Management of Meloidogyne javanica in Tomato using Extracts from Asteraceous Plants for Enhanced Productivity and Quality

Abstract

The Javanese root knot nematode, Meloidogyne javanica (Treub) Chitwood, is a major threat to solanaceous plants globally, particularly impacting smallholder tomato farmers in Africa due to its rapid reproduction and resistance to synthetic nematicides. This study assessed the impact of extracts from three asteraceous plants (Tithonia diversifolia, Bidens pilosa, and Tagetes minuta) on M. javanica in tomato cultivation. Various plant parts (roots, stems, flowers, and leaves) were ground and mixed with sterile soil in pots. Tomato plants were grown in these pots and inoculated with second-stage juveniles (J2s) and eggs of M. javanica three weeks post-transplanting. The treatments were evaluated for nematode numbers, damage, plant growth, yield, and soil organic carbon and nitrogen content. Results showed that extracts from the three plants had significant effects (P <0.001) on the nematode’s reproduction and development. Root extracts of T. diversifolia and B. pilosa reduced the J2 population by 89.1% and 84.7%, respectively. Moreover, T. minuta and T. diversifolia root extracts decreased the reproductive potential of M. javanica by 69.8% and 72.3%, respectively. A significant (P = 0.001) interaction effect between time and treatment on tomato root growth was observed. The highest yield was achieved with T. minuta leaf extracts (0.461±0.039 kg/plant). Ascorbic acid content in tomato varied significantly (P <0.001)  with T . minuta stem extract treatments showing doubled levels at the mature green stage. Soil analysis revealed that T. minuta root extracts significantly (P = 0.001) increased soil organic carbon content to 1.96%, with B. pilosa leaf extracts (1.8%) and B. pilosa root extracts (1.4%) also contributing positively. T. diversifolia stem and leaf extracts had the most significant (0.4%, P < 0.001) impact on soil organic nitrogen content. This study highlights the potential of organic extracts from T. diversifolia, T. minuta, and B. pilosa in managing RKNs, improving tomato yield, and enhancing soil properties, offering promising avenues for sustainable agriculture.