Nematology Laboratory

The Nematology Laboratory 

• Conducts co-ordinated investigations on important plant parasitic nematodes.
• Identifies the nematode fauna with particular reference to economically important crops and to record to their frequency of occurrence and develop State wise distribution maps of nematodes.
• Validates and documents crop losses at varying nematode densities.
• Determines damage thresholds of economically important nematodes, population dynamics and nature of host parasite relationship.
• Evaluates the germplasm collections for their degree of resistance to nematodes.
• Develops economically viable and feasible methods of integrated nematode management practices.

Random surveys conducted in different crops have yielded valuable information regarding the occurrence and distribution of predominant plant parasitic nematode species associated with economically important crops in Kerala. The major nematode problems identified in the state include, Radopholus similis in pepper, banana and ginger: root –knot nematode in polyhouses, vegetables, cardamom, pepper, ginger and turmeric; Pratylenchus coffeae in banana; Scutellonema bradys in amorphophallus and yams. Fusarium wilt in cowpea due to Reniform nematode and Fusarium  and slow wilt disease in pepper due to R.similis, Meloidogyne incognita and Phytophthora capsici is severe problem in high ranges. In polyhouses also wilt disease severe due to nematode and pathogen. The hot spot areas of the major nematodes in rice, banana, pepper, ginger, turmeric and vegetables are identified and crop wise maps were prepared. The data on hotspot areas of major nematode infestations was published as Nematode Distribution Atlas from Project Coordinating cell.

The data on crop losses due to M. graminicola in rice, nematode complex (root-knot, burrowing and cyst nematodes) in banana, root-knot and reniform nematode in vegetables, root-knot, reniform, lesion and burrowing nematodes in black pepper and cardamom, helped to fix research priorities and to make appropriate nematode management strategies.

Twelve recommendations evolved from the AICRP trials for the management of  plant parasitic nematodes were included in the State level package of practices of Kerala Agricultural University.

As carbofuran and phorate being banned in Kerala, no nematicides are available with label claim.   Two new chemical nematicides (fluopyram and fluensulfone) were found effective against root-knot nematode in salad cucumber.

Two new bacteria, Stenotrophomonas maltophilia strain W2-7 and Bacillus thuringiensis strain a57 antagonistic to root-knot nematode were identified.

Two native  isolates of entomopathogenic nematodes Metarhabditis rainai and Steinernema sp having biocontrol efficacy against termites and pseudostem weevil grubs were identified from Kerala.

Popularization of the technologies are through demonstration trials resulted elevated rate of their adoption by farmers.

Several publications were brought out to address the emerging nematode problems and to generate an awareness amongst farmers regarding nematode infestation in different crops.  Scientists have conducted field visits, nematode awareness campaigns and agroclinics to benefit thousands of farmers.  Numerous refresher courses, empowered by scientists, have been conducted as part of AICRP on nematodes.  

 

Technologies evolved from AICRP trials during last three years include

I. Rice

• Soil solarization of nursery bed with 25µm polythene sheet for 15 days during May/June significantly reduced the nematode population and increased the yield
• Application of neemcake @100g/m2 in active tillering stage in transplanted rice is effective for management of M. graminicola in rice
• Soil application of carbosulfan@ 1kg a.i/ha at 40 days after transplanting reduced             M. graminicola population in rice
• Application of Trichoderma viride (1X108 cfu)/Pseudomonas flourescens@20g/m2 found effective in reducing the population of M.graminicola

II. Banana

• Biofumigation using crop residues of cabbage/cauliflower or green leaf mulching with glyricidia/chromolaena @ 5 kg/pit is found effective.
• Application of neem cake @ 1 kg/plant at the time of planting is effective for reducing nematode population.
• Soil application of carbosulfan @ 1 kg a.i./ha at the time of planting is effective for nematode management.
• Sucker treatment with Bacillus macerans/Purpuerocillium lilacinum @ 5 g/sucker + pit application @ 20 g 45 days after planting or application of P. flourescens @ 20 g/m2 can reduce nematode infestation.
• Paring of suckers followed by hot water treatment at a temperature of 55° C for 20 minutes is an effective treatment for nematode management.
• In heavily nematode infested area, paring banana suckers and dipping in hot water @ 55 °C for 20 minutes and application of neem cake 1 kg/plant (two split doses, first at planting and second at 3 months after planting) or carbosulfan 0.5 g a.i./ha can effectively manage nematodes. 

