Management of root-knot nematode, Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949 in ginger

Introduction

Ginger (Zingiber officinale Rosc.), belonging to Zingiberaceae family was first described in the book, Hortus Indicus Malabricus in 1692 by Rheede. Its origins are generally attributed to India or China, with references appearing as early as 500 BCE in the writings of the philosopher Confucius. It is highly valued for rhizome known for its significant nutritional and medicinal benefits. Ginger contains essential nutrients such as carbohydrates, dietary fibre, protein and trace amounts of vitamins and minerals including vitamin C, vitamin B6, magnesium, potassium and iron, making it a nutrient-dense food (Bhati and Raghuvanshi, 2021) [1] . It is a major spice with significant production and marketing value in global trade. India has been a large producer of ginger for many years, with the production of 22 lakh tons of fresh ginger cultivated in an area of 1.9 lakh hectares during the year 2024-25 (Spices Board of India, 2025). Among the major biotic constraints of ginger, diseases play an important role. Ginger is severely affected by soil-borne diseases viz. soft rot, bacterial rot, fusarium yellows and nematode-disease complex including Meloidogyne spp., Radopholus similis and Pratylenchus spp. Root-knot nematodes (Meloidogyne spp.) also facilitate secondary infections by different pathogens like Pythium spp., Fusarium spp. and Ralstonia spp. (Udo and Ugwuke, 2010) [17] . Though several plant-parasitic nematodes have been recorded from ginger, the most important nematode pests are root-knot and burrowing nematodes (Guo et al., 2004; Kaur et al., 1989; Luqman et al., 1998; Routaray et al., 1987; Sheela et al., 1995; Vadhera et al., 1998) [5,6,8,13,15,18] . Root-knot nematodes (Meloidogyne spp.) infest several agricultural and horticultural crops all around the world. In India the annual losses due to root knot nematode are around 29 -30 per cent (Kumar, et al., 2020). Various species of Meloidogyne attack nearly every crop sown, where not only are yields greatly affected but quality is also compromised (Sasser, 1980) [14] . In this context the study was conducted to evaluate the efficacy of different bioagents for the nematode management.

Methodology Nematode population isolation and identification

The soil samples were processed by Cobb's decanting (Cobb, 1918) [2] and sieving method and Modified Baermann's funnel technique. First, the soil from the polythene bag was spread on the table, mixed well. Then about 200cc of soil sample was taken into plastic pan, one litre of water was added and stirred well in order to prepare a soil suspension. The suspension was allowed to stand for about 10 seconds so that sand and heavier particles settled down. The muddy soil suspension was passed through an assembly of phosphoro-bronze wire-netted sieves of 20, 60, 200 and 350 mesh sieves. Contents of 200 and 350 mesh sieve were collected into a 200cc beaker by backwashing the sieve with gentle stream of water from the tap. Each soil sample was wet screened in the same manner to collect most of the nematodes. The whole suspension collected in the beaker was poured onto a double layer tissue paper resting on a supporting wire-gauge matching the petri dish. The wire gauge assembly was then placed on petri dish containing sufficient water such that the bottom of the wire gauge tissue assembly was slightly submerged in water. The assembly was covered by lid to prevent loss of water due to evaporation and left as such for 24 hours, so as to allow maximum number of nematodes to wriggle out through the tissue paper into the bottom of petri dish. Next day 1 ml suspension was taken out with the help of micro pipette in counting dish, put on the stage of the stereoscopic microscope to examine the presence of nematodes. In this manner all samples screened were processed following modified Baermann's Funnel Technique to get clear nematode suspension.

Nematode population assessment

The 200 g of composite soil samples were collected from each treatment at the time of observation. The residues of 200 and 350 mesh sieves were collected in plastic beaker and the volume of beaker was adjusted to 200 ml by adding tap water. The nematode count, the average of 10 counts of 1 ml suspension was recorded and from this it was calculated to 200 ml of solution. From these observations, per cent decrease in nematode population was worked out. For roots, these were stained with 0.1 per cent boiling acid fuchsin lactophenol for 1 minute and washed in tap water to remove excess stain and then kept in pure lactophenol for overnight for destaining (McBeth et al, 1941) [9] . The roots were then examined under the stereoscopic binocular microscope for number of root galls and egg masses per 5 g of roots. On the basis of these observations, per cent decrease in root galls and egg masses were worked out. Incidence of root-knot nematode was recorded by using the gall index (Gaur et al., 2001) [4] which is as follows.

