Herbicides for the selective control of barley grass in irrigated clover pastures

Abstract

Three herbicides, 2,2- DPA (2,2-dichloropropzonzc acid), diquat dibromide (9, l0-dihydro-8a, 10a-dizonia phenanthrene dibromide) and paraqmt di (methyl sulphate) (1,l-dimethl-4,4,-bipryridylium di (methyl sulphate) ) were tested with a view to controlling barley grass (Hordeum leporinum Link) in clover pastures. The tolerance of white clover (Trifolium repens L.) and subterranean clover (T. subterraneum L.) to sodium 2,2-DPA was determined. 2,2-DPA caused severe damage to subterranean clover (resulting in the loss of one season's production) and slight damage to white clover at a rate which controlled the grass-2 lb an acre acid equivalents. Diquat dibromide applied at 2 lb an acre (active cation) in mid winter gave complete control of barley grass in a subterranean clover pasture. Springfields of clover on treated plots were double those of the unseated control. Paraquat di (methyl sulphate) gave satisfactory control of barley, grass at 0.5 lb an acre, as an early post emergence spray, with no increase in subterranean clover yields, At the 1 lb an acre rate barley grass control was complete.