Biocontrol potential of Pochonia chlamydosporia var. chlamydosporia isolates against Meloidogyne javanica on pistachio

Abstract

The biocontrol potential of four Pochonia chlamydosporia var. chlamydosporia isolates on the root-knot nematode, Meloidogyne javanica was investigated on pistachio plants in a greenhouse experiment. Isolates were applied at 10,000, 5000 and 1000 chlamydospores per gram of soil; the latter two densities were being used for strain Pcc60 only and designated as PccB and PccA, respectively. Plants were inoculated with a suspension containing 3000 eggs of M. javanica. Nematode reproduction was reduced to 57% by Pcc20 and 36% by Pcc10 and Pcc60C after 4 months. Pcc20 was the most promising isolate as the final egg population of nematodes was reduced by nearly 61 and 36% by Pcc10 and Pcc60C, respectively. All strains infected eggs on the roots to varying degrees. Pcc20 was the most effective colonizer of all the isolates, infecting 37% of the eggs, while Pcc10 and Pcc60C as the second best colonizers caused an average infection rate of 17.5%. The potential of the fungus was reduced at lower densities of spore inoculum. Semi-selective medium was used to re-isolate the fungi from soil and rhizosphere but was not able to detect Pcc60A at 1000 cfu/g soil, despite the fact that 3% of the eggs were parasitized. The efficiency of the different isolates in controlling nematode reproduction parameters and their relationships in terms of survival and abundance is discussed further.