Effect of various treatments on root galls, egg mass per 5 g root and Root-knot Index

The most effective treatment was T 5 (in-situ mulching of sunhemp at 2kg/m² combined with Pochonia chlamydosporia enriched FYM 100g/m² at planting and 3 MAP), which recorded the lowest nematode infestation levels. This treatment recorded 4.33 egg mass per 5 g roots, 14.67 root galls per 5 g roots, with a root knot index as 3.00, indicating strong suppression of root-knot nematode activity. At par with T 5 , the T 3 (soil solarization using a 25µm transparent polythene sheet for two weeks before planting + P. chlamydosporia enriched FYM at planting and 3 MAP) showed excellent results, reducing egg mass to 6.33 and galls to 16.33 per 5 g roots and the root knot index to 3.00. Moderate suppression was observed in T 2 (soil solarization + neem cake @2kg/m² application), which reduced egg mass to 10.33 and galls to 24.33, with a root knot index of 3.00. T 6 (Fluopyram 34.48% SC at planting) also lowered nematode populations (16.00 egg mass, 25.33 galls, root knot index 4.00), but its efficacy was comparatively less than the integrated organic-biological treatments. T 1 (soil solarization) and T 4 (in-situ mulching of sunhemp + P. chlamydosporia enriched FYM at planting) provided partial control, recording higher egg mass counts, 26.67 and 24.67 respectively and root knot indices of 4.00 In contrast, the untreated control (T 7 ) showed the highest nematode reproduction and damage, with 39.67 egg mass, 58.33 root galls, and a root knot index of 4.00, confirming severe infestation under natural conditions. The integrated approaches outperformed chemical nematicides and singlecomponent treatments, highlighting the importance of biological and cultural practices in reducing nematode reproduction, minimizing root damage, and improving crop health. The results of this study have similarities with the findings of Ravindra et al. (2014) [11] who reported that application of Pochonia chlamydosporia along with P. lilacinus showed significant results in reducing population of the root-knot nematodes. Similar findings were also given by Niranjana et al., (2018) [10] who showed that application of bioagents like neem cake in combination with Pacaelonyces lilacinus performed better in managing the Meloidogyne spp. population in Turmeric. The findings recorded in this study are also on similar lines with Eapen et al. (2008) [3] whose final results showed that Pochonia chlamydosporia greatly suppressed root-knot nematodes.

Conclusion

At the termination of experiment, treatments of in-situ mulching @2kg/m 2 + P. chlamydosporia enriched FYM @100g/m 2 , was found highly useful and potent in reducing population of the root-knot nematode, Meloidogyne incognita by 28.57 per cent and 4.33 root galls per 5g roots and 14.67 egg masses per 5g of roots, respectively. This was at par with T 3 (soil solarization using a 25µm transparent polythene sheet for two weeks before planting + P. chlamydosporia enriched FYM at planting and 3 MAP) reducing egg mass to 6.33 and galls to 16.33 per 5 g roots and the root knot index to 3.00 and T 2 (soil solarization + neem cake @2kg/m² application), which reduced egg mass to 10.33 and galls to 24.33, with a root knot index of 3.00. T 6 (Fluopyram 34.48% SC at planting) which also lowered nematode populations (16.00 egg mass, 25.33 galls, root knot index 4.00).

Acknowledgement

AcknowledgementThe author gratefully acknowledges the Head, department of Entomology and Office in charge, AICRP, on Nematodes in Agriculture, Department of Entomology, Mahatma Phule Krishi Vidyapeeth, Rahuri, Maharashtra, for extending the necessary facilities and constant support throughout the course of experimentation

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