MSc

An investigation entitled „Nematode association in cabbage, Brassica
oleracea L. var. capitata and its management using botanicals‟ was carried out at
College of Agriculture, Vellayani during 2012-2014 with an objective to study the
nematode fauna in rhizosphere of cabbage and to evolve an eco-friendly
management strategy using plant products.
A survey was conducted in major cabbage growing tracts of the state viz.,
Idukki, Kollam and Thiruvananthapuram districts. Result of the survey revealed
the presence of Meloidogyne incognita (Kofoid & White) Chitwood.,
Rotylenchulus reniformis Linford and Oliveira, Helicotylenchus sp.,
Tylenchorhynchus sp., Radopholus similis (Cobb) Thorne and Xiphinema sp. The
population of M. incognita ranged from 0-118, 0-247, 0-310 and 0-262 per 200 g
soil in Vattavada (Idukki district), Kanthalloor (Idukki district), Kollam and
Thiruvananthapuram respectively. The average and frequency of occurrence of
M. incognita in these areas ranged from 29 to 104 and 38.5 to 61.5 respectively.
The population of Helicotylenchus sp. ranged from 0-752 and was the dominant
nematode in cabbage growing areas surveyed. The population of R. reniformis
ranged from 0-374 with an average of 94 and frequency of occurrence of 67.3 in
these areas. In the case of Tylenchorhynchus sp. the population ranged from 0-238
per 200 g soil with an average of 45 and frequency of occurrence of 48.73 in the
above four areas. Xiphinema sp. and R. similis was observed in soil samples
collected from Kollam and Thiruvananthapuram districts respectively.
Community analysis of nematodes was also done.
Aqueous leaf extracts of Tithonia diversifolia (Hemsl.) Gray, Lantana
camara L., Eichhornia crassipes (Mart.) Solms and root extract of Chromolaena
odorata L. were screened for ovicidal and larvicidal effect against M. incognita
under in vitro condition. T. diversifolia 100 % recorded minimum egg hatching
(1 to 1.5 %) three to eight days after treatment.
The bio efficacy of fresh leaf extracts of T. diversifolia, L. camara,
E. crassipes and C. odorata on mortality of M. incognita juveniles revealed that
T.diversifolia 100, 50, 33.3 and 25 % were effective in increasing the mortality of
M. incognita juveniles at 24, 48 and 72 hours after treatment (63 to 100 %).
C. odorata 50 and 100% also showed significant superiority over other treatments
giving a mortality of 56 to 98 % at 48 and 72 hours after treatment.
Pot culture study was conducted to find out efficacy of different
preparations of T. diversifolia and appropriate method of application.
T. diversifolia dried powder @100 and 50 g(kg soil)-1 were effective in
decreasing the nematode population in soil and root (98 to 99 %) and improving
the plant growth (31 to 87 %).
Results of field study revealed that highest reduction of nematode
population in soil was observed in thiamethoxam followed by Paecilomyces
lilacinus (Thom)Samson enriched neem cake and nematode population in these
treatments was significantly lower than T. diversifolia dried powder.
T. diversifolia dried powder @ 50 and 100 g plant-1 was statistically on par in
reducing the nematode population (85 % reduction over untreated) in cabbage
rhizosphere.