Abstract:All the root inhabiting migratory endoparasitic nematode populations of Radopholus procured from banana crop of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis. Heat killed females were straight to slightly ventrally curved posteriorly. Female's head was low, rounded, continuous or slightly setoff with the body contour.Females were 500-660 µm long and were comparatively longer than males. Males had button shaped head set off by a constriction; female with three to five lip annuli, four crenate and areolated lateral incisures, stylet 14-18 µm long with rounded knobs, vulva postequatorial (58%), sometimes with slight protuberant lips, ovary paired and equally developed, oesophageal gland overlapped the intestine dorsally, tail elongate-conoid with narrowly rounded terminus. The stylet length (µm), width of stylet knob (µm), distance of excretory pore from anterior end (µm), distance from head to basal bulb (µm), lateral field structure, shape of stylet knob, head region, position of phasmid, tail shape with its terminus, morphometric values like m%, o% and v% and a, c and c´ ratios of females were stable (CV<12%) features. There is an existence of intra-specific variability in the morphological and morphometric features of R. similis. The main morphological diversity was observed with P% of male and female, b ratio of female and stylet length, distance of DEGO from stylet base, o% and T% of male. All the root inhabiting migratory endoparasitic nematode populations of Radopholus Thorne, 1949 procured from banana of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis (Cobb, 1893) Thorne, 1949. A high degree of intra-specific morphometric variability was observed with regard to the total body length (µm), body width (µm), stylet length (µm), distance of dosrsal oesophageal gland orifice (DEGO) from stylet base (µm), number of lip annuli, lip height (µm), distance from head to basal bulb (µm), distance of anus from anterior end (µm), tail length (µm), anal body width (µm), distance of phasmid from tail terminus (µm), number of lateral lines, width of lateral field (µm), b ratio and P % among females of R. similis. Morphometric features like m%, o% and v% of females of R. similis showed least variability. These can be considered as the stable morphometric characters for discrimination of females of R. similis. Ratios like 'a' and 'c' of females of R. similis were found moderately variable. The morphometric feature and of male i.e. distance from head to basal bulb (µm) was found least variable; while number of lip annuli and spicule length (µm) were moderately variable.
An investigation was conducted for the management of root knot nematode Meloidogyne incognita (Kofoid and White) Chitwood infesting tomato through the application of bio-control agent like Bacillus subtilis, Trichoderma harzianum and Pseudomonas fluorescens. Experiment result revealed that minimum no. of galls/25seedlings (17.50) and maximum seedling height (27.6cm) were observed in Bacillus subtilis @50g/m2 in nursery bed + B. subtilis @ 5kg along with 2.5 tons of FYM/ ha. The highest weight/25seedlings (69.50g) was noticed in the B. subtilis @50g/m2 in nursery bed + B. subtilis 2.5kg along with 2.5 tons of FYM/ha. The highest growth of the plant at 45 DAT (49.2cm) and at harvest (81.2cm) and maximum fresh (711.3g) and dry weight (265g) was found in B. subtilis @50g/m2 in nursery bed + B. subtilis 2.5kg along with 2.5 tons of FYM/ha. B. subtilis @50g/m2 in nursery bed + B. subtilis 2.5kg along with 2.5 tons of FYM/ha exhibited lowest gall index (1.2/plant) and highest reduction of nematode population and provided highest yield of tomato fruits (335.75q/ha).
A field study was conducted to evaluate the relative bio-efficacy of bifenthrin 8 SC @60g, 80g, 100g, 120g, 140g a.i./ha against shoot and fruit borer and red spider mite of okra, Abelmoschus esculentus (L.) Moench cv. OH -152 at the Central Research Farm of BCKV, Nadia, West Bengal, for two consecutive seasons. Cypermethrin 10 EC @70g a.i./ha and dicofol 18.5 EC @500g a.i./ha were used as standard treated check in the experiment. Population of beneficial insects like spider, predatory mites and Braconid parasitoid were also recorded during the time of observation on pests' infestation. Among treatments, bifenthrin 8 SC @ 100 to 140g a.i./ha was found significantly (p≤0.05) superior over treated check cypermethrin 10 EC @ 70g a.i./ha and dicofol 18.5 EC @ 500g a.i./ha to bring down Earias vittella and red spider mite (Tetranychus urticae) population, respectively, on okra. Bifenthrin 8 SC @ 140g a.i./ha recorded maximum fruit yield (82.3 q/ha during kharif 2012 and 53.1q/ha during rabi 2012-13) of okra. Also, foliar application of bifenthrin 8 SC did not reveal any significant (p≤0.05) adverse effect on population of spider, predatory mite and Braconid parasitoid in okra crop ecosystem. These findings will facilitate the selection of bifenthrin 8 SC as an effective acaro-insecticides for effective control of shoot and fruit borer and red spider mite of okra.
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