The High Country

Press, Volume XCVII, Issue 28701, 26 September 1958, Page 9 (Supplement)

The High Country

Undoubtedly the weed which is causing greatest worry in the high country today is sweet brier. First reported in Northland by Charles Darwin as early as 1835, brier has since become very widespread and thrives in open, sunny places such as are common on the foothills and high country of the South Island. With the loss of the controlling influence of dense rabbit infestations, the spread of this weed has shown marked acceleration in recent years. Brier is fairly resistant to coverage spraying with the hormone weedkillers available so far. and the most successful

technique evolved to date is the basal application of a concentrated mixture of 245 T ester and diesel oil during the dormant season.

Like most scrub weeds, brier does not compete with a vigorous pasture cover under grazing. In view of the expensive and timeconsuming nature of chemical control, farmers threatened with brier infestation would be wise to endeavour to farm more intensively those parts of their properties likely to be involved. Other high country weeds which attract attention from time to time are manuka, matagouri, mountain tutu 'a'hd St. John’s wort.

limiting pasture vigour such as impeded drainage, poaching of surface when wet or poor initial establishment. There are, however, a number of weeds which do compete with pasture on high fertility land and they 'represent a clear-cut case for the use of selective weedkillers. Buttercups can be removed from pasture and if the new phenoxybutyrics are used, clover damage will be negligible. Californian thistle and young docks can be controlled in the same way. After periods of drought, annual and biennial thistles often invade pastures which, before the dry weather, were able to prevent the establishment of thistles. Once established, the thistles compete quite successfully with pasture and treatment with a hormone weedkiller will probably be needed to restore the balance in favour of the pasture species. Nodding Thistle The spread of nodding thistle on the plains area is causing concern and a number of trials on the control of this weed are in progress. Interim results of Extension Division trials in MidCanterbury indicate that, if used at an early stage of growth, any one of a number of hormone materials will kill nodding thistle

at quite low rates of application. MCPB, one of the phenoxybutyric group already mentioned, is one material successfully used. An additional advantage ih its use is that serious clover damage is avoided.

A weed grass which is assuming increased importance on both flat land and hill country in dry climates is barley grass. It is a weed of high fertility soils and gains entry where soil cover becomes open, particularly on dry, sunny situations such as about stock camps. Where the use of chemicals for the control of barley grass is contemplated, TCA should be the one employed and steps to improve pasture covet after its use should also be taken.