Callus cultures derived from leaf segments of chrysanthemum cultivar 'Snow Ball' which was susceptible to Septoria obesa were successfully used for in vitro selection for resistance to this pathogenic fungus. Resistant cell lines were selected by culturing callus on growth medium containing various concentrations of S. obesa filtrate. Resistant calluses obtained after two cycles (30 d each cycle) of selection were used for plant regeneration. About 30% of the plants regenerated from the resistant calluses and 70-80% of the plants raised from cuttings had acquired considerable resistance against the pathogen in the field. No phenotypic variation was observed in the selected regenerates.

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The present study deals with the impact of temperature on development, survival, reproduction and population growth of a recently invaded and the most destructive pest of tomato, Tuta absoluta (Meyrick) with the aim to understand its possible expansion in different agro-climatic zones. Though T. absoluta was able to develop between 15° and 35°C, temperature around 25°-30°C was more suitable. Survival and fecundity were highest at 25°C and lowest at 35°C. Developmental threshold for different developmental stages of the pest varied from 6.2 to 9.5°C, while the thermal constant required by the insect to complete the development from egg to adult emergence was 500 degree-days. Population growth parameters were also influenced significantly by the rearing temperature. Intrinsic rate of increase, net reproductive rate and finite rate of increase was higher at 25° and 30°C as compared to other temperature regimes. The study concludes that T. absoluta can be a serious pest of tomato in mid-hills of northwestern Himalayan region and the southern plains of India where temperatures varies between 15-35°C. Furthermore, the developmental threshold values indicate that the pest can develop and survive at temperatures as low as 6-9°C without entering the diapause as long as the food is available.

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The persistence pattern and risk assessment of profenofos and triazophos in okra (Abelmoschus esculentus (L.) Moench) and cropped soil were studied in the present study. The insecticides were applied twice at 10 days interval @ 500 and 1000 g a.i./ha. Residues were quantified at 0, 1, 3, 5, 7, 10, 15 and 20 days of second application using GC equipped with Flame Photometric Detector (FPD). The average initial deposits of triazophos (1.838 mg/kg) in okra fruits were higher than profenofos (1.418 mg/kg) at the recommended application rates. Both the insecticides followed a first order kinetics with half-lives of 1.6 and 1.4 days, respectively on okra fruits. The initial deposits of 0.483 and 0.500 mg/kg, for respective insecticides, disappeared to BDL on 5th and 7th day in okra cropped soil. Microwave oven cooking proved more promising than other household processing in dislodging the residues of test insecticides from okra fruits. On the basis of this study, waiting periods of 7.6 and 7.4 days were suggested for consumption of okra sprayed with profenofos and triazophos, respectively.