Control of root-knot nematodes by biological agents (Nematophagous Fungi) in field experiments

Experiments were conducted in three commercial fields in Northern Thailand to examine the effectiveness of isolates of nematophagous fungi to increase lettuce growth parameters and manage root galls caused by Meloidogyne incognita. Experimental nematophagous fungi recovered from that same region included Arthrobotrys spp., Pochonia sp. and Paecilomycessp. One experiment investigated application of each of the biocontrols grown on two different media (B1 and B2) to lettuce seedlings before transplantation. Paecilomycessp. isolate WJI1003 produced the highest lettuce yields representing 201% and 162% increases in shoot fresh weight combined with medium B1 or B2, respectively. Seedling applications of all fungal isolate-media combinations significantly reduced the number of galls per root and caused generally equivalent gall reduction percentages ranging from 31-73%. Another experiment examined the performance of three of the experimental biocontrols alone and in combination when applied to lettuce at planting in a commercial field fertilized chemically (Area 1) or one that was managed organically (Area 2). The biocontrols (A.oligospora MTI2-001, A. conoides API3-001, Paecilomycessp. WJI1-003) generally produced plant growth increases equivalent to or greater than the commercial biocontrol and Dazomet in both Areas 1 and 2. Experimental biocontrols and their combinations, the commercial biocontrol and Dazomet produced equivalent reductions in galls per root and very dramatic gall reduction percentages ranging from 64-99% in both areas. Nematophagous fungi isolates A.oligospora MTI2-001, A. conoides API3-001 andPaecilomycessp. WJI1-003 consistently reduced root galls caused by Meloidogyne incognita in three commercial fields.