries, including Brazil. However, it faces significant challenges from diseases like dry root rot (DRR) and black root rot (BRR) caused by soil-borne fungi. This study explores the use of cover crops to suppress these diseases and improve cassava's agronomic traits. Over four cultivation cycles, various cover crops were alternated with cassava varieties 'BRS Kiriris' (resistant) and 'BRS Formosa' (susceptible) in soil infested with DRR and BRR pathogens. In the 2nd cycle, only germination showed significant differences, but by the 4th cycle, various agronomic parameters, including fresh weight (FW.AP), dry weight (DW.AP) of the aerial part, fresh weight (FW.Root), dry weight (DW.Root) of the roots, and plant vigor, exhibited significant improvements. Cowpeas were identified as the most effective cover crop in disease reduction (ID%) and promoting healthier and taller cassava plants. Jack beans and peanuts also had positive effects on vigor, FW.AP, DW.AP, FW.root, and DW.root. In contrast, cover crops like maize, black oats, Crotalaria ochroleuca, cassava, and fallow soil had minimal impacts. Throughout the cycles, these selected cover crops consistently contributed to disease reduction and improved cassava's agronomic characteristics. This research highlights their potential in holistic disease management strategies.