H. Brewerton, H. Mcgrath, G. S. Grandison
Feb 1, 1969
Citations
0
Influential Citations
0
Citations
Journal
New Zealand Journal of Agricultural Research
Abstract
Abstract Foliar spray trials of thionazin (Cynem; Nemaphos; Zinophos; O,O-diethyl 0-2- pyrazinyl phosphorothioate) on lucerne (Medicago sativa L.) and red clover (Trifolium pratense L.) at various treatment rates are described. No control of the stem and bulb eelworm Ditylenchus dipsaci (Kuhn) was achieved. Phytotoxicity on lucerne was noted. A method of thionazin residues analysis was devised in which the parent compound and its only known toxic metabolite, the oxygen analogue “thionazinoxon”, are separated and analysed by gas chromatographyand cholinesterase inhibition respectively. The method was sensitive to 0.02 p.p.m. of thionazin and 0.01 p.p.m. of its oxygen analogue metabolite in both lucerne and red clover extracts, calculated on the wet weight of the plants. Thionazin residues were high initially, but declined to less than 1 p.p.m. within 7 days in lucerne in late spring and within 16 days in red clover in late autumn for all the treatments tried.