Bio Management of Citrus Nematode, Tylenchulus semipenetrans infecting Citrus in Assam

The experiment was conducted in an established Assam lemon orchard to know the effect of biocontrol agents viz., Pseudomonas fluorescens @20g/m² (2x10⁸cfu/g), Trichoderma viride@20g/m² (2 x 10⁸cfu/g), Paecilomyces lilacinus @20 kg/ha (2x10⁶ spores/g) and Pochonia chlamydosporia (Verticillium chlamydosporium) 20kg/ha talc (2x10⁶ spores/g) as well as organic amendments viz., Neem cake @ 100g/m² and FYM @1kg/m² on Tylenchulus semipenetrans. The above bioagents and organic amendments were applied near the base of the plants and compared with carbofuran (Furadan 3G) @ 100g/tree as chemical check. An untreated check without bioagents and chemical was maintained. Observation on soil and root population of nematode, population of biocontrol agents at 2 months of interval up to harvest of the crop, number of fruits per plant and fruit yield at harvest were recorded. The experimental results reveal that all the tested bioagents and organic amendments significantly reduced the soil and root population of T. semipenetrans as compared to untreated control. The maximum reduction (55.60%) of nematode population was recorded in the carbofuran treated plants followed by T.viride treated plants. The nematode population declined up to 6 months and thereafter started increasing up to the harvest. However, the population of nematode showed an increasing trend till harvest of the crop. Maximum number of fruits per plant with corresponding yield per hectare was recorded in carbofuran treated plants (277/plant and 46.12 ton/ha respectively), which was an increase of 33.27% of yield over untreated control. Among the bioagents, maximum yield was recorded in T. viride treated plants (271/plant and 44.82ton/ha), which was an increase of 20.38% of yield over untreated control. In this treatment, the ICBR was calculated to be 1:2.20. Among the organic amendments, maximum yield was recorded in neem cake treated plants (264/plant and 43.14ton/ha), which was an increase of 15.87% of yield over untreated control and the ICBR was calculated to be 1:1.30. The maximum ICBR was recorded in carbofuran treated plants (1:4.50).