Two Million Acres Of Nassella In New South Wales

Press, Volume CI, Issue 29832, 26 May 1962, Page 7

Two Million Acres Of Nassella In New South Wales

Most of Australia’s nasseila tussock, or serrated or Yass tussock as it is known there, is in New South Wales. The area in the State, which is infested to varying degrees, has been estimated at about two million acres with some 750,000 to one million acres of this on the central tablelands.

In the Oberon, Black Springs. Rockley, and Mount David districts, on the central tablelands, whole hillsides are at present pockmarked with a sea of yellow tussocks. One farm in this locality is considered to have perhaps the highest proportion of nassella of any farm in the Commonwealth. Of 1418 acres it has some 1024 acres of ‘■pure tussock,” 272 acres with “tussocks all through it,” and 122 acres of “scattered tussock.” The tussock has been known in the district for some 30 years and for 20 years some farmers have recognised it as a serious weed and have been grubbing it. While the incidence of the tussock varies markedly from farm to farm in relation to the energy that landholders have displayed in dealing with it, and some have been successful in keeping their properties free of tussock by eternal vigilance, the tendency has been for the tussock to be constantly turning up in new places. At present, and it seems likely that for some time to come, nasseila tussock control in New South Wales will remain very much a personal responsibility. A little Government aid is being given to the Upper Macquarie County Council, which has been set up in the area to grapple with the tussock, but as the individual farmer has almost always to foot the bill the research effort on the control of the tussock has been directed to methods that are most economical. Mr Malcolm Campbell, research agronomist at the New South Wales Department of Agriculture’s experiment farm at Bathurst, has been studying the tussock since 1958. Ploughable On ploughable country, of which there is a great deal in the infested area. Mr Campbell says that the recommendation is ploughing followed by sowing of a mixture of 11b of perennial ryegrass, 21b of phalaris, 31b of subterranean clover, 11b of white clover, and 21b of red clover about early April, with at least 2cwt and up to 4cwt of superphosphate. The most essential feature of the treatment is the subsequent spelling of the new pasture for a year to enable it to shoot away in the spring and by shading eliminate an estimated 95 to 99 per sent of the seedling tussocks, of which up to 250 have been measured to the square yard. It is then a case of mopping up the adult tussocks that were missed in the initial ploughing, perhaps because they were on a fence line or by a rocky outcrop, and here spot spraying may have a place. Farmers have, however, proved loath to leave the improved pasture for the vital year’s spell and frequently expense and effort has been wasted by premature grazing with the new pasture being bared down and the tussock infestation returning to normal in two years. In one trial where the recommended procedure was followed and grubbing of odd tussocks was carried out, the area was clear of tussock in five years, whereas a pretna-

turely grazed area was back to where it started off. In such a set of circumstances, Mr Campbell calculated that the area receiving the former treatment would return £5 an acre a year, including the year' it was spelled, compared with only £2 an acre for the area that was mismanaged. He asserts that the return from heavily infested tussock country is so small that farmers have little to lose in spelling for a year with much to gain in maintaining an improved pasture. As in New Zealand tussock is not so easily controlled on non-ploughable country, but on semi-ploughable terrain with a chisel plough forming a fairly rough sort of seed bed with 14 tussocks still being left to the square yard, three years after sowing with periodic spelling and autumn grazing tussock numbers were down to four to the square yard with the country then capable of carrying two sheep to the acre without further tussock encroachment. Rabbits On the more difficult country Mr Campbell regards checking of rabbits as an essential prerequisite of action. Then it is a case of oversowing from the air 41b of subterranean clover and ‘alb of white clover, with 2cwt of super, followed by annual dressings of lewt. A three or four-year spell is then allowed for the clovers to build up among the tussock and under favourable conditions possibly eliminate some of the tussocks. The stage is then set to eliminate the tussock using a light weight of chemical. Mr Campbell has secured kills of tussock with as low as 2*£lb of dalapon followed by burning a month to two months later. The clover then remains to take the place of the tussock and the final step would be the aerial oversowing of grasses with the fertility built up. The point about chemicals is that while they are known to kill tussocks it is unlikely that farmers will look very favourably on large-scale applications of even 51b of dalapon costing £2 10s an acre and for that reason the combination of a light application of chemical and burning with a satisfactory kill looks more attractive to Australian research workers seeking the most economical method of control.

Mr Campbell has just completed the first large scale chemical oversowing trials in

Australia on an area of 135 to 140 acres. In this trial rates of chemical up to 251 b are being tested, low and high flying and rates of application in water from four to 20 gallons to the acre are being compared, and after spraying oversowing will be done into the dead tussock and into burnt tussock. One of the fundamental reasons for failure of oversowing on unploughable country, according to Mr Campbell, is failure to eliminate the rabbit. He was able to show an area which had been sprayed after burning with pelleted TCA and subsequently oversown with red, white and subterranean clover. Clover Where it had been fenced from rabbits there was a good mat of clover in spite of six weeks of dry conditions and tussocks were few in number but over the fence where the treatment was identical clovers could only be found by searching amongst a fairly thick mat of tussock. The department has established throughout the area some 22 demonstration areas to show farmers how nasseila may be tackled. On one of these areas at Mount David now six years old where red. white and subterranean Cleveland phalaris were introduced after ploughing there is now a fine stand of phalaris with a good covering of clover at its foot and only a few tussocks. This has been carefully managed but has been carrying three sheep to the acre.

Phalaris is particularly well thought of as a pasture species to provide competition for nasseila. One farmer In the Oberon area said this week that he had not once seen a tussock in a sward of phalaris on his property in the last 20 years. A ' particularly striking example of what can be done against nasseila is to be seen at Mount David where a Bathurst businessman has recently taken up a holding of some 1800 acres. Last March after clearing of timber with seven bulldozers some 600 acres was ploughed and sowed to the recommended mixture with 3cwt of superphosphate. Last month it was knee deep in red clover with fine Hereford cattle helping to make a picture-book scene against a background of yellow nassella-covered hills.

Mr Campbell looks forward to the day when special advisory officers may be available to help plan the attack on the tussock on individual farms on a farm scale gradually building up the areas of improved pastures.