SUCCESSFUL CONTROL OF NASSELLA

Press, Volume XCVIII, Issue 28938, 4 July 1959, Page 8

SUCCESSFUL CONTROL OF NASSELLA

Encouraging Results On Marlborough Farm

To North Canterbury farmers whose properties are infested with nassella tussock the control of the weed achieved by the Marlborough Nassella Tussock Board on its Wrekin property and on adjoining farms must be some encouragement to them in their efforts.

In the opinion of the instructor in agriculture at Blenheim, Mr J. P. Beggs, and the chief inspector of the Marlborough board, Mr Bruce Jackson, the nassella there has been controlled in its nucleus area and zones of high-infestation and ordinary farming practice can be resumed while seedling regrowth is eliminated.

An article in the June issue of the Journal of Agriculture by Mr Beggs and Mr W. F. Leonard, weeds research officer of the Department of Agriculture in Christchurch, says that the notable victory achieved in the control of nassella in Marlborough demonstrates the importance of

accompanying the use of modern weedicides with pasture improvement and the rapid progress that is made when practical application follows closely on research work in the field. A recent visit to The Wrekin, a property which was taken over by the Government and vested in the Marlborough board, was an encouraging sight. Oversowing after chemical treatment has replaced the 400 to 500 acres of dense nassella, which over-ran the former rough danthonia sward, with introduced grasses and clovers. Admittedly, the cover on the most recently treated block is not complete because of the severe drought since the oversowing; but spring growth will close these patches up. Seedling regrowth of nassella is being controlled by twice-yearly grubbing and experiments on seedling control in the established pasture by light applications of chemicals are promising and so far indicate an economic proposition.

Normal Farming The Marlborough board has now reached the stage where it is considering the resumption of normal farming on The Wrekin. The cost of achieving this has not been small but the country has been improved to a new and much higher level and the money paid by other landowners in Marlborough has been good insur* ance for their own protection.

In the early stages of the board it was found that while sheep would not survive on dense nassella, cattle could be used for seed control, but the heavy grazing tended to lead to complete dominance of the nassella over the useful species between the tussocks. The same fault was found with burning when used for seed control.

Extensive research work showed the necessity for the application of chemical weedicides at definite times of the year and for immediate replacement of the killed nassella by oversowing and topdressing. In Marlborough the chemical T.C.A. has been used in preference to dalapon, the one most widely used by the North Canterbury board. T.C.A. was used on the Wrekin as it had shown the most promising results in the early experiments carried out on the property Dalapon, a more recently developed weedicide, has the advantage of lighter application rate! per acre.

September spraying of 251 b per acre of T.C.A. for seed control, followed by spraying for a kill with 751 b per acre at the end of January and oversowing and topdressing with grass and clover in the following April, is now considered by the authors of the article as the optimum with T.C.A. The price of the sequence of work is about £2O an acre. On the most recently treated block of 225. acres the early October spraying was made for seed control but a large amount of seed appeared to have been subsequently set. Rather than risk this seed going on to the ground before the spraying for a kill in January, the board decided to burn off the tussock.

However, Mr Beggs said during the visit that he felt the same success would have been achieved with the second- spraying, and that the killed tussock would have given protection to the young grasses and clovers coming away during the drought period

and a better cover would have been achieved.

Not all the densely infested area was treated in this way. The bottom fenceline was extended to include all the land which could be cultivated and temporary pastures were sown in this area. Although these were expected to only last a few years before .regrowth of the tussock again dominated, it was found the improved and vigorous clover held the nassella in check. On the flats lower, which had been depleted in fertility by intensive cropping, the new cover and the spelling they have received have shown that the tussock could be retarded and controlled by strict policing and grubbing. Mr Jackson has marked out a large number of randomly selected plots over the hillsides to tabulate the amount of regrowth in the new pastures and from these he hopes to be able to establish the point of economic balance whether spraying or grubbing is to be employed.

With these, and the experimental plots where different rates of chemicals for regrowth control are being tried, the future of farming with nassella on an economic basis is hopad to be determined. /

Adjoining properties and other farms in the board’s area are being closely attended to by the board, which has a target of ranging and grubbing—where necessary by the gangs—twice a year. This has practically been achieved. Of the cost of grubbing—about 7s an hour—half is met by the board.

According to Mr Jackson, there is not a great problem in obtaining men for the grubbing gangs as transport is provided from Blenheim itself and a good type of man is available.

A lot of work has still to be done in Marlborough before

the board and the farmers, whose co-operation has contributed in no small way to the success so far, can rest on their laurels, but their achievement may well point to the ultimate eradication of the weed.