INVESTIGATION OF AN EMULSIFIABLE OIL ADJUVANT AND ITS COMPONENTS ON THE ACTIVITY OF A NEW GRASS HERBICIDE BY FACTORIAL EXPERIMENTATION

The herbicidal activity of a new compound ]-3-hydroxy-6-(4-cyanophenyl )cyclohex-2-ene-1-one] (I), selective to broad-leaf plants, and partia lly selective in some cereal crops was enhanced by an emulsifiable par affinic oil (HVI 60E). In order to determine the amount of HVI 60E to be applied with an emulsifiable concentrate of I (IE) a factorial herb icidal assay involving six concentrations of I and five concentrations of HVI 60E (both sets including zero concentration) was conducted to obtain response surfaces of herbicidal activity. The total selectivity of IE in broad-leaf species remained for all HVI 60E concentrations. The activity against grass weeds, except Poa annua L., increased marke dly with increasing HVI 60E concentration and enhancement of performan ce of IE by HVI 60E in broad-leaf crops could be pursued without fear of crop phytotoxicity. However, the increases in activity against gras s weeds were accompanied by increases in phytotoxicity against cereal crops. The response surfaces of Echinochloa crus-galli (L.) Beauv. and Zea mays L. were coincident and this result terminated further testin g in this outlet. However, the response surfaces of Avena fatua L. and Triticum aestivum L. were reasonably well separated. Further tests in this outlet and in broad-leaf crops are planned around optimum cost-p erformance ratios derived from combinations with cost-response surface s. The results of a further test showed that both components (oil and emulsifier) of HVI 60E were approximately equivalent in adjuvant enhan cement activity and so, on cost grounds, a crop oil (low emulsifier co ntent) would be preferred over a crop oil concentrate (high emulsifier content).