In vitro compatibility of Brassicaceae extracts with nematophagous fungi and their effects against Nacobbus celatus

Abstract

Nacobbus celatus sp. n. is one of the main root-knot nematodes in the eld destined for horticultural production of the central region of Argentine due to its ability to infect several host plants. The lack of new and safe active ingredients against this nematode has restricted control alternatives for growers. Egg-parasitic fungi and biofumigation with brassicaceae have been considered as potential candidates for the development of bionematicides. Nematicidal effects of Brassica oleracea var. italic (broccoli) and Brassica oleracea var. capitata (cabbage) aqueous extracts (AEs) against second-stage juveniles (J2) of N. celatus were evaluated in vitro. Fisher LSD tests evidenced signi cant nematicidal (α = 0.05) effects of the two AEs tested, with LD100 of 250 and 500 µL mL − 1 for broccoli and cabbage, respectively. Compatibility assays between AEs and ve nematophagous fungi were performed on soil extract solid medium (SESM) conditioned at 0.99 water activity and incubated at 30, 25 and 20°C. Purpureocillium lilacinum SR14 was the fungal strain that showed compatibility at levels of spore viability, growth rate and conidia productions at LD 50 (125 µL mL − 1 ) and LD 25 (60 µL mL − 1 ) of broccoli aqueous extract (BAE) y enhanced the nematophagous effect. Moreover, phytotoxic studies revealed that the 125 of BAE applied at the transplantation time could be safely used without affecting tomato culture. In conclusion, the integrated application of BAE with the nematophagous fungus, which combines two action mechanisms, represent a promising integrated strategy to control phytoparasitic nematodes.

Sustainable strategies for management of the “false root-knot nematode” Nacobbus spp.

“…The in vitro compatibility of the P. lilacinum SR14 was tested with broccoli AE and anise EO to control N. celatus. The combined treatment (200 mL/L) induced a higher (86%) J2 mortality (Sosa et al, 2020;Sosa et al, 2022). The broccoli AE increased the growth rate (by 8%) and conidiation (by 27%) of SR14 and its ability to J2 infection (by 76%) (Sosa et al, 2022).…”

“…The combined treatment (200 mL/L) induced a higher (86%) J2 mortality (Sosa et al, 2020;Sosa et al, 2022). The broccoli AE increased the growth rate (by 8%) and conidiation (by 27%) of SR14 and its ability to J2 infection (by 76%) (Sosa et al, 2022). This latter combined strategy was also evaluated in tomato plants grown on a sterile substrate under greenhouse conditions, showing a lower gall index and egg masses numbers, as well as a lower nematode reproduction rate for treated plants (Sosa et al, 2021c).…”

“…egg hatching at a concentration of 5 mg/mL, 12 h after treatment, with 100% J2 mortality achieved at 10 mg/mL, 24 h after treatment ( Páez-León et al., 2022 ). Sosa et al. (2022) reported high mortalities of N. celatus J2 exposed to broccoli ( Brassica oleracea var.…”