Assessment of flubendiamide residues in pigeon pea in different agro-climatic zones of India.

Supervised field trials were conducted at the research farms of four agricultural universities located at different agro-climatic zones of India to find out the harvest time residues of flubendiamide and its des-iodo metabolite on pigeon pea (Cajanus cajan) during the year 2006-2007. Two spray applications of flubendiamide 20 WDG at 50 g (T(1)) and 100 g (T(2)) a.i./ha were given to the crop at 15-days interval. The foliage samples at different time intervals were drawn at only one location, however, the harvest time samples of pigeon pea grain, shell, and straw were drawn at all the four locations. The residues were estimated by HPLC coupled with UV-VIS variable detector. No residues of flubendiamide and its des-iodo metabolite were found at harvest of the crop at or above the LOQ level of 0.05 µg/g. On the basis of the data generated, a pre-harvest interval (PHI) of 28 days has been recommended and the flubendiamide 20 WDG has been registered for use on pigeon pea by Central Insecticide Board and Registration Committee, Ministry of Agriculture, Government of India and the MRL has been fixed by Ministry of Health and Family Welfare, Government of India under Prevention of Food and Adulteration as 0.05 µg/g on pigeon pea grains.

Degradation of atrazine by an acclimatized soil fungal isolate.

A fungal strain able to use atrazine (2-chloro-4-ethylamino-5-isopropylamino-1,3,5-triazine) as a source of nitrogen was isolated from a corn field soil that has been previously treated with the herbicide. This strain was purified and acclimatized to atrazine at a higher level in the laboratory. A supplemented N was required to trigger the reaction. Atrazine was degraded at a faster rate in inoculated mineral salt medium (MSM) than non-inoculated MSM. Within 20 days, nearly 34% of the atrazine was degraded in inoculated medium while only 2% of the herbicide was degraded in non-inoculated medium. Degradation of atrazine by the isolated fungal strain was also studied in sterile and non-sterile soil to determine the compatibility of the isolated strain with native microorganisms in soil. The degradation of atrazine was found to be more in inoculated sterile soil than in inoculated non-sterile soil. Cell free extract (CFE) of fungal mycelium degraded about 50% of the atrazine in buffer in 96 hours compared to the control. Four atrazine metabolites were isolated and characterized by LCMS. On the basis of morphological parameters the isolate was identified as Penicillium species. Results indicated that the microorganism may be useful for remediation of atrazine-contaminated soil.