Abstract:
There has been increasing reports on health hazards in human beings from
the unscientific and intensive use of pesticides in crops, especially vegetables. It
was in this backdrop, a scientific investigation was designed to evolve safer and
eco-friendly methods in pesticide use to control the major pests of the popular
leafy vegetable amaranths. Field experiments were conducted at the college of
Horticulture, Vellanikkara during 2000-2001 to identify the safer, eco-friendly
insecticides. For the first experiment, thirteen different commercial formulations
of neem, microbial and chemical pesticides were evaluated for the control of
amaranths leaf webbers viz., H. recurvalis, P. basalis, weevil H. truncatulus and
grasshopper A. crenulata. The best six effective components were further screened
at lower doses, so as to identify the most promising one in the second experiment.
The effect of the tested components on the natural enemies and other bio control
agents were also studied.. Organoleptic quality evaluation of cooked amaranths
leaves was done to know, whether the applied insecticides have any effect on the
taste, appearance, colour, flavour, texture and bitterness.
Of the insecticides tested in the first experiment, Econeem, N eem Azal,
Halt, Dipel, Delfin and Nuvan were the most effective in controlling the pest
population. The results of the second experiment indicated that the plots treated
with Dipel @ 0.7 ml r' gave better control of both the leaf webbers. Halt @ 0.7
g r' gave comparably good results for the control of weevil. All the microbial
insecticides tested were found ineffective to grasshopper. No disease symptom or
deformities were observed in any of the natural enemies and other bio control
agents. In the field, though Nuvan was found to control the pests, it was not
effective in the long run. All the microbial products were found to protect the crop
for a longer period of time. The crop sprayed with Delfin @ O.7g r' gave an yield
of 5481 kg green leaves per acre compared to untreated control (2963 kg).
Organoleptic quality evaluation of cooked amaranths leaves revealed that, there
was no significant difference in qualities of cooked amaranths due to treatments
compared to untreated control.
