T. S. Kathpal

Monitoring of Seasonal Vegetables for Pesticide Residues

Market samples (60) of six seasonal vegetables were monitoredduring 1996–1997 to determine the magnitude of pesticidalcontamination. The estimation of insecticide residuesrepresenting four major chemical groups i.e. organochlorine,organophosphorous, synthetic pyrethroid and carbamate, was doneby adopting a multiresidue analytical technique employingGC-ECD and GC-NPD systems with capillary columns. The testedsamples showed 100% contamination with low but measurableamounts of residues. Among the four chemical groups, theorganophosphates were dominant followed by organochlorines,synthetic pyrethroids and carbamates. About 23% of the samplesshowed contamination with organophosphorous compounds abovetheir respective MRL values. More extensive studies coveringdifferent regions of Haryana state are suggested to get a clearidea of the magnitude of vegetable contamination with pesticideresidues.

Magnitude of Pesticidal Contamination in Winter Vegetables from Hisar, Haryana

Monitoring of 80 winter vegetable samples during 1997–1998 for pesticidal contamination was carried out on GC-ECD and GC-NPD systems with capillary columns following multiresidueanalytical technique. The tested samples were found 100%contaminated with low but measurable amounts of pesticideresidues. Among the four major chemical groups, residue levels oforganophosphorous insecticides were highest followed bycarbamates, synthetic pyrethroids and organochlorines. About 32%of the samples showed contamination with organophosphorous andcarbamate insecticides above their respective MRL values. On thebasis of observations made in these studies, it is suggested thatmore extensive monitoring studies covering all vegetable cropsfrom different agro-climatic regions of the state be carried outto know exact level of pesticidal contamination, which may serveas basis for future policy on chemical use.

Dissipation of Systemic Organophosphorous Insecticides in Mustard (Brassica Juncea) Flowers

Cross-pollination in flowers of entomophilous crops by bees is the most effective and cheapest method to maximize cross-fertilization and produce hybrid vigour in crop seeds. It is well known that bees play a leading role in pollination by visiting flowers for nectar and pollen. Mustard is a good forage plant for bees. For effective pest management, pesticides are used on oilseed crops including mustard. Pesticides are generally 179

Toxicity in relation to structure of substituted 2H-1-benzopyran-2-ones against root-knot and seed-gall nematodes

The toxicity of various hydroxy substituted 2H-1-benzopyran-2-ones (la-c, 2 and 3), ester (la-c, 5 and 6) and hydrazide (7a-c, 8 and 9) derivatives of 2H-l-benzopyranyloxyacetic acids and 2H-l-benzopyranyloxyacetylpiperidines (10a-c, 11 and 12) and corresponding morpholines (13a-c, 14 and 15) was determined against second stage juveniles of root-knot nematode (Meloidogyne javanica) and seed-gall nematode (Anguina tritici). Several of the compounds showed appreciable toxicity against both the tested nematodes. The activity results are discussed in relation to structure of the compounds. In general, the free phenolic compound and derived esters exhibited better toxicity.