Biological Control of Parasitic Nematodes and Pathogenic Fungi Damaging Black Pepper in Vietnam: A Case Study

Root disease caused by various soil-borne pathogens affect the production of black pepper (Piper nigrum L.) in Vietnam. The present study aimed at evaluating the efficacy of a consortium of a nematode-trapping fungus (Arthrobotrys oligospora) and antagonistic microorganisms (Bacillus velezensis, Streptomyces enissocaesilis, and Trichoderma asperellum) on the plant-parasitic nematode (PPN) Meloidogyne incognita and on black pepper pathogenic fungi (Phytophthora capsisi, Fusarium solani, and Rhizoctonia solani), in greenhouse and field conditions. Data showed that combining the nematode-trapping fungus with antagonistic microorganisms significantly reduced the population of nematodes and pathogenic fungi, in black pepper-planted soils. The consortium efficacy (% reduction) for pathogenic fungi was 60.6–83.3% and 77.8% for M. incognita, in greenhouse conditions. Efficacy was 73.5–81.5% for pathogenic fungi and 81.9% for M. incognita after a 9 months treatment, in field conditions. In this study, a new biopesticide formulation, named VAAS-AT1, composed of T. asperellum Trivass, A. oligospora NVC7.4, B. velezensis P9.1, and S. enissocaesilis 2P, was used for the management of PPN and pathogenic fungi. The results revealed that VAAS-AT1 had a significant effect on the root-knot nematode. Its efficacy reached 79.3% in Dak Lak province and 82.7% in Gia Lai province, after a 9 months treatment. The results of this case study indicated that VAAS-AT1 can be proposed as a new microbial biopesticide to control pepper root rot and root-knot nematode disease complex in Vietnam.