Compatibility of Velum® (Synthetic Nematicide) with Endophytic Colletotrichum nigrum and Commercial Trichoderma asperellum against Root-Knot Nematodes on Tree Tomato

Abstract

Root-knot nematodes (RKNs) hinder agricultural production worldwide. Many methods of managing RKNs have been used. However, an approach of combining velum® with endophytic fungi and commercial Trichoderma asperellum has not been tested against RKNs. This study was carried out between September 2022 to February 2023 to evaluated compatibility of Velum® with endophytic Colletotrichum nigrum isolated from roots of tree tomato and commercial Trichoderma asperellum to contain RKNs in vitro and in the greenhouse on tree tomato. Leading mycelial discs from the colony of C. nigrum and T. asperellum were removed using a cork borer and inoculated onto PDA media amended with Velum® and incubated for seven days at 25oC. Colletotrichum nigrum and T. asperellum alone and in combinations with Velum® were tested for their efficacy against second stage juveniles (J2s) of RKN in the greenhouse. In vitro and greenhouse tests were replicated four times in Completely Randomized Design. Data was analyzed by Anova SAS, 9.2 and significant means separated by Tukey's Honestly Significant Differences test at P ≤ 0.05. There was no significant inhibition in the colony growth of C. nigrum and T. asperellum by Velum® in vitro and therefore were found to be compatible. Colletotrichum nigrum combined with Velum® significantly (P≤0.05) reduced the RKN J2s, nematode reproduction factor, galling and egg mass indices in both experiments more than when applied alone. There was also a significant increase in plant growth parameters of tree tomato treated with C. nigrum combined with Velum®. This study has shown that combining Velum® with C. nigrum and T. asperellum successfully controlled RKNs on tree tomato. These findings could be used to promote integrated nematode management using less toxic nematicides and biocontrol agents.