III. Vegetables

• Biofumigation using crop residues of cabbage and cauliflower @ 2.5 kg/m2 reduce the nematode population and increase yield in okra.
• Crop rotation with sweet potato var. Sree Bhadra, reduced the nematode population and increased yield of bhindi and brinjal crops to a tune of 21-22%.
• Application of saw dust/paddy husk @ 500 g per plant or neem leaves/eupatorium leaves @ 250 g/plant in the basins 3 weeks prior to planting and watering daily was effective for managing root-knot nematode in okra. Application of neem cake found to be effective in managing root-knot nematode in bitter gourd.
• Soil solarization in nursery using 150 gauge LDPE film for 15-20 days reduced nematode population in tomato and brinjal.
• Trichoderma harzhianum  and P. lilacinum are found as effective biocontrol agents for the management of nematodes in vegetables. The following treatments are standardized for the management of nematodes in Kerala. 
  • Okra:
    • Seed treatment with T. harzianum @ 20 g/kg of seed + main field application of T. harzianum @ 2.5 kg along with 2.5 tons of FYM/ha.
    • Seed treatment with P. lilacinum @ 20 g/kg (cfu 2x106) seed in combination with mainfield application application of P. lilacinum @ 2.5 kg along with 2.5 tons of FYM/ha prior to sowing
    • Seed treatment with P. lilacinum @ 5 ml/kg followed by soil application of vermicompost @ 2.5 ton/ha enriched with P. lilacinum @ 10 ml/kg reduced nematode population in okra
  • Brinjal:
    • ​Application of P. lilacinum (cfu 2x106) @ 50 g/m2 in nursery bed + main field application of  P. lilacinum(cfu 2x106) @ 5 kg along with 2.5 tons of farm yard manure/ha prior to transplanting for the management of root-knot nematode in brinjal. 
  • Bittergourd: 
    • Application of P. lilacinum (cfu 2x106) @ 2.5 kg along with 2.5 tons of FYM/ha + P. fluorescens (cfu 2x106) @ 2.5 kg along with 2.5 tons of FYM/ha reduced nematode population and increased yield in bittergourd.
  • Integrated Management: 
    • Integrated nematode management strategies involving seed or nursery treatment, deep ploughing and application of granular insecticide in the main field were evolved for the control of nematode pests of okra and brinjal. The combined effect of nursery treatment + cultural practices and spot application of bio agents can be recommended for transplanted vegetable crops. Integrated management of root knot nematode in tomato by solarisation and addition of botanical materials revealed that under solarized condition the germination percentage was uniform and highest (97-100%). There was drastic improvement in the vigour (weight) of seedlings and yield.
  • Polyhouse grown salad cucumber:
    • ​Oil application of neem cake @ 200 g/m2 three weeks prior to sowing + soil application of P. lilacinum  @ 50 g/m2 at sowing reduced soil nematode population and increased the yield of salad cucumber under polyhouse condition.

IV. Pepper

• Use nematode-free rooted cuttings for raising new plantations.(Artocarpus heterophyllus)
• Addition of chopped leaves of Glyricidia maculata (10 g/kg soil) as mulch around the rhizosphere, application of neem seed cake @ 200 g/vine was found effective. 
  • Carbosulfan 6G @1 kg a.i/ha was found to be superior treatment in reducing the population of nematodes in 200 cc soil and 5 g roots followed by cartap hydrochloride 4G @1 kg a.i/ha.
  • Apply talc based formation of P. fluorescens (1.2x108 cfu/g) @ 20 g/plant at the time of planting of vines or just before the monsoon period in established plantations were effective.

V. Cardamom

• Proper weeding schedule should be followed, since many of weeds are good host of nematodes.
  • Application of neem cake @ 300-500 g/plant. Application of Tithonia diversifolia (Wild sun flower) leaves as mulch @ 5 kg /plant around the vines reduced nematode population and increased the yield of cardamom.
  • Carbosulfan 6G @1 kg/ha was found to be superior treatment in reducing the population of nematodes in 200 cc soil and 5 g roots followed by cartap hydrochloride 4G @ 1 kg/ha.