Fungal pathogens associated with maize crown and root rot under maize/legume intercropping system in the Limpopo province, South Africa
Mapotso Kena: University of Limpopo
<div>Smallholder farmers in Limpopo practice cereal/legume intercropping to mitigate risks of total crop failure due to various factors including diseases. Knowledge on the effect of this cropping practice on the prevalence of fungal pathogens causing maize crown and root rot is generally lacking in Limpopo despite its wide application. The main aim of this study was to evaluate maize/legume intercropping as a means for managing soil-borne diseases. Field experiments were set up under rain-fed and supplementary irrigation conditions as 2x4 factorial arranged in randomised complete block design with block replicated 2 times (irrigated experiment) and 3 times (rain-fed experiments). Disease assessment was carried out during seedling stage, flowering and harvesting. Fungal species were isolated from symptomatic roots, crown and stems and identified using morphological and DNA sequence analyses. Intercropping maize with groundnut and cowpea significantly reduced disease severity (<20%) in both experiments. A significant increase in disease severity (>90%) was recorded in maize/soybean intercropping under rain-fed experiments. More than 80% of isolates obtained from symptomatic roots and crown belonged to <em>Fusarium </em>spp with <em>F. oxysporum</em> (98.3%) being the most dominant. <em>Stenocarpella maydis</em> was also isolated from all treatments except in maize/soybean intercropping. <em>Macrophomina phaseolina</em> was most isolated pathogen in this treatment. <em>Rhizoctonia solani</em> was associated with more than 90% of seedling damping-off and blight in control treatments. There was more than 50% reduction in seedling damping-off under maize/legume intercropping in both irrigated and rain-fed trials. Results show that groundnut and cowpea when intercropped with maize can be effective in managing soil-borne maize diseases under smallholder farming systems.</div>
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